Functionalized biochar from vegetable waste for phosphorus removal from aqueous solution and its potential use as a slow-release fertilizer

Abstract

Agricultural runoff of phosphorus leads to the loss of this critical nutrient into the waterbodies and causes environmental problems like eutrophication. To tackle the growing concern, functionalized biochar as an adsorbent provides a sustainable method to capture the phosphorus from wastewater. Additionally, the P-laden biochar as a slow-release fertilizer improves plant nutrient uptake and crop yield. In this work, metal chloride-doped biochar derived from non-edible vegetable waste was prepared and applied as an adsorbent. Zinc chloride-doped biochar (ZBC) showed a better phosphorus adsorption capacity of 47.83 mg/g among the prepared biochar. The desorption study suggested that around 42 % of total adsorbed P was released within 336 h. The growth of mung plants over 70 days was monitored, along with mung bean yield, to assess the effectiveness of P-laden ZBC as a slow-release phosphorus fertilizer. The presented approach of non-edible waste valorization into slow-release fertilizer could contribute to tackling nutrient depletion and achieving a circular economy.