Regeneration study of MB in recycling runs over nickel vanadium oxide by solvent extraction for photocatalytic performance for wastewater treatments

Silver sulphide nanoparticles (Ag2SNPs) synthesized using Phyllanthus emblica fruit extract for enhanced antibacterial and antioxidant properties

In this study, silver sulfide nanoparticles (Ag2SNP's) were successfully produced by using fruit extracts of Phyllanthus emblica. UV-vis, FTIR, XRD with SEM and EDX techniques were used for the synthesis process and for characterization of the resulting nanostructures. According to the findings, the fabricated nanostructure had a monoclinic crystal structure, measuring 44 nm in grain size, and its strain was 1.82 × 10-3. As revealed by SEM analysis, the synthesized nanostructure consists of irregular spherical and triangular shapes. The presence of silver (Ag) and sulfur (S) was also confirmed through EDX spectra. Furthermore, Ag2S nanoparticles were tested for their ability to effectively inhibit gram-positive and gram-negative bacterial growth. As a result of this study, it was clearly demonstrated that Ag2S nanoparticles possess powerful antibacterial properties, particularly when it came to inhibiting Escherichia coli growth. Ag2S nanoparticles had high total H2O2 and flavonoid concentrations and the greatest overall antioxidant activity, according to the evaluation of antioxidant activity of the samples. The results obtained from the P. emblica fruit extract were followed by those obtained from Ag2S nanoparticles were reported in detail. RESEARCH HIGHLIGHTS: Innovative Ag2SNP synthesis using Phyllanthus emblica fruit extract. SEM with EDX revealed a monoclinic crystal structure with a grain size of 44 nm and a strain of 1.82 × 10-3. Many of these applications are demonstrated by the potential of Ag2SNPs to treat and combat bacteria, particularly Escherichia coli. A peak at 653 cm-1 indicates the presence of primary sulfide aliphatic C-S extension vibrations. The abundant H2O2 and NO2 found in P. emblica nanocomposites make them potent antioxidants.

Time-Dependent Hydrothermal Synthesis of La2O3 NPs for Effective Catalytic Activity of Ionic Dye

Lanthanum oxide was successfully synthesized by hydrothermal method by varying the reaction time such as 6, 12, and 24 h. In XRD, study confirms the presence of a hexagonal structure, and the phase remains the same at different times; the main goal is to assess the average crystallite size of prepared La2O3 nanoparticles, which was found in the range of 6 to 8 nm. An interesting observation from the XRD data was the apparent increase in crystalline nature as the synthesis time was extended. The UV-Vis spectroscopic studies show a change in the band gap when the reaction time is changed. The morphology analysis shows that the image revealed that the particles formed were agglomerated and formed a spherical shape, with diameters ranging between 35 and 86 nm. When tested for photocatalytic activity, the La2O3 nanoparticles show a degradation of methylene blue dye when the time varies. Remarkably, the nanoparticles synthesized exhibited a profound ability to degrade the dye, with an efficiency rate hitting as high as 89% under halogen light illumination.

Addition of silver nanoparticles to the zinc ferrite/polyaniline composition for boosting its visible photocatalytic degradation

Enhancing the photocatalytic activity of ZnFe2O4 with a good energy band gap to degrade industrial waste under sunlight illumination can help to develop green environments. Here, to improve the photocatalytic efficiency of ZnFe2O4 ferrites, they were merged with polyaniline (PAni) and silver (Ag) nanoparticles to synthesize Ag@ZnFe2O4-PAni plasmonic nanostructures. The as-synthesized nanostructures were characterized using a series of advanced characterization techniques to confirm successful formation and investigate photocatalytic improvement origins. It was found that incorporating Ag NPs along with the PAni to ZnFe2O4 increases its absorption power and red-shifts its energy band gap, which increases the electron-hole production rate by exposure to light in ZnFe2O4. Contribution of the surface plasmon resonance effect of Ag NPs and conjugated double bonds of PAni to charge transfer mechanisms in Ag@ZnFe2O4-PAni material increased charge separation during photocatalytic process, boosting the photodegradation performance of ZnFe2O4.

AgIn5S8/g-C3N4 Composite Photocatalyst Coupled with Low-Temperature Plasma-Enhanced Degradation of Hydroxypropyl-Guar-Simulated Oilfield Wastewater

The effective treatment and recovery of fracturing wastewater has always been one of the difficult problems to be solved in oilfield wastewater treatment. Accordingly, in this paper, photocatalytic-coupled low-temperature plasma technology was used to degrade the simulated wastewater containing hydroxypropyl guar, the main component of fracturing fluid. Results indicated that hydroxypropyl-guar wastewater could be degraded to a certain extent by either photocatalytic technology or plasma technology; the chemical oxygen demand and viscosity of the treated wastewater under two single-technique optimal conditions were 781 mg·L-1, 0.79 mPa·s-1 and 1296 mg·L-1, 1.01 mPa·s-1, respectively. Furthermore, the effective coupling of AgIn5S8/gC3N4 photocatalysis and dielectric-barrier discharge-low-temperature plasma not only enhanced the degradation degree of hydroxypropyl guar but also improved its degradation efficiency. Under the optimal conditions of coupling treatment, the hydroxypropyl-guar wastewater achieved the effect of a single treatment within 6 min, and the chemical oxygen demand and viscosity of the treated wastewater reduced to below 490 mg·L-1 and 0.65 mPa·s-1, respectively. In the process of coupled treatment, the AgIn5S8/gC3N4 could directly absorb the light and strong electric field generated by the system discharge and play an important role in the photocatalytic degradation, thus effectively improving the energy utilization rate of the discharge system and enhancing the degradation efficiency of hydroxypropyl guar.

Application of Electrochemical Oxidation for Water and Wastewater Treatment: An Overview

In recent years, the discharge of various emerging pollutants, chemicals, and dyes in water and wastewater has represented one of the prominent human problems. Since water pollution is directly related to human health, highly resistant and emerging compounds in aquatic environments will pose many potential risks to the health of all living beings. Therefore, water pollution is a very acute problem that has constantly increased in recent years with the expansion of various industries. Consequently, choosing efficient and innovative wastewater treatment methods to remove contaminants is crucial. Among advanced oxidation processes, electrochemical oxidation (EO) is the most common and effective method for removing persistent pollutants from municipal and industrial wastewater. However, despite the great progress in using EO to treat real wastewater, there are still many gaps. This is due to the lack of comprehensive information on the operating parameters which affect the process and its operating costs. In this paper, among various scientific articles, the impact of operational parameters on the EO performances, a comparison between different electrochemical reactor configurations, and a report on general mechanisms of electrochemical oxidation of organic pollutants have been reported. Moreover, an evaluation of cost analysis and energy consumption requirements have also been discussed. Finally, the combination process between EO and photocatalysis (PC), called photoelectrocatalysis (PEC), has been discussed and reviewed briefly. This article shows that there is a direct relationship between important operating parameters with the amount of costs and the final removal efficiency of emerging pollutants. Optimal operating conditions can be achieved by paying special attention to reactor design, which can lead to higher efficiency and more efficient treatment. The rapid development of EO for removing emerging pollutants from impacted water and its combination with other green methods can result in more efficient approaches to face the pressing water pollution challenge. PEC proved to be a promising pollutants degradation technology, in which renewable energy sources can be adopted as a primer to perform an environmentally friendly water treatment.

MnO2 Doped with Ag Nanoparticles and Their Applications in Antimicrobial and Photocatalytic Reactions

A wide range of nanoparticles have been produced for photocatalysis applications. Nonetheless, degrading organic dyes requires nanoparticles that are efficient and excellent. As a photocatalyst, pure manganese oxide (MnO2) was prepared via a sol–gel method using silver (Ag) nanoparticles of transition metal oxide. In addition to X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX), the crystal structure and elemental composition were analysed. According to XRD data, the transition metal of MnO2 oxide is highly pure and has a small crystallite size. The presence of functional groups was confirmed and clarified using Fourier-transform infrared spectra (FTIR). By irradiating the transition pure and doped MnO2 photocatalysts with visible light, the UV-vis, μ-Raman, and surface areas were determined. As a result, of using the photocatalysts with aqueous methylene blue (MB) solutions under visible light irradiation, the MnO2 doped with Ag nanoparticles demonstrated high degradation efficiencies and were utilised to establish heterogeneous photocatalysis dominance. In this paper, we demonstrate that the photocatalytic efficiency of transition metal oxides is exclusively determined by the particle size and surface area of nano-sized materials. Due to their high surface charge ratio and different surface orientations, have the highest photocatalytic efficiency. Generally, MnO2 doped with Ag nanoparticles is resistant to bacteria of both Gram-positive and Gram-negative types (B. sublittus and Escherichia coli). There is still a need for more research to be performed on reducing the toxicity of metal and metal oxide nanoparticles so that they can be used as an effective alternative to antibiotics and disinfectants, particularly for biomedical applications.

Novel La3+/Sm3+ co-doped Bi5O7I with efficient visible-light photocatalytic activity for advanced treatment of wastewater: Internal mechanism, TC degradation pathway, and toxicity analysis

Controlling semiconductor photocatalysts by doping rare-earth ions is an effective strategy to improve photocatalytic performance. Simple solvothermal and calcination methods were used to prepare La³⁺ and Sm³⁺ modified Bi₅O₇I nanomaterials. Some characterizations such as XRD, XPS, SEM, TEM, UV-vis, etc. were carried out to explore its structural composition and photoelectrochemical properties. The photocatalytic activity was investigated by simulating the degradation of TC and RhB under visible-light irradiation. The degradation results showed that the photocatalytic efficiency of 4S4L-Bi₅O₇I was the best among the samples with the 100% degradation rate of TC (Tetracycline hydrochloride) and 93% of RhB (Rhodamine B). The capture experiment and ESR test proved that the active substances that play a role in the photocatalytic degradation of pollutants were ·O₂^-, ¹O₂ and h⁺, and on this basis, the possible degradation mechanism was proposed. The final results showed that La/Sm co-doping expanded the light absorption range of Bi₅O₇I and improved the charge separation efficiency and the specific surface area. Besides, the surface defects were formed on the surface of Bi₅O₇I due to ion-doping, which could catch e^- to promote the separation and transfer of carriers and improve the photocatalytic activity. LC-MS was used to analyze the possible degradation pathways of TC. And the toxicity of TC was also analyzed via T.E.S.T and Toxtree. The results showed comprehensive toxicity of TC was decreased by 4S4L-Bi₅O₇I so that the overall water pollution was reduced. This work can provide a reference for the subsequent development of bismuth-based photocatalysts.

Innovative progress in graphene derivative-based composite hybrid membranes for the removal of contaminants in wastewater: A review

Graphene derivatives (graphene oxide) are proved as an innovative carbon materials that are getting more attraction in membrane separation technology because of its unique properties and capability to attain layer-to-layer stacking, existence of high oxygen-based functional groups, and generation of nanochannels that successively enhance the selective pollutants removal performance. The review focused on the recent innovations in the development of graphene derivative-based composite hybrid membranes (GDHMs) for the removal of multiple contaminants from wastewater treatment. To design GDHMs, it was observed that at first GO layers undergo chemical treatments with either different polymers, plasma, or sulfonyl. After that, the chemically treated GO layers were decorated with various active functional materials (either with nanoparticles, magnetite, or nanorods, etc.). By preparing GDHMs, properties such as permeability, porosity, hydrophilicity, water flux, stability, feasibility, mechanical strength, regeneration ability, and antifouling tendency were excessively improved as compared to pristine GO membranes. Different types of novel GDHMs were able to remove toxic dyes (77-100%), heavy metals/ions (66-100%), phenols (40-100%), and pharmaceuticals (74-100%) from wastewater with high efficiency. Some of GDHMs were capable to show dual contaminant removal efficacy and antibacterial activity. In this study, it was observed that the most involved mechanisms for pollutants removal are size exclusion, transport, electrostatic interactions, adsorption, and donnan exclusion. In addition to this, interaction mechanism during membrane separation technology has also been elaborated by density functional theory. At last, in this review the discussion related to challenges, limitations, and future outlook for the applications of GDHMs has also been provided.

Self-assembly of CdSe 3D urchins and their photocatalytic response

Photocatalysis is found to be one of the best suited processes that respond to the purification of water systems and the semiconductor nanomaterials are learned to be incredible materials which carry out the photocatalytic process as they readily decompose the pollutants effectively. In this present work, CdSe nanoparticles belonging to II-VI group semiconductor compounds were synthesized using a facile hydrothermal process with different precursor concentrations and were analysed for various characterization studies such as X-ray diffraction (XRD), Transmission electron microscopy (TEM), UV-vis absorption spectroscopy, Fourier transform infrared spectroscopy (FTIR) and Photoluminescence (PL) studies. The XRD study of the synthesized CdSe nanostructures revealed that the average crystallite size was ranging from 18.5 nm to 24 nm pointing out the increase in size with increase in molar concentrations. The morphological structure of synthesized CdSe samples exhibited urchin-like structure for a lower concentration with several rod-like projections appearing in diverse directions. These CdSe nano-urchins synthesized with lower concentrations are found suitable to carry out the process of photocatalytic activity. The process was carried out under visible light radiation for 180 min with aqueous solution of methylene blue (MB) as the ideal toxin to be degraded. The attained degradation efficiency was nearly 80% clearly displaying that the synthesized samples are good photocatalysts. By tuning the bandgap, through the optimization of the precursor concentrations, greater efficiency can be achieved in future.

Laser induced plant leaf extract mediated synthesis of CuO nanoparticles and its photocatalytic activity

Metal nanoparticles furnished by the green synthesis approach have exhibited fascinating attributes owing to their biocompatibility with biomolecules, and their rapid environmentally friendly synthesis. On copper oxide (CuO) nanoparticles, a laser induced bio reduction work has been accomplish using Centella asiatica aqueous extract at room temperature is the pioneer in the field. This synthesis technique is easy, fruitful, eco-friendly, and counterfeit for the size-tunable synthesis of diverse shapes of stable copper nanoparticles. UV-visible spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), Energy - Dispersive X-ray Spectroscopy (EDX), X-ray diffraction (XRD) and photodegradation study have astounding properties of regulating the formation, crystalline nature, and morphology of an integrated specimen. Moreover, the obtained copper oxide nanoparticle has the tendency to decrease the absorbance maximum value of methylene blue because of the catalytic activity posed by these nanoparticles on the reduction of methylene blue by Centella asiatica. It has been studied and confirmed by UV-visible spectrophotometer, and it has been recognised as an electron relay effect.