Synergistic adsorption-photocatalysis-PDS activation system based on CTAB-modified geopolymer/Ag9(SiO4)2NO3/g-C3N4 for efficient moxifloxacin degradation

The construction of a synergistic adsorption-photocatalysis-peroxydisulfate (PDS) activation system holds great promise for efficient organic pollutants degradation. Herein, cetyltrimethylammonium bromide (CTAB)-modified geopolymer/Ag 9 (SiO 4 ) 2 NO 3 /g-C 3 N 4 (GACC) adsorbent-photocatalyst powder and porous membranes were rationally designed by combining geopolymerization and co-precipitation reactions. The CTAB was successfully introduced to endow the material with positively charged active sites via electrostatic anchoring and hydrophobic assembly. This enabled GACC to effectively capture of both negatively charged PDS and positively charged or zwitterionic moxifloxacin (MOX) species within a wide range of pH values. And the outstanding adsorption response capability of GACC exhibited rapid adsorption-degradation kinetic matching without pre-adsorption. The introduction of CTAB increased the specific surface area, and broadened the visible-light absorption range and reduced the band gap, thereby enhancing charge separation efficiency and facilitating PDS activation. Additionally, the fluorescence lifetime of GACC was found to be prolonged, and the electric double-layer capacitance (C dl ) results confirmed that CTAB facilitated the increase of available active sites. Under simulated sunlight, the GACC powder achieved a MOX removal efficiency of 93.67% within 10 min. Moreover, the GACC porous membranes prepared via H 2 O 2 foaming exhibited comparable degradation performance to powder counterpart (94.10% at 30 min). Furthermore, under dynamic conditions, these membranes exhibited excellent recyclability, highlighting their potential for practical applications. Mechanistic studies revealed that photogenerated electrons dominated PDS activation, while h + , ·OH, ·O 2 − , ·SO 4 − , and 1 O 2 collectively contributed to MOX degradation. This work provides a promising strategy for designing high-performance monolithic adsorbent-photocatalyst systems with synergistic adsorption-photocatalysis-PDS activation for efficient and sustainable wastewater treatment.