Integrated activation strategy of mahua seed cake for efficient wastewater treatment: a sustainable approach for methylene blue removal

The continuous search for sustainable and cost-effective water treatment solutions led to the investigation of activated mahua seed cake for wastewater treatment. The mahua seed cake was activated using hydrogen peroxide and phosphoric acid to develop an eco-friendly adsorbent. The activated material was characterized by Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Brunauer Emmett Teller (BET) surface area analysis, and pH at zero point of charge. The results confirmed that phosphoric acid activation introduced the phosphate (PO₄³⁻) group, as demonstrated by FTIR analysis. The FESEM micrograph revealed a very porous channel-like topology that was incredibly feasible for enhancing dye uptake. Following the adsorption of methylene blue (MB) onto phosphoric acid-modified de-oiled mahua seed (PDM), the pHzpc was found to be 7.2, confirming the material’s viability in neutral pH media. The pseudo-second kinetic (R² = 0.999) and Langmuir isotherm models (R² = 0.998) were found to best describe the mechanism of interaction. The reported negative ∆G⁰ value denotes the spontaneity of the scavenging process, which is endothermic and accompanied by increased randomness. Within the first 15 min, 95% of adsorption took place, and by 45 min, it reached saturation (98.25%). Inducing > 74% regeneration with dilute hydrochloric acid provided multiple-cycle reusability. Industrial wastewater was successfully treated up to 56.77%. With a neutral pH range, the material performs well with an adsorption ability of 60.15 mg/g. These findings suggest that phosphoric acid-activated mahua seed cake is a viable and sustainable option for wastewater treatment.

Graphical abstract