JMS 符号注释

JMS 符号注释

JMS 符号注释

Feed concentration and pH effect on arsenate and phosphate rejection

via polyacrylonitrile ultra?ltration membrane

M.R.Muthumareeswaran,Gopal P.Agarwal n

Department of Biochemical Engineering&Biotechnology,Indian Institute of Technology Delhi,Hauz Khas,New Delhi110016,India

a r t i c l e i n f o

Article history:

Received28February2014

Received in revised form

23May2014

Accepted24May2014

Available online2June2014

Keywords:

Pore size distribution

Surface roughness

Volumetric charge density

Arsenate rejection

Phosphate rejection

a b s t r a c t

The aim of the present work was to study the retention properties of arsenate and phosphate at various

feed concentrations and to investigate the effect of pH on the rejection of these ions through modi?ed

polyacrylonitrile(PAN)ultra?ltration membrane.In one component solution with feed concentration of

10ppm arsenate and phosphate separately showed Z90%rejection at Z pH7with PAN UF as well as

nano?ltration membranes.Similarly,the mixture of arsenate and phosphate showed more than90%

rejection for feed concentration of100ppm each.However,the arsenate rejection decreased to55–60%

for10ppm arsenate and100ppm phosphate mixture in the feed,while phosphate rejection remained

Z90%.The rejection of arsenate and phosphate reversed to Z90%and$60%respectively for100ppm

arsenate and10ppm phosphate in the feed.The solution pH played an important role in changing the

membrane surface properties.The rejection coef?cient of arsenate and phosphate varied from5%to95%

by changing pH between3to10.Donnan steric-partitioning pore model incorporating dielectric

exclusion used to investigate the arsenate rejection and good agreement was found between experi-

mental and simulated data.

&2014Elsevier B.V.All rights reserved.

1.Introduction

In recent years,the removal of heavy metals and organic

pollutants from drinking water and wastewater stream is major

interest to environmental as well as process engineers.The

presence of heavy metal like arsenic compounds in water stream,

and eventually in potable water,is a serious environmental

problem[1].Generally,arsenic contamination in the water occurs

due to the natural phenomena such as the presence of arsenical

minerals,volcanic emissions;human activities like wood preser-

vatives,fertilizers,industrial processes and waste treatment.On

the other hand,the existence of large amount of phosphate in

domestic and industrial wastewater causes the eutrophication

which is a serious environmental issue in aquatic sources[2].

According to the World Health Organization(WHO)and US

Environmental Protection agency(EPA)guidelines,the permissible

limit for total arsenic and phosphate are0.01mg/l and0.1mg/l

respectively[3,4].The existing technique for separation of arsenic,

phosphate consists of either reduction and precipitation or ion

exchange or adsorption or electro-dialysis,and these traditional

technologies have two common disadvantages of high-energy

requirements and production of toxic sludge[5].Thus,removal

of arsenic and phosphate from water streams is very important

from both environmental and economic points of view.

Reverse osmosis(RO)and nano?ltration(NF)membranes were

used to separate the heavy metals and organic pollutants from

water and it consumes more energy i.e.high operating pressure

than UF and MF membranes.Generally,the predominant forms of

arsenic in water are arsenite(As-III)and arsenate(As-V)and the

pentavalent arsenic is thermodynamically stable and dominant in

oxygenated waters especially in the surface water.On the other

side,the phosphorus found in solutions includes orthophosphate,

polyphosphate,and organic phosphate[6].Brandhuber et al.[7]

examined the applicability of UF membrane,which consists of

sulfonic and carboxylic acid groups which exhibited72%of

arsenate rejection.It was also reported that ultra?ltration mem-

brane gave88%rejection of As-V due to Donnan principles which

were sensitive to membrane operating conditions[8].ZrO2UF

membrane was studied by Noordman et al.,which gave490%

rejection of phosphate ions[9].Some reports also showed arsenic

ions removal by ultra?ltration membranes which incorporated

coagulation agents or ionic ligands;however,these processes may

result in sludge formation[10,11].Furthermore,Ballet et al.[6]

show the ef?ciency of monovalent and divalent phosphate ions via

NF membrane and the rejection behavior was dependent on its

feed concentration,ionic strength,applied pressure and pH.Abidi

Contents lists available at ScienceDirect

journal homepage:http://m.wendangku.net/doc/171a64969e314332396893c9.html/locate/memsci

Journal of Membrane Science

http://m.wendangku.net/doc/171a64969e314332396893c9.html/10.1016/j.memsci.2014.05.040

0376-7388/&2014Elsevier B.V.All rights

JMS 符号注释

reserved.

n Corresponding author.Tel.:t911126591005;fax:t911126582282.

E-mail address:gopal@dbeb.iitd.ac.in(G.P.Agarwal).

Journal of Membrane Science468(2014)11–19

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