PREPARATION OF BIOCHAR FROM WASTE NUTSHELLS AND ITS APPLICATION IN NITROGEN-CONTAINING WASTEWATER TREATMENT
Keywords:
Nutshell biochar, Agricultural waste, Iron modification, Nitrogen pollutantsAbstract
Due to their unique pore structures and physicochemical properties, agricultural nutshell wastes serve as ideal precursors for the preparation of biomass biochar. However, traditional nutshell-derived biochars exhibit limitations in adsorption selectivity and capacity, showing poor removal efficiency for nitrate and nitrite nitrogen from rural domestic wastewater. In this study, walnut shells were used as feedstock to prepare pristine biochar via carbonization and physical activation. Subsequently, the biochar was modified through oscillatory impregnation with acid, alkali, and Fe³⁺ loading. The effects of modification conditions, adsorbent dosage, and adsorption time on the removal efficiency of the target nitrogen pollutants were investigated. The results indicated that the biochar achieved the optimal removal efficiency for the target nitrogen pollutants under the following conditions: a carbonization temperature of 700°C, Fe³⁺ modification, an Fe³⁺ loading ratio of 20%, an adsorbent dosage of 2.0 g, and an adsorption time of 60 min. Featuring simple operation and controllable costs, this process achieves the dual goals of “high-value utilization of waste” and “water pollution control”.References
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