Please cite this article in press as: Md.I.H. Mondal, et al., Int. J. Biol. Macromol. (2015), http://dx.doi.org/10.1016/j.ijbiomac.2015.04.061 ARTICLE IN PRESS G Model BIOMAC 5067 1–7 International Journal of Biological Macromolecules xxx (2015) xxx–xxx Contents lists available at ScienceDirect International Journal of Biological Macromolecules j ourna l h o mepa ge: www.elsevier.com/locate/ijbiomac Preparation of food grade carboxymethyl cellulose from corn husk agrowaste Md. Ibrahim H. Mondal ∗ Q1 , Mst. Sarmina Yeasmin, Md. Saifur Rahman Polymer and Textile Research Lab., Department of Applied Chemistry and Chemical Engineering, Rajshahi University, Rajshahi 6205, Bangladesh a r t i c l e i n f o Article history: Received 9 February 2015 Received in revised form 17 April 2015 Accepted 23 April 2015 Available online xxx Keywords: Cellulose Carboxymethyl cellulose Corn husk Food grade Etherification a b s t r a c t Alpha-cellulose extracted from corn husks was used as the raw material for the production of food-grade carboxymethyl cellulose (CMC). Preparation of CMC from husk cellulose was carried out by an etherifica- tion process, using sodium hydroxide and monochloroacetic acid (MCA), with ethanol as the supporting medium. Characterizations of CMC were carried out by analyzing the spectra of FTIR, XRD patterns and SEM photomicrographs. Degree of substitution (DS) was determined with respect to particle size using chemical methods. Solubility, molecular weight and DS of CMC increased with decreased cellulose particle sizes. Microbiological testing of the prepared CMC was done by the pour plate method. Concentrations of heavy metals such as arsenic, lead, cadmium and mercury in the purified CMC were measured by Atomic Absorption Spectroscopy technique and found to be within the WHO/FAO recommended value. A comparative study with CMC available in the international market was conducted. The purity of the prepared CMC was higher, at 99.99% well above the purity of 99.5% for standard CMC. High purity CMC showed a yield 2.4 g/g with DS 2.41, water holding capacity 5.11 g/g, oil holding capacity 1.59 g/g. The obtained product is well suited for pharmaceutical and food additives. © 2015 Published by Elsevier B.V. 1. Introduction Q3 Cellulose is a common natural polymer. It can be found widely Q4 in plants which are used as raw material for producing modified cellulose. Due to the abundant supply of the polymer in nature, modified cellulose is now advancing in terms of production and innovation. The sources can range from wood even to the agricul- tural waste. Corn or maize husk is an agricultural waste obtained from corn fields which is a rich source of cellulose. Cellulose is a linear, high molecular weight, biodegradable polymeric material. However, due to its strong inter- and intra- molecular hydrogen bonds, cellulose neither melts nor dissolves readily in hot or cold water [1] and in most common organic solvents [2,3]. In order to utilize cellulose in the food indus- try, cellulose must be converted into its derivatives. One of the most common derivatives is carboxymethyl cellulose (CMC), also referred to as Na-CMC which is currently finding an increasing number of applications. CMC is manmade modified cellulose, a linear, long-chain, water-soluble, anionic polysaccharide which is ∗ Corresponding author. Tel.: +880 1914254992; fax: +880 721750064. Q2 E-mail addresses: mihmondal@yahoo.com, mihmondal@gmail.com (Md.I.H. Mondal). prepared by the reaction of monochloroacetic acid with alkali cel- lulose [4]. There are several grades of CMC depending on their applica- tions such as technical, semi-purified and purified. Purified CMC is a white to cream colored, tasteless, odorless, free-flowing powder [5] and used in a variety of industries including the food, deter- gents, personal care, pharmaceutical etc. [6,7]. High purity grades are employed as food additives [4] also known as cellulose gum [8]. In the food industry, it can be used as suspending agent, water loss reducer, thickener, emulsifying agent and stabilizer or dispers- ing agent. It is used as a preservative for coating of fresh fruit and thickener for pharmaceutical products [9–11]. Some authors have reported the synthesis of CMC from various cellulosic sources such as raw cellulose [7], paper sludge [12], wood residue [13], cotton linters [14,15], fibers [16] etc. There is consid- erable interest in finding cheaper alternative methods to produce CMC. Recently cultivation of corn has tremendously increased in Bangladesh [17] and huge amounts of corn husks are either thrown away as waste or burnt. However, these are applications with low added value, causing disposal as well as environment pollution problems. The purpose of the present research is to investigate the suitabil- ity of the corn husk as a source to produce high purity food-grade CMC. Every year in Bangladesh, large amounts of CMC are being http://dx.doi.org/10.1016/j.ijbiomac.2015.04.061 0141-8130/© 2015 Published by Elsevier B.V. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62