Remediation Efficiency Research Articles

Field Study on Washing of 4-Methoxy-2-Nitroaniline from Contaminated Site by Dye Intermediates

Dye intermediates are important industrial chemicals; there is a lack of systematic field experiments and relevant validation data regarding the remediation of groundwater contamination by dye intermediates. This study examines the eluting effects of alcohol eluting agents, non-ionic surfactants, and deionized water on 4-methoxy-2-nitroaniline (4M2N) in a contaminated aquifer medium from a historically polluted dye intermediate production site in northwest China. The findings indicate that alcohol eluting agents exhibit superior eluting effects compared to non-ionic surfactants. Under optimized conditions, including 60% n-propanol concentration, a liquid-to-solid ratio of 15:1, two eluting cycles, an elution pH of 3, and a 2 h eluting duration, the eluting concentration of 4-methoxy-2-nitroaniline reached 75.49 mg/kg, exceeding that of the composite eluting agent by two times more and deionized water by three times further. Analysis revealed that the liquid-to-solid ratio and number of eluting cycles are the primary factors influencing eluting efficiency. Field trials conducted using treated groundwater involved injecting 31,560 m3 of treated groundwater over 152 days, resulting in the extraction of 38,550 m3 and the removal of about 1887 kg of 4-methoxy-2-nitroaniline. The concentrations of contaminants in both pumping wells and monitoring wells exhibited a certain degree of increase at various times. Field applications of treated groundwater washing facilitated the release of 4-methoxy-2-nitroaniline from the aquifer medium, which significantly enhances remediation efficiency. This provides theoretical support for data analysis and the promotion of similar remediation efforts.

Light harvesting S-scheme g-C3N4/TiO2/M photocatalysts for efficient removal of hazardous moxifloxacin

The development of advanced photocatalysts with enhanced efficiency for environmental remediation is critical for addressing persistent organic pollutants like Moxifloxacin. In this study, we present a novel S-scheme heterojunction g-C3N4/TiO2/M photocatalyst designed to optimize light harvesting and charge separation for the effective degradation of Moxifloxacin. The innovative S-scheme configuration enables superior charge transfer dynamics by retaining potent photogenerated electrons in the conduction band of TiO2 and holes in the valence band of g-C3N4, significantly improving photocatalytic performance compared to conventional Type-II systems. Heterogeneous photocatalysis, particularly using TiO2-based materials, offers a promising approach. Here, we synthesized TiO2 hybridized with metal-doped g-C3N4 (GCNTM) via a simple hydrothermal method. The fabricated nanocomposites were characterized using SEM, XRD, FTIR, and UV–Vis (DRS). These GCNTM nanocomposites were employed for the degradation of hazardous Moxifloxacin (MXF) under visible light. Detailed analysis of the photocatalytic mechanism reveals that the synergistic interaction between g-C3N4, TiO2, and the co-catalyst M not only broadens the light absorption spectrum but also enhances the separation and lifespan of charge carriers. Among the synthesized materials, GCNTLa demonstrated the highest degradation efficiency, achieving 96 % removal of MXF. This enhanced activity is attributed to the effective suppression of charge recombination, leading to the generation of reactive species responsible for MXF degradation. Additionally, GCNTM showed remarkable stability and reusability, with only a 6 % reduction in efficiency after five cycles, confirming its high reusability and mechanical stability. Our S-scheme photocatalyst demonstrates a marked increase in the degradation rate of Moxifloxacin under visible light irradiation, highlighting its potential for practical environmental applications.

UiO-67 metal-organic framework loaded on hardwood biochar for sustainable management of environmental boron contaminations

Boron contamination in water poses significant potential risks to human health and the environment, necessitating the development of efficient, cost-effective, and sustainable remediation technologies. This study introduces a novel composite material combining a zirconium-based metal-organic framework (UiO-67) and a low-cost carbonaceous material (hardwood biochar, BC) with synergetic efficiency to address boron-polluted waters. The UiO-67-biochar (UBC) composite exhibits effective surface chemistry and a remarkably high specific surface area of approximately 881.9m²/g, substantially increasing from the 19.7m²/g of biochar. Our experimental results demonstrate that UBC removed up to 88.5% of boron from 20 ppm polluted water, achieving levels compliant with the WHO standards. The composite also showed excellent reusability, maintaining 95% efficiency over multiple cycles without loss of crystallinity. Life cycle assessment and cost analysis indicate that an optimal MOF to biochar ratio of approximately 60wt% minimises CO2 emissions and costs while maximising the boron removal efficiency. The UiO-67-biochar composites proposed here offers a promising scalable solution for boron contamination and potentially other environmental pollutants, combining the high functionality of UiO-67 with the practical and economic advantages of biochar.

Multi-enzyme-immobilized robust self-floating covalent organic framework/chitosan aerogels for the efficient remediation of emerging pollutants in water

Organic contaminants of emerging concern (OCECs) as a new class of organic pollutants have initiated intense global concerns. The efficient enzymatic water treatment was consider the crucial for the potential remediation process. However, the widespread application of enzymatic systems faces significant obstacles, including low enzyme activity and the lower value of recovery. Thus, a novel multi-enzymes immobilized biocatalytic system (multi-enzyme@COF@Chitosan aerogels) was synthesized via the combine the in-situ direct immobilization process and double-cross linking strategy in this study. Results showed that multi-enzyme@COF@Chitosan aerogels exhibits good mesoporous structure (the pore size distribution is 2.5nm) and mechanical strength, leading to remarkable stability a broader pH range (4-7) and temperature range (30~70 ℃). For typical OCECs, including 2-mercaptobenzothiazole (MBT), paracetamol (PCM), sulfamethoxazole (SMO), bisphenol A (BPA), Sulfamerazine (SMR), the remediation activities reached 100%, 87%, 68%, 69%, and 100%, respectively. Likewise, the multi-enzyme@COF@Chitosan aerogels exhibited good reusability, with the relative activity still maintained approximately 75.7% after seven cycles. Moreover, the electrochemical characteristics of multi-enzymes@COF@Chitosan aerogel and enzymes activities were contributed to degradation the OCECs.

Co-cultivation of high-value microalgae species with filamentous microalgae for dairy wastewater treatment

The study examined the feasibility of co-culturing high-value microalgae sp. (Chlorella vulgaris (C.), and Scenedesmus (S.)) with filamentous microalgae sp. (Tribonema (T.) and Lyngbya (L.)) to remediate dairy wastewater (DW) and enhance biomass production and harvesting. The results showed that biomass productivity increased by 12‒174% compared to monocultures, and the best consortium was S:T. This consortium achieved the highest biomass productivity of 84.25 mg L−1 d−1 while removing 86.7% of chemical oxygen demand (COD), >88.7% of NO3−-N and >98.5% of PO43–-P. The study also tested the effect of harvesting time on the accumulation of biochemical components and found the optimal harvesting times of day 9 and day 11 to achieve maximum carbohydrate and lipid productivity, respectively. Additionally, the microalgae consortium S:T achieved a high biomass recovery of 78.5%, compared to 32.4% obtained for S. alone, highlighting its potential for efficient DW remediation and resource recovery.

Rhamnolipid production from waste cooking oil by a newly isolated thermo- and salt-tolerant Pseudomonas aeruginosa GH01.

Biological treatment has become a promising approach for the efficient remediation of WCO. Identifying effective oil-degrading microorganisms is critical for optimizing these processes. This study focuses on isolating thermo- and salt-tolerant microbes capable of utilizing WCO as a carbon source for the production of high-value compounds. A newly isolated strain of Pseudomonas aeruginosa GH01 demonstrated exceptional degradation of over 92% of WCO at a concentration of 22g/L within 5 days, producing 1011.2mg/L of rhamnolipids. Notably, P. aeruginosa GH01 exhibited tolerance to NaCl concentrations up to 40g/L and grew optimally at 45°C, which is higher than that of most other P. aeruginosa strains. The strain also secreted thermotolerant lipases, with a half-life (T1/2) of 75°C for 15min. These characteristics make P. aeruginosa GH01 a promising candidate for the bioremediation of WCO and the production of valuable biosurfactants like rhamnolipids. The ability to thrive in high salt and temperature environments also suggests its potential for industrial-scale applications, particularly in the WCO biodegradation and biosurfactant production industries.

Numerical simulation and experimental study on electrochemical recovery of copper using cylindrical and conical flow reactors

This study investigates the electrochemical recovery of copper from wastewater using cylindrical and conical flow reactors. Electrochemical approaches offer advantages such as environmental compatibility, operational versatility, and energy efficiency for heavy metal remediation. However, effective recovery from dilute effluents remains challenging due to mass transfer limitations. In this work, numerical simulations were conducted to analyze the flow field and current distribution in the reactors, with a focus on the copper reduction process. Experimental results were compared with transient simulations to assess the influence of geometry and operating parameters on the performance of the reactors. The study identified that conical reactors, particularly those with a narrowing electrode gap, enhanced mass transfer rates, leading to improved copper removal efficiency. Key findings include the relationship between electrolyte flow rates, Coulombic efficiency, and copper recovery efficiency. This work contributes to the investigation of electrochemical processes for sustainable heavy metal remediation.

Enhanced photocatalytic performance of SnS2/ZnO Z-scheme composite photocatalysts for efficient environmental remediation

Photocatalysts based on zinc oxide (ZnO) are promising for environmental applications, but their weak photoresponse and low photocarrier separation efficiency limit their practical use. To tackle this issue, we constructed Z-scheme composite photocatalysts of ZnO to boost its photocatalytic performance. We achieved the Z-scheme structure by hydrothermal modification of SnS2 nanoparticles onto ZnO microspheres. Its photocatalytic performance was evaluated through the degradation of Rhodamine B (RhB) under visible light with the assistance of magnetic stirring. The composite photocatalyst exhibited superior performance compared to individual ZnO and SnS2, achieving an optimal degradation rate of 0.0706 min⁻¹. This rate was 15.08 times higher than that of individual ZnO and 10.51 times higher than individual SnS2. Free radical trapping experiments showed that ·O2⁻ and ·OH radicals played a key role in RhB degradation. The Z-scheme composite structure established novel charge transport pathways, guided the migration of photogenerated carriers, and improved spatial separation, thereby enhancing photocatalytic performance. This study provides valuable insights into the design of highly efficient photocatalysts for environmental remediation, offering a promising solution for addressing challenges in pollution control and wastewater treatment.

Remediation of Cd and Cu compound contaminated soil with ryegrass (Lolium perenne L.) combined with electrokinetics

ABSTRACT The process of ryegrass combined with electrokinetics (REK) was developed to remediate the soil contaminated with Cd and Cu. The effects of voltage gradient, soil moisture content, and heavy metal concentration on the remediation efficiency of the process were investigated. Three voltage gradients (1.0, 2.0, 3.0 V/cm), three moisture contents (20%, 40%, 60%), and two heavy metal concentrations (Cd: 100 mg/kg, Cu: 150 mg/kg; Cd: 200 mg/kg, Cu: 300 mg/kg) were set. The ryegrass calculated for 5 d with uniform growth was selected, and directed-current (DC) was supplied and energized for 8 h/d for 5 d. The results showed that heavy metal ions migrated to the root system of ryegrass and the vicinity of the cathode under the action of an electric field, and were absorbed, degraded, and enriched to achieve the purpose of removal. The 3 factors had a significant impact on the remediation of REK. When the voltage gradient was 2.0 V/cm, the moisture content was 40%, and the concentration of heavy metals was low, the growth status of ryegrass was best. After remediation, the height of ryegrass increases by 4.4 cm, reaching a maximum of 13.5 cm. The fresh weight and dry weight of ryegrass were 0.68 g and 0.122 g. At this time, the removal rates of Cd and Cu in soil were 37.0% and 13.0%, respectively. It demonstrated that the application of ryegrass combined with electrokinetic technology in the remediation of heavy metal contaminated soil was promising.

Long-lasting and efficient peroxydisulfate-based groundwater remediation driven by the slowly released Fe(II) from natural chlorite

The rapid depletion of peroxydisulfate (PDS) and the competitive inactivation of reactive species by excessive Fe restrict the oxidation duration and performance of iron (Fe)-based catalysts activated PDS for in situ chemical oxidation (ISCO). Here, natural chlorite, one of the Fe-rich clay minerals, is used as activator to enhance the performance and efficiency of PDS-based ISCO. It was found that acidification of contaminated groundwater drives the slowly release of aqueous Fe(II) from chlorite and serving as the source of multiple reactive species including hydroxyl radical (•OH), sulfate radical (SO4•−), and Fe(IV). Benefitting from the controlled release of Fe(II), the scavenging of oxidative species by Fe(II) is notably alleviated, leading to the oxidant utilization efficiency of chlorite/PDS improved by 24–95 % compared to the Fe(II)/PDS and ZVI/PDS, and the costs of oxidants reduced by over 50 %. Long-term experiments indicate that PDS is relatively persistent and slowly consumed by chlorite, hence the oxidative ability for pollution control remains for over one month. This work not only proposes an effective, low-cost and promising alternative process for groundwater remediation, but also demonstrates the significance of slowly released Fe(II) in breaking the trade-off between peroxide activation rate and peroxide utilization efficiency in ISCO.

Fabrication of magnetic Cu2O nanocomposites for enhanced iodide removal: Adsorption properties, mechanism and application

The presence of iodine in water poses significant health risks to humans and aquatic ecosystems, necessitating the development of efficient and sustainable remediation strategies. Here, we present Fe3O4/Ti3C2Tx/Cu2O-Cu nanocomposites as high-performance adsorbents for iodide removal. A multistep process was utilized in the fabrication of the nanocomposite, which involved the modification of Fe3O4 nanoparticles with polydopamine (PDA) and the assembly of Ti3C2Tx nanosheets, followed by the growth of Cu2O/Cu nanoparticles. The nanocomposites showed a maximum iodide adsorption capacity of 41.34 mg/g at 25 °C, following quasi second-order adsorption kinetics and the Langmuir adsorption isotherm. A thermodynamic study revealed that the adsorption process was exothermic and spontaneous. Additionally, the nanocomposite displayed excellent selectivity for iodide despite competing anions and retained over 50 % of its adsorption capacity after two washing cycles. A mechanistic investigation indicated that the removal of iodide was primarily due to the formation of insoluble CuI under acidic conditions and surface complexation between Cu2O and iodide under neutral conditions. Owing to its high adsorption capacity, good selectivity, magnetic separability, and reusability, the Fe3O4/Ti3C2Tx/Cu2O-Cu nanocomposite offers great promise for the effective remediation of iodide-contaminated water. This study provides valuable insights into the development and application of advanced functional materials for addressing the critical issue of water pollution due to iodine.

Microbial Bioremediation of Petroleum Contaminated Soil: Structural Complexity, Degradation Dynamics and Advanced Remediation Techniques

Soil contamination with petroleum hydrocarbons poses a significant environmental challenge, necessitating effective remediation strategies to mitigate ecological risks. This review paper systematically examines the current state of knowledge regarding soil contamination with petroleum hydrocarbons, focusing on diverse sources and the extent of contamination. The investigation encompasses a range of hydrocarbon compounds, including aliphatic and aromatic fractions, emphasizing the dynamic nature of the contamination scenarios. A thorough review of bioremediation techniques, which have shown promise and sustainability as methods for cleaning up soil contaminated with petroleum hydrocarbons are also involved in order to solve these issues. Each of the three microbial processes, biodegradation, bioaugmentation, and biostimulation, is covered in detail in the paper, along with the complex mechanics underlying each technique. The report also emphasises new developments in genetics and molecular biology that add to our understanding of the metabolic pathways and microbial interactions involved in hydrocarbon breakdown. The effectiveness of plant-assisted bioremediation coupled with bioaugmentation and stimulation, specifically phytoremediation, is also explored, emphasizing the potential of certain plant species to enhance the removal of petroleum hydrocarbons from contaminated soils through rhizosphere interactions and plant-associated microbial activities. Furthermore, the paper evaluates the influence of environmental variables including soil composition, temperature, and moisture content on the effectiveness of bioremediation techniques, offering valuable perspectives on enhancing remediation efficiency through optimal conditions. The possibility for enhancing conventional bioremediation techniques through the incorporation of cutting-edge technology like nano-remediation is also explored.

Zero Valent Iron/Ni (FeNi) bimetallic heterostructure for scalable fabrication of polyvinylidene fluoride/FeNi films and efficient organic contaminant removal under UV/persulfate system

Surface heterogeneity on nano zero-valent iron (nZVI) with an additional metal is expected to enhance the catalytic performance and stability by inhibiting metal corrosion and leaching. The influence of passivation by Ni/NiO on the stability of nZVI is examined through degradation performance of uniformly aged nZVI and nZVI/Ni (FeNi) samples via photo-Fenton like reactions under UV/potassium persulfate (PS) system. FeNi bimetallic nanoparticles (BNPs) exhibits enhanced degradation than bare nZVI as thin layers of Fe3O4 and NiO which contribute towards photocatalytic degradation and anticorrosive effects by nickel inclusion. FeNi BNPs achieve 98 % degradation for pharmaceutical antibiotic levofloxacin (LEVO) within 120 min and 93 % degradation for Methylene Blue dye (MB) within 60 min, outperforming nZVI. To overcome secondary pollution, a stable polyvinylidene fluoride (PVDF)/FeNi film was fabricated to treat the contaminated water. The free-floating PVDF/FeNi film achieved 95 % degradation of MB and 98.3 % degradation of LEVO, maintaining a degradation efficiency of 95.9 % after five successive cycles. FeNi BNPs are also immobilized in the dialysis membrane resulting in 99.9 % and 99 % removal of MB and LEVO respectively. MB degradation using PVDF/FeNi film is validated through the micro reactor model developed in COMSOL Multiphysics. The parameters determined from the Langmuir-Hinshelwood (L-H) kinetic model include an intrinsic rate constant of 2.18 ×10−6 mol m−3 min−1 and an adsorption constant of 1.43 ×1019 m3 mol−1. This work introduces a cost-effective and scalable technique for the efficient remediation of contaminants in wastewater.

Genome streamlining of Pseudomonas putida B6-2 for bioremediation.

Microbial transformation is a favored approach for environmental remediation. However, the effectiveness of microbial remediation has been limited by the lack of chassis cells with satisfactory contaminant degradation performance. Pseudomonas putida B6-2, with a wide substrate spectrum and high solvent tolerance, is a chassis strain with great potential for application in environmental remediation. Here, guided by bioinformatic analyses and genome-scale metabolic model (GEM) predictions, we successfully optimized P. putida B6-2 by rationally reducing its nonessential genetic components and generating a more robust genome-streamlined strain, P. putida BGR4. Several improvements were observed compared with the original P. putida B6-2 strain, including a 1.4 × 105-fold increase in electroporation efficiency, an 8.3-fold increase in conjugation efficiency, improved glycerol utilization capability, and increased phenol utilization after heterologous expression of the phenol monooxygenase encoded by dmpKLMNOP. Additionally, P. putida BGR4 exhibited enhanced tolerance to several stressors, including starvation, oxidative stress, and DNA damage. Transcriptomic analysis revealed that genome streamlining led to the upregulation of genes involved in the "carbon metabolism" and "tricarboxylic acid cycle" pathways in P. putida BGR4, which likely contributed to the superior phenotype of P. putida BGR4 in terms of carbon source utilization and contaminant degradation capabilities. Furthermore, the absence of four prophages was identified as a potential cause of the enhanced stress resistance observed in P. putida BGR4. Overall, we developed a combined genome-streamlining strategy involving bioinformatic analyses and GEM predictions and generated a more robust chassis strain, P. putida BGR4, which expands the repertoire of chassis cells for environmental remediation.IMPORTANCEDespite the development of many chassis cells, there is still a lack of robust chassis cells with satisfactory contaminant degradation performance. Targeted genome streamlining is an effective way to provide powerful chassis cells. However, genome streamlining does not always lead to the improved phenotypes of genome-streamlined chassis cells. In this research, a novel procedure that combined bioinformatic analyses and GEM predictions was proposed to guide genome streamlining and predict the effects of genome streamlining. This genome streamlining procedure was successfully applied to Pseudomonas putida B6-2, which was a chassis cell with great potential for application in environmental remediation and resulted in the generation of a more robust chassis cell, P. putida BGR4, thereby providing a superior chassis cell for efficient and sustainable environmental remediation and a valuable framework for guiding the genome streamlining of strains for other applications.

Bioremediation of Spent Engine Oil Polluted Soil Enhanced with Blends of Poultry Manure and Pig Dung

The disposal of spent oil into open vacant plots and farms, gutters and water drains is an environmental risk. This study was conducted to explore the bioremediation of spent engine oil polluted soil enhanced with blends of poultry manure and pig dung, as well as its effects on microbiological composition of the soil. Top soil (0-15 cm depth) samples were collected from areas with history of spent engine oil contamination within Anyigba, Kogi State, Nigeria. One kilogram of soil was measured into nine clean dry containers of three litres each. The prepared blends of poultry manure and pig dung (PMPD) was mixed with the soil samples at the rate of 0, 50 and 100 g kg-1 soil in triplicates. The experiment used a Completely Randomized Design. Soil samples were taken from each container at 0 and 28 days for hydrocarbon utilizing bacteria and total petroleum hydrocarbon determination using standard methods. Data obtained from the experiment were subjected to descriptive and inferential statistics. The species identified were Enterobacter sp and Pseudomonas aeuginosa. Enterobacter sp was the most predominant isolate. The total petroleum hydrocarbon (mgkg-1) of the soil on day 0 was 59.78±1.84. After the amendments (at control, 50 and 100 g kg-1), the total petroleum hydrocarbon (mgkg-1) values were 44.92 ±2.26, 35.54 ± 2.78 and 29.52±1.28 at 28 days respectively. The blends of PMPD and the high level carbon utilizing bacteria, Enterobacter sp, showed promising potentials in the bioremediation of spent engine oil polluted soil by significantly enhancing the biodegradation process, as an impressive 50.62% remediation efficiency was achieved 28 days after amendment in soil treated with 100g of PMPD blend.

Arsenic Enhances the Degradation of Middle-Chain Petroleum Hydrocarbons by Rhodococcus sp. 2021 Under Their Combined Pollution.

The efficient and green remediation of petroleum hydrocarbon (PH) contamination has emerged as a viable strategy for environmental management. Here, we investigated the interaction between arsenic and PH degradation by Rhodococcus sp. 2021 under their combined pollution. The strain exhibited disparate responses to varying concentrations and valences of arsenic. The elevated concentration of arsenic (>100 mg/L) facilitated the degradation of PHs, and there was a positive correlation between arsenic-promoted degradation of PHs and their carbon-chain length. The degradation of PHs changed with arsenic conditions as follows: trivalent arsenic groups > pentavalent arsenic groups > arsenic-free groups (control). Arsenite and arsenate significantly promoted the gene expression of arsenic metabolism and alkane degrading. But unlike arsenite, arsenate also significantly promoted the gene expression of phosphate metabolism. And arsenite promoted the up-regulation of the expression of genes involved in the process of PHs oxidation and fatty acid oxidation. These results highlight the potential of Rhodococcus sp. 2021 in the remediation of combined total petroleum hydrocarbon (TPH) and heavy metal pollution, providing new insights into the green and sustainable bioremediation of combined pollution of organic matters such as PHs and heavy metals/heavy metal-like elements such as arsenic.

Influence of Environmental Factors and Epiphytic Bacteria on Arsenic Accumulation and Biotransformation in Hydrilla verticillata (L.f.) Royle

Submerged aquatic plants have potential applications in the phytoremediation of aquatic environments contaminated with arsenic (As). However, the role of epiphytic bacteria that grow on the surface of plants in As uptake and metabolism in plants has often been overlooked. An orthogonal experimental design with nine treatments, four factors, and three levels was conducted to inspect the effects of nitrogen (N, KNO3, 2, 4, 10 mg/L), phosphorus (P, NaH2PO4·2H2O, 0.02, 0.2, 1 mg/L), pH (6, 7, 9), and arsenate (As(V), Na3AsO4·12H2O, 15, 75, 375 μg/L) on As accumulation and biotransformation in sterilized plants and to further explore the role of epiphytic bacteria in the metabolism of As by Hydrilla verticillata (L.f.) Royle. The results indicate that low N, intermediate P, and intermediate pH were beneficial for As accumulation (117.2 ± 62.2 μg/g DW) in sterilized plants, and epiphytic bacteria exhibited promotion (68%) in plants. High N promoted As absorption and transformation in non-sterilized plants but reduced As absorption in sterilized plants. Epiphytic bacteria in the medium showed significant As(III) oxidation, which was affected by environmental factors. These findings can promote remediation efficiency by regulating environmental factors for the phytoremediation of As-contaminated waters.

Direct Ag-Hg amalgamation in the nanoscale on the surface of biosourced amorphous silica

Mercury poses a significant threat to air, soil, and water ecosystems. Mercury-based alloys, aka amalgams, are already known for their effectiveness in mercury capture in water and gaseous streams. However, limited research has been published on direct amalgamation, the process involving a direct redox reaction between two metals, occurring on the surface of amorphous silica. This study investigates the amalgamation process in nanoscale, in particular the direct interaction between silver (Ag⁰) nanoparticles supported on functionalized bio-derived amorphous silicon dioxide (SiO₂) and mercury (Hg2⁺) ions in aqueous solutions. Also, the influence of aqueous mercury speciation on amalgamation is studied in detail. The results reveal that the presence of chloride (Cl⁻), acetate (OAc⁻), and nitrate (NO3⁻) ions significantly influences the interaction between mercury and silver. We propose plausible mechanisms to explain these observations. Our findings demonstrate that the maximum mercury uptake capacity followed the order HgCl2 > Hg(OAc)2 > Hg(NO3)2, while the reaction rate followed the order Hg(OAc)2 > HgCl2 > Hg(NO3)2. These findings hold significant implications for the design of efficient mercury remediation processes. By elucidating the influence of aqueous speciation on amalgamation, our work paves the way for tailored strategies that can maximize mercury capture from water.

Nano-resolutions for Environmental Salvation: Leaping to Sustainability

Abstract: Nanoparticles have emerged as a transformative technology in environmental remediation, addressing the pressing challenges of pollution across air, water, and soil. Nanoparticles, particularly metal oxides, carbon-based materials, and polymers, demonstrate remarkable capabilities in addressing water, air, and soil contamination. Their high surface area to volume ratio enhances their efficiency in pollutant removal while minimizing toxicity, making them suitable alternatives to conventional methods. As traditional remediation methods often carry their environmental risks, there is a pressing need for innovative and sustainable solutions. This review delves into the mechanisms and applications of nanoparticles in various remediation techniques, including photocatalysis, Nanoadsorption, and nanomembranes for water treatment, as well as their effectiveness in soil and air purification. The findings underscore the potential of nanomaterials to enhance remediation efficiency while reducing environmental toxicity. By integrating these innovative solutions into existing environmental management frameworks, nanoparticles can play a crucial role in achieving sustainable environmental practices and mitigating contamination. This review advocates for continued research, development, and application of nanotechnology as a promising avenue for fostering a cleaner, healthier environment and contributing to global sustainability goals.

A nitrogen-enriched strategy to accelerate the remediation of Cr(VI)-contaminated soil by iron-based materials in microwave fields

The existing remediation technologies for Cr(VI) contamination soil suffer from long processing times. Microwave catalysis is an efficient environmental remediation technology, and the reasonable design of microwave catalysts can enable a microwave catalytic system to rapidly complete the remediation of Cr(VI). In this study, a microwave catalyst, NRFC-3, with high microwave absorption performance and electron density was designed via a nitrogen enrichment strategy. Density functional theory (DFT) calculations verified that the electron density of the material was increased by nitrogen-enriched strategy. Under the experimental conditions, the electrons (e−) of NRFC-3 originate from “hot spots” and the current density is not lower than 3.78 × 109 e·g−1·s−1. In addition, the reduction of Cr(VI) in the MW/NRFC-3 system is feasible through DFT predictions, and this conclusion was experimentally verified. The MW/NRFC-3 system has a remediation efficiency of 100 % for Cr(VI)-contaminated soil within 25 min, significantly reduced the toxicity of Cr(VI) to the environment and humans, and had long-term stability. The potential application of the MW/NRFC-3 system was verified by remediation experiments on Cr(VI)-contaminated soils of different degrees. This study provides a new technology for the rapid and harmless treatment of Cr(VI)-contaminated soil.