Sorption of malachite green (MG) by cassava stem biochar (CSB) kinetic and isotherm studies

Abstract

Cassava stem biochar (CSB) was produced by pyrolyzing CS at 500°C for 2 hours at nitrogen
environment. Proximate and ultimate analyses were conducted on CS and CSB. Batch
sorption experiment on synthetic MG wastewater was optimized for the sorbent dosage, MG
solution pH and contact time. Sorption data was analysedwith linearized sorption kinetic and
linearized isotherm models. Pyrolysis of CS produced carbon-rich and stable CSB
yield of 11.94%. The optimum sorption sorbent dosage, MG solution pH and contact time
1.67 g/L, > pH 7.4 and 10 minutes respectively. The sorption of MG by CSB was best
described by the pseudo-second-order kinetic model and the Langmuir isotherm model. The
Langmuir sorption capacity of CSB was 40.5 mg/g. Monolayer of MG molecules formed
chemical bonds on the homogenous surface of CSB.

Keywords: Manihotesculenta Crantz charcoal; black carbon; adsorption.