A novel composite, biochar derived from spent coffee grounds with immobilized TiO₂ (biochar–TiO₂) was prepared, characterized, and applied as an alternative, effective, and sustainable photocatalyst for degrading diclofenac from aqueous solution. Composites with different mass ratios between TiO₂ and biochar were prepared by mechanical mixing and subsequent pyrolysis in an inert atmosphere of N₂ at 650°C. The sample with biochar–TiO₂ ratio of 1:1 presented a degradation efficiency of 90% at just 120 min versus 40% for TiO₂ used as reference. This fact is associated with a set of intrinsic characteristics obtained during the formation of the composite, such as superior pore size, avoiding the recombination of the ē/h⁺ pair, bandgap reduction, and promotion of reactive oxygen species due to phenolic groups present on the biochar surface. The dominant reactive species involved during the photocatalytic degradation of diclofenac were h⁺ and ^•OH. The diclofenac degradation pathways were determined based on the identification of intermediates and nonpurgeable organic carbon (NPOC) analysis. The novel biochar–TiO₂ composite prepared in this work showed high physical–chemical stability and efficiency over five consecutive cycles of reuse, proving to be a highly promising photocatalyst for degrading diclofenac in water.

中文翻译：

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将用过的咖啡渣转化为生物炭是有希望的TiO2载体，可有效降解水中的双氯芬酸

制备，表征和表征了一种新颖的复合材料，其由废咖啡渣中固定化的TiO ₂（biochar–TiO ₂）衍生而来，并被用作替代，有效且可持续的光催化剂，用于从水溶液中降解双氯芬酸。通过机械混合并随后在N ₂的惰性气氛中于650°C下进行热解，制备了TiO ₂与生物炭之间质量比不同的复合材料。生物炭-TiO ₂比例为1：1的样品在120分钟内的降解效率为90％，而TiO ₂为40％用作参考。这一事实与在复合材料形成过程中获得的一组固有特性有关，例如优异的孔径，避免了ē / h ⁺对的重组，带隙减少以及由于存在于基团上的酚基团而促进了活性氧的产生。生物炭表面。双氯芬酸的光催化降解过程中涉及的主要反应物种为h ⁺和^• OH。基于中间体的鉴定和不可净化的有机碳（NPOC）分析，确定了双氯芬酸的降解途径。新型生物炭–TiO ₂ 这项工作中制备的复合材料在五个连续的重复使用周期中显示出很高的物理化学稳定性和效率，被证明是降解水中双氯芬酸的极有希望的光催化剂。