Application of Agrowaste-based Hydrochar as Soil Amendments and Its Utilization for Lead Adsorption

Lead (Pb) contamination in Bangladesh requires cost-effective and sustainable remediation solutions to protect the population from devastating health consequences. This study attempted to develop a convenient method to reduce the amount Pb from soil. Chicken feather hydrochar (CFH) was prepared by hydrothermal carbonization (HTC) at 160 ℃ for 3 h. Subsequently, a CFH-soil mixture was used for Pb adsorption via several batch adsorption experimental parameters; initial concentration, temperature, contact time, and pH. The study investigated the adsorption equilibrium, isotherms, kinetics, as well as the thermodynamics, specifically analyzing the impact of the initial pH on the removal process. The findings revealed that the Langmuir model provided a more accurate explanation of the adsorption process than the Freundlich model. The highest limits of adsorption capacities were 671.1, 1426, and 1044 mg/g at 30, 40, and 50 ℃ respectively, according to Langmuir model. The study also showed that there was an increase of adsorption capacity (233 mg/g) up to pH 4 and then gradually decreased. This may be due to the pH point of zero charge (pHpzc) of 4.5. The most accurate depiction of the kinetic data was provided by the pseudo-second-order kinetic model. In a thermodynamic analysis, it was determined that adsorption is a spontaneous, practical, endothermic process that has a strong affinity for Pb. The study highlights CFH as a promising solution for mitigating Pb contamination in soil. Additional micro-level field trials are necessary to evaluate the CFH's effectiveness in practical applications.