Regenerable green aluminium organic frameworks supported orange peel biochar/hydroxyapatite decorated chitosan/pectin hybrid composite for selective malachite green removal.

The various industries used synthetic dyes for coloring purposes and also untreated dyes were released into the environment. Due to its high carcinogenic nature, the removal of dye was essential for a safe environment. In this effort, orange peel biochar (OPB) implanted hydroxyapatite (H) supported aluminium fumarate-based metal-organic frameworks (AlOFs) cross-linked with chitosan/pectin (CP) biopolymer namely OPBHCPAlOFs were fabricated for effective adsorption of malachite green (MG) from water bodies. The enhanced MG adsorption capacity of OPBHCPAlOFs was greater than (48.50 mg/g) with parent materials like chitosan, hydroxyapatite and AlOFs were 7.00 (40 min), 14.50 (40 min), 21.20 (40 min) and 28.00 (40 min) mg/g correspondingly. Within a basic pH medium, the high adsorption capacity was noticed due to the OPBHCPAlOFs surface becoming negative so it was electrostatically attracted to MG (positive nature). The isotherms equilibrium data of OPBHCPAlOFs were well suited with Langmuir models than other models (Fruendlich and D-R). Thermodynamic studies of MG onto OPBHCPAlOFs were followed on endothermic and spontaneous nature. The kinetics of OPBHCPAlOFs was well-fitted with pseudo-second-order (PSO) and intraparticle diffusion (IPD) models. The aptness of OPBHCPAlOFs at field conditions was also checked and their results exhibited that the equilibrium MG concentration was identified to be very small, hence well suitable at field conditions. Regeneration studies of OPBHCPAlOFs were performed and their result revealed that OPBHCPAlOFs were regenerable upto six cycles in nature.