Alessandrino Luigi, Colombani Nicolò, Mastrocicco Micòl
DiSTABiF - Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, Campania University "Luigi Vanvitelli", Via Vivaldi 43, 81100 Caserta, Italy.
SIMAU - Department of Materials, Environmental Sciences and Urban Planning, Marche Polytechnic University, Via Brecce Bianche 12, 60131 Ancona, Italy.
Sci Total Environ. 2023 Nov 10;898:165558. doi: 10.1016/j.scitotenv.2023.165558. Epub 2023 Jul 15.
Graphene production has dramatically increased in the last years and new ways to recycle this engineered material need to be investigated. To this purpose, a reactive model network was developed using PHREEQC-3 code to quantify the relevant biogeochemical reactions induced by graphene scraps' incorporation in a calcareous sandy soil. The numerical model was calibrated versus a complete dataset of column experiments in water saturated conditions using two different fertilizers, a synthetic NPK fertilizer and fertigation water produced in a wastewater treatment plant. Column experiments consisted of 50 cm columns filled with a mixture of graphene scraps (0.015 % dry weight) and soil in the first 10 cm, while the remaining 40 cm had only soil. The model performance was tested using classical statistical indices (R, Modelling Efficiency, and Index of Agreement), resulting to be satisfactory. Besides, a simple sensitivity analysis via the perturbation of relevant parameters showed a low degree of uncertainty. The main outcome of this study was the quantification of the increased denitrification rate triggered by graphene incorporation into the soil. Moreover, graphene incorporation substantially increased soil CEC and DOC sorption capacity, demonstrating a good adsorption capacity for ammonium and organic compounds, thus decreasing nutrients leaching that represents a major concern related to agricultural practice. Indeed, Graphene incorporation increased by 40 % the CEC in the first 10 cm of the CSG_NPK column (2.50e mol/L) respect to the CS_NPK column (1.75e mol/L) and increased it by 150 % in the first 10 cm of the CSG_FW column (2.50e mol/L) in comparison with the CS_FW column 1.00e (mol/L). pH fluctuations were most likely due to the precipitation of Ca(PO)OH, indeed the consumption of H ions could have triggered the pH lowering during the experiment. These results could be relevant for future graphene applications as a soil improver or as suitable material to enhance soil bioremediation in order to include graphene in a circular economy loop.
近年来，石墨烯的产量急剧增加，因此需要研究回收这种工程材料的新方法。为此，利用PHREEQC - 3代码开发了一个反应模型网络，以量化石墨烯碎片掺入钙质砂土中引发的相关生物地球化学反应。该数值模型针对在水饱和条件下使用两种不同肥料（一种合成NPK肥料和一个污水处理厂生产的施肥水）进行的柱实验的完整数据集进行了校准。柱实验包括50厘米长的柱子，在前10厘米填充石墨烯碎片（干重0.015%）和土壤的混合物，而其余40厘米仅含土壤。使用经典统计指标（R、建模效率和一致性指数）对模型性能进行测试，结果令人满意。此外，通过对相关参数的扰动进行的简单敏感性分析显示不确定性程度较低。本研究的主要成果是量化了石墨烯掺入土壤引发的反硝化率增加。此外，石墨烯的掺入显著提高了土壤阳离子交换容量（CEC）和溶解性有机碳（DOC）吸附能力，表明对铵和有机化合物具有良好的吸附能力，从而减少了养分淋失，而养分淋失是与农业实践相关的一个主要问题。事实上，与CS_NPK柱（1.75e mol/L）相比，在CSG_NPK柱的前10厘米中，石墨烯的掺入使CEC增加了40%（2.50e mol/L）；与CS_FW柱（1.00e mol/L）相比，在CSG_FW柱的前10厘米中，CEC增加了150%（2.50e mol/L）。pH值波动最有可能是由于Ca(PO)OH的沉淀，实际上在实验过程中H离子的消耗可能引发了pH值降低。这些结果对于未来石墨烯作为土壤改良剂或作为增强土壤生物修复的合适材料的应用可能具有重要意义，以便将石墨烯纳入循环经济循环。
