Yang Yicheng, Wan Yongshan, Chen Jianjun, Chen Hao, Li Yuncong, Muñoz-Carpena Rafael, Zheng Yulin, Huang Jinsheng, Zhang Yue, Gao Bin
Department of Agricultural and Biological Engineering, University of Florida, Gainesville, FL 32611, USA.
US EPA Center for Environmental Measurement and Modeling, Gulf Breeze, FL 32561, USA.
Water (Basel). 2025 Mar 2;17(6):881. doi: 10.3390/w17060881. Epub 2025 Mar 19.
Caffeine in aquatic ecosystems is an emerging contaminant causing significant environmental concern. In this work, spent coffee ground (SCG) was pyrolyzed at 300, 450, and 600 °C to produce pristine SCG biochars (CG), which were then ball-milled to produce ball-milled SCG biochars (BMCG). A batch experiment with ball-milled and pristine biochars showed that ball-milled biochars pyrolyzed at 450 °C and 600 °C had the highest capacities to adsorb caffeine. Subsequently, ball-milled CG450 (BMCG450) was selected for further analysis. The results showed that ball milling dramatically augmented the specific surface area and oxygen-containing functional groups of the biochar. The Langmuir maximum caffeine adsorption capacity was 82.65 mg/g. Both solution pH and ionic strength affected caffeine removal by BMCG450. As pH increased, increased electrostatic repulsion limited caffeine adsorption onto the biochar. However, an increase in ion strength slightly enhanced caffeine adsorption because of the electrostatic screening effect of cations. The ball-milled SCG biochar also showed high adsorption efficiency in a completely mixed flow reactor under continuous flow conditions. Our study indicates that ball-milled SCG biochar at 450 °C can serve as a viable sorbent for the removal of caffeine from water.
咖啡因在水生生态系统中是一种新出现的污染物，引发了重大的环境问题。在这项工作中，将咖啡渣（SCG）在300、450和600℃下进行热解，以制备原始SCG生物炭（CG），然后对其进行球磨以制备球磨SCG生物炭（BMCG）。一项使用球磨生物炭和原始生物炭的批次实验表明，在450℃和600℃下热解的球磨生物炭具有最高的咖啡因吸附能力。随后，选择球磨CG450（BMCG450）进行进一步分析。结果表明，球磨显著增加了生物炭的比表面积和含氧官能团。朗缪尔最大咖啡因吸附容量为82.65mg/g。溶液pH值和离子强度均影响BMCG450对咖啡因的去除。随着pH值升高，静电斥力增加限制了咖啡因在生物炭上的吸附。然而，离子强度的增加由于阳离子的静电屏蔽效应而略微增强了咖啡因的吸附。球磨SCG生物炭在连续流动条件下的完全混合流反应器中也表现出高吸附效率。我们的研究表明，450℃下的球磨SCG生物炭可作为从水中去除咖啡因的可行吸附剂。
