Biosorption of Methyl Orange Dye in Single, Binary and Ternary System onto Gingerbread Plum Seed Shell Activated Carbon

Abstract

The research investigated the potential of gingerbread plum seed shell activated to function as a biosorbent for eliminating methyl orange (MO) dye from water in various dye combinations, including single, binary, and ternary systems alongside methylene blue (MB) and Congo red (CR) dyes. The characteristics of the adsorbent were analyzed through techniques like Scanning Electron Microscopy, Fourier Transform Infrared spectroscopy, and pH point of zero charges. Batch adsorption tests were conducted to examine the adsorption processes' equilibrium behaviors, thermodynamics, and kinetics. The collected data were subjected to different isotherm and kinetics equations. The pseudo-second-order kinetics model provided the best fit for all the sorption systems, irrespective of composition differences, with higher rate constants observed for binary MO+MB= 0.031 g/mg/min system and lower for binary MO+CR= 0.028 g/mg/min and ternary MO+MB+CR= 0.029 g/mg/min systems compared to the single system MO= 0.030 g/mg/min. The maximum monolayer capacity of the adsorbent for methyl orange demonstrated synergistic interaction with the presence of methylene blue and antagonistic interaction with the presence of Congo red dye. The findings indicated that the adsorption processes varied based on the system's composition; they were all spontaneous (with Δ𝐺 values ranging from -1.146 to -10.415 kJ/mol) and exothermic (with Δ𝐻 values between -17.94 and -54.63 kJ/mol). Additionally, randomness decreased, as reflected by Δ𝑆 values of -054.43 and -382.62 J/K for the entire process.