Chemical Engineering Journal 170 (2011) 209–219 Contents lists available at ScienceDirect Chemical Engineering Journal journal homepage: www.elsevier.com/locate/cej Chitosan based ceramic ultrafiltration membrane: Preparation, characterization and application to remove Hg(II) and As(III) using polymer enhanced ultrafiltration Somen Jana a , Anirban Saikia b , M.K. Purkait a,∗ , Kaustubha Mohanty a,∗ a Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati 781039, India b Department of Chemical Engineering, National Institute of Technology Raipur, Chhattisgarh 492001, India article info Article history: Received 26 November 2010 Received in revised form 11 March 2011 Accepted 14 March 2011 Keywords: Chitosan impregnation Ceramic membrane Crosslinking Heavy metals PEUF abstract This work presents the fabrication of chitosan based ceramic membranes using dip coating technique. Low-cost ceramic supports were prepared from local clay of IIT Guwahati and kaolin with an average pore size of 1093 nm and porosity of 0.37. Different ceramic membranes were prepared by varying chitosan concentration and dipping time and were characterized using scanning electron microscope (SEM), air and hydraulic permeability tests. The average pore sizes were in the range of 760–13 nm which confirmed that the chitosan impregnated ceramic membranes were applicable for both microfiltration (MF) and ultrafiltration (UF) applications. An increase in both chitosan concentration and dipping time was found to reduce the pore size. The lowest pore size ultrafiltration membrane (pore size: 13 nm) was used for the removal of mercury and arsenic from wastewater by polymer enhanced ultrafiltration (PEUF) technique using polyvinyl alcohol (PVA) as the chelating agent. The effects of initial concentrations of mercury, arsenic and PVA on the extent of removal of both the heavy metals were investigated in detail. The efficiency of PEUF was explored in terms of rejection of metals and permeates flux. Almost 100% removals were observed for both 500 gL -1 mercury and 1000 gL -1 arsenic. © 2011 Elsevier B.V. All rights reserved. 1. Introduction The uses of ultrafiltration membranes are gaining a lot of interest now-a-days due to their higher selectivity, permeation rate, and chemical and thermal stability. In recent years, vari- ous UF membranes were synthesized with very good structural integrity, fouling resistance and high selectivity. These membranes were not tried industrially due to the high cost of the support (1600–20,000 $/m 2 ) [1]. Generally, the ceramic supports were pre- pared from alumina, kaolin, ball clay and quartz [2]. So there is a need to look for alternative low-cost materials for preparing the ceramic support so as to make the prepared membrane commer- cially competitive. The composite UF membranes constitute of different types of thin polymeric layers such as; polysulfone [3], styrene acry- lonitrile [2], cellulose acetate [4], polyvinyl acetate, polyvinyl pyrrolidone [5], polydimethylsiloxane [6]. Chitosan, which is an amino polysaccharide with many reactive amino and hydroxyl group, is a promising precursor for UF membrane preparation. ∗ Corresponding authors. Tel.: +91 361 2582267/2582262; fax: +91 361 2582291. E-mail addresses: mihir@iitg.ernet.in (M.K. Purkait), kmohanty@iitg.ernet.in (K. Mohanty). During crosslinking with glutaraldehyde, solubility of chitosan is decreased sharply and hydrophilicity increased which are very important factors for a membrane precursor [7]. This article focused on the preparation of chitosan based ultrafiltration membrane using low cost ceramic support. To prepare the UF top layer over the ceramic support, many techniques were reported such as spray coating [4], grafting [5], spin coating [8], self assembly [9], dip coating [4] and vapor deposition [10]. Among these methods, dip coating is simple, inex- pensive and thus most desirable choice for industrial purpose. UF membranes were used for the removal of high molecular weight substrate, oil from water, colloidal material, polymer molecules and organic–inorganic pollutants. Pollution due to the discharge of heavy metals to water bodies is one of the serious environmental problems worldwide. Metals like mercury and arsenic are found in industrial effluents and in groundwater and pose serious threats to the environment. These pollutants are not only non-biodegradable but are toxic even at low concentration. The general methodologies for removal of mercury ions (safe limit 2 ppb) from aqueous solution are absorp- tion [11], chelation-enhanced method [12] and electrocoagulation [13]. Arsenic (safe limit 10 ppb) was separated by inorganic and organic adsorbents [14] including bioadsorbents [15]. However, these methods have several disadvantages like incomplete metal 1385-8947/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.cej.2011.03.056