Sharma Lalita, Rohilla Jyoti, Ingole Pravin P, Halder Aditi
School of Chemical Sciences, Indian Institute of Technology Mandi, Kamand 175005, India.
Department of Chemistry, Indian Institute of Technology Delhi, New Delhi 110016, India.
ACS Mater Au. 2024 Mar 1;4(5):459-467. doi: 10.1021/acsmaterialsau.4c00006. eCollection 2024 Sep 11.
Electrocoagulation (EC) as a wastewater treatment process for the removal of pollutants has been demonstrated in numerous studies. However, proper management of solid waste generated after EC treatment is essential to minimize its environmental impact. Hence, more emphasis needs to be paid towards unused solid waste after EC treatment. The present study investigates the possibilities of utilizing waste released after the EC process as an electrocatalyst in the presence of sunlight. In this study, the sludge produced after domestic wastewater treatment by the EC process is collected and tested for water oxidation reaction under AM 1.5 illumination of simulated solar light. The sludge produced after EC treatment was characterized meticulously and confirmed to be the magnetite phase of iron oxide, which is used as a photoanode for photoelectrochemical (PEC) water splitting. The chemical composition of sludge is majorly dependent on the treatment time, which plays a crucial role in deciding the metal ions present in the sludge. After 30 min, which is the optimized time for EC treatment, sludge was studied as an efficient photoanode material. The band gap illumination of sludge (iron oxide) as working electrodes results in anodic current; the photocurrent appears at a bias of ca. 390 mV with respect to the flat-band potential. The PEC activity of waste is treatment-time dependent and decreases after reaching an optimal time of 30 min. A photocurrent density of 4.6 × 10 A cm was found at the potential of 1.23 V (vs RHE) for sludge collected after 30 min of treatment time. It indicates that the sludge-derived photoanode has the potential to be an efficient component in PEC systems, contributing to the overall efficiency of water-splitting processes. Our experimental results show a new pathway of a waste to energy approach that aligns with the principles of circular economy and sustainable resource management.
电凝（EC）作为一种去除污染物的废水处理工艺，已在众多研究中得到证实。然而，对EC处理后产生的固体废物进行妥善管理对于将其环境影响降至最低至关重要。因此，需要更加重视EC处理后的未使用固体废物。本研究探讨了在阳光照射下将EC过程后释放的废物用作电催化剂的可能性。在本研究中，收集了通过EC工艺处理生活污水后产生的污泥，并在模拟太阳光的AM 1.5光照下测试其水氧化反应。对EC处理后产生的污泥进行了细致表征，证实其为氧化铁的磁铁矿相，用作光电化学（PEC）水分解的光阳极。污泥的化学成分主要取决于处理时间，处理时间在决定污泥中存在的金属离子方面起着关键作用。在30分钟（即EC处理的优化时间）后，将污泥作为一种高效的光阳极材料进行了研究。以污泥（氧化铁）作为工作电极的带隙光照会产生阳极电流；光电流出现在相对于平带电位约390 mV的偏压下。废物的PEC活性取决于处理时间，在达到30分钟的最佳时间后会降低。对于处理30分钟后收集的污泥，在1.23 V（相对于可逆氢电极）的电位下发现光电流密度为4.6×10 A/cm²。这表明污泥衍生的光阳极有潜力成为PEC系统中的高效组件，有助于提高水分解过程的整体效率。我们的实验结果展示了一种符合循环经济和可持续资源管理原则的废物转化为能源的新途径。
