Kan Xurundong, Suo Yao, Shi Bingfei, Zheng Yan, Liu Zaiqiong, Ma Wenhui, Li Xianghong, Zhang Jianqiang
College of Materials and Chemical Engineering, Southwest Forestry University, Kunming 650224, China.
International Union Laboratory of China and Malaysia for Quality Monitoring and Evaluation of Agricultural Products in Yunnan, School of Biology and Chemistry, Pu'er University, Pu'er 665000, China.
Molecules. 2025 Jun 27;30(13):2769. doi: 10.3390/molecules30132769.
Biochar-based adsorbents synthesized from agricultural wastes have emerged as economical and environmentally sustainable materials for water purification. In this study, coffee shell-derived biochars were synthesized via pyrolysis at 500 and 700 °C, with and without water washing, and comprehensively characterized to evaluate their potential for removing Rhodamine B (RhB) from aqueous solution. Structural and surface analyses indicated that a higher pyrolysis temperature enhanced pore development and aromaticity, whereas water washing effectively removed inorganic ash, thereby exposing additional active sites. Among all samples, water-washed biochar pyrolyzed at 700 °C (WCB700) exhibited the highest surface area (273.6 m/g) and adsorption capacity (193.5 mg/g). The adsorption kinetics conformed to a pseudo-second-order model, indicating chemisorption, and the equilibrium data fit the Langmuir model, suggesting monolayer coverage. Mechanism analysis highlighted the roles of π-π stacking, hydrogen bonding, electrostatic interaction, and pore filling. Additionally, WCB700 retained more than 85% of its original capacity after five regeneration cycles, demonstrating excellent stability and reusability. This study presents an economical approach to valorizing coffee waste as well as provides mechanistic insights into optimizing biochar surface chemistry for enhanced dye removal. These findings support the application of engineered biochar in scalable and sustainable wastewater treatment technologies.
由农业废弃物合成的生物炭基吸附剂已成为用于水净化的经济且环境可持续的材料。在本研究中，通过在500和700°C下热解合成了咖啡壳衍生的生物炭，有无水洗处理，并进行了全面表征以评估其从水溶液中去除罗丹明B（RhB）的潜力。结构和表面分析表明，较高的热解温度促进了孔隙发展和芳香性，而水洗有效地去除了无机灰分，从而暴露出更多活性位点。在所有样品中，700°C下热解的水洗生物炭（WCB700）表现出最高的比表面积（273.6 m/g）和吸附容量（193.5 mg/g）。吸附动力学符合准二级模型，表明是化学吸附，平衡数据符合朗缪尔模型，表明是单层覆盖。机理分析突出了π-π堆积、氢键、静电相互作用和孔隙填充的作用。此外，WCB700在五个再生循环后保留了超过85%的原始容量，显示出优异的稳定性和可重复使用性。本研究提出了一种将咖啡废料增值的经济方法，并为优化生物炭表面化学以增强染料去除提供了机理见解。这些发现支持了工程生物炭在可扩展和可持续废水处理技术中的应用。
