ADSORPTION OF METHYLENE BLUE DYE FROM INDUSTRIAL EFFLUENTS BY POLYMER POLYANILINE SYNTHESIZED ON JUTE FIBER

Abstract

During the last few decades, growth of industrialization and modernization at a rapid rate has created a negative impact on environment due to pollution of both the surface and subsurface waters. Anthropogenic activities which are of prime concern such as industrial activities majorly pollute the water through discharging toxic chemicals contaminated effluents. Toxic chemicals include heavy metals, such as chromium, copper, cadmium, mercury, zinc etc and also dyes. The presence of dye even at trace quantity is easily visible and physiologically can’t accept for further use besides its toxic effects. Conventional treatment for dyes such as membrane technique, reverse osmosis, adsorption etc are widely practiced. Out of these methods, adsorption is the most commonly applied due to its ease in operation, cost effective, easy maintenance and effective dye removal. Activated carbon based adsorbents again are the most conventionally and effectively used adsorbents however production of dyes contaminated sludge etc is the main drawbacks. Employment of functionalized polymers containing several functional groups such as amines, carboxylate, ether, hydroxyl, sulphate, etc., as adsorbent for removal of dye ions has become a recent trend. However many of the reported functionalized polymers have complex synthesis procedure and cost ineffective. Therefore development of low cost functional polymer with easy synthesis procedure, moderate to high metal removal, rapid adsorption kinetics and reusability is necessary. One of the most effective metal binding functional group is amine (-NH2) due to presence of lone pair of electron in sp3 hybridized atom of nitrogen. In the present study, an amine based polymers namely polyaniline (PANI) is synthesized to use as an adsorbent for dye removal from aqueous solution. Since polyaniline are very fine particles and segregation after adsorption is difficult, it’s synthesized over the surface of jute fiber. Methylene blue (MB) was selected as model dye and study was carried out in batch mode operation. Optimum pH of MB adsorption by PANI-jute was observed at the range of pH 7- 10 due to formation of coordinate bond between the cationic MB dye & amines of the PANI-jute. Adsorption equilibrium time was observed to be highly rapid with almost 90% uptake within 5 minutes for higher concentration till 100 mg/L methylene blue. Chemical adsorption behavior is further well confirmed through fixing of kinetic data in Lagergren’s Pseudo second order kinetic model. Insignificant adsorption through physical adsorption was confirmed through diffusion model and concluding the predominantly adsorption of MB by PANI-jute through chemical bond formation. Adsorption of MB by PANI-jute was able to be explained by both Langmuir and Freundlich isotherm with comparative value 31& 29 error square respectively. Maximum amount of MB uptake capacity of PANI-jute was observed to be 111.11 mg/g from Langmuir’s isotherm. Freundlich’s isotherm ’n’ value of 1.75 which is less than 10 and greater than 0 suggest the favorable adsorption of MB 7 by PANI-jute. The adsorbed methylene blue in PANI-jute were still able to recovered back almost 90% by mineral acids desorption. Further, the polymer adsorbent PANI-jute was reuse for more than 10 cycles, without any decreasing its MB uptake capability. Thus, the maximum uptake capacity of PANI-jute is higher than 1100 mg/g. The performance of PANI-jute when subjected to sactual industrial wastewater decrease by 10-15% due to the presence of other coions. PANI-jute showed stability during storage for as long as 12 months time period and provide a platform for its commercial purposes.