NiO/TiO2 adsorbent for efficient removal of toxic gas phosphine and recycling of spent adsorbent for photocatalytic degradation of malachite green (MG)

Efficient removal of the highly toxic gas phosphine (PH 3 ) from various exhaust gases is a major challenge. To address this, we developed a cost-effective NiO/TiO 2 adsorbent (Ni X /TiO 2 ) via facile impregnation, achieving efficient anaerobic PH 3 removal at a low temperature (350 °C) with an exceptional breakthrough capacity of 232.23 mg(PH 3 ) g −1 . Characterization revealed that superior performance stems from abundant surface basic sites, developed porosity, and strong NiO-TiO 2 interfacial interactions promoting PH 3 adsorption and dissociation. During PH 3 capture, phosphorus incorporation transforms active NiO into Ni 2 P species, leading to adsorbent deactivation. Crucially, recognizing the photocatalytic potential of both TiO 2 and Ni 2 P, we repurposed the spent adsorbent as a Ni 2 P/TiO 2 heterojunction photocatalyst. Proof-of-concept experiments demonstrated its high efficacy in visible-light-driven wastewater treatment, achieving 91 % degradation of malachite green (MG). This work advances PH 3 purification technology while establishing a sustainable circular economy strategy via repurposing deactivated adsorbents into photocatalysts, aligning with resource conservation and recycling.