Actual Wastewater Research Articles

Simultanous Electricity Production and Wastewater Ttreatment in a Microbial Fuel Cell Inoculeted with Anaerobic Sludge

In order to reduce the environmental pollution associated with the conventional energy sources and to achieve the increased global energy demand, alterative and renewable sustainable energy sources need to be developed. Microbial fuel cells (MFCs) represent a bio-electrochemical innovative technology for pollution control and a simultaneous sustainable energy production from biodegradable, reduced compounds. This study mainly considers the performance of continuous up flow dual-chambers MFC fueled with actual domestic wastewater and bio-catalyzed with anaerobic aged sludge obtained from an aged septic tank. The performance of MFCs was mainly evaluated in terms of COD reductions and electrical power output. Results revealed that the COD removal efficiency up to 89% was obtained for wastewaters having an average initial COD concentration of 350 mg/L. Stabilized power outputs were clearly observed achieving a maximum value of 170 mW/ m2.

Highly selective and efficient electrocatalytic removal of low-concentration nitrate ions using self-supported porous Ni0.8Cu0.2O@CuO heterostructure arrays

The electrocatalytic conversion of nitrate (NO3−) to nitrogen (N2) is a promising strategy for addressing the global issue of NO3− pollution in surface water and groundwater. However, the scarcity of efficient denitrification catalysts hinders the development of the aforementioned process, particularly at low NO3− concentrations. Herein, a self-supporting array of defect-rich heterostructured nanowires (Ni0.8Cu0.2O@CuO@NF) was synthesized for highly selective reduction of NO3− to N2. The introduction of Cu accelerated the rate-limiting step (NO3− to NO2−), and the presence of defect-rich heterojunctions increased the catalytic active sites of the catalyst, thereby accelerating the reduction of NO3− and improving the selectivity towards N2. Ni0.8Cu0.2O@CuO@NF exhibited excellent denitrification capacity, with approximately 100% of NO3− degradation and 99.9% of N2 selectivity under optimum parameter conditions, as well as ultra-high stability during the 8-cycle test. Significantly, NO3− conversion and N2 selectivity for actual wastewater with complex ingredients were 70.7% and 99.1%, respectively. This study presents a novel concept for the development of cost-effective and highly effective catalysts for water and environmental restoration.

Mechanism of antibiotic resistance development in an activated sludge system under tetracycline pressure.

The mechanism of antibiotic resistance (AR) development in an activated sludge system under tetracycline (TC) pressure was discussed and analyzed. According to the variation of macro-factors, including TC, COD, TN, TP, NH3-N, pH, heavy metals, and reactor settings, the tet genes respond accordingly. Consequently, the enrichment sites of tet genes form an invisible AR selection zone, where AR microorganisms thrive, gather, reproduce, and spread. The efflux pump genes tetA and tetB prefer anaerobic environment, while ribosome protective protein genes tetM, tetO, tetQ, tetT, and tetW were more concentrated in aerobic situations. As a corresponding micro-effect, different types of tet genes selected the corresponding dominant bacteria such as Thauera and Arthrobacter, suggesting the intrinsic relationship between tet genes and potential hosts. In summary, the macro-response and micro-effect of tet genes constitute an interactive mechanism with tet genes as the core, which is the crucial cause for the continuous development of AR. This study provides an executable strategy to control the development of AR in actual wastewater treatment plants from the perspective of macro-factors and micro-effects.

Anaerobic starvation realizes partial nitrification and starts anammox bacteria self-enrichment in mainstream municipal sewage treatment in a low filling ratio sequencing batch reactor

The initiating and stable preservation of partial nitrification (PN) and achievement of anammox bacteria self-enrichment in domestic sewage is a purposeful subject. In this article, an originality tactics of anaerobic starvation for 100 days was adopted for rapidly achieving PN in actual wastewater, the nitrite accumulation rate (NAR) improved from 4.95% to 81.73% in 18 days. After anaerobic starvation was stopped, the stable PN effect furnished enough stroma for the growth of anammox bacteria. The abundance of Candidatus Brocadia grew from 0% to 0.42% in floc sludge and 0.43% in blank biofilm, which promoted nitrogen removal effect. Anaerobic starvation continuing 74 days generated further decrease in the abundance of Nitrobacter and Nitrospira of nitrite-oxidizing bacteria (NOB), indicating that anaerobic starvation can restore the destroyed partial nitrification. In conclusion, this article furnished a low-cost method for achieving anammox bacteria self-enrichment in mainstream municipal wastewater in 10% filling ratio without chemicals addition.

Responses of halophilic microbial communities to changes in salt composition: Comparison between autotrophic nitrification and heterotrophic ammonia assimilation biosystems

The concentration and proportion of chlorine (Cl−) and sulfate ions (SO42−) in actual high salinity wastewater exhibit significant fluctuations due to their diverse sources. This study compared the response of halophilic autotrophic nitrification (AN) and heterotrophic ammonia assimilation (HAA) sludges to changes in salt composition. The results demonstrated that both the AN and HAA systems maintained high ammonia removal efficiency even when exposed to mixed salt ions or pure sulfate conditions. Increasing the concentration of SO42− resulted in an increase in extracellular polymeric substances content, sludge settleability, sludge hydrophobicity, and the relative abundance of Nitrosomonas in the AN system (from 2.3% to 10.4%). The dominant heterotrophic bacteria in the HAA system underwent turnover in response to changes in salt composition conditions. The robustness and the cooperation between microorganisms of the HAA system surpassed those of the AN system. This study provides scientific foundation for treating multi-ion high salinity wastewater.

Highly efficient removal of Cr(VI) from wastewater using electronegative SA/EGCG@Ti/SA/PVDF sandwich membrane

The use of green, non-toxic raw materials is of great significance to the sustainable development of the environment, among which epigallocatechin gallate (EGCG) is a renewable carbon source from plants. At present, there is a lack of research on the metal-polyphenol nanomaterials their use in water decontamination. In this study, a novel SA/EGCG@Ti/SA/PVDF (SESP) sandwich membrane was prepared to effectively solve the problems of difficult recovery of nanomaterials and the leaching of metal ions. The membrane was made by scraping SA on the surface of the PVDF substrate as the bottom protective layer, depositing EGCG@Ti NPs as the functional layer, then coating SA as the surface isolation layer, and finally cross-linking with anhydrous calcium chloride. Results showed that EGCG@Ti NPs dispersed well on the surface of the SA/PVDF basement membrane. SESP sandwich membrane had good hydrothermal and acid-base stability, and it can be applied to wastewater with multiple co-existing heavy metals (e.g., Cu, Pb, Cd, and Ni). The contact angle and pure water flux of the SESP sandwich membrane with a negatively charged surface were 14.0–15.6° and 171.40 L/m2 h, respectively. The pure water flux of the regenerated membrane after BSA pollution recovered to 98.68 L/m2 h, and the interception efficiency and the interception flux of Cr(VI) were 100 % and 72.92 L/m2 h at 40 min of interception, respectively. Additionally, the removal efficiency of Cr(VI) by SESP sandwich membrane was maintained above 83 % for simulated wastewater and 100 % for actual wastewater after five adsorption-desorption cycles. Cr(VI) and Cr(III) can be removed simultaneously with the negatively charged SESP sandwich membrane. EDS and XPS analysis showed that the removal of Cr(VI) was controlled by the Donnan effect, anion exchange, chelation/complexation, and reduction mechanism. In contrast, Cr(III) was mainly influenced by electrostatic attraction and chelation/complexation mechanisms. In conclusion, the newly prepared sandwich membrane has good application potential in treating Cr(VI) wastewater.

Adsorption of Pb2+ and Cu2+ in wastewater by lignosulfonate adsorbent prepared from corn straw

The heavy metal ions contained in industrial wastewater are a great threat to human health. Exploring a adsorbent which have low-cost, green environmental friendly, high adsorption capacity, good recycle is key to solve heavy metal ions pollution. Lignin sulfonate was obtained by treating corn stover, and then modified lignin sulfonate was obtained by hydrothermal method. The porous structure makes heavy metal ions occupy more internal adsorption sites. Modified lignosulfonate adsorbent efficiency removes heavy metals in wastewater especially Cu2+ and Pb2+. The adsorption capacity of Cu2+ on modified lignosulfonate is 450.3 mg g−1, Pb2+ is 475.4 mg g−1. In addition, for 40 mg L−1 Cu2+ and Pb2+ using 0.4 g L−1, the adsorption equilibrium is only reached within 60 min. Meanwhile, the removal ratio of Pb is 83 %, Cd is 72 %, Cu is 87 %, Zn is 36 %, Mn is 25 %, Cr is 95 %, and Fe is 99 % in wastewater using 0.4 g L−1 adsorbent in 2 h. This research develops a practical adsorbent to remove heavy metals from actual wastewater.

Desalination performance of shale gas produced water by flow-electrode capacitive deionisation process

The cost-effective desalination of shale-gas produced water (PW) has long been an industrial research hotspot. Flow-electrode capacitive deionisation (FCDI), a recently developed electrochemical desalination technology, may be a novel option for PW disposal because of its attractive advantages. However, reports on the desalination test of actual high-salinity industrial wastewater by FCDI are lacking. In this study, a laboratory-scale FCDI device with an online monitoring system was used to desalinate shale-gas PW. FCDI achieved relatively stable desalination efficiency for pretreated PW with a salinity of 2.65 % and reached an energy-normalised salt removal of 0.479 mg/J. The flow electrode chemically activated by KOH increased the FCDI average desalination rate by 98.5 % for the pretreated saline PW. Electrochemical impedance spectroscopy analysis revealed that the majority of fouling accumulated on the anion-exchange membrane (AEM) side. Residual pollutants were adsorbed by the flow electrode in the AEM chamber, which destroyed the optimal ion-transport path and electric double-layer structure. Results showed that FCDI was more suitable for PW’s reverse-osmosis (RO) permeate desalination to form an RO–FCDI hybrid. This study provided a practical experimental case on the electrochemical desalination of saline PW by FCDI.

Effect mechanism of iron conversion on adsorption performance of hydrochar derived from coking sludge

In this study, Fe conversion during hydrothermal carbonization (HTC) of coking sludge were investigated, and the effect mechanism of Fe component on the adsorption performance of coking sludge hydrochar (CHC) was explored. The results showed that after HTC treatment, more than 95 % of Fe remained in the CHC. Fe3+ was reduced to Fe2+ by sugar and amino acids. Fe was stabilized during the HTC process and was still predominantly in the Fe manganese oxidation state. The CHC prepared at 270 °C exhibited excellent adsorption capacities for Congo red (CR), tetracycline (TC), and Cr (VI). Their maximum adsorption capacities were 140.85, 147.06, and 19.92 mg/g, respectively. Quantitative adsorption mechanism experiments, XRD and VSM characterization revealed that Fe component played a significant role in adsorption, and CHC with more Fe3O4 exhibited better adsorption capacity. The results of the XPS characterization of CHC before and after adsorption showed that Fe3O4 provided rich Fe adsorption sites on the surface of CHC to strengthen the adsorption efficiency of pollutants through Fe3+/Fe2+ reduction and complexation of Fe-O/N. In addition, the formed Fe3O4 also imparted CHC with magnetic properties (Ms = 4.12 emu/g) to facilitate the subsequent separation and recovery. These results demonstrated that the prepared CHC has great potential for treating actual wastewater containing CR and TC.

CoFe2O4 with MoS2‐xOy Nanosheets as a Co‐catalyst for Enhanced Activation of Peroxydisulfate in Advanced Oxidation Processes

AbstractThe application of advanced oxidation processes (AOPs) based on sulfate radicals for degrading persistent organic pollutants faces challenges due to the inefficient activation of peroxydisulfate (PDS) oxidant. Herein, a composite CoFe2O4/MoS2‐xOy (CFM) catalyst consisting of CoFe2O4 nanoparticles uniformly dispersed on the nanosheets of oxygen‐incorporated MoS2 (MoS2‐xOy) with flower‐like morphology are fabricated through a facile two‐step hydrothermal method, which results in the enhanced activation of PDS and a highly efficient degradation of phenolic pollutants. The oxygen‐doping in MoS2‐xOy leads to unsaturated sulfur and active sites on the surface of MoS2 for accelerating the rate limiting step of FeIII/FeII reduction cycle in PDS‐CFM reaction. Aiming at the refractory organic pollutants in actual coking wastewater, CFM co‐catalyst is introduced into a hydrogel made up of polyvinyl alcohol (PVA) and coal‐tar pitch oxides (PO) to construct a multifunctional CFM@PO/PVA hydrogel. Upon hybrid CFM@PO/PVA, the coupling of the enhanced AOP with solar‐driven interfacial vapor generation (SIVG) technology contributes to the degradation efficiency, the removal rate of phenol in solution and the total organic carbon in coking wastewater can reach 98 % and 91 %, respectively. The integration of heterogeneous AOPs with SIVG system provides a feasible strategy for the eco‐friendly efficient purification of industrial wastewater.

Efficient nitrogen removal by a novel extreme strain, Pseudomonas reactans WL20-3 under dual stresses of low temperature and high alkalinity: Characterization, mechanism, and application

Although many studies report the resistance of heterotrophic nitrification-aerobic denitrification (HN-AD) strains to single environmental stress, there is no research on its resistance to dual stresses of low temperature and high alkalinity. A novel bacterium Pseudomonas reactants WL20-3 isolated in this study showed removal efficiencies of 100%, 100%, and 97.76% for ammonium, nitrate, and nitrite, respectively, at 4 °C and pH 11.0. Transcriptome analysis revealed that the resistance of strain WL20-3 to dual stresses was attributed not only to the regulation of genes in the nitrogen metabolic pathway, but also to genes in other pathways such as the ribosome, oxidative phosphorylation, amino acid metabolism, and ABC transporters. Additionally, WL20-3 removed 83.98% of ammonium from actual wastewater at 4 °C and pH 11.0. This study isolated a novel strain WL20-3 with superior nitrogen removal under dual stresses and provided a molecular understanding of its tolerance mechanism to low temperature and high alkalinity.

Advanced Photocatalytic Uranium Extraction Strategies: Progress, Challenges, and Prospects

Nuclear energy with low carbon emission and high-energy density is considered as one of the most promising future energy sources for human beings. However, the use of nuclear energy will inevitably lead to the discharge of nuclear waste and the consumption of uranium resources. Therefore, the development of simple, efficient, and economical uranium extraction methods is of great significance for the sustainable development of nuclear energy and the restoration of the ecological environment. Photocatalytic U(VI) extraction technology as a simple, highly efficient, and low-cost strategy, received increasing attention from researchers. In this review, the development background of photocatalytic U(VI) extraction and several photocatalytic U(VI) reduction mechanisms are briefly described and the identification methods of uranium species after photocatalytic reduction are addressed. Subsequently, the modification strategies of several catalysts used for U(VI) extraction are summarized and the advantages and disadvantages of photocatalytic U(VI) extraction are compared. Additionally, the research progress of photocatalytic technology for U(VI) extraction in actual uranium-containing wastewater and seawater are evaluated. Finally, the current challenges and the developments of photocatalytic U(VI) extraction technology in the future are prospected.

Papermaking wastewater treatment coupled to 2,3-butanediol production by engineered psychrotrophic Raoultella terrigena

The simultaneous bioremediation and bioconversion of papermaking wastewater by psychrotrophic microorganisms holds great promise for developing sustainable environments and economies in cold regions. Here, the psychrotrophic bacterium Raoultella terrigena HC6 presented high endoglucanase (26.3 U/mL), xylosidase (732 U/mL), and laccase (8.07 U/mL) activities for lignocellulose deconstruction at 15 °C. mRNA monitoring and phenotypic variation analyses confirmed that cold-inducible cold shock protein A (CspA) facilitated the expression of the cel208, xynB68, and lac432 genes to increase the enzyme activities in strain HC6. Furthermore, the cspA gene-overexpressing mutant (strain HC6-cspA) was deployed in actual papermaking wastewater and achieved 44.3%, 34.1%, 18.4%, 80.2% and 100% removal rates for cellulose, hemicellulose, lignin, COD, and NO3--N at 15 °C. Simultaneously, 2,3-butanediol (2,3-BD) was produced from the effluent with a titer of 2.98 g/L and productivity of 0.154 g/L/h. This study reveals an association between the cold regulon and lignocellulolytic enzymes and provides a promising candidate for simultaneous papermaking wastewater treatment and 2,3-BD production.

Mechanochemical Activation of Antigorite to Provide Magnesium and Hydroxide Ions for Recovering Phosphorus and Nitrogen from Wastewater as Struvite

Phosphorus (P) and nitrogen (N) can be simultaneously recovered by struvite (MgNH4PO4·6H2O) crystallization, and this has attracted more and more attention. However, the cost of producing struvite from wastewater is high due to the chemical inputs, which makes the struvite process unattractive in terms of economic benefits. Thus, it is important to develop a new struvite technology with low cost and simple operation. In this work, the antigorite was activated by a ball-milling process. The crystal form of the antigorite was destroyed by the mechanical forces, leading an increase in the dissolution of Mg2+ and OH− in the structure. The concentration of Mg2+ dissolved into water increases with the milling time, as well as the pH. Additionally, the dissolution of the activated antigorite depends on the concentration of phosphate-ammonium. The responsive dissolution makes the activated antigorite adaptively adjust the dissolution of Mg2+ and OH− and maintain a stable recovery of nitrogen and phosphorus from wastewater. The performance of P and N recovery was investigated by moderating variables, including the molar ratio of N/P, activation time, reaction time, and dosage. The results showed that the activated antigorite in the wastewater can be automatically converted into struvite. Actual swine wastewater was treated by the activated antigorite process, and a recovery rate of 98% was achieved by adding 1.2 g/L activated antigorite. The economic evaluation shows that the cost of the activated antigorite process is only 36% of an ordinary chemical process (MgSO4 and NaOH).

Synthesis of novel MnFe2O4/BiOI green nanocomposite and its application to photocatalytic degradation of tetracycline hydrochloride: (LC-MS analyses, mechanism, reusability, kinetic, radical agents, mineralization, process capability, and purification of actual pharmaceutical wastewater)

Antibiotics in water bodies pose a serious threat to public health and the environment, leading to increased efforts to eliminate them from wastewater. In this study, a green nanocomposite catalyst of MnFe2O4/BiOI and Calendula officinalis was evaluated for its ability to decompose tetracycline in simulated sunlight. Characterization techniques including DRS, DLS, VSM, FTIR, XRD, TEM, FESEM, EDX, LC-MS, and pHpzc were used, revealing MnFe2O4/BiOI 's average crystal size of 14.47 nm, band gap of 1.7 eV, and magnetic saturation of 23.63 emu/gr. Under optimal conditions of a pH level of 9, tetracycline concentration of 20 mg/L, MnFe2O4/BiOI dosage of 0.5 g/L, and a reaction time of 200 min, the MnFe2O4/BiOI catalyst effectively broke down tetracycline, resulting in complete degradation. The pseudo-first-order equation accurately predicted degradation rates, and reusability tests showed only a 5% drop in efficiency after six cycles. The recommended method achieved high mineralization rates, with COD and TOC elimination efficiencies of 83.04% and 61.45%, respectively. Maximum removal efficiency for TOC and COD in pharmaceutical wastewater was achieved after 200 min, with 44.73% and 57.19%, respectively. Under optimal conditions, with 20 mg/L of tetracycline and sunlight exposure, the maximum tetracycline removal rate was 76.02%. This study demonstrated that the MnFe2O4/BiOI catalyst-based Xenon-photocatalytic approach is effective and adaptable for treating wastewater containing antibiotics from drug production and manufacturing processes.

Dual stimuli pH-responsive nanofiltration membranes with tunable permeability and selectivity during separation of antitumor drug doxorubicin

This research aims to separate doxorubicin (as a pH-sensitive antitumor-drug) by dual pH-responsive-membranes (pH-Res-Mems). Since the trade-off between flux and rejection is a limiting factor for pH-Res-Mems with pH alteration, the focus of this research is to apply a novel approach i.e., inducing pH sensitivity to both membrane surface and sub-layer, to resolve the mentioned problem. To this aim, metal-oxides with Close-Gate (CG) mechanism (changing pore-size based on OH- functional-group) including copper-oxide (Cu-pH-Res) and silicon-oxide (Si-pH-Res) or metal-organic-frameworks with Open-Gate (OG) mechanism (changing pore-size based on H+ functional-group) including ZIF-8 (Zn-pH-Res) and ZIF-67 (Co-pH-Res) were added to both membrane layers simultaneously, where SurCun/SubSim and SurZnn/SubCom membranes were synthesized. Addition of Zn-pH-Res and Cu-pH-Res to the surface-layer led to improved superficial properties including hydrophilicity and roughness, while adding Co-pH-Res and Si-pH-Res to the sub-layer resulted in improvement of structural properties such as porosity and pore tortuosity. Furthermore, investigation of the pH sensitivity of membranes indicated that for the SurCu3/SubSi3 membrane, with pH reduction, the overall performance (OP) was enhanced from 2.17 to 6.40, while for the SurZn3/SubCo3 membrane, with pH elevation, OP was enhanced from 2.19 to 16.8. Eventually, the investigations revealed that the SurZn3/SubCo0 single pH-Res-Mem at neutral pH offered rejection of 89%, permeability of 4.41 LMH, and fouling of 70.4%. Meanwhile, these values for the SurZn3/SubCo3 dual pH-Res-Mem at pH= 5.5 were 95%, 21.9 LMH, and 27.2%, respectively. Overall, SurCu3/SubSi3 and SurZn3/SubCo3 membranes succeeded in 91.9% and 94.5% DOX removal from actual hospital wastewater, respectively, indicating the high-efficiency of pH-Res-Mems.

Fiberglass cloth coated by coffee ground waste-derived carbon quantum dots/titanium dioxide composite for removal of caffeine and other pharmaceuticals from water

Coffee ground waste from the coffee beverage preparation is mainly discarded and consequently ends up in landfill, which cause the contamination of caffeine in various environmental compartments. This study focuses on the upcycling of coffee-ground waste to carbon quantum dots (CQDs) for use as a modifying material to improve the visible light activity of titanium dioxide (TiO2). The CQD solution was synthesized by hydrothermal method, which has an average size of 2.80 ± 0.63 nm. The CQDs/TiO2 photocatalysts were prepared by combining CQD solutions at various amounts with sol-gel TiO2 and then coated on the fiberglass cloths (FGCs). The photocatalytic application mainly focuses on the removal of caffeine from the water. The photocatalytic experiment was preliminary run in a simple batch reactor under visible light. The 5CQDs/TiO2 coated FGC (5 mL of CQD solution/g of Ti-based on sol-gel) showed the best performance, and it was selected for the removal of caffeine and other pharmaceuticals (i.e., carbamazepine and ibuprofen) in the recirculating reactor. The removals of caffeine, carbamazepine, and ibuprofen after irradiation for 9 h were 82%, 88%, and 84%, respectively. The residual concentrations were significantly lower than the reported toxicity levels based on specific species. The changes in total organic carbon were observed, indicating the mineralization of pharmaceuticals in water. The 5CQDs/TiO2 coated FGC showed good flexible performance. No obvious loss of activity was observed for five runs. The actual wastewater from the coffee pot cleaning process was also tested. The removal was 80% for caffeine and 86% for color in the unit of the American Dye Manufacturers Institute (ADMI).

Rapid acceleration of Cu(II)/peroxymonosulfate oxidation of phosphonate by hydroxylamine

Developing simple and effective activation approaches to degrade phosphonate is crucial due to its potential aquatic environmental risks. Recently, Cu(II)-mediated activation processes provide a feasible method via nonradical oxidation mechanism to remove phosphonate, but is yet challenged under neutral conditions. Herein, a strategy for enhancing the Cu(II)/peroxymonosulfate (PMS) process by adding hydroxylamine (HA) could efficiently degrade 1-hydroxyethane1,1-diphosphonic acid (HEDP) at pH = 7.0. After 15-min reaction, 85.7% of total phosphorus (TP) in HEDP transformed into PO43− in the Cu(II)/PMS/HA process is observed, which is 3.4 times than that in the Cu(II)/PMS process. The results of multiple experiments confirm that the presence of HA accelerates the reduction of Cu(II) and the generation of reactive species, SO4•− and Cu(III) induced intramolecular electron transfer as the primary reactive species play a significant role in the degradation of HEDP. Additionally, the removal of HEDP is inhibited with the addition of Cl− and HCO3− in the Cu(II)/PMS/HA process. However, the Cu(II)/PMS/HA process demonstrates a superior removal effectiveness of HEDP in different actual wastewater samples compared to the Cu(II)/PMS process under neutral conditions. This study provides an effective method for removing phosphonate from actual wastewater.

Enhanced photocatalytic performance of W-doped TiO2 nanoparticles for treatment of Procion Red MX-5B azo dye in textile wastewater

Sol-gel synthesis of W-doped TiO2 nanoparticles (W-TiO2) as a photocatalyst for Procion Red MX-5B (MX-5B) azo dye treatment in textile wastewater was the main focus of this research. Scanning electron microscopy (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), and energy dispersive spectroscopy (EDS) structural studies of nanostructured photocatalysts showed that W was successfully incorporated into the TiO2 lattice. According to EIS investigations, W-TiO2 has a greater rate of charge transfer and excellent charge separation capabilities compared to a sample of pure TiO2. It shows the W-TiO2 nanostructured photocatalyst sample's exceptional photocatalytic performance. The band gap energies of TiO2 and W-TiO2 were determined through optical studies to be 3.22 eV and 2.93 eV, respectively, showing an improvement in the photocatalytic activity of TiO2 in the visible light domain. Studies of the photocatalytic performance indicated that the full treatment of MX-5B molecules was achieved after 105, 100, 95, 80, 70, 85, and 90 min of exposure to visible light for pure TiO2, W0.5-TiO2, W1-TiO2, W3-TiO2, W5-TiO2, W8-TiO2, and W10-TiO2, respectively. These studies revealed the great and quick photocatalytic treatment of MX-5B in the presence of doped TiO2. The results of a study that used 400 mL of a 40 mg/L MX-5B solution prepared with deionized water as a control sample and a sample of actual textile wastewater as a real sample showed that MX-5B from actual textile wastewater was effectively photocatalytically degraded in the presence of W5-TiO2 photocatalyst.

La3+ substituted Ni0.5 Co0.5 Fe2 O4 nanoferrites: Magnetically separable catalysts for sunlight-driven photo-oxidative degradation of Methylene Blue

LaxNi0.5Co0.5Fe2−xO4 nanoparticles (x = 0.0, 0.03, 0.06, 0.09, 0.12) were investigated in the current work as Methylene Blue degradation catalysts. Using the citrate-aided sol-gel auto-combustion approach, the nanoferrites with homogenous size distribution were produced. Powder X-ray diffraction was used to analyse the structure of the material. The optical characteristics of ferrite nanoparticles were investigated using diffused UV–visible reflectance spectroscopy. It was noted that when the concentration of La3+ increased, the band gap of produced ferrites shrank. Morphological and compositional studies were performed by FE-SEM and EDX spectra. Surface area was depicted using BET analysis. Raman Spectroscopy was used to estimate the parameters of vibration. Testing has been done on synthesized nanoferrites to see whether they can remove Methylene Blue's concentration in water. In addition, it was examined how La3+ incorporation in Ni0.5Co0.5Fe2O4 nanocomposites resulted in aspects of doping ratio, reaction time and amount of catalyst. The most effective material, La0.06Ni0.5Co0.5Fe1.94O4, achieved a 98.69 per cent efficiency in 140 min. Due to three positive characteristics, including high recycling (up to five cycles), stability, and simplicity of separation using an external magnet, toxic dyes in actual wastewaters can be photodegraded in sunlight using La3+ substituted Ni0.5Co0.5Fe2O4 nanoferrites as an efficient and competitive catalyst.