Development of microcrystalline cellulose from groundnut shells for ...

375Development of microcrystalline cellulose from groundnutshells for cadmium degradationL.R. Hemanth 1 , Rashmi S. Hulagurmath 2 , R. Suresh 1 ,Roopa L. Farshi 1 , S.H. Kavitha 31 Department of Chemical Engineering, R.V. College of Engineering, Bangalore, Karnataka,560059, India; E-mail: hemanthlr@rvce.edu.in2 Department of Chemical Engineering, S.D.M. College of Engineering and Technology, Dharwad,580002, Karnataka.3 Department of Biotechnology, PES Institute of Technology, Bangalore, Karnataka, 560085, India.ABSTRACTWater is the vital element for the living organisms and also for the ecological balance of the environment. Thewater resources are being polluted continuously by the various activities of the man. The industrial activitiesare the direct methods for water pollution. The industrial activities release metals, non-metals, unreactedcompounds and byproducts to the water resources. The polluting compounds mainly include dyes, chlorinecompounds, cadmium, fluorides, ketones and other compounds. The works are being carried out fordegradation of pollutants and to develop suitable methods for the removal of these polluting compounds. Thepresent experiment involves the preparation of cellulose powder from agricultural products and its applicationfor removal of cadmium material. The paper describes the development of microcrystalline cellulose fromgroundnut shells by the digestion process. The raw material is digested in a steam jacket reactor followed bytreatment with an alkali, bleaching and drying. The dried powder is characterized for its properties and theparticle size is estimated. The final dried powder is used for batch adsorption studies for degradation ofcadmium compounds and for the kinetic studies. From adsorption studies the parameters such as effect of pH,concentration, adsorption isotherms and kinetics of adsorption process are estimated.Keywords: cadmium, groundnut shells, mineral acids, digester, cellulose, adsorption isotherms, Dubinin-Radushkveich isothermINTRODUCTIONThe availability of clean water has become a prime issue in all countries due to the depletion ofwater resources by industries, over population and due to non-compliance of environmentalregulations. The wastewater can be treated by variety of techniques such as electrodialysis,distillation, use of water sediment filters and chemical agents, reverse osmosis, activated carbon andion exchange [1,2]. The adsorption technique is a frequently applied method in the industries.Industrial waste streams of metal cleaning, plating baths, mining, printed circuits, metallurgical,pulp and paper, fertilizers, petroleum refining, wood preserving and excessive use of agro-chemicalscause the contamination of water and soil. The adsorbents are either chemical compounds orcompounds developed from biological material. Some of the biological materials employed asadsorbents are sawdust, maize corns, rice husks and sugarcane [3,4].Cadmium is one of the water-polluting compounds that are let off from the various industrialactivities. Cadmium is used commonly in battery industries, coating and plating industries and inplastic industries. Naturally a very large amount of cadmium is released into the environment, about25,000 tons a year. About half of this cadmium is released into rivers through weathering of rocksResearch Article, Biotechnol. Bioinf. Bioeng. 2011, 1(3):375-380© 2011 Society for Applied Biotechnology. Printed in India; ISSN 2249-9075

378isotherm equation is derived for adsorption on microporous and mesoporous solids from statisticalmechanical principles [13]. The adsorbed phase is assumed to be a two-dimensional fluid subjectedto a force field represented by a mean potential (Phi). For adsorption in micropores and mesopores,the fractional adsorption (theta) is much greater than the relative pressure. From the approximatedforms of the general isotherm, it is shown that the exponent n in the equation is related to the degreeof pore filling at the reference state; as a consequence it depends on the adsorbate as well as the porestructure of the adsorbent. Thus, the dependence off on pore size can be obtained directly from firstprinciples without resorting to empirical correlations.ln q=ln q e -βε 2 --------------------------------------------Equation 2andε=RT ln(1+1/c) --------------------------------------------Equation 3where, C e is the liquid phase concentration of cadmium ions at equilibrium, mg/l, C is the liquidphase concentration of cadmium ions (mg/l), q is the amount of cadmium ions adsorbed (mg/g), q eis the amount of cadmium ions adsorbed at equilibrium (mg/g), ε is potential and β is D-Rparameter with q, T.RESULTS AND DISCUSSIONThe groundnut shell that contains more than 93% of alpha cellulose was used as a primary rawmaterial for the development of microcrystalline cellulose. The groundnut husk is used as cattlefeed, carrier of insecticide and for manufacture of briquettes. In the process the secondary standardsolution hydrochloric acid (1N) was standardized by nitric acid (1N), which was again standardizedby sodium hydroxide solution (1N) with potassium hydrogen phthalate (1N) and phenolphthaleinindicator. The dried microcrystalline powder was subjected to various tests to confirm its propertieswith standard microcrystalline powder [14]. The powder was dispersed in iodinated zinc chloridesolution; the appearance of violet blue indicates the identification test. The solubility test wascarried out by dissolving in copper tetramine solution; the developed compound completelydissolves without residue confirming the solubility of compound. The loss on drying at 105°C was1.2% for 3 hours for the developed material whereas the value is greater than 6% for othermicrocrystalline materials. The particle size of the material was 75.87 mm, which was determinedby ICI sedimentation technique.The developed microcrystalline cellulose was applied for the cadmium removal in a batchoperation. The analysis was carried out by atomic absorption spectrophotometer. The cadmiumabsorption increased as shown in figure 1 for the duration of 60 minutes. The stock solutioncontaining 663 ppm of cadmium was reduced to 83.36 ppm over the 60 minutes operation. After theabove time there was no change in concentration and material was reused again for the same initialconcentrations and constant result was obtained. The isotherms were developed by the aboveconcentration values and are represented in figure 2 and 3. The regression value of the Dubininisotherm is higher and nearer to 1 compared to Langmuir isotherm. Hence, the material obeys theDubinin isotherm, which is applicable for porous material. The material was repeated with somemore trials and the regression values were found to be higher than other isotherm. The resultsindicate that the material can be successfully employed for cadmium degradation in batch operation.The material can be even tested for degradation of other polluting compounds, heavy metals andother dyes.

379% Absorbance vs Time% absorbance8060402000 20 40 60 80time(min)Figure 1. The concentration behavior of the cadmium removal in a batch adsorption process.Langmuir plot1/qe0.30.250.20.150.1R 2 = 0.81330.0500 1 2 3 41/CeFigure 2. Langmuir plot for cadmium degradation.ε 2Dubinin plotln qe108R 2 = 0.94464200 5000000 10000000 15000000ε*εFigure 3. Dubinin plot for cadmium degradation in a batch adsorption process.

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