Journal of Engineering Science and Technology (Aug 2014)
ADSORPTION OF CHROMIUM (VI) FROM AQUEOUS SOLUTIONS BY DIFFERENT ADMIXTURES – A BATCH EQUILIBRIUM TEST STUDY
Abstract
Wide variety of inorganic compounds such as nutrients and trace metals, organic chemicals, radioactive contaminants and pathogens are commonly present as contaminants in the groundwater. Migration of contaminants in soil involves important mechanisms such as molecular diffusion, dispersion under physical processes, adsorption, precipitation and oxidation - reduction under chemical processes and biodegradation under biological process. Cr (VI) is a major and dangerous contaminant as per the ground water is concerned. There are numerous research work carried out with concentrated efforts by the researchers towards removal of Cr (VI) contaminant from aqueous solutions. There are few studies relevant to Cr (VI) removal with respect to utilization of low cost admixtures and also soil type. In the present study, different low cost admixtures like rice husk (RH), shredded tyre (ST) and fly ash (FA) are used to understand the performance in removal of Cr (VI) from aqueous solution and also two different soil types are used along with the admixture. The results are discussed in terms of sorption capacity and performance of individual admixture and combination of admixture with soil in removal of contaminant. The fly ash, rice husk and shredded tyre admixtures are used and the results revealed that the shredded tyre showed higher performance in removal of contaminant concentration. Also, the soil which has more fine particle content (size<0.075 mm IS sieve) showed reasonable reduction in concentration of contaminant at the lower levels of contaminant initial concentration. The sorption capacity results of Cr (VI) contaminant, treated with various admixtures are further validated with the published work of other investigators. The shredded tyre (ST) showed more adsorption capacity, i.e., 3.283 mg/g at pH of 4.8. For other admixtures, adsorption capacity value is varying in the range of 0.07 mg/g to 1.7 mg/g. Only in case of activated alumina and modified saw dust, its value is varying 1.6 to 1.7 mg/g whereas for remaining admixtures, the adsorption capacity is less than 1 for the pH range of 2 to 3.
