Activation of hydrochar derived from food waste via hydrothermal carbonization for Cu(II) adsorption

Currently, heavy metal pollution is a challenge that needs to be solved urgently, and there is a broad prospect for food waste(FW) utilization. In this paper, activated hydrochar (AHC) made from FW according to actual proportion was produced by hydrothermal carbonization (HTC) and activated with K₂CO₃. The effects of the AHC on Cu(II) adsorption were investigated using static adsorption experiments. The results indicated that the sample fabricated at 160°C (FW-160) for 6 h had the best adsorption performance with the maximum adsorption amount of Cu(II) (36.77 mg/g). The oxygenated functional group on the surface of FW-160 was observed. The pseudo-second-order kinetic model fitted the experimental results better, which proved that chemisorption was the main adsorption mechanism, and the surface complexations, including oxygenated functional groups, were the predominant factors in hydrochar(HC) sorption for Cu(II). The adsorption amount of the sample simulating rotten FW with Aspergillus niger (FW-160A) was 24.82 mg/g. Through the HTC process, the rotten FW can be made into heavy metal absorbents which can be stored for long term, and finally realize the reduction of volume and cost of storage.

当前，重金属污染是亟待解决的环境难题，餐厨垃圾（Food Waste, FW）的资源化利用拥有广阔前景。本文以餐厨垃圾为原料，按实际配比通过水热碳化（Hydrothermal Carbonization, HTC）工艺制备活化水热炭（Activated Hydrochar, AHC），并以K₂CO₃对其进行活化改性。通过静态吸附实验，探究了该活化水热炭对Cu(II)的吸附性能。结果表明，在160℃下制备6小时的样品（FW-160）吸附性能最优，对Cu(II)的最大吸附量可达36.77 mg/g。经表征观测到FW-160表面存在含氧官能团。准二级动力学模型能够更好地拟合实验数据，表明化学吸附为该吸附过程的主导机制，而包括含氧官能团在内的表面络合作用是水热炭（Hydrochar, HC）吸附Cu(II)的关键影响因素。经黑曲霉（Aspergillus niger）模拟腐熟的餐厨垃圾制备的样品（FW-160A），其吸附量为24.82 mg/g。通过水热碳化工艺，可将腐熟餐厨垃圾制备为可长期储存的重金属吸附剂，最终实现餐厨垃圾的减量化与存储成本降低。