Tea waste as a potential biowaste for removal of hexavalent chromium from wastewater: equilibrium and kinetic studies

摘要

Chromium (Cr) is considered as one of the 14 most toxic heavy metal(loid)s worldwide. In this experiment, the potential of tea waste was investigated in batch sorption experiments for the removal of Cr(VI) from aqueous solutions under various experimental conditions. The results depicted that the maximum Cr(VI) sorption was achieved at pH 5.2 which was 99.2%. The biosorbent dose of 0.6 g L-1 and 2-h contact time were sufficient to achieve successful removal of Cr(VI) from water. Sorption isotherm data revealed that Langmuir isotherm model fitted well with the experimental data which suggested that Cr(VI) sorption was dominated by chemisorption process. Kinetic modeling was also applied on kinetic experimental data and results described that pseudo-second-order model has given the best fit to the kinetic data over the pseudo-first-order model. The sorption process was significantly impacted by the presence of co-occurring anions including sulfate, phosphate, and nitrate; however, during the presence of sulfate, sorption of Cr(VI) was highly reduced (about 64.70%) compared to other anions. It could be concluded that tea waste is a low-cost and potential biowaste to remove Cr(VI) from wastewater.