Biotreatment of clay-based adsorbent to eliminate arsenic (V) ions and malachite green from wastewater: Isotherm, kinetics, thermodynamics, reusability and mechanism

Abstract

To address environmental pollution caused by dyes and heavy metals, it is crucial to fabricate effective adsorbent material to remove contaminants from the environment. In this research, a biogenic-assisted treatment was applied to kaolin clay to eliminate arsenic ions (As(V)) and malachite green (MG) using an adsorption technique. An environmentally friendly ultrasonic method was used to incorporate Pterocarpus mildraedii into the mesoporous structure of kaolin clay (PMKC) material with a unique flake-like morphology characterized by hexagonal structures formed by quartz and kaolin. Various analytical techniques were employed to analyze the functional groups, crystallographic structures, and surface properties of PMKC. The findings reveal that PMKC, an eco-friendly adsorbent, effectively removed As(V) and MG from wastewater under specific conditions: a solution pH of 6, a PMKC dosage of 40 mg/L, a contact time of 60 min, an initial concentration of As(V)/MG of 100 mg/L, and an adsorption temperature of 40 °C. Furthermore, PMKC exhibited high adsorption capacities of 337.22 mg/g towards As(V) and 274.73 mg/g towards MG. Dubinin-Radushkevich and the pseudo-first-order models were found to best describe the experimental data obtained from the isotherm and kinetic studies. Because PMKC can be reused effectively and remains stable for up to ten cycles, it holds promise as a valuable material for removing dye and heavy metal pollutants.

Keywords

• Kaolin clay
• Leaf extract
• Adsorption
• Arsenic
• Malachite green
• Reusability