MFO@NZVI/hydrogel for sulfasalazine degradation: Performance, mechanism and degradation pathway

Rational synthesis of two isostructural thiophene-containing metal-organic frameworks toward photocatalytic degradation of organic pollutants

In this work, thiophene moieties (as the crucial functional groups) have been successfully incorporated into the skeleton of metal-organic frameworks (MOFs) by using thienyl-substituted triazole ligands. Reaction of AgCF3SO3 with 3-phenyl-5-(2-thienyl)-1,2,4-triazole (PTTzH) or 3,5-bis(2-thienyl)-1,2,4-triazole (BTTzH) afforded two isostructural MOFs (AgTz-3 and AgTz-4) in gram-scale. AgTz-4 with higher thiophene content showed significantly stronger photocatalytic activity than AgTz-3 with lower thiophene content. Noteworthy, the photodegradation rate constants of AgTz-4 were 0.055 mg·L-1·min-1 for rhodamine B and 0.24 min-1 for salazosulfapyridine, which is comparable or even higher than some MOF-based materials reported in the literature. More importantly, AgTz-4 demonstrated good reusability and stability after four cycles of photodegradation. Our experimental results revealed that the enhanced photodegradation efficiency can be attributed to the increased light absorption capacity and optimized band structure of Ag-MOFs resulting from the introduction of thiophene groups into MOF structures.

Evaluation of the photodegradation activity of bismuth oxoiodide/bismuth sub-carbonate nanocatalyst: Experimental design and the mechanism study

In this study, a binary BiOI/(BiO)2CO3 catalyst was prepared and used for sulfasalazine (SSZ) photodegradation in an aqueous phase. The semiconductors were identified by XRD, SEM-EDX, and UV-Vis diffuse reflectance spectroscopy (DRS) methods. Applying the Kubelka-Munk model on DRS results, the band gap energies of 2.09, 3.5, and 2.07 eV were obtained for BiOI, (BiO)2CO3, and BiOI/(BiO)2CO3 samples. pHpzc values of 6.3, 10.1, and 8.1 were estimated for BiOI, (BiO)2CO3, and BiOI/(BiO)2CO3, respectively. After observing the boosted photocatalytic activity by the coupled system, the interaction effects of the influencing variables in SSZ photodegradation were evaluated via the response surface methodology (RSM) approach. The optimal RSM-run conditions were 8.5 ppm SSZ at pH 8, which contained 0.28 g/L of the BiOI/(BiO)2CO3 catalyst and 29 min illumination time, resulting in 87% SSZ photodegradation. The effects of some scavenging agents were also studied to elucidate the relative roles of the reactive species in the SSZ photodegradation by the proposed catalyst, that is, hydroxyl radicals ∼ photoinduced electrons > superoxide radicals ∼ photoinduced holes. The proposed catalyst retained good activity after 5 successive reusing runs.

High interfacial charge separation in visible-light active Z- scheme g-C3N4/MoS2 heterojunction: Mechanism and degradation of sulfasalazine

Examination of highly proficient photoactive materials for the degradation of antibiotics from the aqueous solution is the need of the hour. In the present study, a 2D/2D binary junction GCM, formed between graphitic-carbon nitride (g-C3N4) and molybdenum disulphide (MoS2), was synthesized using facile hydrothermal method and its photo-efficacy was tested for the degradation of sulfasalazine (SUL) from aqueous solution under visible-light irradiation. Morphological analysis indicated the nanosheets arrangement of MoS2 and g-C3N4. The visible-light driven experiments indicated that 97% antibiotic was degraded by GCM-30% within 90 min which was found to be quite high than pristine g-C3N4 and MoS2 at solution pH of 6, GCM-30% dose of 20 mg, and SUL concentration of 20 mgL-1. The degradation performance of GCM-30% was selectively improved due to enhanced visible-light absorption, high charge carrier separation, and high redox ability of the photogenerated charges which was induced by the effective Z-scheme 2D/2D heterojunction formed between g-C3N4 and MoS2. The reactive radicals as determined by the scavenging study were •O2-, and h+. A detailed degradation mechanism of SUL by GCM-30% was also predicted based on the detailed examination of the band gaps of g-C3N4 and MoS2.