微波制备改性的三乙烯四胺氧化石墨烯

Carbohydrate Polymers 131(2015)280–287

Contents lists available at ScienceDirect

Carbohydrate

Polymers

j o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /c a r b p o

l

Microwave preparation of triethylenetetramine modified graphene oxide/chitosan composite for adsorption of Cr(VI)

Huacai Ge ∗,Ziwei Ma

College of Chemistry and Chemical Engineering,South China University of Technology,Guangzhou 510640,China

a r t i c l e

i n f o

Article history:

Received 13February 2015

Received in revised form 4June 2015Accepted 6June 2015

Available online 16June 2015

Keywords:

Graphene oxide Modified chitosan Microwave Adsorption Cr(VI)

a b s t r a c t

A novel triethylenetetramine modified graphene oxide/chitosan composite (TGOCS)was successfully synthesized by microwave irradiation (MW)method and compared with one prepared by conventional heating.This composite was characterized by FTIR,XRD,SEM,BET and elemental analysis.Adsorption of Cr(VI)on the composite was studied.The experimental results indicated that the product obtained by MW had higher yield and uptake than one obtained by the conventional and uptake of TGOCS for Cr(VI)was higher than that of the recently reported adsorbents.The effects of various variables on adsorption of Cr(VI)by TGOCS were further researched.The highest adsorption capacity of 219.5mg g −1was obtained at pH 2.Adsorption followed pseudo-second-order kinetic model and Langmuir isotherm.The capacity increased as increasing temperature.The adsorbent could be recyclable.These results have important implications for the application expansion of microwave preparation and the design of new effective composites for Cr(VI)removal in effluents.

©2015Elsevier Ltd.All rights reserved.

1.Introduction

Chromium (VI)(Cr(VI))has been commonly used in a number of industrial processes,such as leather tanning,electroplating,metal polishing,paint manufacturing,and textile coloring (Bhattacharya,Naiya,Mandal,&Das,2008;Li et al.,2013;Ouaissa,Chabani,Amrane,&Bensmaili,2013).Due to its high toxicity and bioac-cumulation,the Cr(VI)from effluents must be removed.Various methods of removing Cr(VI)have been developed,such as chem-ical precipitation (Carlos,Violeta,&Bryan,2012),adsorption (Hu et al.,2011;Huang,Yang,&Liu,2013),electrodeposition (Golder,Samanta,&Ray,2011),membrane systems (Gherasim &Bourceanu,2013),and ion exchange process (Rengaraj,Joo,Kim,&Yi,2003).Among these methods,adsorption is one of the most economically favorable and a technically easy method (Hu et al.,2011).

Chitosan (CS),a bio-adsorber,is a biocompatible polysaccha-ride obtained from deacetylation of chitin (Ge &Wang,2014).It can chemically or physically entrap various metal ions due to the presence of amine and hydroxyl groups that can serve as the chelating and reaction sites (Aydın &Aksoy,2009;Ge &Fan,2011;Repo,Koivula,Harjula,&Sillanpää,2013;Wang &Ge,2015).Therefore,chitosan presents as a very promising starting mate-rial for chelating resins (Kandile &Nasr,2009).Several metals are

∗Corresponding author.Tel.:+862087112900;fax:+862022236337.E-mail address:chhcge@ (H.Ge).

preferentially adsorbed in acidic media while chitosan can dis-solve in acid condition.To overcome this problem,chitosan must be chemically modified with different crosslinking reagents,such as epichlorohydrin and glutaraldehyde (Ge &Huang,2010;Ngah,Endud,&Mayanar,2002).However,the adsorption capacity of crosslinked chitosan would be largely reduced due to the con-sumption of amine groups and hydroxyl groups after chemical modification.Hence,the crosslinked chitosan must be further mod-ified to improve the adsorption performance (Ge,Chen,&Huang,2012;Wu,Li,Wan,&Wang,2012;Zhang,Xia,Liu,&Zhang,2015).Graphene,which can be prepared from the low cost material graphite,is intensively investigated as adsorbents for heavy metal ions (Chowdhury &Balasubramanian,2014;Jabeen et al.,2011).Graphene oxide (GO)obtained by the oxidation of graphene con-tains a wide range of oxygen functional groups both on the basal planes and at the edges of GO sheets,such as –COOH,and –OH.These functional groups are essential for the high sorption of heavy metal ions,and allows GO to participate in a wide range of bond-ing interactions (Guo et al.,2014;Zhang et al.,2014).However,GO is a nano-material with high dispersibility in aqueous solution (Cheng et al.,2013)and has the potential toxicity in environment (Sanchez,Jachak,Hurt,&Kane,2011).These problems may restrict the practical applications of GO as an adsorbent.To overcome these problems,various methods have been investigated,such as for-mation of ethylenediamine modified GO and magnetic graphene nanocomposites (Wang et al.,2014;Zhu et al.,2011).However,these methods revealed low adsorption capacity due to the reduced

/10.1016/j.carbpol.2015.06.0250144-8617/©2015Elsevier Ltd.All rights reserved.