Process parameter study and kinetic of remazol dye adsorption onto local rice husk-based organic porous materials

Abstract

Remazol Brilliant Blue dye (RBB) is a harmful dye from the textile industry that can damage the environment and aquatic life. Since RBB is impossible to degrade in water by primary and secondary wastewater treatment, its removal is a challenge. An excellent treatment procedure is urgently anticipated to avoid the pollution spreading into the environment. Moreover, rice husk waste (RH) in Malaysia is abundant and generally dumped into landfills. Turning the waste into a value-added product such as biochar as an effective adsorbent material for treating water pollutants is one of the initiatives in realizing the circular economy agenda. This study develops an organic porous material of biochar from RH and assesses the kinetic of RBB adsorption onto the rice husk biochar (RHB) in aqueous solution. The production of RHB was optimized by pyrolysis procedure at various temperatures, times, and particle sizes. The removal of RBB dye by RHB was investigated at different exposure times from 0 to 120 min under 100 rpm shaken and immersed conditions. The reduction of RBB concentrations using different RHB pyrolysis conditions has also been investigated. The dye removal efficiency by RHB increased with time and the highest removal efficiency (69.3%) was achieved by the smallest particle size of RHB which was produced at the highest pyrolysis temperature of 400°C (RHB-400). The total pore volume and BET surface area of RHB-400 were found to be 50.4827 m2/g and 0.00875 cm3/g, respectively. The adsorption kinetic study signifies that maximum adsorption has been completed within 90–120 min depending on the RHB conditions whereas two kinetic models such as pseudo-first order and pseudo-second order kinetic models were utilized to fit the experimental data and the results are more consistent with pseudo-second order kinetic models. This study revealed that RHB can be used as adsorbent materials for dye removals, yet it is economical, environmentally friendly, and sustainable.