MXene/biochar composites for enhanced wastewater reclamation and bioenergy production: A kinetics and thermodynamics...

The study explores the synthesis and utilization of biochar (BC) and multi-layer MXene to MXene/biochar (MB) composites for wastewater treatment. Simultaneously, it also investigates their energy generation potential through biomass and soil property assessments. The integrated column and batch treatments have shown significant results, elevating total dissolved solids from 63.7 to 125.5 mg L^-1 with column treatment, while reducing them to 6.37 % and 1.35 % with BC and MB treatment, respectively. BC with high carbon content, demonstrated increased hydrophobicity, which was amplified by the integration of MXene, thereby enhancing its potential for advanced wastewater treatment. Treated wastewater exhibited elevated nutrient concentrations (Ca, Cu, Fe, K, Na, and NH₄⁺), promoting the growth of Pennisetum purpureum. WW_B shows promising energy potential, with a higher heating value of 25.03 MJ kg^-1 and a lower heating value of 23.57 MJ kg^-1. They demonstrated high volatile matter exceeding 70.9 wt %, and a fixed carbon from 10.02 to 27.53 wt %, signifying their potential for efficient conversion and bio-oil yield during pyrolysis. The ultimate analysis emphasized significant carbon, with oxygen content ranging from 43.42 to 47.78 wt %., influencing combustion characteristics. MT_B exhibited its suitability for energy production through thermochemical conversion, underlined by its high flammability and low volatile ignition values. In the absence of BC, the E_a ranged from 24.77 to 77.88 kJ mol^-1 in wastewater and from 21.67 to 69.6 kJ mol^-1 in MB treated wastewater. Meanwhile, when soil contained BC and was irrigated with wastewater, the E_a varied from 24.66 to 80.91 kJ mol^-1. In the case of MB treated wastewater, it ranged from 25.01 to 75.79 kJ mol^-1. The research thereby affirms the potential of MB composites to advance water and energy sustainability setting us for broader nexus-based applications.