Functionalised Seed Pods for The Sorption of Crystal Violet from Aqueous Solution: Kinetics And Equilibrium Studies

Abstract

The release of dye-containing effluents from several industries into natural water bodies continues to pose a serious threat to the ecosystem. Even though several conventional wastewater treatment technologies abound, their usage in developing nations has been limited due to their high cost. This has prompted research into the use of low-cost materials, such as agricultural waste biomass for sequestering such dyes from wastewater. The ability of CH₃COOH-functionalised Millettia thonningii seed pods (FMTP), an agricultural waste, as an adsorbent for the sequestration of Crystal Violet (CV) dye from aqueous solutions is investigated in this study. The pseudo-first-order, the pseudo-second-order, and Elovich's kinetic models were used to analyze the kinetic data, while the Langmuir and Freundlich isotherm models were used to analyze the equilibrium data using the non-linear regression method. To evaluate the adsorption data and identify the best-fitting kinetic and isotherm models, four error functions were used: Coefficient of Determination (R²), Chi-Square (χ²), Sum of Error Squares (SSE), and Percent Deviation (% D). The adsorption kinetics was best described by Elovich's kinetic model, while the adsorption equilibrium was better described by the Freundlich model, indicating that the mechanism of adsorption is predominantly chemisorption onto a heterogeneous adsorbent surface. Fourier Transform Infrared spectroscopy (FTIR) was used to characterize the functionalized adsorbent and its precursor. Experimental results revealed that acetic acid functionalized biomass is a suitable adsorbent for removing CV from aqueous solutions. Its application in the treatment of industrial wastewater should be investigated further