Photocarriers regulation strategy applicable to photocatalytic flow-through systems with chloroplast inspired electrode for removal and detoxification of organic-heavy metal complexes

Large abundance and severe toxicity of organic-heavy metal complexes as refractory pollutants have started to attract attention. To break through bottleneck of high energy consumption in refractory pollutant removal, a novel photocatalytic flow-through system with C3N4-Cu-TCPP/3DG (anode) and CeO2-BiOCl/3DG (cathode) using solar and resourced heavy metals was designed to simultaneously achieve decomplexation, organic pollutant removal and metal recovery for in situ utilization. Hydrothermal was applied for the photocatalytic anode and cathode electrodes preparation; batch experiment, electrochemical workstation, toxicity experiments and model analysis were used to construct the new photocatalytic system, analyze its efficiency and study its mechanism. The key to achieving efficiency in the whole photocatalytic system was the application of an “overall four-step electron-hole regulation strategy” including high electron-hole generation, separation, transfer and utilization. Multistep collaborative design effectively accomplishes “four-high” electron-hole regulation strategy, which consists of novel biomimetic structured photoanode, energy level matching between the photoanode and cathode, optimized flow-through operation mode, and photoanode oxidation combined with indirect oxidation by an in situ Fenton-like process to increase electron-hole utilization. With tetracycline (TC)-Cu complex as model pollutant, 99% decomplexation, 83.2% TC removal and 70.8% Cu recovery were realized. The solution showed to be non-toxic range after treatment. This novel system achieved high efficiency for treatment of refractory pollutants by only solar, and provide win–win situation in terms of environmental and energy considerations.