Optimization and mass transfer simulation of remazol brilliant blue R dye adsorption onto meranti wood based activated carbon

Abstract

Remazol brilliant blue R dye (RBBR) brings toxicity to living organisms once it enters the environment. This study utilized response surface methodology (RSM) and Polymath software for optimization and mass transfer simulation purposes, respectively. RSM revealed that the optimum preparation conditions of meranti wood-based activated carbon (MWAC) were 441 W, 5.76 min, and 1.35 g/g for radiation power, radiation time, and KOH:char impregnation ratio (IR), respectively, which translated into 86.39 mg/g of RBBR uptakes and 31.94 % of MWAC’s yield. The simulation study predicted the mass transfer rate, rm to be 112.20 to 1007.50 s−1 and the adsorption rate, k1 to be 3.96 to 4.34 h−1. The developed model predicted the adsorption surface area, am to be 790.04 m2/g and this value is highly accurate as compared to the actual mesopores surface area of 825.58 m2/g. Mechanism analysis divulged that the interaction that occurred between RBBR molecules and MWAC’s surface were hydrogen bond (methylene and alkyne), dipole–dipole force (alkyl carbonate, terminal alkyne, and methoxy), and ion–dipole force (primary amine). The isotherm and kinetic studies found that the adsorption data obeyed the Freundlich model and pseudo-first-order (PFO) model the best, respectively. The Langmuir maximum adsorption capacity, Qm was computed to be 327.33 mg/g. Thermodynamic parameters were calculated to be −4.06 kJ mol−1, 0.06 kJ mol−1 K−1, –22.69 kJ mol−1, and 16.03 kJ mol−1 for ΔH°, ΔS°, ΔG°, and Ea, respectively, which signified the adsorption process studied was exothermic, spontaneous and governed by physisorption.