SDS‑modified geopolymer/Ag9(SiO4)2NO3/g-C3N4 for synergistic adsorption‑photocatalysis-peroxydisulfate activation toward pymetrozine degradation

SDS-modified geopolymer/Ag 9 (SiO 4 ) 2 NO 3 /g-C 3 N 4 (SGC) unites adsorption, photocatalysis and PDS activation • SGC powder removes 94.12% of pymetrozine at 2   min under simulated sunlight with 3   mM PDS. • 3D-printed SGC monolithic device achieves 96.97% removal at 60   min and stays stable over 5 dynamic cycles. • The h⁺, ·OH, ·O₂⁻, ·SO₄⁻, and ¹O₂ all contribute to PYM degradation by SGC. Photocatalysis combined with peroxydisulfate (PDS) offers a promising route for degrading organic pesticides, but rational design of adsorption and catalytic sites at the nanoscale remains challenging. Here, an innovative sodium dodecyl sulfate (SDS)-modified geopolymer/Ag 9 (SiO 4 ) 2 NO 3 /g-C 3 N 4 (SGC) adsorbent-photocatalyst was reported, which integrated rapid pollutant capture, photocatalysis and PDS activation into a synergistic system for pymetrozine (PYM) degradation. The SDS promoted the uniform intergrowth of GP nanoclusters and ASN nanocrystals on g-C 3 N 4 , and also endowed the SGC with a relatively high surface negative charge density over a wide pH range and could quickly capture cationic or zwitterionic PYM molecules via electrostatic attraction. And the SDS also enhanced the visible-light response capability and narrowed the energy band gaps of SGC, contributing to improving photogenerated charge separation and more efficient PDS activation. The SGC powder achieved a PYM removal efficiency of 94.12% within 2   min, while the 3D-printed SGC fabricated by direct ink writing exhibited a removal efficiency of 96.97% at 60   min under simulated sunlight. Mechanistic investigations revealed that photogenerated electrons were primarily responsible for PDS activation, while h + , ·OH, ·O 2 - , ·SO 4 - , and 1 O 2 all contributed to PYM oxidation. Toxicity assessment of intermediate products and seed germination tests demonstrated a marked reduction in biotoxicity following degradation treatment. Moreover, the 3D-printed SGC maintained high stability over five dynamic cycles, and the in-situ photoreduction of Ag 0 during the cyclic process helped sustain radical generation. This work provides a new design strategy for high-performance adsorption-photocatalysis-PDS synergy systems and demonstrates a practical route for sustainable pesticide wastewater treatment. Download: Download high-res image (274KB) Download: Download full-size image