Ricerca sul ruolo dell’agitazione nel processo di desalinizzazione della ceramica
10.6092/issn.1973-9494/6173
Ceramiche da scavo e ceramiche antiche di solito sono sature di sali all’interno della loro struttura porosa. La desalinizzazione è una delle fasi principali per il restauro di materiali porosi storici. Poiché la salinità può causare danni significativi ai manufatti in ceramica, questi devono essere esposti ad un attento processo di desalinizzazione. Siccome le ceramiche sono sensibili all’acqua e potrebbero deteriorarsi o collassare durante di lungo periodo di contatto con essa, un metodo di desalinizzazione alternativa dovrebbe essere identificato per ridurre al minimo il danno potenziale alle ceramiche. Nuovi metodi come l’aumento della temperatura dell’acqua di lavaggio e / o l’impiego di tensioattivi sono stati suggeriti come tecniche alternative per il processo di dissalazione per evitare il lungo periodo di tempo del contatto. In questa attività, l’accelerazione del processo di dissalazione, basato su una formulazione teorica unificata, è stata discussa ed è stato dimostrato il ruolo dell’agitazione per migliorare il tasso di desalinizzazione. Si è constatato infatti che la principale causa della carenza del processo di dissalazione attuale è dovuto ad uno strato di liquido stagnante vicino all’interfaccia dell’oggetto antico e dell’acqua, così chiamato polarizzazione di concentrazione. L’agitazione migliora l’efficienza della desalinizzazione minimizzando lo spessore dello strato di polarizzazione di concentrazione.
application/pdf
1973-9494
6173
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Mohammad Amin Emami
Conservation Science in Cultural Heritage
restoration
Investigation on the Role of Agitation in the Desalination Process of Ceramics
Text.Serial.Journal
https://conservation-science.unibo.it/
15
Articles
2015-12-30
2016-05-30
2015-12-30
2017-09-04
111-132
CSCH
Mohammad Amin Emami
2015/12/30
10.6092/issn.1973-9494/6173
111
University Siegen
1973-9494
restoration
en
132
KOOB, S., NG, W., 2000, The Desalination of Ceramics Using a Semi-Automated Continuous Washing Station, Studies in Conservation, 45, pp. 265-273.
Investigation on the Role of Agitation in the Desalination Process of Ceramics
https://conservation-science.unibo.it/article/download/6173/5941
15
INVESTIGATION ON THE ROLE OF AGITATION IN THE
 DESALINATION PROCESS OF CERAMICS

    Mohammad C. Amiri
    Department of Chemical Engineering,
    Isfahan University of Technology, Isfahan, Iran

    Somayeh Noghani*
    Faculty of conservation, Art University of Isfahan

    Mohammad Amin Emami
    Faculty of Chemistry,
    Department of Building Material Chemistry,
    University Siegen, Germany

    Keywords: ceramics, desalination, restoration


    1. Introduction

    Many of the findings in archaeological sites are ceramic materials. Ancient ceramics
have an important role in helping to understand the past from different points of view,
such as the history of technology, ethnography and cross-cultural generalization, the
environment, and more [1]. Therefore, careful conservation and restoration of these
historical objects should be appreciated.
    The deterioration of ancient porous materials caused by the crystallization of water-
soluble salts is a well-known phenomenon. Salt crystallization is one of the most im-




                                                                                                    CONSERVATION SCIENCE IN CULTURAL HERITAGE
portant factors in the deterioration of ancient ceramics [2] and will almost always cause
some degree of damage, ranging from exfoliation of the glaze to complete disintegra-
tion of the body [3]. Three essential components in this scenario are water, salt and a
host material to be eroded. Important factors are the relative humidity and temperature
of the surrounding environment, and the porosity and permeability of the host mate-
rial. In subflorescence, crystal growth within the pores of the ceramic material causes
cracking and spalling. Efflorescence, on the other hand, accumulates on the ceramic
surface. The negative effects of efflorescence are not as severe as subflorescence [4].
    Two mechanisms for deterioration by salts have been recognized. The first is based
on the assumption that expansion and shrinkage, during hydration and dehydration pro-
cesses, are responsible for the damage. The second is based on a model in which pres-
sure from crystallization causes damage [5]. Desalination is therefore, one of the most
important treatments in the conservation and restoration process of ancient ceramics.
    Desalination is the process of removing soluble salts from a material. One of the
standard treatments consists of immersing the ceramics in a static bath of water and
waiting a period of time for the soluble salts to go into solution with a daily change
method (i.e. waiting 24 hours for the soluble salts to go into solution) and/or equilibrium
method [6].

* Corresponding author: somayeh.noghani@yahoo.com


                                                                                              111
                                                                                                                One disadvantageous aspect of desalination by immersion is that the low-fired ce-
                                                                                                           ramic surface may soften. This can lead to changes in reflectance of the ceramics,
                                                                                                           with possible disintegration and segregation of the original components in mid to late
                                                                                                           desalination, possible biodeterioration [6, 7], and rehydration of clay minerals with re-
                                                                                                           sultant damage, such as the formation of microcracks and cracks due to the expansion
                                                                                                           of minerals [2, 8]. These negative aspects, related to desalination by immersion, are
                                                                                                           furthermore made worse, the longer the contact period is.
M.C. Amiri, S. Noghani, M.A. Emami - Investigation on the role of agitation in the desalination process




                                                                                                                An alternative desalination method should consequently be identified to minimize any
                                                                                                           potential damage to potteries. Jang and colleagues have suggested raising the tempera-
                                                                                                           ture of the water as an alternative desalination process, in order to avoid potential damage
                                                                                                           to potsherds [7]. Although this is a more efficient desalination method and can reduce the
                                                                                                           contact period, it seems that warm water is not safe enough to use. The structure of ancient
                                                                                                           objects may be damaged with water at 50˚C, due to the aggressive action of higher solubil-
                                                                                                           ity. In addition, using this method in situ at excavation sites is not always easy.
                                                                                                                Another suggested method for desalination of porous materials is the use of surfactants
                                                                                                           in water [9, 10]. Surfactants can enhance the desalination process by decreasing the sur-
                                                                                                           face tension of water. However, it seems that more research is necessary to evaluate the
                                                                                                           potential effects of surfactants or surfactant mixtures on desalination processes [9].
                                                                                                                Another suggested method in this field is agitation. There is no systematic detailed study
                                                                                                           on the role of agitation in desalination processes in the relevant scientific literature [3, 7].
                                                                                                                In this study, the importance of agitation in the desalination process has been for-
                                                                                                           mulated theoretically and validated by experimental results.


                                                                                                                2. Theory

                                                                                                               The desalination of excavated ancient ceramics such as potteries, is a mass transfer
                                                                                                           operation. Water, as a solvent, after contacting with entrapped salts in the pores of an an-
                                                                                                           cient object dissolves them as ions. A transport of mass will take place in a fluid mixture
                                                                                                           of two or more species whenever there is a spatial gradient (concentration, pressure or
                                                                                                           electric field) in the proportions of the mixture. In a hydrodynamic system there is also a
                                                                                                           contribution to the species flux due to convection. The flux contributions from diffusion,
                                                                                                           electromigration, and convection can be linearly superposed, giving the Nernst–Planck
                                                                                                               𝑗𝑗! = −𝜈𝜈
                                                                                                           equation      ! 𝑧𝑧! 𝐹𝐹𝜌𝜌! ∇∅
                                                                                                                      (equation          − 𝐷𝐷corresponding
                                                                                                                                     1). The ! ∇𝜌𝜌! + 𝜌𝜌! 𝑢𝑢                                                                                                                  (1)
                                                                                                                                                                    mass transfer flux of i-th species is:

                                                                                                                ν i is the mobility of the species i
                                                                                                                 𝑗𝑗! = −𝜈𝜈! 𝑧𝑧! 𝐹𝐹𝜌𝜌! ∇∅ − 𝐷𝐷! ∇𝜌𝜌! + 𝜌𝜌! 𝑢𝑢                                                                                                                  (1)   (1)

                                                                                                                vzi is is the charge      number
                                                                                                                                            species of
                                                                                                                                                    i the species                                                     i
                                                                                                                 ν ii the   mobility of the
                                                                                                                        is the mobility of the species i
                                                                                                                zi is the charge number of the species i
                                                                                                                F is Faraday’s constant equal to the charge of 1 mole of singly ionized molecules
                                                                                                                Fzis is     the charge
                                                                                                                        Faraday’s           number
                                                                                                                                     constant  equal toofthe
                                                                                                                                                           the species
                                                                                                                                                             charge       i
                                                                                                                                                                     of 1 mole of singly ionized molecules
                                                                                                                      i
                                                                                                                          is density
                                                                                                                rρi iis the   the density     of the ispecies i
                                                                                                                                      of the species
                                                                                                                 F is Faraday’s constant equal to the charge of 1 mole of singly ionized molecules
                                                                                                                 ∇φ , ∇ρi are      arethe
                                                                                                                                        the  electrostatic
                                                                                                                                           electrostatic      potential
                                                                                                                                                         potential        and gradients
                                                                                                                                                                   and density density gradients
                                                                                                                                                                                          respectively respectively
                                                                                                                 ρ         is  the  density   of  the   species    i
                                                                                                                  i
                                                                                                                 D
                                                                                                                 Dii isis the
                                                                                                                           thediffusivity
                                                                                                                               diffusivityof the
                                                                                                                                              of species i
                                                                                                                                                  the species i
                                                                                                                u∇isφthe
                                                                                                                      , ∇average
                                                                                                                          ρi arevelocity
                                                                                                                                 the electrostatic
                                                                                                                                         of liquid                                               potential and density gradients respectively
                                                                                                                u is the average velocity of liquid
                                                                                                     112         D i is the diffusivity of the species i
                                                                                                                Equation (1) is called the Nernst–Planck equation.
                                                                                                                u is the average velocity of liquid
                                                                                                                Nernst–Planck equation can be used both for describing desalination flux and al
   u is the average velocity of liquid

   Equation                     (1) is called the Nernst–Planck equation.
   Nernst–Planck equation can be used both for describing desalination flux and a
   for monitoring of desalination by Electrical conductivity meter.
    The Nernst–Planck equation (equation 1) can be used both for describing the desalina-
     Desalination flux [sub-heading]
tion flux and also for monitoring desalination by means of an electrical conductivity meter.
    Desalination flux
     In ordinary desalination process, the electric field is absent; therefore, t
    In ordinary desalination processes, the electric field is absent; therefore, the cor-
     corresponding
responding              massflux
               mass transfer     transfer    flux of can
                                    of i-th species  i-th be
                                                          species     canfrom
                                                             calculated    be the
                                                                               calculated
                                                                                    modified from the Nern
     Planck equation
Nernst–Planck     equation, that   modifies
                             equation           to the the
                                       (2) by ignoring   equation     (2)ofby
                                                            contribution    theignoring     the contribution
                                                                                electric field
     electric
gradient       field gradient
           in equation (1).      in equation (1).

   𝑗𝑗! = −𝐷𝐷! ∇𝜌𝜌! + 𝜌𝜌! 𝑢𝑢                                                                                                                                                      (2)           (2)

    Equation
    Equation    (2)(2)  is called
                    is called Fick’sFick’s
                                    first lawfirst  law of and
                                               of diffusion  diffusion
                                                                 it showsand   it shows
                                                                           the mass         thedue
                                                                                     transfer   mass transport d
to the
    to concentration
        concentration     gradient.
                             gradient.
    The first term in the right hand side of equation (2) shows the molecular diffusion,
but the second term shows the advectional mass transfer. D i is the diffusivity of the
    The first term in the right hand side of equation (2) shows the molecular diffusion
species i. D i is the molecular diffusion coefficient in a stationary liquid, but in an agi-
    theliquid
tated     second
               it modifies      De , thethe
                       termtoshows         eddyadvectional               De can beDasi high
                                                                mass transfer.
                                                 diffusion coefficient.                    is the
                                                                                                as diffusivity of
orders of magnitude of D i in a well agitated liquid.
    species i. mass
    Advectional      D i istransfer
                             molecular
                                    can bediffusion
                                              enhancedcoefficient
                                                           by inducing in   stationary
                                                                         convection.      liquid but in an agita
                                                                                      Convection
flowliquid
       can beit produced
                 modifiesbytoboth De pressure     gradient and
                                       , eddy diffusion
flow due to the surface tension gradient
                                                                               De effect.
                                                                  surface tension gradient.
                                                              coefficient.
                                               is usually termed the Marangoni
                                                                                    can be The as high as orders
                                                                                           Mineral
saltmagnitude             D i intension
      increases theofsurface      a wellofagitated      liquid. the surface tension of water in
                                             water; therefore,
the pores is greater than the bulk water; this surface tension gradient smoothes the
progress of the water downwards into the pores. The Marangoni effect improves de-
     Advectional mass transfer can be enhanced by inducing convection. Convect
salination.
    flow   can be
    Convection     flowproduced
                         can also beby     both pressure
                                        improved                gradient
                                                     by decreasing          and surface
                                                                      the surface  tension oftension
                                                                                               the     gradient. T
    flow   induces       due   to surface     tension     gradient    is usually   termed
washing water. This is possible either by increasing temperature [7] and/or using sur-        the  Marangoni    effe
    Mineral
factant  agentssalt     increases the surface tension of water; therefore, surface tension
                   [9, 10].
   water into of pores is more than of bulk water and this surface tension gradie




                                                                                                                                                                                                           CONSERVATION SCIENCE IN CULTURAL HERITAGE
   smoothes the progress of water downward the pores. This Marangoni eff
   3. Experimental
   improves        method
              the desalination.
   Three industrial brick samples were chosen with nearly similar weight and volume
    Convection flow can also be improved by decreasing the surface tension of wash
(Table 1). The firing temperature of the samples is about 950- 1000˚C. The presence
    water. This is possible both increasing temperature [7] and/or using surfact
of hematite in the matrix of the samples was detected by Polarizing Microscope (Pol.
    agents
Microscopy, [9,     10]. SA Iran). This finding indicates that the kiln had an oxidation
                 PM-240
atmosphere. The porosity of the samples was calculated with ASTM designation C20
and also helium porosimetry (Helium Porosimeter, POROPERM,3	
       core diameter: 1” and
1.5”,
    	
   core length: 0.75” to 3”, maximum pressure: 10000 psi).
Table 1. Sample characterization
  Sample                                           Weight                   Weight after salt                            Volume                   Porosity                     Water
                          Shape
  Number                                            (g)                      absorption (g)                               (g/ml)                    (%)                     Absorption (%)
      1                    Cone                   115.295                               116.0                            61.969                      52.31                             28.11
      2                 Pyramid                   108.602                              109.14                              58.37                     51.29                             27.57
      3                 Cylinder                   171.87                              172.95                              92.38                     48.67                             26.16


   To investigate the matrix of the samples, thin section petrography was performed


                                                                                                                                                                                                     113
                                                                                                           using polarizing microscopy. It was known that the matrix of the samples is argillifer-
                                                                                                           ous-calcareous (Figure 1). The tempers are quartz and fragments of granitic stones
                                                                                                           with different sizes and shapes (mostly sub-angular); in some cases grog was detect-
                                                                                                           ed. Pyroxenes (augite and diopside), micas (muscovite and biotite) and plagioclases
                                                                                                           were other observed minerals in these matrixes.
M.C. Amiri, S. Noghani, M.A. Emami - Investigation on the role of agitation in the desalination process




                                                                                                           Figure 1. Thin section petrography of samples; a) general argilliferous-calcareous matrix of
                                                                                                           samples with quartz, micas, etc. (sample no. 1), b) oxidation condition evidenced by formation
                                                                                                           of hematite in argil, c) muscovite in the texture of samples, and d) grog in the texture of samples
                                                                                                           (sample no. 3).

                                                                                                              All samples were initially immersed in distilled water before the saturation step to
                                                                                                           remove already existing soluble salts in the structure of the specimens. The required
                                                                                                           soaking time in this stage was found to be about 72 hours. The specimens were then
                                                                                                           dried in an oven at a temperature of (105±5) ˚C until a constant mass was reached
                                                                                                           (about 10 hours). They were then allowed to cool to room temperature and weighted
                                                                                                           to ±0.001 g.
                                                                                                              The saturation process entailed the use of a 3.5% solution of sodium chloride. In
                                                                                                           this step, samples were completely immersed and covered with the NaCl solution to a
                                                                                                           depth of 30 mm above the top of the specimens for 96 hours at (20±1)˚C. There were
                                                                                                           30 mm between each specimen and at least 30 mm between the specimens and the
                                                                                                           sides of the container. To reduce the rate of evaporation, the immersion bath was kept
                                                                                                           covered. After immersion, the samples were removed from the solution and dried in
                                                                                                           ambient temperature for 24 hours and then left in the oven at 50°C for 8 hours.
                                                                                                              Progress of the desalination process was monitored by measuring the electrical
                                                                                                           conductivity of the washing water at certain times. In the international system of units
                                                                                                           (SI) electrical conductivity is expressed in Siemens per centimeter (Siemens which is
                                                                                                           the reciprocal of resistance in ohm).
                                                                                                              The desalination test was done in three stages. In each stage, the dried samples


                                                                                                     114
                  were placed in separate 1000 ml containers (one sample in one container) with 800
                  ml distilled water of 6 µS.cm-1 EC (Electrical Conductivity Meter, inoLab 740, WTW,
                  Germany). All containers were covered to reduce evaporation rate. The washing wa-
                  ters were changed after 72 hours (in the first stage), and after one week (168 h, at the
                  second stage) for each sample. Conductivity of each sample, in the first 72 hours, was
                  examined at 1, 2, 4, 6, 7, 8, 9, 24, 48 and 72 hours. In the second week conductivity
                  of the samples was recorded at 24, 48, 72 and 168 hours. In the final stage EC was
                  measured after 24 and 48 hours.
                     To differentiate the effect of eddy diffusion on mass transfer, EC measurements
                  were done without mixing washing water samples, except for sample no.1 at the sev-
                  enth hour and sample no. 2 at the eighth hour. Sample no. 3, without any mixing, was
                  used as a blank.
                     In the first run of tests, the samples were agitated before the EC reading (except no.
                  3, blank sample). In the second run of tests, after a week, the EC of each sample was
                  measured both before and after agitation of the washing water. The agitation rate was
                  50 rpm (revolutions per minute) for 100 seconds. The EC measurements were done
                  after a minute of agitation stop to obtain a stable EC reading.


                          4. Result and discussion

                    Figure 2 shows the cumulative EC of two samples versus time in the first day.
                  Weight and volume of samples are approximately the same.




                                                                                                                      CONSERVATION SCIENCE IN CULTURAL HERITAGE
(μS.cm-1)
Cumulative conductivity




                  Figure 2. Result of EC measurment for sample no.1 (●), sample no.2 (○), sample no.3 (▼) and
                  distilled water (∆) in the first day.

                                                                                                                115
                                                                                                                               There is a progressive trend of EC versus time, but with a sharp change at the 7th
                                                                                                                            hour for sample no. 1 and at the 8th hour for sample no. 2 where, before each EC meas-
                                                                                                                            urement, the washing water was agitated. Agitation causes eddy diffusion.
                                                                                                                               The effect of eddy diffusion on increasing the conductivity of water was discussed in
                                                                                                                            Section 2, “Theory”. As mentioned, high EC indicates a high rate of salt extraction (EC
                                                                                                                            increases due to the increase in ions in the immersion bath, as a result of salt transfer
                                                                                                                            from object to washing water).
M.C. Amiri, S. Noghani, M.A. Emami - Investigation on the role of agitation in the desalination process




                                                                                                                               Figure 3 shows the cumulative EC of the same samples versus time in the first 72
                                                                                                                            hours. As can be seen, the trend of progressive EC continues after the first day.
                                                                                                          (μS.cm-1)
                                                                                                          Cumulative conductivity




                                                                                                                            Figure 3. Result of EC measurment for sample no.1(●), sample no.2 (○), sample no.3 (▼) and
                                                                                                                            distilled water (∆) in the first 72 hours.

                                                                                                                                The washing water was changed after the first 72 hours and the three samples
                                                                                                                            were immersed in fresh distilled water. In the second week, each EC measurement
                                                                                                                            was read before and after agitating the washing water (Figure 4). It can be observed
                                                                                                                            that agitation has a profound effect on the rate of salt extraction, which is manifested
                                                                                                                            in the EC measurement.
                                                                                                                                The jump in EC value due to agitation can be explained as follows:
                                                                                                                                In the bath method (immersion) desalination, diffusion is the main mechanism for
                                                                                                                            mass transfer [11]. However, diffusion is essentially a slow process that depends on
                                                                                                                            the concentration gradient of salt ions in the pores and washing water.




                                                                                                     116
(μS.cm-1)
Cumulative conductivity




                  Figure 4. Result of EC measurment for sample no.1(●) sample no.2 (○), sample no.3 (▼) and
                  distilled water (∆) in the second week.




                                                                                                                        CONSERVATION SCIENCE IN CULTURAL HERITAGE
                      As a consequence of dissolving entrapped salts in pores, the concentration of sol-
                  utes at the solid and liquid interface tends to be higher than in the bulk of the liquid.
                  This concentration gradient generates a mass transfer flow from the interface into
                  the bulk of the liquid. As this is a pure molecular diffusion and very slow, there is a
                  build-up of salts in the water immediately surrounding the object. The extracted ions
                  concentrate only in a very thin liquid layer near the interface, called the concentration
                  boundary layer (CBL). This phenomenon is called concentration polarization. The most
                  deleterious effect of concentration polarization is the local increase in osmotic pressure
                  due to the increased solute concentration in the CBL. The result is that the solubility
                  rate of salts in the washing water is gradually decreased because of decreasing the ef-
                  fective driving force. This decrease in the rate of desalination can be seen in Figure 5.
                      Figure 5 shows the differential conductivity versus time of a two-stage desalination
                  experiment of the sample. The sample was initially immersed in fresh water and after
                  72 hours the washing water was renewed. The differential conductivity curve, i.e. de-
                  salination rate, shows similar trends in both stages: the desalination rate is initially high
                  and decreases with time due to concentration polarization. The initial desalination rate
                  in the second stage is higher than that at the end of the first stage, because fresh water
                  removes the CBL and eliminates concentration polarization. However, the initial rate of
                  the second stage is lower than the initial rate of the first stage due to partial depletion
                  of salt in the sample’s porous structure.



                                                                                                                  117
M.C. Amiri, S. Noghani, M.A. Emami - Investigation on the role of agitation in the desalination process




                                                                                                           Figure 5. Differential EC (∆EC) vs. time for sample no.1(●) and sample no.2 (○) during two stages
                                                                                                           of desalination.

                                                                                                              The extent of concentration polarization depends on the hydrodynamics and geom-
                                                                                                           etry of the system [12, 13]. Agitation reduces concentration polarization by increasing
                                                                                                           the flow around the object and magnifying convective mass transfer. This high increase
                                                                                                           in mass transfer rate is observed in the EC reading jump.
                                                                                                              The sharp increase in the conductivity reading after every agitation validates the
                                                                                                           potential efficacy of this method for accelerating the desalination process without any
                                                                                                           need to use harmful methods, such as hot washing water.
                                                                                                              Figure 6 shows the conductivity data of all stages. It is a good indication of comple-
                                                                                                           tion of the desalination process in ceramics by aqueous soaking while the salinity of
                                                                                                           the washing water is between 75 to 100 μS.cm -1 as reported by Koob and Ng [14].
                                                                                                           However, conductivity in this work was always less than 100 μS.cm -1 in the final stage.




                                                                                                     118
(μS.cm-1)
Cumulative conductivity




                     Figure 6. Result of EC measurment for sample no.1(●) sample no.2 (○), sample no.3 (▼) and
                     distilled water (∆) in all stages from 24 h in the first week to the 216 h at third week.


                          5. Conclusion




                                                                                                                       CONSERVATION SCIENCE IN CULTURAL HERITAGE
                        One of the main disadvantages of desalination by immersion is the long duration
                     of contact time between the washing water and the ancient ceramics. This study
                     highlighted the influence of concentration polarization on reducing ion extraction with
                     this method (by decreasing the concentration gradient in the water layer closest to
                     the object). The results of the experiments indicate that agitation has a high potential
                     for avoiding long time contact by minimizing concentration polarization. This gain is
                     achieved by decreasing the concentration of ions in the CBL, resulting in a high in-
                     crease in the concentration gradient and rate of salt removal. Therefore agitation, in
                     comparison to other methods for enhancing the efficiency of desalination processes
                     such as raising the temperature of washing water or using surfactants, is a much
                     safer method without any possible harmful side effects.




                                                                                                                 119
                                                                                                                 References

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   Biographical notes

Mohammad C. Amiri is associate Prof. in the Department of Chemical Engineering,
Isfahan University of Technology (B.Sc. in Chemical Engineering, Sharif University of
Technology, Tehran, Iran, 1978; M.Sc. in Chemical Engineering, UMIST, Manchester,
UK, 1986; PhD in Chemical Engineering, UMIST, Manchester, UK, 1989). His research
area covers separation processes, aphron separation, transport phenomena, surface
phenomena, and waste handling. His professional interest and consulting is in the
optimization of water treatment processes.

Somayeh Noghani is a PhD student at the faculty of Conservation and Restoration,
Art University of Isfahan, Iran (B.A. in conservation and restoration of cultural and
historical objects, 2008; and M.A. in conservation and restoration of cultural and histo-
rical objects, 2011, faculty of Conservation and Restoration, Art University of Isfahan,
Iran). Her main research interests are the archaeometrical investigation of ancient
potteries and treatment of salt damage in the field of ceramics.

   Mohammad Amin Emami is a mineralogist and archaeometallurgist (B.Sc. in
Mineralogy, Johannes Gutenberg University of Mainz, 1999; M.Sc. in Mineralogy, Jo-
hannes Gutenberg University of Mainz, Germany, 2002; PhD in Mineralogy & Archaeo-
metallurgy, University Siegen, faculty of Building Material Chemistry, Siegen, Germany,
2008). He is Assistant Prof. at the Art University of Isfahan, faculty of Conservation. His
expertise is mainly related to Crystallographical and phase characterization through
the Rietveld Refining Method, Characterization of ancient ceramic structures and pro-
cedures, mineralogical chemical investigation of ore, slag and building materials, Sur-
face Modification Technology, and Archaeometallurgy & Archaeometry.




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