Synergetic influence between adsorption and photodegradation of Rhodamine B using synthesized fly ash based inorganic polymer

•The inorganic polymer material was synthesized by geopolymerization method.•The kinetic models of adsorption-photodegradation of Rhodamine B dye by inorganic polymer composite were studied and discussed.•The synergy between adsorption-photodegradation of Rhodamine B dye was evaluated and elucidated.•The interactions between Rhodamine B dye and inorganic polymer surface were evaluated by experimental and theoretical (DFT) studies.•The inorganic polymer composite was used as a remarkable adsorbent and catalyst for Rhodamine B dye treatment. Modification of fly ash using alkaline activator medium was implemented to develop fly ash-based inorganic polymer composite as an adsorbent and catalyst. The Physico-chemical properties of prepared material were characterized using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy with Energy Dispersive X-ray (SEM/EDX), Transmission Electron Microscopy (TEM), Brunauer–Emmett–Teller (BET), Particle Size Analyzer (PSA) and UV–Vis spectroscopy (UV–Vis) analysis methods. Experimental and theoretical studies were done for the adsorption of Rhodamine B (Rh-B) on the inorganic polymer as an adsorbent. The effect of contact time was evaluated to characterize the mechanism of the Rh-B dye adsorption and photodegradation processes by inorganic polymer composite. The XRD, FTIR, SEM, PSA, and TEM characterizations showed the formation of new composite material. The bandgap of the inorganic polymer is found to be around 3.72 eV, proving the semiconductor state of this material. For a concentration of 30 mg/g, the efficiencies reach approximately 62.45 % and 31.62 %, respectively for adsorption and photodegradation processes leading to a synergistic efficiency of approximately 94.07 %. The kinetic data of Rh-B dye adsorption-photodegradation on the inorganic polymer composite were in good agreement with the pseudo-first-order model. Experimental and theoretical studies produce comparable results. From these conclusions, the inorganic polymer composite had great potential as an economical and efficient adsorbent and catalyst for removing Rh-B dye from aqueous solutions. Its application possibilities are important for the degradation and elimination of hazardous pollutants present in water. [Display omitted]