Functionalized MgAl-layered hydroxide intercalated date-palm biochar for Enhanced Uptake of Cationic dye: Kinetics, isotherm and thermodynamic studies

Abstract MgAl-layered hydroxide intercalated date-palm biochar composites (B-MgAl-LDH) functionalized with improved textural properties and surface functionalities were fabricated by a facile co-precipitation technique and fully characterized by various techniques. The B-MgAl-LDH were employed for enhanced aqueous uptake of methylene blue (MB) (Langmuir qmax = 302.75 mg/g at 100 mg/L in 180 min), compared with the virgin biochar (qmax = 206.61 mg/g in 480 min). Higher MB removal is attributed to the excellent hybridization of the two adsorbents which resulted in substantial improvement in surface area, micropore volume, and abundant surface functional groups, facilitating fast and better adsorptive removal of MB from water. The B-MgAl-LDH showed good adsorptive performances of MB at varied pH values (4–10). The kinetic data were best described by the pseudo-2nd-order while the adsorption isotherms fitted best to the Langmuir model. The thermodynamic parameters indicated the exothermic nature of MB adsorption and reduction in the degree of randomness at the B-MgAl-LDH /MB interface. The adsorption mechanism of MB onto biochar-MgAl composite is mainly governed by the surface adsorption and internal pore diffusion along with chemical and ion-exchange interaction as confirmed by BET, SEM, and FTIR characterization after the MB adsorption. Therefore, the modification of date palm biochar with MgAl via co-precipitation method is an effective approach to produce B-MgAl-LDH composite for the excellent removal of toxic dyes from wastewater streams.