Delivered by Publishing Technology to: University of Houston IP: 129.7.158.43 On: Tue, 02 Apr 2013 09:25:53 Copyright American Scientific Publishers RESEARCH ARTICLE Copyright © 2013 American Scientific Publishers All rights reserved Printed in the United States of America Journal of Computational and Theoretical Nanoscience Vol. 10, 54–58, 2013 Flux Decline and Rejection Characteristics During Nanofiltration of Iron and Deionized Water Oluranti Agboola 1 ∗ , Jannie Maree 2 , Richard Mbaya 1 , Andrei Kolesnikov 1 , Jakob Johannes Schoeman 3 , and Caliphs Musa Zvinowanda 2 1 Faculty of Engineering and the Built Environment, Department of Chemical and Metallurgical Engineering, Tshwane University of Technology, Pretoria 0001, South Africa 2 Department of Environmental Water and Earth Sciences, Tshwane University of Technology, Pretoria 0001, South Africa 3 Department of Chemical Engineering, Water Utilisation Division, University of Pretoria, 0001, South Africa This work was studied to determine the flux decline during nanofiltration of iron and deionised water. The rejection characteristic of iron was also studied. A stirred-cell was used for the experiment and Inductively Coupled plasma optical emission was used for iron analysis at various pH and pressure. The significant increased in flux declined at pH 3.01 and 3.44 is possibly caused by crystallized solids formed at the surface of the membrane and thus lead to the reduction of iron rejection at pH 3.01 and 3.44. At higher pressure more water passes through the membrane, thereby increasing the iron rejection. Experiment of clean water flux was done using the deionised water after the different pH experiment to see if the membrane is not fouling. The rejection characteristic of iron was also studied. Keywords: Nanofiltration, Flux Decline, Rejection, pH, Pressure, Iron, Deionised Water. 1. INTRODUCTION A membrane is a permselective barrier that is capable to selectively separate components as a function of physi- cal and chemical properties from a solution when a driv- ing force is applied. Nowadays, membrane separation systems have become very important wastewater treat- ment technology, which facilitate the removal and recov- ery of pollutants, solvent i.e., water. Nanofiltration is a pressure-driven membrane process that has intermediate characteristics between ultrafiltration and reverse osmosis. Nanofiltration membranes find its applications in waste water and industrial water treatment (e.g., water softening, removal of colorants, heavy metals and organic matter). 1 The application of nanofiltration for environmental prob- lems provides the best opportunity out of all other mem- brane systems. This is because of the high efficiency of separation achieved by nanofiltration membranes at rela- tively lower pressure of operation and their ability to sep- arate organic as well as inorganic solutes. Consumption of energy in nanofiltration membrane is much lower than the reverse osmosis, which makes it an economically feasible unit operation. Usually, nanofiltration membranes are negatively charged with a selective layer of thickness of ∼ 1 m ∗ Author to whom correspondence should be addressed. coated over the ultra-porous membrane layer support that controls all the transport properties by diffusion, con- vection and Donnan exclusion mechanisms. The charged nature of the membrane surface allows selective separation of certain ions over the other with very high efficiency of operation particularly for ionic species other than the monovalent ones. When dealing with ionic solutions, the existence of fixed charge in the membrane influences the ion distribution inside the membrane. 2 The operational parameters such as flowrate, pressure, pH, the membrane molecular weight cutoff (MWCO), pure water permeability and surface charge play an important role in the separation performance of nanofiltration membrane. 1 3–7 The separa- tions of metal compounds have been found to be dependent on the pH of the solution in specific conditions. 8 9 The aim of this work is to test the performance of Nano- Pro membrane through the reproducibility of deionised water and to determine the flux decline during nanofiltra- tion of iron and deionised water. 2. MATERIALS AND METHODS 2.1. Experimental Device and Nanofiltration Membrane The investigation was carried out using Memcom labora- tory stirring cell. A polyamide flat sheet of NF membrane (Nano-Pro-3012) with effective surface area of 0.01075 m 2 54 J. Comput. Theor. Nanosci. 2013, Vol. 10, No. 1 1546-1955/2013/10/054/005 doi:10.1166/jctn.2013.2656