Water hyacinth biochar for trivalent chromium adsorption from tannery wastewater

Abstract

This investigation studied the utilization of water hyacinth (Eichhornia crassipes) as biochar for adsorption of trivalent chromium ion. The prepared biochar has been characterized by Fourier transforms infrared spectroscopy (FTIR) before and after the experiment. The trivalent chromium ion adsorption efficacy on biochar was investigated considering parameters e.g., adsorbent dose, interaction time, and relative pH. In the batch-wise treatment process, 70 ​mL chromium loaded tannery wastewater was treated with prepared biochar as adsorbent, shaken for a fixed period, rested, and the chromium, as well as pollution load, was measured. Chromium content in the untreated wastewater and treated wastewater at optimized conditions was 3190.1 and 27.3 ​mg/L, respectively. The chromium ion adsorption on biochar was 99%. The chloride, biochemical oxygen demand (BOD), and chemical oxygen demand (COD) reduction were by 56%, 93.4%, and 92.6%, respectively. The use of aquatic weed Eichhornia crassipes as biochar could be a novel economical alternative to adsorb trivalent chromium ion from the tannery wastewater. Keywords: Chromium, Biochar, Tannery, Biochemical oxygen demand, Chemical oxygen demand