When Ag3PO4 was the primary part of Ag3PO4/g-C3N4, the migration of photogenerated electron-hole showed a Z-scheme mechanism.
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Composite or hybrid photocatalysts are gaining increasing ...interests due to the unique and enhanced photocatalytic activity. In this study, Ag3PO4/g-C3N4 with different ratios of Ag3PO4 and g-C3N4 were synthesized using a facile in situ precipitation method. The photocatalysts were characterized by transmission electron microscopy (TEM), X-ray diffraction pattern (XRD), Fourier transform infrared spectra (FTIR), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) and ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS). The photocatalytic performance was evaluated by the degradation of sulfamethoxazole (SMX), a model antibiotic compound, under visible light irradiation. It was found that the composite photocatalyst Ag3PO4/g-C3N4 with a mass ratio of Ag3PO4:g-C3N4 of 98:2 exhibited a higher photocatalytic activity than Ag3PO4/g-C3N4 with the mass ratio of 2:98 for the degradation of SMX. When Ag3PO4 was the primary part of Ag3PO4/g-C3N4 photocatalyst, the migration of photogenerated electron-hole showed a Z-scheme mechanism with photongenerated holes on the valance band of Ag3PO4 to oxidize pollutants. The separation mechanism was investigated by the photoluminescence technique and the scavengering of reactive oxygen species.
Investigating the long-term effects of microplastics (MPs) in vivo is necessary for evaluating its biological toxicity. Previously, we showed that MPs elicit vascular dysfunctions in atherosclerotic ...mice. However, the effects of long-term treatment with environmental levels of MPs on biological functions and RNA expression profiles in wild-type mice are unknown. Here, C57BL/6 mice were administered 1000 μg/L MPs through their drinking water for 180 days. Transcriptomic analyses, biochemical analysis, and histopathological examination were conducted to determine the key signals and molecular mechanisms triggered by MPs in vivo using whole transcriptome sequencing, enzyme-linked immunosorbent assay, and histopathological analysis. Notably, our data revealed that MPs aggravated vascular lesions and organ injuries, particularly liver, kidney, and heart injuries. Additionally, MPs exacerbated oxidative injuries by inhibiting the activities of antioxidant enzymes and increasing the levels of the serum biochemistry indicator of organ damage. RNA sequencing of vascular tissues showed that 674 mRNAs, 39 lncRNAs, 196 miRNAs, and 565 circRNAs were abnormally expressed in MPs-treated mice compared with the untreated group. Pathway enrichment analyses identified pathways linked to the toxicity of MPs, including lysosomal, NOD-like receptor, and peroxisome proliferator-activated receptor pathways. Additionally, competing endogenous RNA networks were constructed and hub RNAs were identified using bioinformatics analysis. Taken together, our data suggested that toxicity induced by long-term exposure to MPs continually presents with extensive changes in biological features and global gene expression profiles. Our data provides new insights into the biological toxicity of MPs.
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•MPs aggravated vascular lesions and organ injuries, especially of the liver, kidney, and heart.•MPs exacerbated oxidative injuries by inhibiting the activities of antioxidant enzymes and the levels of selenoenzymes.•RNA sequencing data showed that 674 mRNAs, 39 lncRNAs, 196 miRNAs, and 565 circRNAs were abnormally expressed in MP-treated mice.
A new visible-light-driven heterojunction Ag3PO4/g-C3N4 was prepared by a simple deposition-precipitation method for the degradation analysis of diclofenac (DCF), a model drug component, under ...visible-light irradiation. The heterojunction photocatalysts were characterized by a suite of tools. The results revealed that the introduction of Ag3PO4 on the surface of g-C3N4 greatly promoted its stability and light absorption performance. In addition, the effects of the heterojunction mixing ratios were studied, when the molar ratio of Ag3PO4 to g-C3N4 in the composite was 30%, the as-prepared photocatalyst Ag3PO4/g-C3N4 (30%) possessed the best photocatalytic activity toward the photodegradation of DCF, and the optimal photocatalyst showed a DCF degradation rate of 0.453 min−1, which was almost 34.8 and 6.4 times higher than those of pure g-C3N4 (0.013 min−1) and Ag3PO4 (0.071 min−1) under visible light irradiation (λ ≥ 400 nm). The trapping experimental results showed that h+, ·OH, and ·O2− were the main reactive oxygen species during the photocatalytic reaction. The improved performance of the composites was induced by the high charge separation efficiency of the photogeneration electron-hole pairs as well as the surface plasmon resonance (SPR) endowed in the Ag0 nanoparticles, and ultimately enhanced the DCF photodegradation.
► Bromide concentration, MIEX dosage and pH affect significantly bromide removal. ► The equilibrium data can be well fitted by the Freundlich isotherm model. ► The adsorption kinetics agrees with the ...pseudo second-order model. ► The intra-particle diffusion is not the only rate limiting step. ► The adsorption is an exothermic and thermodynamically spontaneous process.
It is necessary to remove bromide from raw water owing to the fact that bromide directly leads to the brominated disinfection byproducts during the disinfection process for drinking water. The adsorption characteristics of bromide by MIEX resin are investigated in a batch mode. Some factors such as initial bromide concentration, contact time, adsorbent dosage, pH of solution and coexistent anions, have significant effect on bromide removal. Five isotherm models, namely, Langmuir, Freundlich, Temkin, Dubinin–Radushkevich and Redlich–Peterson, are used to fit the equilibrium data of bromide on MIEX resin at 303K. The results show that the adsorption equilibrium can be well fitted by the Freundlich and Redlich–Peterson isotherm models. The pseudo first-order and second-order kinetics models are used to fit the kinetics process of bromide adsorption on MIEX resin. The results demonstrate the adsorption kinetics agree with the pseudo second-order model, indicating the adsorption of bromide on MIEX is chemical sorption. The intra-particle diffusion model is used to further analyze the diffusion mechanism of bromide during the adsorption process. The results imply that the intra-particle diffusion is not the only rate limiting step. The negative ΔG° values indicate that the adsorption of bromide on MIEX resin is thermodynamically feasible and is a spontaneous process. The negative ΔH° and ΔS° show that the adsorption is an exothermic process in nature and the randomness degree at the solid/liquid interface decreases after adsorption.
Propranolol (PRO) is widely detected in the aquatic environment and proved to be detrimental to multifarious aquatic organisms. In view of some virtues of sulfate radicals than hydroxyl radicals, ...advanced oxidation technologies that involve the activation of peroxymonosulfate (PMS) have stimulated wide-ranging research on the PRO removal. In this paper, a composite (C2NOMS-2) of amino-functionalized manganese octahedral molecular sieve (NOMS-2) and binuclear cobalt phthalocyanine (Co2CPc) was synthesized easily, and utilized as a catalyzer for PMS to degrade PRO in water. The apparent rate constants of PRO degradation by PMS with C2NOMS-2 as a catalyst was found to be higher than with NOMS-2, Co2CPc and the composite of uninuclear cobalt phthalocyanine (CoCPc) and NOMS-2. The catalytic ability of C2NOMS-2 was investigated under various reaction conditions: catalyst dosages (0.5–2.0 g/L), PMS doses (50–500 mg/L), initial pH (5–11), reaction temperature (20–35 °C), and natural water constituents (Cl−, HCO3−, and sodium huminate). Radical scavenging tests and electron paramagnetic resonance spectroscopy showed that 1O2 was the most critical reactive oxygen species, and conceivable mechanisms of PMS activation with C2NOMS-2 were proposed established on the curve estimation of high-resolution XPS spectra, revealing that the generation of reactive oxygen species was mainly resulted from the cycles of Mn3+/Mn4+, Co3+/Co2+ and surface lattice oxygen/surface adsorbed oxygen. The intermediate products of propranolol degradation were identified by LC-MS/MS. Cycling experiments and ion dissolution detection suggested that C2NOMS-2 could maintain satisfactory stability in an aqueous system.
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•Synthesized binuclear cobalt phthalocyanine-amino-functionalized OMS-2 (C2NOMS-2)•Heterogeneous C2NOMS-2 catalyst was highly efficient for PRO catalytic degradation.•1O2 species proved more significant than OH and SO4− in degrading PRO.•C2NOMS-2 showed good stability and high catalytic activity even after four cycles.
•Degradation of clofibric acid (CA) was studied by UV/PS and UV/chlorine.•The second-order rate constants of CA with SO4−, OH and Cl were determined.•Impacts of different conditions including oxidant ...dosage, pH, Cl− and HCO3− were discussed.•UV/chlorine was found to be more cost-effective.•The disinfection by-products (DBPs) formation was evaluated during followed chlor(am)ination.
This study investigated the UV/persulfate (UV/PS) and UV/chlorine processes as alternative method for the removal of clofibric acid (CA). The formation of disinfection byproducts (DBPs) during subsequent chlor(am)ination was also evaluated. The degradation of CA followed the pseudo-first order kinetics. The second-order rate constants of CA with SO4−, OH and Cl were respectively determined as kSO4-,CA=(1.73±0.01)×109M−1s−1, kOH,CA=(2.72±0.08)×109M−1s−1 and kCl,CA=(9.76±0.15)×1010M−1s−1. The degradation rate constant increased with increasing oxidant dosage in UV/PS and UV/chlorine processes. The degradation rate constant was found to be the highest at pH 9 and decreased dramatically at pH 11 in UV/PS process. For UV/chlorine, the rate constant continuously decreased with increasing pH from 3 to 11. Presence of HCO3− and Cl− had different effects (promotion and/or inhibition) on CA degradation in both processes. An inhibition effect was observed in the presence of NOM for the two UV-based processes. The higher CA removal in real water suggested the two processes were suitable for treating water containing CA, and the UV/chlorine was more cost-effective than UV/PS based on the total cost of electrical energy. Compared with the chlor(am)ination of CA, the UV/PS and UV/chlorine pre-oxidation significantly impacted the DBP formation during subsequent chlor(am)ination, which indicated the application of the two UV-based processes needs to be carefully balanced against the downstream effect on DBP formation.
Coagulation imposes major impact on the removal of humic acids (HAs) and the reduction of ultrafiltration (UF) membrane fouling. In this study, titanium was used instead of iron and aluminum as a ...novel alternative sacrificial anode, and the removal of HAs from water by titanium-based electrocoagulation with submerged flat sheet ultrafiltration membrane was investigated. Results clearly indicate that the current intensity did have an apparent effect on the size and fractal structure of flocs. A combination of electrocoagulation with ultrafiltration can increase HAs rejection, reduce membrane fouling and decrease transmembrane pressure. Membrane permeability and the specific resistance of cake layer were controlled directly by coagulated floc structure, which was affected strongly by the applied current intensity. Hydrous titanium dioxide (TiO2) flocs were formed by anodizing of titanium and one-step hydrolysis process with titanium salt solution. TiO2 nanoparticles with large specific surface area produced by the processes showed high photocatalytic activity. Thus, the processes are not only efficient in the removal of HAs from water but also economical in sludge recycling and reduction. It may offer a novel solution to many economic and environmental problems associated with handling iron and aluminum salt coagulation.
► Current intensity has apparent effect on the size and fractal structure of flocs. ► Membrane‐specific cake resistance is controlled by floc structure. ► Ti-EC-UF processes can increase HAs rejection and decrease hydraulic resistance. ► TiO2 flocs are formed by anodizing of titanium and one step hydrolysis process. ► EC TiO2 with large specific surface area shows high photocatalytic activity.
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► Various impact factors have effects on the removal of phosphate to some degree. ► The equilibrium data can be described by Freundlich and Koble–Corrigan models. ► The adsorption of ...phosphate on MIEX resin may be controlled by chemisorptions. ► The adsorption of phosphate on MIEX resin is mainly governed by film diffusion. ► Coexistent anions influence the adsorption of phosphate on MIEX resin.
This study investigated the potential of MIEX resin as the adsorbent for the removal of phosphate from aqueous solutions. In our batch experiments, we studied the effect of some parameters on the removal of phosphate. It was observed that uptake of phosphate was mainly affected by initial phosphate concentration, adsorbent dosage, initial pH of solution, and coexistent anions. The adsorption equilibrium data at 288K fitted well to Freundlich and Koble–Corrigan isotherm models. The kinetics studies displayed that the adsorption process followed the pseudo-second-order model. The diffusion studies showed that the intra-particle diffusion was not the only rate-controlling step and, the diffusion process of phosphate from solution to MIEX resin was controlled by film diffusion. The thermodynamics parameters were evaluated. The results showed that the adsorption process was spontaneous thermodynamically, endothermic, and entropy driven. These results have established a good potentiality for MIEX resin to be used as an adsorbent for the removal of phosphate from aqueous solutions. This work will deepen our understanding of the adsorptive characteristics of phosphate by MIEX resin and provide a better way to remove phosphate from wastewater.
Batch experiments are carried out to evaluate the adsorption performances of 2,4-D from aqueous solutions by MIEX resin. The initial 2,4-D concentration, adsorption time, adsorbent dosage, inorganic ...ions, natural organic matter, and initial pH of solution have considerable effect on the removal of 2,4-D, but temperature has less effect. The isotherm experiments show the Redlich–Peterson and Sips models are the most appropriate models to simulate the equilibrium data at 293 K. The kinetic study demonstrates the pseudo-second-order model gives a best fitting to the adsorption of 2,4-D on the resin and the intraparticle diffusion is not the only rate-controlling step. The thermodynamic parameters are calculated. The results show that the adsorption of 2,4-D on the resin is a thermodynamically spontaneous and endothermic process. Accordingly, it can be concluded that MIEX resin can potentially be employed as an adsorbent for removing 2,4-D from raw water.
•Synthesis magnetic reduced graphene oxide (RGO)-Fe3O4 non-nano composite.•The non-nano composite can reduce cell toxicity in water treatment processes.•The composite is effective for fast chromium ...removal from aqueous solution.•The RGO-Fe3O4 can be easily separated from water under an external magnetic field.
A simple one step solvotermal strategy using non-toxic and cost-effective precursors has been developed to prepare reduced graphene oxide (RGO)-Fe3O4 non-nanocomposite for removal of Cr(VI). Compared with the nano-adsorbent, the RGO-Fe3O4 hybrid particles with size larger than 100nm can reduce cell toxicity in water treatment processes. The structure, surface and magnetic characteristics of the non-nanocomposite were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET), and Vibrating sample magnetometer (VSM). The RGO-Fe3O4 composite with the highest loading of Fe3O4 demonstrates the fastest removal of 500μg/L Cr(VI) which can reach 85% within 5min at neutral pH. The adsorption kinetics follows the pseudo-second-order model and the adosorbent exhibits better Cr(VI) removal efficiency in water at low pH. However, the removal efficiency of Cr(VI) decreased when common hazardous ions were added in water. The large saturation magnetization (41.12emu/g) of the synthesized non-nanoparticles allows fast separation of the adsorbent from water. The RGO-Fe3O4 non-nanocomposite could be utilized as an efficient, stable, less toxic and magnetically separable adsorbent for environmental cleanup.
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