Remediation Of Organic Pollutants Research Articles

Paracoccus benzoatiresistens sp. nov., a benzoate resistance and selenite reduction bacterium isolated from wetland.

A Gram-stain-negative, aerobic, non-motile, catalase- and oxidase-positive, pale orange, rod-shaped strain EF6T, was isolated from a natural wetland reserve in Hebei province, China. The strain grew at 25-37°C (optimum, 30°C), pH 5-9 (optimum, pH 7), and in the presence of 1.0-4.0% (w/v) NaCl (optimum, 2%). A phylogenetic analysis based on 16S rRNA gene sequence revealed that strain EF6T belongs to the genus Paracoccus, and the closest members were Paracoccus shandongensis wg2T with 98.1% similarity, Paracoccus fontiphilus MVW-1T (97.9%), Paracoccus everestensis S8-55T (97.7%), Paracoccus subflavus GY0581T (97.6%), Paracoccus sediminis CMB17T (97.3%), Paracoccus caeni MJ17T (97.0%), and Paracoccus angustae E6T (97.0%). The genome size of strain EF6T was 4.88Mb, and the DNA G + C content was 65.3%. The digital DNA-DNA hybridization, average nucleotide identity, and average amino acid identity values between strain EF6T and the reference strains were all below the threshold limit for species delineation (< 32.8%, < 88.0%, and < 86.7%, respectively). The major fatty acids (≥ 5.0%) were summed feature 8 (86.3%, C18:1 ω6c and/or C18:1 ω7c) and C18:1 (5.0%) and the only isoprenoid quinone was Q-10. The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, two unidentified glycolipids, five unidentified phospholipids, and an unidentified aminolipid. Strain EF6T displays notable resistance to benzoate and selenite, with higher tolerance levels (25 g/L for benzoate and 150 mM for selenite) compared to the closely related species. Genomic analysis identified six benzoate resistance genes (acdA, pcaF, fadA, pcaC, purB, and catA) and twenty selenite resistance and reduction-related genes (iscR, ssuB, ssuD, selA, selD and so on). Additionally, EF6T possesses unique genes (catA, ssuB, and ssuC) absent in the closely related species for benzoate and selenite resistance. Its robust resistance to benzoate and selenite, coupled with its genomic makeup, make EF6T a promising candidate for the remediation of both organic and inorganic pollutants. It is worth noting that the specific resistance phenotypes described above were not reported in other novel species in Paracoccus. Based on the results of biochemical, physiological, phylogenetic, and chemotaxonomic analyses, combined with comparisons of the 16S rRNA gene sequence and the whole genome sequence, strain EF6T is considered to represent a novel species of the genus Paracoccus within the family Rhodobacteraceae, for which the name Paracoccus benzoatiresistens sp. nov. is proposed. The type strain is EF6T (= GDMCC 1.3400T = JCM 35642T = MCCC 1K08702T).

Piezo-enhanced photocatalysis of MoS2/Bi4O5Br2/PVDF-HFP film for wastewater purification

To date, the piezoelectric field has been demonstrated as a promising approach to inhibit the recombination of photogenerated carrier in photocatalyst applications. Herein we propose a MoS2/Bi4O5Br2/PVDF-HFP piezo-photocatalytic film in the organic pollutants remediation. MoS2/Bi4O5Br2 as the photocatalytic material is incorporated to poly(vinylidene fluoride)-hexafluoro propylene (PVDF-HFP) as the supporting layer via a simple phase transition method. The polarised electric field generated on PVDF-HFP and MoS2/Bi4O5Br2 under aeration synergised with the built-in electric field formed between MoS2/Bi4O5Br2 Z-scheme heterojunction to promote the interfacial charge transfer. The degradation rates of rhodamine B (RhB) and tetracycline hydrochloride (TC) under aeration and visible light irradiation in 60min reached 98.9% and 92.2%, respectively. Meanwhile, density functional theory calculations (DFT) further demonstrated the effective charge separation and transfer induced by the Z-scheme charge transfer mechanism constructed by MoS2 composite with Bi4O5Br2, as well as the synergistic effect of the double electric field in favour of suppressing carrier recombination. This work provides an interesting solution for effectively combining piezoelectric catalysis with photocatalysis.

Efficient photocatalytic remediation of persistent organic pollutants using magnetically recoverable spinel manganese ferrite nanoparticles supported on activated carbon

Magnetically recoverable spinel manganese ferrite (MFO) nanoparticles (NPs) supported on activated carbon (AC) (MFC), a promising photocatalyst, were prepared by simple and cost-effective gel combustion. AC supports prevented particle agglomeration and functioned as electron acceptors to promote charge separation on MFO. MFC samples demonstrated significant surface area, paramagnetic characteristics, and visible-light absorption bandgap of 2.02 eV. Pentachlorophenol (PCP) photodegradation using MFC showed degradation efficiency of at least 90% after 150 minutes at pH 6.0 with the catalyst dose and PCP concentration of no more than 10 mg.L−1 and 9.0 ppm, respectively. MFC exhibited durability and recyclability with approximately 4% decrease in degradation efficiency after five reuses while maintaining its material structure. The crucial roles of photo-generated electrons and hydroxyl radicals related to dechlorination and hydroxylation during PCP photodegradation were also highlighted in active species investigations with appropriate scavengers. Subsequently, a plausible PCP photodegradation mechanism with intermediates was proposed.

Graphene-based photocatalytic membrane application for the remediation of organic dye pollutants: A review

The inadequate elimination of emerging organic contaminants, such as pharmaceuticals and personal care items, presents a substantial risk to water security in treating wastewater and its subsequent discharge into the receiving water bodies or recharging ground water. A practical solution can be found by combining hybrid photocatalytic oxidation with membrane separation technologies. The review examines the crucial process of strengthening photocatalytic membranes by including graphene and its derivatives. Further, it highlights the graphene’s ability to improve anti-fouling properties with increased efficiency of pollutant degradation. An in-depth analysis of the synthesis method and its impact on graphene-based photocatalytic membranes' morphology and photocatalytic characteristics is conducted. In addition to discussing membrane alteration, the review delves into the different elements and complexities involved in optimising filtration performance. Adding a comparison with carbon-based support membranes enhances the overall understating of graphene's importance in the membrane matrix. Economic and life cycle aspects have also been elaborated to gauge the practical viability of these neoteric photoactive membranes. The present article also pinpoints the existing lacuna and lays forward potential solutions that can assist in broader acceptance of these membrane for contaminant remediation. Though development of graphene-based photocatalytic membranes is still in embryonic phase, the review advocates it as a sustainable successor to conventional membrane-based treatment in the future.

0D/1D CuO-Cu2O/ZnO p-n heterojunction with high photocatalytic activity for the degradation of dyes and Naproxen

The development of highly active photocatalysts with broad spectrum response is of paramount importance for photocatalytic applications. Herein, heterostructured CuO-Cu2O/ZnO photocatalysts were prepared in a single step and under mild conditions using a photodeposition process which allows to deposit CuO-Cu2O particles with an average size of ca. 2.4nm on the surface of ZnO nanorods. The p-n heterojunction built between CuO-Cu2O and ZnO allows to increase both the visible light response of the photocatalyst and the charge separation. The CuO-Cu2O(10%)/ZnO catalyst exhibits the highest activity for the degradation of dyes (Rhodamine B and Remazol Brilliant Blue R) and of Naproxen under simulated solar light irradiation. Based on scavenging experiments, holes, superoxide radicals O2●- and singlet oxygen 1O2 are the dominant species involved in the photocatalytic degradation and a mechanism is proposed. Due to its high stability and photocatalytic performance in various water matrices, the CuO-Cu2O(10%)/ZnO nanohybrid is of high potential for the large scale remediation of organic pollutants in wastewater.

Fabricating of Pd and Ni bimetal modified halloysite nanotube composite and its application for photocatalytic degradation of tetracycline

Tetracycline (TC) is extensively employed as a broad-spectrum antibacterial agent, and its byproducts have been identified in a variety of water bodies, posing a significant risk to both aquatic ecosystems and human health. Among the prevalent techniques for treating water contaminants, photodegradation stands out. In this research, we synthesized a novel nanocomposite material, embedding bimetallic nanoparticles onto halloysite nanotubes (HNT) (Pd@Ni/N-HNT), aimed at photocatalytically degrading TC. The Pd@Ni/N-HNT demonstrated the capability to enhance the TC degradation efficiency to 100 % under visible light for a duration of 120 min, effectively doubling the performance of pure H2O2 degradation. The influence of pH levels in aquatic environments on the TC degradation efficiency was explored. Through electron spin resonance (EPR) studies and free radical scavenging tests, it was verified that •O2− and h+ are pivotal in the degradation process. Furthermore, Pd@Ni/N-HNT showcased effective degradation capabilities in both tap and river water, achieving degradation rates exceeding 70 % in 120 min and 95 % in 180 min, respectively. This investigation not only sheds light on the potential of utilizing Pd@Ni/N-HNT as a potent catalyst for the photocatalytic degradation of TC but also offers a comprehensive framework for the future development of nanomaterials aimed at the environmental remediation of organic pollutants. The findings herein provide a pivotal reference and guide for advancing the application of nanotechnology in the purification of water, thereby contributing to the safeguarding of aquatic ecosystems and public health.

Ternary Metal Oxide–Chitosan Hybrids for Efficient Photocatalytic Remediation of Organic Pollutants from Wastewater

Ternary Metal Oxide–Chitosan Hybrids for Efficient Photocatalytic Remediation of Organic Pollutants from Wastewater

Multifunctional N, Fe dual active site hydrothermal biochar for efficiently degrading paclobutrazol and promoting crop growth

The development of a low-cost, highly catalytic, and soil fertility-improving biochar material is of significant importance for the sustained remediation of organic pollutants in the environment. In this study, multifunctional N, Fe dual active site biochar (NF-BC) was successfully synthesized by hydrothermal method using cotton straw, urea, and FeCl3 as raw materials. Compared to the original biochar, NF-BC exhibits high graphitic-N content and abundant Fe2+, enabling efficient activation of Peroxymonosulfate (PMS) for the removal of Paclobutrazol (PBZ) in water and soil. EPR and quenching experiments confirm that the free radical pathway (•OH) and the non-free radical pathway (1O2) act together in PBZ degradation. The DFT results illustrate the benzene and pyridine rings of PBZ are electron-rich regions, which can be attacked by reactive oxygen species. Then three possible degradation pathways are provided by combining them with the LC/MS test. After remediation by the NF-BC/PMS system, the soil fertility index and plant growth are significantly improved. Compared to CK, the pH value and SOM content of the soil remained unchanged after remediation with the NF-BC/PMS system, while the content of available K and hydrolyzed N increased by 27.18 and 2.27 times, respectively. The pot experiments showed that the NF-BC/PMS system not only alleviates the stress of PBZ on mung bean seedlings, but also promotes an increase in leaf area, accumulation of dry biomass, and root growth. This work provides a new idea for the preparation of low-cost and multifunctional biochar for the efficient removal of pesticides in soil and water environments.

Sunlight-mediated efficient remediation of organic pollutants from water by chitosan co-decorated nanocomposites of NiO loaded with WO3: Green synthesis, kinetics, and photoactivity

Azo dyes such as Tropaeolin OOO (TOOO) and Eriochrome black T (EBT) are used in various industrial and laboratory applications. However, their recalcitrant properties make them toxic chemicals and require efficient removal-strategy based on polymer decorated semiconductor nanocomposite. Herein, photodegradation of TOOO and EBT in water was investigated at different reaction parameters through NiO@WO3-chitosan synthesized by green procedure using A. indica. PXRD spectra peaks show semi-crystalline behaviour with spherical morphology and chitosan around metal oxide. In FT-IR, New spectral peaks observed at 1023 cm−1, 870 cm−1, and 540 cm−1 vibration indicated between Ni-O-W, Ni-N, and W-N confirmed effecting coupling. Both dyes (10 mg/L) were found completely colourless within 3 h under sunlight with pH of 7 at 20 mg of catalyst load. Difference in max degradation of 96 % and 92 %, respectively to TOOO and EBT dye credit to structure difference. 1st-order reaction kinetics following early Langmuir adsorption and degradation at optimum condition rate constant k (0.26–0.19-min−1) and half time t1/2(2.68––3.64 min−1). Efficiency of NiO@WO3-chitosan was maintained due to its fine morphology with elevated surface-area (75 m2g−1), large negative zeta potential (−29.5 mV), and lesser value of band distance (2.1 eV). Involvement of •OH, O2–• and holes in photocatalysis mechanism to break complex molecules of TOOO and EBT was revealed in Scavenger analysis. After degradation, small-safer metabolites were confirmed by LC-MS. Reusability up to 8th cycle of NiO@WO3-chitosan without photoactivity reduction makes it a cost-effective cum sustainable composite for industries and wastewater pollutants removal with good surface properties.

The effect of graphene oxide content on the photocatalytic activity of (ZnCdS/MnFe2O4/GO) nanocomposite

Novel ternary Zinc cadmium sulfate/Manganese ferrite/Graphene oxide (ZnCdS/MnFe2O4/GO) nanocomposites were synthesized via a hydrothermal process in this study, with a focus on optimizing the graphene oxide (GO) content. Characterization techniques such as X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), UV–visible spectroscopy, photoluminescence (PL) spectroscopy, and N2 physisorption were employed. The investigation revealed that nanocomposites with 3 wt% GO content exhibited superior adsorption capacity and visible-light photocatalytic activity for the removal of Methylene blue (MB) from wastewater. The ZnCdS/MnFe2O4/GO 3 % composite demonstrated exceptional stability and efficiency, achieving nearly 96 % MB removal within 220 min. Moreover, the ZnCdS/MnFe2O4/GO 3 % nanocomposites displayed promising reusability with sustained photocatalytic activity over multiple degradation-regeneration cycles. These findings highlight the potential of ternary GO/ZnCdS/MnFe2O4 nanocomposites as effective photocatalysts for the practical remediation of organic pollutants in wastewater systems.

A novel nano-cerium oxide functionalized biochar composite for degradation of organic dye: insight of the photocatalysis mechanism.

Recently, visible-light-driven photocatalysis attracts much concerns in the remediation of environmental organic pollutants. In this study, the cerium doped biochar was fabricated through the hydrothermal method, and served as an efficient photocatalyst towards rhodamine B degradation under visible light irradiation. Almost 100% of rhodamine B was removed by 2.0g·L-1 cerium doped biochar after 60min of visible light irradiation at pH 3, but only about 25.50% and 29.60% of rhodamine B was removed by cerium dioxide and biochar under identical conditions. The degradation process coincided well with the pseudo-first-order kinetic model, and the photodegradation rate constant of cerium doped biochar was 0.0485·min-1, which was respectively 97 and 44 times that of biochar (0.0005·min-1) and cerium dioxide (0.0011·min-1). According to the trapping experiments and electron spin resonance spectroscopy analysis, h+, O2-∙ and ∙OH all participated in the degradation of rhodamine B in the cerium doped biochar photocatalytic systems, and the function of h+ and ∙OH was dominated. Consequently, the biochar could not only be an excellent carrier for supporting cerium dioxide, but also greatly improved its photocatalytic activity. The band gap of cerium doped biochar was narrower than cerium dioxide, which could improve the separation and migration of photogenerated electron-hole pairs under visible-light excitation, thus ultimately enhanced the degradation of rhodamine B. This work provided a deeper understanding of the preparation of biochar-based photocatalyst and its application in the remediation of environmental organic pollution.

Novel NiFeAl hybridized layered double hydroxide nanofibrous for photocatalytic degradation and CO2 reduction

In this investigation, a novel NiFeAl-LDH/PVP/PVA is harnessed to concurrently transmute the brilliant green (BG) dye and carbon dioxide (CO2) into valuable hydrocarbons. This procedure entails a photocatalytic reaction that encompasses both oxidation and reduction phases. In the initial stage, the BG dye is subjected to oxidation in the presence of photogenerated vacancies, culminating in the generation of CO2 and H2O. The CO2 then interacts with the excited electrons to form methanol (CH3OH) and acetone (C3H6O) via a reduction reaction. Among the synthesized catalysts, NiFeAl-LDH/PVP/PVA composite exhibited a generation of CH3OH (84.01 mmolL−1h−1) and C3H6O (44.12 mmolL−1h−1) with an electron consumption rate of 1209.98 mmolL−1h−1 for the initial hour BG conversion reaction. Pure CO2 reduction employing the composite also displayed a generation of 56.4 mmolL−1−h−1 CH3OH and 12.71 mmolL−1−h−1 under the influence of an LED light source. Next, a comprehensive mechanism is proposed to comprehend the transformation of dye into valuable hydrocarbons. The present study suggests a synchronized approach to organic pollutant remediation along with CO2 reduction, offering a sustainable pathway to address both environmental remediation and the energy crisis.

Conventional technologies and recent developments in the nanotechnological approach for the remediation of persistent organic pollutants

ABSTRACT Persistent organic pollutants (POPs) are one of the important concerns in the environmental sciences and ecotoxicology fields. Various deadly illnesses and environmental problems are caused by them. It is a major issue in society that there are no new and effective ways to eliminate POPs from the atmosphere. Nanotechnology is a rapidly developing area that has uses in every aspect of life. A lot of attention is being paid to the investigation of novel synthetic methods for shaping and controlling the size of nanomaterials due to their outstanding uses and qualities. One of the most significant groups of nanoparticles is the magnetic nanoparticles. A novel class of magnetic separation techniques for water treatment has been made possible through the utilization of magnetic nanoparticles as nano adsorbents. Our aim in this study is to give a concise, focused review of POP, emphasize the sources, types, and potentially hazardous impacts they have on living organisms, and to offer some observations on their detection and monitoring strategies. To highlight specific conventional removal technologies of importance, as well as recent advancements such as nanotechnology and magnetic nanoparticles, including their synthesis methods. Finally, hybrid nanotechnology for POP removal has been investigated.

Comparative study of reactive oxygen species and tetracycline degradation pathways in catalytic peroxodisulfate activation by asymmetric mesoporous TiO2 and the corresponding controlled-release materials

The removal of trace amounts of antibiotics from water environments while simultaneously avoiding potential environmental hazards during the treatment is still a challenge. In this work, green, harmless, and novel asymmetric mesoporous TiO2 (A-mTiO2) was combined with peroxodisulfate (PDS) as active components in a controlled-release material (CRM) system for the degradation of tetracycline (TC) in the dark. The formation of reactive oxygen species (ROS) and the degradation pathways of TC during catalytic PDS activation by A-mTiO2 powder catalysts and the CRMs were thoroughly studied. Due to its asymmetric mesoporous structure, there were abundant Ti3+/Ti4+ couples and oxygen vacancies in A-mTiO2, resulting in excellent activity in the activation of PDS for TC degradation, with a mineralization rate of 78.6%. In CRMs, ROS could first form during PDS activation by A-mTiO2 and subsequently dissolve from the CRMs to degrade TC in groundwater. Due to the excellent performance and good stability of A-mTiO2, the resulting constructed CRMs could effectively degrade TC in simulated groundwater over a long period (more than 20 days). From electron paramagnetic resonance analysis and TC degradation experiments, it was interesting to find that the ROS formed during PDS activation by A-mTiO2 powder catalysts and CRMs were different, but the degradation pathways for TC were indeed similar in the two systems. In PDS activation by A-mTiO2, besides the free hydroxyl radical (·OH), singlet oxygen (1O2) worked as a major ROS participating in TC degradation. For CRMs, the immobilization of A-mTiO2 inside CRMs made it difficult to capture superoxide radicals (·O2−), and continuously generate 1O2. In addition, the formation of sulfate radicals (·SO4−), and ·OH during the release process of CRMs was consistent with PDS activation by the A-mTiO2 powder catalyst. The eco-friendly CRMs had a promising potential for practical application in the remediation of organic pollutants from groundwater.

Nitrogen-doped metal-free granular activated carbons as economical and easily separable catalysts for peroxymonosulfate and hydrogen peroxide activation to degrade bisphenol A.

The fabrication of low-cost, highly efficient, environmentally friendly, and easily separable metal-free heterogeneous catalysts for environmental remediation remains a challenge. In this study, granular nitrogen-doped highly developed porous carbons with a particle size of 0.25-0.30mm were prepared by preoxidation and subsequent NH3 modification of a commercially available coconut-based activated carbon, and used to activate peroxymonosulphate (KHSO5) or hydrogen peroxide (H2O2) to degrade bisphenol A (BPA). The nitrogen-doped carbon (ACON-950) prepared by NH3 modification at 950°C, with the addition of only 0.15g/L could remove 100% of 50mg/L BPA in 150min, and more than 90% of the removed BPA was due to degradation. The removal rates of total organic carbon of ACON-950/KHSO5 and ACON-950/H2O2 systems reached 60.4% and 66.2% respectively, indicating the excellent catalytic activity of ACON-950. The reaction rate constant was significantly positively correlated with the absolute content of pyridinic N (N-6) and graphitic N (N-Q) and negatively and weakly positively correlated with pyrrolic N (N-5) and defects. Quenching experiments combined with electron paramagnetic resonance demonstrated that singlet oxygen was the dominant reactive oxidative species for BPA degradation. ACON-950 was characterized before and after the degradation reaction using N2 adsorption-desorption analyzer, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results confirmed the prominent contribution of both the N-6 and N-Q to the catalytic performance of nitrogen-doped carbons. The reusability of ACON-950 and its application in actual water bodies further demonstrated its remarkable potential for the remediation of organic pollutants in wastewater.

Mechanism and ecological environmental risk assessment of peroxymonosulfate for the treatment of heavy metals in soil

Oxidation technologies based on peroxymonosulfate (PMS) have been effectively used for the remediation of soil organic pollutants due to their high efficiency. However, the effects of advanced PMS-based oxidation technologies on other soil pollutants, such as heavy metals, remain unknown. In this study, changes in the form of heavy metals in soil after using PMS and the risk of pollution to the ecological environment were investigated. Furthermore, two risk assessment methods, the mung bean germination toxicity test and groundwater leaching soil column test, were employed to evaluate the soil before and after PMS treatment. The results showed that PMS has a strong ability to degrade complex compounds, enabling the transformation of heavy metals, such as Cd, Pb, and Zn, from stable to active states in the soil. The risk assessments showed that PMS treatment activated heavy metals in the soil, which delayed the growth of plants, increased heavy metal content in plant tissues and the risk of groundwater pollution. These findings provide a new perspective for understanding the effects of PMS on soil, thus facilitating the sustained and reliable development of future research in the field of advanced oxidation applied to soil treatment.

Superior photocatalytic performance of ZnMoO4/Ag2WO4 for degradation of trimethoprim and methylene blue

ABSTRACT In the present work, ZnMoO4/Ag2WO4 nanocomposite was synthesized via facile hydrothermal and chemical precipitation method for determination of photocatalytic performance on organic contaminants such as methylene blue and trimethoprim. The synthesized nano-photocatalyst was characterized using various instrumental techniques. Photocatalytic degradation of methylene blue and trimethoprim by the samples was realized under UV light irradiation. The obtained results demonstrated that photocatalytic degradation of methylene blue by ZnMoO4/Ag2WO4 was 99.6% in 30 min. The bare ZnMoO4 produced 57.8% and Ag2WO4 produced 76.7% photocatalytic degradation of methylene blue in 60 min. The synthesized ZnMoO4/Ag2WO4 nanocomposite, about which there is little information on remediation of organic pollutants, had possessed the outstanding photocatalytic degradation performance on methylene blue and trimethoprim due to pseudo first order kinetic.

Role of Structural Decisive via Ultra‐Sonication on Photocatalytic Response of MWCNTs Intercalated ZnO Composites

AbstractIn this manuscript role of MWCNTs on the photocatalytic response of zinc oxide (ZnO) semiconductor photocatalyst is reported. Developing a cheap, stable, and effective photo catalyst is necessary for remediation of persistent organic pollutants. To address this challenge, ZnO/MWCNT composites are fabricated via sonication technique with interfacial engineering for effective photocatalytic response. X‐ray diffraction spectra confirms hexagonal structure of ZnO/MWCNT composites with the average particle size distribution of 73–80 nm. FT‐IR spectra confirms bonding structure, however SEM images confirm the homogeneous distribution of MWCNTs in the ZnO system which acts as an effective adsorbent sites. The highest degradation (90%) of methylene blue (MB) dye on ZnO95MWCNT5 composite has been observed. It is expected that MWCNTs taking part to electron transfer facilitation in spatial separation and electron–hole pairs of ZnO during photo catalysis mechanism.

New Y0.045Ni0.045Fe2.91O4 nanowires decorated over mesoporous silica for crystal violet removal: Response surface methodology optimization, kinetics, and isothermal studies

Recently, there has been considerable interest in developing an efficient, easily separable, cost-effective, and environmentally friendly catalyst for treating toxic environmental pollutants. In this study, we successfully designed yttrium–nickel-doped magnetite nanowires (Y0.045Ni0.045Fe2.91O4) and their mesoporous silica (MS)-coated composite (Y0.045Ni0.045Fe2.91O4/MS) using a simple coprecipitation method. The resulting composite demonstrated effective adsorption and photocatalytic degradation of crystal violet (CV) dye under sunlight. Various instrumental characterization techniques were employed to assess the nanowires' morphological, chemical, and surface functional properties and their composite. The existence of metal–oxygen bonds in Y0.045Ni0.045Fe2.91O4 within the 500–800 cm−1 range was verified through FTIR analysis. According to the Brunauer–Emmett–Teller analysis, the composite exhibited a surface area of 285 m2/g, a pore volume of 0.436 cm³/g, and an average pore width of 5 nm. The composite's high surface area and mesoporous nature underscored its porous structure, confirming its enhanced adsorption capacity for contaminants. High resolution XPS spectrum justified the presence of surface silanol groups (Si–OH) which are responsible for adsorption phenomena. Photocatalytic experiments revealed that Y0.045Ni0.045Fe2.91O4 nanowires and their composites achieved 89% and 90% degradation rates for CV dye within 60 and 10 min, respectively. The removal efficiency was assessed under optimized conditions of pH (8), dose (15 mg), time (60 and 10 min), and concentration (10 mg/L). Statistical analysis revealed that pH significantly impacted CV dye removal because functional group activation varied at different pH values. To elucidate the adsorption mechanism and kinetics, the Temkin isotherm model and pseudo-second-order kinetics model (R2 = 1.996 mg min−1) were the best fit for the composite. Furthermore, approximately 99% of the nanowires were magnetically separated from the reaction mixture in an external magnetic field. The demonstrated synergy of efficient adsorption–photocatalysis, coupled with easy recovery, suggests that innovatively designed nanomaterials are optimal for the water remediation of organic pollutants in wastewater.

Review on Research and Application of Enhanced In-Situ Bioremediation Agents for Organic Pollution Remediation in Groundwater

Groundwater is an important part of the water resources, crucial for human production and life. With the rapid development of industry and agriculture, organic pollution of groundwater has attracted great attention. Enhanced in-situ bioremediation of groundwater technology has gradually gained attention because of its high efficiency and low environmental impact. Bioremediation agents are crucial for bioremediation technology. In this review, bioremediation agents were classified into three categories: biological nutrition agents, slow-release agents, and microbial agents. Biological nutrition agents are a specific mixture of mineral salt and carbon source; slow-release agents may contain mineral salt, carbon source, pH buffers, and oxygen-releasing material and microbial agents with specific microbial culture. By adding bioremediation agents to the polluted sites, they can improve population density and degradation efficiency for microbial degradation of pollutants. To assist future development and application of bioremediation agents, the development of different agents in laboratory and commercial to date was retrieved online via publisher sites and cooperation case studies. The data collected were analyzed and reviewed, as well as application and remediation effects of enhanced in-situ bioremediation agents were summarized. Current studies mainly focus on laboratory development and experiments, while field tests and remediation effects between different agents are of less concern. Further study may focus on developing new materials, especially coating or loading materials, and systematic evaluation of different agents, considering both laboratory research and on-site experiments, in order to improve the efficiency of in situ organically contaminated groundwater bioremediation.