Fabrication of a bio-adsorbent material by grafting CeO2 quantum dots (QDts) over Areca nut shell biochar using Saccharum officinarum extract as a solvent/capping agent for adsorption of Methylene blue dye: Synthesis, material analyses, adsorption kinetics and isotherms studies

Abstract

The presence of diverse organic compounds, such as dyes, in wastewater may pose potential environmental hazards. Therefore, it is imperative to remove these harmful substances from the various water resources. In this work, the composite of Ceria (CeO2) and areca nut shell biochar (CB) were used as adsorbents to extract Methylene blue dye (MB) from synthetic effluent. The study involved conducting batch experiments to investigate the effects of various factors, including initial MB concentration, solution pH, contact time, and CB dosage, on the adsorption process. Multiple characterization techniques were employed to examine the characteristics of CB. The study identified the most optimal values of variables for the removal of MB as follows: a CB dosage of 0.5 g L−1, an initial concentration of 50 mg L−1, a pH of the solution of approximately 10, and a contact time of 75 min. These conditions resulted in a ∼ 96% efficiency in the removal of MB in 75 min. The impact of the pH of the solution on the removal of MB was found to be more substantial in comparison to the sorbate dosage. The superior effectiveness of CB in eliminating MB in comparison to ASB and CeO2 can be attributed to its porous structure and uneven surfaces, which offer numerous active sites for MB adsorption. The study determined that CB exhibited a maximum adsorption capacity for MB at a concentration of 250 mg L−1 under optimal conditions, it was 492.2 mg g−1. The pseudo-second-order model was found to be the most suitable for describing the kinetics of adsorption, whereas the adsorption isotherms were best fitted by the Freundlich equation. Thermodynamically spontaneous and endothermic physisorption of MB over CeO2 @ASB. The efficiency of MB removal remained above 93% even after undergoing five cycles of recycling. The primary processes responsible for the elimination of MB on the adsorbent were electrostatic and pi-pi interactions. The utilization of CB exhibits significant potential for the elimination of MB from polluted solutions owing to its robust adsorption capability and efficient reusability.