Liu Qing, Ying Wanying, Gou Hailing, Li Minghui, Huang Ke, Xu Renyuan, Ding Guanzhi, Wang Pengyu, Chen Shuoping
College of Materials Science and Engineering, Guilin University of Technology, Guilin 541004, China.
Nanomaterials (Basel). 2024 Dec 31;15(1):51. doi: 10.3390/nano15010051.
This study is the first to convert two waste materials, waste rice noodles (WRN) and red mud (RM), into a low-cost, high-value magnetic photocatalytic composite. WRN was processed via a hydrothermal method to produce a solution containing carbon quantum dots (CQDs). Simultaneously, RM was dissolved in acid to form a Fe ion-rich solution, which was subsequently mixed with the CQDs solution and underwent hydrothermal treatment. During this process, the Fe ions in RM were transformed into the maghemite (γ-FeO) phase, while CQDs were incorporated onto the γ-FeO surface, resulting in the CQDs/γ-FeO magnetic photocatalytic composite. Experimental results demonstrated that the WRN-derived CQDs not only facilitated the formation of the magnetic γ-FeO phase but also promoted a synergistic interaction between CQDs and γ-FeO, enhancing electron-hole pair separation and boosting the production of reactive radicals such as O and ·OH. Under optimized conditions (pH = 8, carbon loading: 10 wt%), the CQDs/γ-FeO composite exhibited good photocatalytic performance against methylene blue, achieving a 97.6% degradation rate within 480 min and a degradation rate constant of 5.99 × 10 min, significantly outperforming RM and commercial γ-FeO powder. Beyond methylene blue, this composite also effectively degraded common organic dyes, including malachite green, methyl violet, basic fuchsin, and rhodamine B, with particularly high efficiency against malachite green, reaching a degradation rate constant of 5.465 × 10 min. Additionally, due to its soft magnetic properties (saturation magnetization intensity: 16.7 emu/g, residual magnetization intensity: 2.2 emu/g), the material could be conveniently recovered and reused after photocatalytic cycles. Even after 10 cycles, it retained over 98% recovery and 96% photocatalytic degradation efficiency, underscoring its potential for cost-effective, large-scale photocatalytic water purification.
本研究首次将两种废料——废弃米粉（WRN）和赤泥（RM）转化为低成本、高价值的磁性光催化复合材料。通过水热法对WRN进行处理，以制备含有碳量子点（CQDs）的溶液。同时，将RM溶解在酸中形成富含铁离子的溶液，随后将其与CQDs溶液混合并进行水热处理。在此过程中，RM中的铁离子转变为磁赤铁矿（γ-FeO）相，而CQDs则结合到γ-FeO表面，从而得到CQDs/γ-FeO磁性光催化复合材料。实验结果表明，由WRN衍生的CQDs不仅促进了磁性γ-FeO相的形成，还促进了CQDs与γ-FeO之间的协同相互作用，增强了电子-空穴对的分离，并提高了诸如O和·OH等活性自由基的产生。在优化条件（pH = 8，碳负载量：10 wt%）下，CQDs/γ-FeO复合材料对亚甲基蓝表现出良好的光催化性能，在480分钟内实现了97.6%的降解率，降解速率常数为5.99×10 min，显著优于RM和商业γ-FeO粉末。除亚甲基蓝外，该复合材料还能有效降解常见有机染料，包括孔雀石绿、甲基紫、碱性品红和罗丹明B，对孔雀石绿的降解效率尤其高，降解速率常数达到5.465×10 min。此外，由于其软磁性能（饱和磁化强度：16.7 emu/g，剩余磁化强度：2.2 emu/g），该材料在光催化循环后可方便地回收再利用。即使经过10次循环，其回收率仍超过98%，光催化降解效率仍为96%，突出了其在经济高效、大规模光催化水净化方面的潜力。
