Singlet oxygen-dominated peroxymonosulfate activation by wastewater-borne copper phthalocyanine for simultaneous dye degradation and pigment recovery.

The coexistence of high-value pigment copper phthalocyanine (CuPc) and synthetic dyes in textile wastewater presents a dual challenge of environmental pollution and resource wastage. Herein, a novel singlet oxygen (1O2)-dominated self-derived catalytic system was developed to simultaneously degrade rhodamine B (RhB) and recover valuable CuPc. Instead of requiring of the addition of external catalysts, wastewater-borne CuPc acted as an efficient heterogeneous activator for peroxymonosulfate (PMS). The system achieved 93.1% RhB removal within 30 min with an apparent rate constant of 0.089 min-1, significantly outperforming the individual systems. Mechanistic studies combined with theoretical calculations revealed that the unique Cu-N4 active sites facilitated PMS activation to generate 1O2 as the primary reactive oxygen species. This 1O2-dominated pathway enabled the selective oxidation of electron-rich RhB while preserving the electron-deficient CuPc macrocycle, resulting in an over 80% recovery yield of CuPc. The system exhibited robust performance across a wide pH range (3.0-11.0) and in the presence of interfering anions. Moreover, the practical applicability of the system was further validated in simulated textile wastewater. This work provides a cost-effective, waste-derived catalytic strategy for complex textile wastewater treatment, promoting both pollution control and circular resource recovery.