Continuous dialysis of selected salts of sulphuric acid Helena Bendova, Pavel Šnejdrla and Zden k Palaty
Abstract; Full Text (606K) .	pages 171-179.	DOI: 10.12989/mwt.2010.1.3.171

Abstract
The transport of selected salts of sulphuric acid (cobalt, copper, iron(II), manganese, nickel and zinc sulphate) through an anion-exchange membrane Neosepta-AFN was investigated in a countercurrent continuous dialyzer at various salt concentrations and volumetric liquid flow rates. The basic transport characteristics − the rejection coefficient of salt and the permeability of the membrane − were calculated from measurements at steady state. The salt concentration in model mixtures was changed in the limits from 0.1 to 1.0 kmol m−3 and the volumetric liquid flow rate of the inlet streams was in the limits from 8

Key Words
diffusion dialysis; anion-exchange membrane; continuous dialyzer; salt of sulphuric acid; permeability of membrane.

Address
Institute of Environmental and Chemical Engineering, Faculty of Chemical Technology,
University of Pardubice, Studentska 573, 532 10 Pardubice, Czech Republic

Prediction of retention of uncharged solutes in nanofiltration by means of molecular descriptors Alicja Nowaczyk, Jacek Nowaczyk and Stanis aw Koter
Abstract; Full Text (795K) .	pages 181-192.	DOI: 10.12989/mwt.2010.1.3.181

Abstract
A linear quantitative structure-property relationship (QSPR) model is presented for the prediction of rejection in permeation through membrane. The model was produced by using the multiple linear regression (MLR) technique on the database consisting of retention data of 25 pesticides in 4 different membrane separation experiments. Among the 3224 different physicochemical, topological and structural descriptors that were considered as inputs to the model only 50 were selected using several criteria of elimination. The physical meaning of chosen descriptor is discussed in detail. The accuracy of the proposed MLR models is illustrated using the following evaluation techniques: leave-one-out cross validation procedure, leave-many-out cross validation procedure and Y-randomization.

Key Words
nanofiltration; retention; pesticides; QSPR analysis.

Address
Department of Organic Chemistry, Faculty of Pharmacy, Collegium Medicum in Bydgoszcz,
Nicolaus Copernicus University, 9 Sklodowskiej-Curie St., 85-094 Bydgoszcz, Poland
Faculty of Chemistry, Nicolaus Copernicus University, 7 Gagarin St., 87-100 Torun, Poland

PVDF-TiO2 coated microfiltration membranes: preparation and characterization H.K. Shon, S. Puntsho, S. Vigneswaran, J. Kandasamy, J.B. Kim, H.J. Park and I.S. Kim
Abstract; Full Text (8518K) .	pages 193-206.	DOI: 10.12989/mwt.2010.1.3.193

Abstract
Organic fouling and biofouling pose a significant challenge to the membrane filtration process. Photocatalysis-membrane hybrid system is a novel idea for reducing these membranes fouling however, when TiO2 photocatalyst nanoparticles are used in suspension, catalyst recovery is not only imposes an extra step on the process but also significantly contributes to increased membrane resistance and reduced permeate flux. In this study, TiO2 photocatalyst has been immobilized by coating on the microfiltration (MF) membrane surface to minimize organic and microbial fouling. Nano-sized TiO2 was first synthesized by a sol-gel method. The synthesized TiO2 was coated on a Poly Vinyl Difluoride (PVDF) membrane (MF) surface using spray coating and dip coating techniques to obtain hybrid functional composite membrane. The characteristics of the synthesized photocatalyst and a functional composite membrane were studied using numerous instruments in terms of physical, chemical and electrical properties. In comparison to the clean PVDF membrane, the TiO2 coated MF membrane was found more effective in removing methylene blue (20%) and E-coli (99%).

Key Words
TiO2 photocatalyst; photocatalysis; microfiltration (MF); organic fouling; biofouling.

Address
School of Civil and Environmental Engineering, University of Technology,
Sydney (UTS), P.O. Box 123, Broadway, NSW 2007, Australia
Photo & Environmental Technology Co. Ltd., Gwangju 500-460, Korea
Center for Seawater Desalination Plants, Gwanju Institute of Science and Technology,
Gwanju, South Korea

Municipal wastewater reclamation for non-potable use using hollow- fiber membranes Sujata Waghmare, Smita Masid, A. Prakash Rao, Paramita Roy, A.V.R. Reddy,T. Nandy and N.N. Rao
Abstract; Full Text (2417K) .	pages 207-214.	DOI: 10.12989/mwt.2010.1.3.207

Abstract
Approximately 80% of water used in urban areas reappears as municipal wastewater (MWW). Reclamation of MWW is an attractive proposition under the present scenario of water stressed cities in India. In this paper, we attempted to reclaim MWW using lab-scale hollow- fiber (HF) membrane modules for possible reuse in non-potable applications. Experiments were conducted to evaluate the efficiency of virgin HF (M1) and modified HF (M2) modules. The M2 module consists of HF modified with a skin layer formed through interfacial polymerization of m-phenylenediamine with trimesoyl chloride (MPDTMC). The molecular weight cut-off (MWCO) of M1 was 44000 g/mol and that of M2 10000 -14000 g/mol on the basis of rejection of polyethylene glycol. The combination of M1 and M2 modules was able to reduce concentrations of most of the pollutants in sewage and improved the treated water quality to the acceptable limits for non potable reuse applications. It is found that about 98-99% of the initial flux is recovered by the backwashing process, which was approximately two times in a month when operated continuously.

Key Words
sewage reclamation; hollow fiber; ultrafiltration; non potable water; reuse.

Address
Wastewater Technology Division, National Environmental Engineering Research Institute (CSIR),
Nehru Marg, Nagpur-440020, India
Reverse Osmosis Discipline, Central Salt & Marine Chemicals Research Institute (CSIR),
Gijubhai Badheka Marg, Bhavnagar-364002, India

Water desalination by membrane distillation using PVDF-HFP hollow fiber membranes M.C. Garcia-Payo, M. Essalhi, M. Khayet, L. Garcia-Fernandez,K. Charfi and H. Arafat
Abstract; Full Text (4349K) .	pages 215-230.	DOI: 10.12989/mwt.2010.1.3.215

Abstract
Poly(vinylidene fluoride-co-hexafluoropropylene), PVDF-HFP, hollow fiber membranes were prepared by the dry/wet spinning technique using different polyethylene glycol (PEG) concentrations as non-solvent additive in the dope solution. Two different PEG concentrations (3 and 5 wt.%). The morphology and structural characteristics of the hollow fiber membranes were studied by means of optical microscopy, scanning electron microscopy, atomic force microscopy (AFM) and void volume fraction. The experimental permeate flux and the salt (NaCl) rejection factor were determined using direct contact membrane distillation (DCMD) process. An increase of the PEG content in the spinning solution resulted in a faster coagulation of the PVDF-HFP copolymer and a transition of the cross-section internal layer structure from a sponge-type structure to a finger-type structure. Pore size, nodule size and roughness parameters of both the internal and external hollow fiber surfaces were determined by AFM. It was observed that both the pore size and roughness of the internal surface of the hollow fibers enhanced with increasing the PEG concentration, whereas no change was observed at the outer surface. The void volume fraction increased with the increase of the PEG content in the spinning solution resulting in a higher DCMD flux and a smaller salt rejection factor.

Key Words
water treatment; poly(vinylidene fluoride-co-hexafluoropropylene); hollow fiber; membrane distillation.

Address
Department of Applied Physics I, Faculty of Physics, University Complutense of Madrid,
Av. Complutense s/n, 28040, Madrid, Spain
Department of Chemical Engineering, Faculty of Engineering, An-Najah National University,
P.O. Box 7, Nablus, Palestine