Magnetized Tectona grandis sawdust as a novel adsorbent: preparation, characterization, and utilization for the removal of methylene blue from aqueous solution

Abstract

In the submitted research work, adsorption characteristic of magnetized Tectona grandis sawdust for methylene blue from aqueous media was explored. The prepared adsorbent was characterized by SEM/EDXS, TEM, BET, XRD, FTIR, TGA-DTG/DTA, VSM, and point of zero charge. To investigate the adsorption capacity and mechanisms prevailing for the adsorption of methylene blue, batch adsorption studies were performed by changing adsorbate/adsorbent contact time, pH, initial dye concentration, and temperature. The removal efficiency was found to be 90.8% under the optimized adsorption conditions. The optimal process parameters were 1 g/L of magnetized adsorbent, 60 min contact time, pH 8, and temperature of 30 °C for 100 mg/L MB solution. The laboratory generated adsorption data was best conformed by pseudo-second-order kinetics and Langmuir adsorption isotherm models. The maximum monolayer adsorption capacity was determined to be 172.41 mg/g. The adsorption process was established to be thermodynamically feasible and accompanying with the absorption of heat and escalation of entropy. Regeneration study revealed that magnetized Tectona grandis sawdust could be reused efficaciously up to four repeated adsorption–desorption cycles using HCl as the best desorbing agent. The magnetized Tectona grandis sawdust has been proved to be novel, efficient, and cost-effective adsorbent. The combined advantages of easy preparation, good affinity towards dyes, excellent separability, reusability, and cost-effectiveness of magnetized Tectona grandis sawdust make it a novel adsorbent.