Large-scale Remediation Research Articles

Wastewater management by using effective phytoremediator duckweed

Water pollution and the increasing discharge of untreated wastewater into natural water bodies are intensifying the pressure on aquatic environments. Sustainable and eco-friendly methods are essential for restoring water quality and mitigating pollution. One such approach is water phytoremediation, which involves the use of aquatic plants to remove pollutants from water bodies and ecosystems. This study explored the removal of contaminants from municipal wastewater using floating aquatic plants such as Lemna minor, which have proven highly effective for phytoremediation due to their low cost, high pollutant uptake capacity, minimal generation of chemical and biological sludge, ease of transport, adaptability to diverse climatic conditions, and rapid reproduction rates. Notable findings from the research include reductions in chemical oxygen demand (COD) by 82.2%, biological oxygen demand (BOD) by 84.3%, phosphates by 63.8%, ammonium nitrogen by 75.4%, and nitrates by 79.1% for Lemna minor. Maximum plant growth occurred during the experiment at pH levels between 7 and 8. The study demonstrated that large-scale remediation could be effectively achieved using Lemna minor as a phytoremediation agent within 17 days. This method offers a cost-effective, efficient tertiary treatment for heavily polluted wastewater. Additionally, it can serve as an independent treatment solution when integrated with preliminary wastewater treatment systems in smaller communities.

Flexible carbonaceous silica nanofibers with superior toughness and strength for oil-in-water emulsions separation

Ceramic materials have a host of applications from thermal insulation, catalysis, and laser lighting to high temperature filtration due to its unique features, such as high temperature resistance, corrosion proof, and low thermal conductivity, etc. However, current ceramic materials are usually brittle with small toughness and poor tolerance to vibration and buckling, which have restricted its applications in various areas. Herein, the flexible carbonaceous silica (CS) nanofiber membranes with superior toughness and strength were facile fabricated via the sol–gel method and electrospinning technique. The in-situ generated carbonaceous materials and force-induced lamellar structure played important roles in enhancement of mechanical properties and regularity of wettability. The unique features of CS nanofibers favored the membranes with robust mechanical properties with the tensile strength of 6.8 MPa and breaking elongation rate of 78 %, which is much higher than that of conventional ceramic fibers. The resultant membranes exhibited outstanding separation performance towards oil-in-water emulsions with high separation efficiency of ∼ 98.4 %, large permeation flux of 7345.4 L m-2h−1, good reusability within 10 cycles, and long-term usability. In addition, the membranes also exhibited good separation performance towards emulsion in hash environment. In addition, the flexible CS nanofiber membrane based spoon was used to vividly separate oil/water mixture and emulsions, which is promising for large-scale remediation of wastewater under extreme conditions.

Enhanced phosphate removal from aqueous environments using three-dimensional La-doped carboxylic carbon nanotubes/alginate: Performance and mechanisms

The excessive amounts of phosphorus (P) discharged and usage have caused eutrophication and algal blooms, which seriously jeopardize the environment even the human health. In this study, carbon nanotubes (CNTs) served as carriers to develop a lanthanum-based sodium alginate hydrogel (La-CNT-COOH/SA) aimed at efficiently removing phosphate from wastewater. Characterization results confirmed successful deposition of La(OH)3 nanoparticles onto CNT-COOH. The optimal adsorption efficiency of La-CNT-COOH/SA hydrogels occurred at pH 4, with a maximum adsorption capacity of 54.4 mg/g under an initial phosphate concentration of 60 mg/L. Batch experiments demonstrated that La-CNT-COOH/SA performed well across a favorable pH range and exhibited high tolerance to common coexisting ions during phosphate adsorption. Adsorption isotherms indicated a dominance of both physical and chemical mechanisms in phosphate removal by La-CNT-COOH/SA. At elevated phosphate concentrations, the adsorption process followed quasi-second-order kinetics, primarily driven by chemical adsorption. Multi-instrument characterization emphasized that the substantial loading of La(OH)3 on CNT-COOH significantly contributed to adsorption, alongside crosslinked lanthanum ions on sodium alginate and abundant hydroxyl groups. Mechanisms of adsorption by La-CNT-COOH/SA encompassed electrostatic interactions, surface precipitation, and in-sphere complexation (La-O-P). These findings on fabrication, properties, and adsorption mechanisms of the phosphate-removal hydrogel lay a theoretical foundation for applying biomass-based materials in large-scale remediation practices.

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. 2.4 nm 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.

Superhydrophobic/ superoleophilic polystyrene-based porous material with superelasticity for highly efficient and continuous oil/water separation in harsh environments

Three-dimensional separation materials with robust physical/chemical stability have great demand for effective and continuous separation of immiscible oil/water mixtures and water-in-oil emulsions, resulting from chemical leakages and discharge of industrial oily wastewaters. Herein, a superelastic polystyrene-based porous material with superhydrophobicity/superoleophilicity was designed and prepared by high internal phase emulsion polymerization to meet the aforementioned requirements. A flexible and hydrophobic aminopropyl terminated polydimethylsiloxane (NH2-PDMS-NH2) segment was introduced into the rigid styrene-divinylbenzene copolymer through 1, 4-conjugate addition reaction with trimethylolpropane triacrylate. The addition of NH2-PDMS-NH2 simultaneously improved the mechanical and hydrophobic properties of the porous material (the water contact angle from 141.2° to 152.2°). The material exhibited outstanding reversible compressibility (80% strain, even in liquid N2 environments) and superhydrophobic stability, even after being repeatedly compressed 100 times, water contact angle still remained above 150°. Meanwhile, the as-prepared material had outstanding hydrophobic stability in corrosive solutions (strong acidic, alkaline, high-salty, and even strong polar solvent), presence of mechanical interference, strong UV radiations, and high/low temperature environments. More importantly, the material could continuously and efficiently separate immiscible oil/water mixture and water-in-oil emulsions under the above conditions, showing huge potential for the large-scale remediation of complex oily wastewaters.

Remediation of polycyclic aromatic hydrocarbons polluted soil by biochar loaded humic acid activating persulfate: performance, process and mechanisms

The remediation for polycyclic aromatic hydrocarbons contaminated soil with cost-effective method has received significant public concern, a composite material, therefore, been fabricated by loading humic acid into biochar in this study to activate persulfate for naphthalene, pyrene and benzo(a)pyrene remediation. Experimental results proved the hypothesis that biochar loaded humic acid combined both advantages of individual materials in polycyclic aromatic hydrocarbons adsorption and persulfate activation, achieved synergistic performance in naphthalene, pyrene and benzo(a)pyrene removal from aqueous solution with efficiency reached at 98.2%, 99.3% and 90.1%, respectively. In addition, degradation played a crucial role in polycyclic aromatic hydrocarbons remediation, converting polycyclic aromatic hydrocarbons into less toxic intermediates through radicals of ·SO4-, ·OH, ·O2–, and 1O2 generated from persulfate activation process. Despite pH fluctuation and interfering ions inhibited remediation efficiency in some extent, the excellent performances of composite material in two field soil samples (76.7% and 91.9%) highlighted its potential in large-scale remediation.

Prodigious catalytic activity towards reduction of 4-hydroxynitrobenzene sodium salt using one-pot synthesized ZnO-Pd nanobolts

4-Hydroxynitrobenzene sodium salt (4-HNBS) is primarily used to manufacture pesticides, p-aminophenol, paracetamol, and dye intermediates. However, it is released into aquatic systems, which can cause severe health issues in humans. Therefore, novel approaches for detoxifying excessive 4-HNBS must be devised using ultralow amounts of cost-effective catalysts with high reduction efficiencies. To that end, an innovative one-pot, sustainable, and cost-effective method was developed in this study to synthesize ZnO–Pd nanobolt catalysts. The nanobolts were characterized using UV–vis spectroscopy, dynamic light scattering analysis, X-ray diffractometry, field-emission scanning electron microscopy, transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). TEM images indicated that the nanobolts were 13.8–66.6-nm-thick and that they had a 44.5-nm-diameter central hole. The EDS results suggested that the weight percentages of Zn, O, and Pd were 37.12 %, 23.63 %, and 39.24 %, respectively. This is the first report on the catalytic conversion of 4-HNBS into 4-hydroxyaniline sodium salt (4-HAS), whereas previous studies have mainly focused on converting small amounts of 4-hydroxynitrobenzene (4-HNB) into 4-HAS using high catalyst concentrations. Additionally, the reusability of the catalyst was studied to prevent the problems encountered in large-scale remediation. The synthesized nanobolts exhibited outstanding catalytic properties for converting 4-HNBS to 4-HAS. The rate constant k was estimated to be 0.068 min−1 from the linear plot of ln(C/C0) versus the conversion time. Notably, the nanobolts achieved 99 % reduction of 0.125 mM 4-HNBS after only 30 min of incubation.

Simultaneous immobilization enhances synergistic interactions and crude oil removal of bacterial consortium

Oil spillage has serious adverse effects on marine environments. The degradation of crude oil by microorganisms may be an effective and sustainable approach. In this study, the removal of crude oil from seawater by immobilized bacterial consortium was performed and the enhancement of crude oil degradation efficiency by varying immobilization methods and inoculum volume ratio was examined. The nonpathogenic and heavy metal-tolerant bacterial consortium of Sphingobium naphthae MO2-4 and Priestia aryabhattai TL01-2 was immobilized by biofilm formation on aquaporousgels. The simultaneous immobilization of strains MO2-4 and TL01-2 showed better crude oil removal efficiency than independent immobilization, which indicated positive interactions among consortium members in the mixed-culture immobilized systems. Moreover, the immobilized consortium at a 2:1 (MO2-4:TL01-2) inoculum volume ratio showed the best crude oil removal capacity. The immobilized consortium removed 77% of 2000 mg L−1 crude oil in seawater over 7 days. The immobilized consortium maintained crude oil removal efficacy in semicontinuous experiments. In addition, the immobilized consortium was used to remediate seawater contaminated with 1000 mg L−1 crude oil in a 20 L wave tank. After 28 days, the crude oil degradation efficiency of immobilized consortium was approximately 70%, and crude oil degradation through natural attenuation was not observed. Moreover, the genomic features of strains MO2-4 and TL01-2 are reported. Genomic analyses of both strains confirmed the presence of many genes involved in hydrocarbon degradation, heavy metal resistance, biosurfactant synthesis, and biofilm formation, supporting the biodegradation results and characterizing strain properties. The results of this work introduce the potential benefit of simultaneous immobilization of bacterial consortia to improve efficiency of crude oil biodegradation and has motivated further investigations into large-scale remediation of crude oil-contaminated seawater.

Selective removal of 90Sr by a novel IDA-chelating resin from contaminated groundwater

The preparation of cost-effective, environmentally friendly, and highly selective adsorbents is crucial for capturing 90Sr from radionuclide-contaminated wastewater due to its long half-life and chemical toxicity. In this study, a novel IDA-type chelating resin (PS-IDA) was synthesized by chloroacetylating polystyrene (PS) and introducing iminodiacetic acid (IDA) onto it. Batch adsorption experiments were conducted to investigate the adsorption of Sr2+ on PS-IDA, including pH, contact time, initial concentration of Sr2+, and competing ions. The results indicated that pH 10 was the optimal condition for maximum Sr2+ ion adsorption. According to isotherm and kinetic data, the adsorption was well-fitted to the Freundlich model and pseudo-second-order kinetic model.Notably, PS-IDA exhibited a high removal rate at pH 10, removing 98.0% and 99.6% of non-radioactive Sr2+ and 90Sr, respectively. In simulative groundwater, PS-IDA demonstrated remarkable selectivity for trace levels of 90Sr (90Sr: Na+: K+: Cs+: Mg2+ molar ratio = 1: 6.6 × 1015: 3.8 × 1014: 2.5 × 1014: 1.5 × 1013), indicating its potential for selective capture of 90Sr from contaminated groundwater. Furthermore, PS-IDA resin with a suitable diameter and improved mechanical strength can be used for large-scale remediation of 90Sr-contaminated wastewater bycolumnchromatography method. Finally, the adsorption mechanism was explained based on experimental data and characterizations which included ion exchange between Sr2+ in the solution with H+ on the resin and then the formation of chelates between adsorbed Sr2+ and O, N atoms from IDA.

Strategies for cost-effective remediation of widespread oil-contaminated soils in Kuwait, an environmental legacy of the first Gulf War

The Kuwaiti oil fire during the first Gulf War resulted in the formation of approximately 300 “oil lakes” of varying sizes that covered over 110 km2 of the desert land. This threatens the fragile desert ecosystems and human health. Following the award of over US$2 billion to the State of Kuwait by the United Nations, large-scale remediation of the oil-contaminated soils has now been on the agenda. However, how to implement the remediation program in a cost-effective way represents a major challenge. In this study, cost-effective remediation strategies were developed based on field and laboratory investigations in a typical oil lake area. Overall, most of the lighter petroleum hydrocarbons (PHCs) were lost due to evaporation. Long-chain aliphatic PHCs dominated the PHCs in the investigated oil lake area. This has implications for developing remediation strategies. Toxicity assessment results showed that the majority of soils pose a low environmental risk with a hazard index <1. Therefore, intensive treatment of these PHCs may not be necessary for these soils. Although active treatment methods are needed to remove the contaminants as soon as practical for the relatively small areas of high contamination, more cost-effective passive methods should be considered to minimize the remedial costs for the larger area of the non-hotspot areas. Given the extremely low risk in terms of groundwater contamination by the contaminated soils, it may not be necessary to remove the soils from the contaminated sites. A low-cost capping method should be sufficient to minimize human exposure to the PHC-contaminated soils.

An integrated strategy for ultra-efficient recovery and sustainable reuse of Congo red from wastewater

Adsorption is widely used to treat of toxic dyes represented by Congo red (CR) in wastewater because of its simplicity. However, it is still a challenge to use adsorbents to recover CR efficiently without additional adsorption conditions, and to recycle recovered CR rather than remove it at high temperatures. In this paper, the green and low-cost mesoporous AlOOH bundles were synthesized by a simple hydrothermal method. Batch adsorption results showed that AlOOH bundles had the ultrahigh adsorption capacity (5438.2 mg/g) and ultrafast adsorption equilibrium time (≤5 min) for CR without additional adsorption conditions. CR loaded AlOOH was easily separated from water by natural sedimentation or filtration, and CR adsorption followed the pseudo-second-order model and Langmuir isotherm model. The XPS and FTIR studies revealed adsorption mechanism of CR on AlOOH bundles could be attributed to electrostatic attraction and hydrogen bond. In addition, the dyeing effect of CR recovered from wastewater was reported for the first time. CR loaded AlOOH had a dual function as the dye and filler for epoxy resins and could improve their mechanical properties and flame retardant. Based on the ultra-highly efficient recovery of CR from dye wastewater by AlOOH bundles and its resource utilization in remarkable dyeing of epoxy resin, this paper provides an ideal strategy for the economical, green and large-scale remediation of dye wastewater, and a new route for high value-added resource utilization of CR recovered by adsorbents.

Health and Safety Protocol for the Management of Building Demolition Waste with High Mercury Contamination

The LIFE-funded European research project SUBproducts4LIFE seeks to demonstrate the use of industrial subproducts for the large-scale remediation of contaminated soils and industrial building debris connected to Hg mining. The main purpose of the present research was to ensure worker health and safety by creating a protocol for working in a highly mercury-contaminated demolition debris. A methodology consisting of sampling campaigns with a Lumex RA-915 mercury analyser, evaluating the accuracy of an empirical Hg emission model, evaluating each working task, providing recommendations for minimising the workers’ exposure and calculating the maximum work period in each area was proposed. It was also shown to forecast Hg biological markers. As a result, a work protocol was developed with three scenarios which allow planning the work and forecasting the workers’ mercury exposure as a function of the daily temperature, ensuring that the workers’ mercury exposure is below occupational mercury levels. The working protocol allows planning the works safely with minimum exposure to gaseous mercury and working fulfilling standard requirements. Plans for restoration or new use of industrial mercury-contaminated sites have increased in recent years, and the research improves the knowledge of Hg gas distribution and worker Hg exposure.

Facile synthesis of functional holocellulose fibers for removal of micro-/nanoparticles of plastics from waste water

Micro-/nanoparticles of plastics in water caused by the massive use and high stability of plastic products have become a major global environmental problem. The method based on biomass adsorbent materials to remove plastic fragments from environment is highly needed. In this work, functional polyethylenimine coated holocellulose acetoacetate (HAA-PEI) fibers were synthesized via a facial way for the removal of polystyrene (PS) micro-/nanoparticles with different sizes from wastewater was analyzed in detail. It revealed that HAA-PEI fibers, act as ideal capturing materials, display maximum adsorption efficiency of 99 %, 98 %, and 97 % for PS particles with diameters of 100 nm, 500 nm, and 1 μm, respectively. The adsorption process of HAA-PEI fibers for PS MNPs conforms to pseudo-second-order adsorption kinetics model and Langmuir isotherm model. Meanwhile, the adsorbed PS micro-/nanoparticles can be easily removed via the alkali treatment or used directly with holocellulose fibers for paper-making. Therefore, the prepared HAA-PEI fibers can be applied as high extraction efficiency, easy to obtain, easy to desorption adsorbents for green, rapid, and large-scale remediation in the future.

Potential of plant growth promoting rhizobacteria to mitigate chromium contamination

The main threats to human health and agriculture from heavy metals are associated with exposure to chromium, lead, cadmium, mercury, and arsenic. Among the metals, Chromium is one of the most lethal heavy metals because of its toxicity and hazardous nature. It affects biological activities in soil and metabolism of animals, plants, and human health. Among various forms of chromium, trivalent Cr (III) and hexavalent Cr (VI) are more stable in nature. The higher concentration of Cr (VI) in soil may affect many biochemical and physiological processes and consequently inhibits plant growth. Plant growth promoting rhizobacteria (PGPR) are involved in regulation of seed germination, growth promotion, metabolic rate, and other physiological activities of plants. PGPR may reduce toxic effects of Cr (VI) on plant growth through reducing Cr (VI) to Cr (III). Many recent reports describe the application of heavy metal resistant-PGPRs to enhance agricultural yields without accumulation of metal in plant tissues. This review provides information about the mechanisms possessed by heavy metal resistant-PGPRs that ameliorate metal stress to plants and decrease the accumulation of these metals in plant, and finally gives some perspectives for research on these bacteria in agriculture in the future. • Cr(VI) of industrial effluents impact negatively on human health and environment. • The removal of Cr(VI) from wastewater and soil requires serious and immediate attention. • Biological removal of Cr(VI) is a sustainable and environmentally friendly technology. • Cr(VI)-bioremediation strategies are applied in different systems and scales. • Research is essential to solve the problems associated to the large-scale remediation.

Supercritical fluid remediation for soil contaminants: Mechanisms, parameter optimization and pilot systems

Soil contamination is one of the major sustainable development issues which requires increasing efforts from multidisciplinary collaborations. In recent years, supercritical fluid remediation has been proposed as one “green technology” that is suitable with various types of contaminants without destroying the soil nature. Supercritical fluid process employs the high solubility and zero surface tension of supercritical states as well as the large solubility variations in the supercritical region for high efficiency separation. In this analysis, characteristics of soil contaminants in representative “matrix” conditions and related effects on remediation process with supercritical fluid technology are analyzed. Mechanisms and procedures of supercritical remediation technology are summarized and compared for different contaminants. Operation conditions, flow design, processing time and the entrainer applications in supercritical fluid remediation systems are shown to act more as coupled parameter groups rather than single-parameter controlled system. From a summary of existing remediation prototypes, a remediation efficiency around 80 % were shown. It is recommended that large-scale remediation trials be operated and optimized soon.

PH-responsive magnetic artificial melanin with tunable aggregation-induced stronger magnetism for rapid remediation of plastic fragments

The global occurrence of plastic fragment pollutants in water resources has raised concerns about food safety, drinking water security, and long-term ecological impacts worldwide. The different chemical nature, the persistence, and the smaller size make micro-plastics accumulators for toxins that pose a potential threat to human health. Generally, the smaller the size of the plastic fragments is, the more difficult it is to remove them from the aquatic environment. Methods to remove plastics from water or other media are highly needed. Here, we develop core-shell superparamagnetic melanin nanoparticles, which can put magnetism on nano-/micro-plastics within 30 s and then rapidly remove them from water by applying an external magnetic field. The shell material (artificial nano-melanin) provides simultaneously attractive electrostatic, hydrophobic interaction, and van der Waals' forces to attract nano-/micro-plastics, which plays a key role in the rapid remediation of the plastic fragments. With this principle applied to a simple method, the average removal efficiency achieves 89.3%. We show a method for high-throughput remediation of various micro-plastics with simple materials and processes, which have the potential for rapid, green, and large-scale remediation in the future.

Functionalization of mesoporous carbons derived from pomelo peel as capacitive electrodes for preferential removal/recovery of copper and lead from contaminated water

• Waste pomelo peel converted into a novel adsorbent for use in CDI. • Removal of Pb and Cu ions strongly enhanced by functionalizing with pyrrolic-N. • Strong selectivity of Pb 2+ from water containing multiple competing ions. • Easy regeneration of adsorbent on no loss in performance over 300 cycles. Water is not only a valuable resource that is needed to sustain life, but also an essential ingredient in many engineering processes, which unavoidably leads to large volumes of water being contaminated. To achieve safe discharge and also recover valuable “pollutants”, better performing sorbents are needed to rapidly and efficiently decontaminate water while generating minimal secondary wastes. Bio-sorbents derived from pomelo peel were functionalized with pyrrolic-N (BNC-5 electrode) and pyridinic-N (BNC-6 electrode) to enhance electroadsorption and selectivity of Pb 2+ and Cu 2+ . The interaction between soft acid ions (Pb 2+ ) and soft base sites (pyrrolic-N) contributed to a strong chemisorption that elevated the electroadsorption capacity to 2.0 mmol g −1 for Pb 2+ at an applied voltage of 1.2 V. With fast removal kinetics (0.077 g mg −1 min −1 of Pb 2+ ), the BNC-5 sorbent performed comparably to other N-doped sorbents prepared using graphene. The large adsorption–desorption hysteresis of BNC-5 in responding to the applied electric voltage confirmed the nature of chemisorption. The results showed only 32.4% of the adsorbed ions being desorbed from the sorbent by reducing the applied voltage to 0 V, but reached almost complete desorption (98.5% of adsorbed ions) at –0.8 V. When operated in adsorption–desorption cycle mode, BNC-5 after ∼ 400 cycles maintained a capacity retention ≥ 80%. After 400 cycles, the electrode capacity was almost fully restored (98.7%) by only mild chemical washing (0.1 M HNO 3 ) of the sorbent and the cycling performance maintained. The study demonstrated the robustness of the sorbent over 1200 cycles and hence the potential to successfully convert waste into high-performance materials for large-scale remediation strategies of contaminated wastewater using CDI.

Isolation of Dibutyl Phthalate-Degrading Bacteria and Its Coculture with Citrobacter freundii CD-9 to Degrade Fenvalerate.

Continued fenvalerate use has caused serious environmental pollution and requires large-scale remediation. Dibutyl phthalate (DBP) was discovered in fenvalerate metabolites degraded by Citrobacter freundii CD-9. Coculturing is an effective method for bioremediation, but few studies have analyzed the degradation pathways and potential mechanisms of cocultures. Here, a DBP-degrading strain (BDBP 071) was isolated from soil contaminated with pyrethroid pesticides (PPs) and identified as Stenotrophomonas acidaminiphila. The optimum conditions for DBP degradation were determined by response surface methodology (RSM) analysis to be 30.9 mg/l DBP concentration, pH 7.5, at a culture temperature of 37.2°C. Under the optimized conditions, approximately 88% of DBP was degraded within 48 h and five metabolites were detected. Coculturing C. freundii CD-9 and S. acidaminiphila BDBP 071 promoted fenvalerate degradation. When CD-9 was cultured for 16 h before adding BDBP 071, the strain inoculation ratio was 5:5 (v/v), fenvalerate concentration was 75.0 mg/l, fenvalerate was degraded to 84.37 ± 1.25%, and DBP level was reduced by 5.21 mg/l. In addition, 12 fenvalerate metabolites were identified and a pathway for fenvalerate degradation by the cocultured strains was proposed. These results provide theoretical data for further exploration of the mechanisms used by this coculture system to degrade fenvalerate and DBP, and also offer a promising method for effective bioremediation of PPs and their related metabolites in polluted environments.

Multi-elemental doped g-C3N4 with enhanced visible light photocatalytic Activity: Insight into naproxen Degradation, Kinetics, effect of Electrolytes, and mechanism

• Multi elemental doped g-C 3 N 4 was prepared by a solid-state method. • 92.9% degradation of naproxen was achieved under visible light irradiation. • Doping increased the Urbach energy of g-C 3 N 4 . • Mechanism for the degradation of naproxen was proposed. The complexity and heterogeneous existence of water pollutants ensures that development of possible large-scale water remediation technologies encompasses mimicking real water compositions. Naproxen (NPX) photocatalytic degradation in the presence of brilliant black and different electrolytes was tested, under visible light irradiation, with rare earth metals (Ce, Er, Gd, and Sm) doped graphic carbon nitride (CN) prepared via one pot solid state method. The materials were characterized with FESEM, TEM, XRD, PL, XPS, BET, UV–vis DRS, TGA, FTIR, and electrochemical techniques. Doping increased the Urbach energy compared to pristine graphitic carbon nitride due to observed shift in absorption towards the visible range of the electromagnetic spectrum, and there was proposed interaction of dopants and CN which decreased photoexcited electrons and holes recombination. The highest degradation efficiency of 92.9% was obtained at 1% loading of Ce, Er, Gd, and Sm metals in CN (1RECN) under visible light irradiation which was ascribed to Z-scheme formation, enhanced visible light absorption and superoxide anion radical’s involvement as the major species based on radical trapping experiments. The 1RECN photocatalyst demonstrated remarkable stability with a 3.4 % efficiency reduction after six photocatalytic degradation cycles. The effective and efficient separation and migration of photoexcited electron-hole pairs resulted in their high photodegradation activity compared to other synthesized composites and pristine CN. The fabricated composites provided an interesting perspective for a highly stable multi-elemental doped CN photocatalysts that could be employed for large scale remediation of different classes of organic pollutants.

Complexation and reduction of soil iron minerals by natural polyphenols enhance persulfate activation for the remediation of triphenyl phosphate (TPHP)-contaminated soil

Peroxydisulfate-based in-situ chemical oxidation (PDS-ISCO) is a promising technology for soil remediation. The weak potential of soil constituents for PDS decomposition results in the low degradation efficiency of soil contaminants. Herein, we propose a new soil remediation strategy by accelerating the activation efficiency of PDS using chelating and reducing reagents (CRs) to complex and reduce soil Fe-minerals. Experimental results demonstrated that the introduction of tea polyphenols (TP) into soil-PDS system could effectively improve the reduction of Fe-minerals and the degradation of triphenyl phosphate (TPHP) in soil. With increasing TP concentration from 0 to 40 mM, the degradation efficiency of TPHP increased from 10.8% to 58.6% in an upland soil (T1 soil). TP could directly complex and reduce the solid-phase Fe-minerals, leading to a significant increase of Fe(II) content, especially the insoluble Fe(II) content, which could further induce the PDS activation. Results of radical quenching experiments, electron paramagnetic resonance (EPR) analysis, and kinetic solvent isotope effect (KSIE) evaluation showed that sulfate radicals (SO4•−, especially surface-bound SO4•−), hydroxyl radicals (HO•, especially surface-bound HO•), and singlet oxygen (1O2) played major roles in TPHP degradation, with the estimated contributions of 39.03%, 43.99%, and 16.98%, respectively. The higher content of high active Fe fractions, such as amorphous Fe, the larger yields of Fe(II) species and TPHP degradation. Increased content of soil organic matter (SOM) and pH value from 2.5 to 8.0 may reduce TPHP degradation. The effects of inorganic anions and Mn-minerals, presented in natural soil, on TPHP degradation were very limited. Simulated in-situ soil remediation using soil column confirmed that this strategy is suitable for the large-scale remediation of contaminated soil.