Adsorption of Chromium (VI) by a Low-Cost Adsorbent Prepared from Tamarind Seeds

The presence of toxic heavy metals such as chromium (VI) contaminants in aqueous streams, arising from the discharge of untreated metal containing effluents into water bodies, is one of the most important environmental problems. Adsorption is one of the effective techniques for chromium (VI) removal from wastewater. In the present study, adsorbent is prepared from tamarind seeds and studies are carried out for chromium (VI) removal. Tamarind seeds are activated with the use of concentrated sulfuric acid (98% w/w). Batch adsorption studies demonstrate that the adsorbent prepared from tamarind seeds has a significant capacity for adsorption of chromium (VI) from aqueous solution. The parameters investigated in this study include contact time, adsorbent dosage, initial chromium (VI) concentration and pH. The adsorption process of chromium (VI) is tested with Langmuir and Freundlich isotherm models. Application of the Langmuir isotherm to the systems yielded maximum adsorption capacity of 11.08 mg/g at a solution pH of 7. The adsorption of chromium (VI) was found to be maximum at low values of pH in the range of 1-3.