Efficient preparation of potassium humate from waste vegetable leaves: Development of a Cu2O@HAK catalyst and innovative application of hydrothermal method

With ongoing economic development, the generation of waste vegetable leaves (WVL) has surged, posing significant environmental risks if not properly managed. To address this challenge, our study developed a copper-based catalyst (Cu 2 O@HAK) derived from WVL, which efficiently catalyzed the conversion of these leaves into artificial potassium humate (C-K-Cu-HAK). Notably, the yield of C-K-Cu-HAK increased from 40.18 % to 95.34 % with the addition of this catalyst. Optimization of the hydrothermal degradation process using response surface methodology (RSM) identified the optimal conditions: a catalyst dosage of 5 %, a reaction temperature of 150 °C, a reaction time of 7 h, and a KOH concentration of 0.6 mol/L. Under these conditions, the extraction efficiency reached 95.25 %. The resulting C-K-Cu-HAK product not only exceeded Chinese national standards for soluble humic acid (HA) content (65.42 %) and K 2 O content (15.48 %), but also demonstrated superior performance in hydroponic trials, significantly enhancing seed germination and plant growth compared to commercial potassium humate (HAK). This study tackles the environmental burden of WVL while introducing an efficient copper-based catalyst that significantly enhances HAK yield. These findings have important implications for environmental protection and sustainable resource utilization, offering a novel approach to HAK production with broad application potential.