Removal Of Organic Pollutants Research Articles

Achievements in Preparation of Cyclodextrin–Based Porous Materials for Removal of Pollutants

Cyclodextrin–based porous materials have been widely applied in removing various organic pollutants from water environments, due to their unique physical and chemical properties, like the size–matching effect and hydrophobic interaction. Large numbers of hydroxyl groups in its external structure give cyclodextrin a high solubility in water, but the existence of these hydroxyl groups also endows cyclodextrin with the ability to be chemically modified with various functional groups to reduce its solubility in water and, meanwhile, to develop some novel functionalized cyclodextrin–based porous materials for selective removal of the target organic pollutants. This review focuses on the recent development in the synthesis of cyclodextrin–based porous materials (crosslinked cyclodextrin polymers and immobilized cyclodextrins), as well as highlighting their applications and mechanisms in the removal of dyes, endocrine disruptors, and mixed pollutants from water. Finally, the challenges and future perspectives in related research fields are discussed.

Sustainable removal of organic pollutants using biochar based ZnO composites: Experimental and theoretical studies of remediation process

The tailoring of biochar to enhance its remediation efficiency for removal of pollutants from water has been a hot topic these days. Fabricating two different biochar materials using metal oxide nano particles in four ratios has been done in this work. The synthesized materials have been characterized by XRD, surface functional groups were analyzed using FTIR and XPS, band gap calculation were carried out using Tauc's method, recombination of charges was studied using photoluminescence spectroscopy, morphological, textural properties and elemental analysis was done using SEM, BET, TGA, EIS and EDX analysis. The removal of organic pollutants including phenol, dibutyl phthalate and gallic acid up to 91.6 %, 84 % and 95 % was observed employing these composites. The band gap reduction from 3.1 eV to 2.5 eV and 2.8 eV was observed in case of ZW(1–10) and ZP(1–10) respectively. The formation of Zn-O-C bond in the composite could be possible reasons for the band gap reduction and excellent performance exhibited by the composite. The results highlight the influence of functional groups on the efficiency of synthesized material. Furthermore, density functional theory (DFT) calculations were performed using Gaussian16 software to propose the adsorption mechanism for the observed results. The energy calculation for different binding modes were carried out. Theoretical findings agreed with the empirically demonstrated remediation mechanism.

Urchin-like Ni-Fe-Mo sulfide: An effective electrochemical calcium sulfite activator for tetracycline degradation

Sulfite is deemed as a promising precursor to produce highly reactive species for contaminants remediation. Herein, the urchin-like Ni-Fe-Mo sulfide (NiFeMoSx) was anchored in-situ on nickel foam as a cathode to activate CaSO3 for efficient degradation of tetracycline (TC) under natural condition. The degradation efficiency reached 92.7% within 60 min, which was about 1.81 times higher than that of the electro-Fenton process based on NiFeMoSx. The beneficial performance came from the synergistic activation of CaSO3 by simultaneous rapid redox cycles of Fe(II)/Fe(III) and Ni(II)/Ni(III) on the NiFeMoSx cathode. Specifically, the primary intermediates Fe(II)-HSO3- and Ni(II)-SO32- triggered a series of radical chain reactions, accompanied the reduction of Ni(III)/Fe(III) by electrochemistry and electron donor of Mo(IV) and S2- on the surface of the catalyst. The regeneration of the Fe(II)/Ni(II) was quickly realized and subsequently triggered the chain reactions, which would accelerate the formation rate of reactive species, such as SO4∙−, ·OH, O2∙− and 1O2, of which 1O2 and O2•- played important roles on degradation TC. This work provides a promising application for the efficient removal of persistent organic pollutants by metal sulfide activated sulfite.

UV/H2O2 produced degradation of 2,4-D and 4-CPA

2,4-dichlorophenoxyacetic (2,4-D) acid and 4-chlorophenoxyacetic acid (4-CPA), as widely utilized organochlorine pesticides, are normally detected in wastewater and atmosphere. Their harmfulness to the ecosystem cannot be ignored. UV/H2O2 is one of the most conventional advanced oxidation processes, which has remarkable advantages for the removal of refractory organic pollutants in wastewater. However, the reaction mechanisms and pathways of pollutants with reactive radicals are still unclear. In this study, the degradation efficacy and mechanisms during the photodegradation of 2,4-D and 4-CPA in UV/H2O2 processes were investigated by experiments and density functional theory calculations. The results showed that 2,4-D was more likely to be degraded by UV/H2O2 treatment than UV photolysis alone. In contrast, 4-CPA can be degraded effectively and rapidly under UV irradiation alone. By LC-MS analysis, the degradation products of 2,4-D and 4-CPA in the UV/H2O2 processes were identified and they were produced by hydroxylation and photolysis. Therefore, we speculated a competition mechanism presented between direct photolysis and indirect photolysis in the UV/H2O2 degradation of 2,4-D and 4-CPA. The OH-initiated reaction mechanisms of 2,4-D and 4-CPA in aqueous environments were investigated using quantum chemical methods SMD/M06–2X/6–311++G (3df, 2p)//SMD/M06–2X/6-311 + G (d,p). The pH dependence of the reaction mechanisms and rate constants in their degradation process induced by ·OH was also investigated. The calculation results showed that the ionic forms (2,4-D- and 4-CPA-) were more prone to react with ·OH in comparison to the corresponding molecular forms (2,4-D and 4-CPA). The total rate constants of 2,4-D and 4-CPA with OH increased with the pH from 1 to 10, and decreased with continued pH increase. The toxicities of 2,4-D, 4-CPA and their products were assessed by the QSAR-based toxicity evaluation software. The results showed that several products were more toxic than their parent compounds, such as 2,4-dichlorophenol, 3,5-dichlorocatechol, 4-chlorophenol and hydroquinone. This work can contribute to clarifying the environmental risks of 2,4-D and 4-CPA and offer a complete understanding for the photodegradation behavior of 2,4-D and 4-CPA in aqueous ecosystems.

In2O3-ZnO nanoporous photocatalyst modified with CuOx cocatalyst for enhanced photocatalytic bacterial inactivation and dye degradation

In this study, CuOx surface passivated In2O3 loaded porous ZnO, (CuOx/In2O3(x%)-ZnO)), were synthesized utilizing a solvothermally produced organic–inorganic ZnS(en)0.5 hybrid material. The high-resolution scanning electron microscopy (HR-SEM) and transmission electron microscopy (TEM) images of the CuOx/In2O3(2.5%)-ZnO nanocomposite reveal a macrosheet-shaped morphology comprising nanosized grains. The photocatalytic behavior of all the synthesized CuOx/In2O3(x = 0,1,2.5, and 5%)-ZnO nanocomposites were examined against aqueous dye solutions of orange II, and bisphenol A, E. coli bacteria under one sun illumination. The CuOx/In2O3(2.5%)-ZnO nanocomposite exhibits enhanced photoactivity for cationic dyes (eosin Y) than that for anionic (orange II). The results indicate that cationic dyes undergo photocatalytic degradation, whereas the anionic dyes adsorb on the CuOx/In2O3(2.5%)-ZnO nanocomposite surface, reducing the removal of organic pollutants. The optimal nanocomposites, CuOx/In2O3(2.5%)-ZnO photocatalyst exhibit maximum photodegradation performance of 99%, 94%, 27% for orange II dye, eosin dye, BPA, and 98% for E. coli inactivation within 180 min, respectively. The CuOx/In2O3(2.5%)-ZnO nanocomposite was successfully demonstrated to be an effective photocatalyst and excellent antibacterial agent. Finally, the charge transfer mechanism during photocatalytic organic decomposition and bacterial inactivation was studied.

Resource utilization of MSWI fly ash supporting TiO2/BiOCl nanocomposite for enhanced photocatalytic degradation of sodium isopropyl xanthate: Mechanism and performance evaluation

The removal of organic pollutants in water environments and the resource utilization of solid waste are two pressing issues around the world. Facing the increasing pollution induced by discharge of mining effluents containing sodium isopropyl xanthate (SIPX), in this work, municipal solid waste incineration fly ash (MSWI FA) was pretreated by hydrothermal method to produce stabilized FA, which was then innovatively used as support for the construction of FA/TiO2/BiOCl nanocomposite (FTB) with promoted photocatalytic activity under visible light and natural sunlight. When the content of FA was 20 wt% and the mass ratio of TiO2 to BiOCl was 4:6, a remarkable performance for the optimal FTB (20-FTB-2) was achieved. Characterizations demonstrated that TiO2 and BiOCl uniformly dispersed on FA contributing to high surface area and broad light adsorption of FTB, which exhibits excellent adsorption capacity and light response ability. Build in electric field formed in the interface of TiO2/BiOCl heterojunction revealed by density functional theory calculations accelerated the separation of photoinduced e− and h+, leading to high efficiency for SIPX degradation. The synergetic effect combined with adsorption and photocatalytic degradation endowed 20-FTB-2 superior SIPX removal efficiency over 99% within 30 min under visible light and natural sunlight irradiation. The photocatalytic degradation pathways of SIPX were determined through theoretical calculations and characterizations, and the toxic byproduct CS2 was effectively eliminated through oxidation of •O2−. For 20-FTB-2, reusability of photocatalyst was showed by cycle tests, also the concentrations of main heavy metals (Pb, Zn, Cu, Cr, and Cd) in the liquid phases released during photocatalyst preparation process (< 1 mg/L) and photodegradation process (< 8.5 μg/L) proved the satisfactory stability with low toxicity. This work proposed a novel strategy to develop efficient and stable support-based photocatalysts by utilizing MSWI FA and realize its resource utilization.

Hydrothermal carbonization of biomass waste and application of produced hydrochar in organic pollutants removal

This novel research, presents the study of utilizing the wild almond shell as biomass waste to fabricate hydrochar using the hydrothermal carbonization (HTC) method based on a central composite design (CCD) with two independent variables (time and temperature) and three responses; productivity, higher heating value (HHV) and norfloxacin (NOR) adsorption capacity. The prepared hydrochar at 200 °C and 8 h was then employed to produce activated carbon (AC) by chemical-thermal activation technique. Hydrochar and AC were characterized using XRD, BET, SEM-EDX, Raman, and FTIR techniques. The pore development, resulting in a rise in the SBET (637.46 m2/g) value occurred after the activation process. Moreover, the results of XRD and Raman analyses revealed a decrease in graphitization degree. The adsorption of norfloxacin, methylene blue (MB), and sunset yellow (SY) by prepared hydrochar and AC were studied to assess the impact of the pH of the solution, initial concentration, temperature, and contact time. The maximum adsorption capacity for NOR, MB, and SY using hydrochar and AC were 85.37, 153.46, 93.35, and 384.1625, 556.465, 264.93 mg/g, respectively. The experimental data for the adsorption of NOR, MB, and SY using hydrochar and AC illustrated a good fit with the PSO model. Besides, the Langmuir and Freundlich models indicated better fitting with empirical data obtained for the adsorption of NOR, MB, and SY, respectively. Thermodynamic study outcomes validated the exothermicity and spontaneity of the adsorption process for both absorbents. This study presents a new opportunity to develop the circular economy by fabrication of sustainable adsorbents with high adsorption capacity for organic pollutants from biomass waste.

Heterojunction CuO thin coated CaO drived from eggshell waste for fast removal of organic pollutants from water under visible light

AbstractThe conversion of food and agro-industrial wastes to produce useful products is one of the goals of economic and sustainable development, as also evidenced in the 2030 Agenda for Sustainable Development, adopted by all United Nations Member States in 2015. This work aims to study the transformation of CaCO3 based eggshell waste (ES) into a face centered cubic oxide form (namely, CaO), followed by CuO coating to be used as photocatalytic material (ES@CuO) for fast removal of basic fuchsin (BF) dye from water under visible light. Different ES@CuO samples with different CuO amounts (2.5, 5 and 10%, respectively) and calcined at different temperatures (600, 800, and 1000 °C) were prepared by hydrothermal method. Samples with CuO from medium to high amounts (5 and 10%) demonstrated excellent photocatalytic activity, as compared to low CuO amount (2.5%). In addition, the samples calcined at higher temperature (800 and 1000 °C) exhibited superior degradation rates, reaching 88.11% and 88.33%, respectively. The effect of operating parameters was investigated to understand the behavior of ES@CuO under different conditions. ES@CuO shows rapid removal of BF which combines adsorption and photooxidation, wherein the removal rate reaches up 99% for a BF dye concentration of 100 ppm within 30 min using 75 mg/L of ES@CuO5%. ES@CuO exhibits superior adsorption ability and excellent photoproduced charges transfer which provide synergistic effects to boost the quick removal of dye from water. The finding of this investigation encourages valorizing food wastes into sustainable materials for water remediation. Graphical abstract

Characteristics of particle formation in O3-UBAC filter and effects of operational parameter on particles

The ozone oxidation and up-flow biological activated carbon (O3-UBAC) process has been recognized for its ability to extend the operating cycle of biological activated carbon (BAC) filters by expanding the carbon layer and maintaining a dynamic balance of the carbon biofilm. However, the primary focus of O3-UBAC is the removal of organic pollutants, often overlooking the treatment of particles. To address this gap, a pilot-scale study was conducted using sedimentation basin effluent samples from a drinking water treatment plant (DWTP), which were added into BAC columns. The study aimed to investigate the seasonal variation of effluent particles during the UBAC operating cycle, including particle counts, size distribution, and mass composition. Based on particle characteristics and the combined effects of adsorption and biodegradation, the UBAC operation cycle was divided into three periods. Results revealed that hydraulic impacts and biofilm desorption on carbon could increase the proportion of particles >5 μm in effluent. Pre-ozonation demonstrated significant effects on particle counts and Heterotrophic Plate Count (HPC) levels (p < 0.05), with the addition of 1 mg/L O3 resulting in a reduction in particle counts in the effluent. Moreover, particle removal could be achieved by adjusting the upward flow velocity, necessitating comprehensive consideration of pollutants. Furthermore, microbial community analysis under optimal operating conditions unveiled significant changes in the microbial diversity of UBAC-treated water particles. Although the influent and effluent exhibited similarities at different phylum levels, the dominant bacteria differed significantly at various levels.

Enhancing photocatalytic wastewater treatment: investigating the promising applications of nickel ferrite and its novel nanocomposites.

Water contamination ranks highest among the challenges posed by the rapidly increasing environmental contamination, which is thought to be the most pressing issue globally. The development of innovative techniques for the successful removal of diverse types of undesirable pollutants from wastewater would therefore yield a huge return on investment. Nowadays, the removal of many organic and synthetic pollutants from the environmental matrix is anticipated to be possible by photocatalytic degradation, owing to its low energy consumption, high catalytic activity, and low overall cost. In this context, magnetic nanoparticles received greater attention as photocatalytic materials from the scientific community in wastewater treatment for the removal of different kinds of pollutants due to their specific properties. The present study provides an overview of the recent advances in water treatment using nickel ferrite nanoparticles and their nanocomposites as photocatalysts. Furthermore, a proposed mechanism for these photocatalysts to generate active free radicals under visible and ultraviolet light has been described. The review concludes that photocatalysts based on NiFe2O4 have potential applications in water purification technologies. However, more research is still needed to determine their practical application in water treatment facilities.

Sulfur doping-induced morphological and electronic structure modification of polyoxometalate FeWO4 for enhanced removal of organic pollutants from water

Wolframite (FeWO4), a typical polyoxometalate, serves as an auspicious candidate for heterogeneous catalysts, courtesy of its high chemical stability and electronic properties. However, the electron-deficient surface-active Fe species in FeWO4 are insufficient to cleave H2O2 via Fe redox-mediated Fenton-like catalytic reaction. Herein, we doped Sulfur (S) atom into FeWO4 catalysts to refine the electronic structure of FeWO4 for H2O2 activation and sulfamethoxazole (SMX) degradation. Furthermore, spin-state reconstruction on S-doped FeWO4 was found to effectively refine the electronic structure of Fe in the d orbital, thereby enhancing H2O2 activation. S doping also accelerated electron transfer during the conversion of sulfur species, promoting the cycling of Fe(III) to Fe(II). Consequently, S-doped FeWO4 bolstered the Fenton-like reaction by nearly two orders of magnitude compared to FeWO4. Significantly, the developed S-doped FeWO4 exhibited a remarkable removal efficiency of approximately 100% for SMX within 40 min in real water samples. This underscores its extensive pH adaptability, robust catalytic stability, and leaching resistance. The matrix effects of water constituents on the performance of S-doped FeWO4 were also investigated, and the results showed that a certain amount of Cl−, SO42−, NO3−, HCO3− and PO43− exhibited negligible effects on the degradation of SMX. Theoretical calculations corroborate that the distinctive spin-state reconstruction of Fe center in S-doped FeWO4 is advantageous for H2O2 decomposition. This discovery offers novel mechanistic insight into the enhanced catalytic activity of S doping in Fenton-like reactions and paves the way for expanding the application of FeWO4 in wastewater treatment.

Design of magnetic photonic crystal microdroplet for sensitive detection of cationic organic pollutants by the coupled resonance effect

Photonic crystals (PCs), periodically arranged nanoparticles, have emerged with extraordinary optical properties for light manipulation owing to their photonic band gaps (PBGs). Here, a novel strategy and method was developed for efficient enrichment and sensitive detection of cationic organic pollutants in water. Size-controlled Fe3O4@poly (4-styrenesulfonic acid-co-maleic acid) (Fe3O4@PSSMA) was prepared, and high surface charge were formed with the coating of PSSMA layer on the surface of Fe3O4, which could be used for adsorption and removal of cationic organic pollutants. The Fe3O4@PSSMA after adsorbing cationic organic pollutant were assembled to magnetic photonic crystal microdroplet (MPCM) structure in an external magnetic field, which was used as surface-enhanced Raman scattering (SERS) substrate. By coupling the magnetically tuned PBGs with Raman laser wavelength, the light utilization efficiency can be improved and the coupled resonance effect was greatly enhanced. The enhancement factor (EF) of MB was more than 800 attributing to the dual function of enrichment and coupled resonance effect of MPCM. The developed analytical strategy is the first time to use MPCM as a SERS substrate to realize the sensitive detection of 10 nmol L−1 MB in real water, which greatly improves the application of MPCM in the field of contaminant analysis and detection in water.

Design of novel FeSe2/ZnO composites and their application in photodegradation of methylene blue

Water pollution has become one of the major global issues, posing serious threat to both humans and aquatic life. The elimination of organic industrial pollutants from wastewater is currently a major area of research. Herein, we report for the first time a novel FeSe2/ZnO composite system for highly efficient removal of organic dyes under visible light. FeSe2/ZnO composites with varying mass ratios of FeSe2 were successfully prepared through simple and low-cost chemical method. The physiochemical properties of the prepared FeSe2/ZnO composites were carefully evaluated and compared with those of pure ZnO rods and FeSe2 flowers. UV–vis spectroscopy confirmed that the coupling of FeSe2 with ZnO caused a significant improvement in the optical absorption of ZnO. The bandgap energies of FeSe2/ZnO composites showed a red shift with increasing the ratio of FeSe2 flowers. The prepared samples were evaluated for their photocatalytic response against the removal of methylene blue dye. Compared to the pure FeSe2 and ZnO, the composites displayed impressive photocatalytic performance. Among the prepared samples, composite with an optimum ratio of 75 wt% FeSe2 revealed outstanding photocatalytic efficiency, making it a promising candidate for the removal of organic pollutants.

Effective removal of organic and inorganic pollutants from abattoir wastewater using magnesium oxide/activated carbon nanocomposites

This study investigated the development and characterization of activated carbon (AC), magnesium oxide (MgO), and a combination of AC and MgO nanocomposite for abattoir wastewater treatment. Activated carbon was derived from Hura crepitans pods, whereas MgO nanoparticles were produced through biosynthesis. Different composite (AC/MgO) ratios (1:1, 1:2, and 2:1) were prepared using a wet impregnation technique. The efficiency of these nanoadsorbents in eliminating heavy metal pollutants were tested through batch adsorption experiments under the influence of the dosage, temperature, and contact time. Various analytical tools were used to characterize the prepared nanoadsorbents. XRD confirmed the formation of a pure MgO periclase phase, indicating a reduction in particle size with the increase in pH. The HRSEM images of the nanocomposites showed porous carbon structures with regular mesopores and spherical MgO nanoparticles. The uniform granules with agglomerated spherical shapes were confirmed by the SAED patterns, suggesting the core/shell structure of MgO from the HRTEM images. Further imaging confirmed the dispersion of carbon and magnesium in the nanocomposites, without the formation of distinct dopant oxides. The specific surface areas were determined as 2.74 m2/g for activated carbon, 27.57 m2/g for MgO, and 40.82 m2/g for activated carbon/MgO, indicating enhanced surface area due to the addition of activated carbon. Batch adsorption studies indicated that the AC/MgO nanocomposite in the 1:2 ratio exhibited the highest pollutant adsorption rate under similar conditions. The adsorption study was calculated by the pseudo-second-order and Langmuir isotherm models. The AC/MgO nanocomposite demonstrated reusability over six cycles, with a slight reduction in removal efficiency from the first cycle (98.05 % for Fe, 96.50 % for Cd, and 94.32 % for Pb) to the sixth cycle (91.10 % for Fe, 86.56 % for Cd, and 84.03 % for Pb). Overall, these findings suggest that AC/MgO nanocomposites can effectively eliminate pollutants from abattoir wastewater.

Influence of aeration-induced air–water interfaces on pollutant degradation in water treatment: A theoretical and experimental study

Advanced oxidation processes (AOPs) based on hydroxyl radicals (OH)-dominant pathway are the most important technologies for the removal of bio-recalcitrant organic pollutants in industrial wastewater. Air–water interface formed by aeration is one of the factors that affect the removal efficiency of pollutants in AOPs. In this work, the mechanistic and kinetic insights into the roles of air–water interface on the hydroxylation of three chlorophenols (CPs) in UV/H2O2 process have been investigated via theoretical calculation and experimental methods. Results show that CPs is more prone to accumulate at the air–water interface as the number of chlorine substituents increases. Consequently, the hydration reaction of CPs occurring at the interfacial influence the electron transfer associated with OH, leading to the non-oxidative consumption of OH. This interfacial reaction diminishes degradation efficiency, resulting in the formation of persistent organic pollutants. Herein, in UV/H2O2 degradation of 2,4,6-TCPs, persistent free radical (PFRs), as well as 1,3,7,9-TCDD and 2,3,6-Trichloro-4-(2,4,6-trichlorophenoxy)phenol, were identified using EPR spectroscopy and LC-Q-TOF-MS mass spectrometry, respectively. Altogether, this work provides a comprehensive understanding of the roles of aeration on OH-initiated degradation behavior of chlorinated phenol pollutants.

Insights into the generation of multiple reactive species in UV254/PMS/I− system and their roles for degradation of phenolic and non-phenolic pollutants

An innovative technology for the removal of phenolic and non-phenolic organic pollutants from aqueous solution was developed by combining UV254 irradiation, peroxymonosulfate (PMS), and iodide ions (I−). Effects of pH, ratio of [I−]/[PMS], initial concentration of pollutant, dissolved organic matter (DOM) and typical inorganic constituents of environmental water on the degradation of studied pollutants with UV254/PMS/I− system were examined. The results showed that pH and [I−]/[PMS] exhibited significant impact on the degradation of pollutants during UV254/PMS/I− process. As the ratio of [I−]/[PMS] increased from 0.1 to 10.0, the removal efficiencies of phenolic pollutants remarkably increased, but those of non-phenolic pollutants decreased. The DOM at high concentration obviously inhibited the degradation of pollutants during UV254/PMS/I− process. Meanwhile, the occurrence of NO3− can slightly enhance the degradation of pollutants, and SO42−, Cl−, and HCO4− ions had no significant effects on UV254/PMS/I− system. The abundant reactive species including OH, SO4−, and I/I2− during UV254/PMS/I− process were generated based on electron spin resonance, fluorescence spectroscopy and steady-state concentration analysis. Quenching experimental results indicated that I/I2− can selectively degrade phenolic pollutants via one-electron oxidation. This study provided a reference for the application of reactive radicals involved oxidative technique in water purification.

New insights into microbial community for simultaneous removal of carbon and nitrogen via heterotrophic nitrification aerobic denitrification process

Heterotrophic nitrification aerobic denitrification (HNAD) process is considered to be a promising strategy for efficient removal of nitrogen and refractory organic pollutants from aquatic environments. However, isolated single strains or microbial communities of HNAD in most studies suffer from severe inadaptability in the face of complex aquatic environments. Therefore, the existence of fundamental microbial communities that is able to adapt to contaminants through shaping its structure and then remove the pollutants is a promising solution to this deficiency. Herein, we introduced three aromatic compounds (ACs) (2,4,6-Trinitrotoluene, Aniline, and Phenanthrene), and established HNAD microcosms containing the different ACs and nitrogen through aeration. Impressively, the removal efficiencies of aerobic microcosms were nearly 94.5%, 99.4% and 100% for 2,4,6-Trinitrotoluene, Aniline and Phenanthrene, respectively, and above 90% for total nitrogen (TN), demonstrating superior ACs and nitrogen elimination capabilities. Meanwhile, analysis of microbial community structure and symbiont networks exhibited that there are eight commonly dominant genera in different microcosms, namely Arthrobacter, Bacillus, Sphingobium, Massilia, Novosphingobium, Noviherbaspinrillum, Lysobacter and Azohydromonas. Notably, these core bacteria changed only in relative abundance with the microcosms, and had been proven that they all have laudable carbon and nitrogen conversion capabilities. This finding confirmed the existence of basic microbial communities whose dominant species coordinate with each other to adapt to different water environments for the purpose of water purification. Finally, the mechanism of nitrogen transformation at both gene and enzyme levels was revealed by KEGG enrichment analysis. Summarily, this study will provide valuable references for future development of water treatment technologies.

A novel bifunctional particle electrode with abundant Fe/Fe3C and Fe-N-C sites to enhance the performance of electro-Fenton in degrading organic pollutant

Electro-Fenton (EF) technology emerges as a promising approach to address the treatment of persistent organic pollutants. Nevertheless, its practical implementation often comes with certain drawbacks, like the low H2O2 activation efficiency, poor pH adaptability, and difficult recycling of the catalysts. To this end, we introduced highly active Fe-N-C sites onto the surface of nitrogen-doped graphene, improved the chemical environment of its central Fe atoms with Fe/Fe3C nanoparticles, effectively regulated the multi-electron oxygen reduction process of the catalyst in the electrochemical reaction, and realized the efficient production and activation of H2O2 in the electro-Fenton process. The synthesized Fe/Fe3C@FeNG-1000 achieved efficient removal of refractory organic pollutants in neutral conditions. The rate constant of degradation for tetracycline hydrochloride (TC) in the electro-Fenton reaction system at pH 7 was recorded as 0.1011 min−1. Additionally, a removal rate of 67.4% for total organic carbon (TOC) was achieved in just 120 min. The treatment of actual wastewater also showed excellent performance, with an average specific energy consumption of 6.16 kWh kg−1 COD−1. Fe/Fe3C@FeNG-1000 can still achieve more than 90% degradation efficiency after 5 consecutive cycles of the experiment, showing excellent stability, and the catalyst can be conveniently retrieved via magnetic methods following the reaction. The results show that the Fe/Fe3C@FeNG-1000-EF system has a wide range of pH applicability, long-term stability and good recyclability, has a good application value in practical wastewater treatment.

Exploring superparamagnetic and intercalated Ag quantum particles in manganese oxide/graphene oxide for rapid and scalable organic pollutant removal

Exploring superparamagnetic and intercalated Ag quantum particles in manganese oxide/graphene oxide for rapid and scalable organic pollutant removal

Research progress of persulfate activation technology.

Persulfate-based advanced oxidation processes (PS-AOPs) have been widely investigated by academia and industry due to their high efficiency and selectivity for the removal of trace organic pollutants from complex water substrates. PS-AOPs have been extensively studied for the degradation of pesticides, drugs, halogen compounds, dyes, and other pollutants. Utilizing bibliometric statistics, this review presents a comprehensive overview of persulfate-based advanced oxidation technology research over the past decade. The number of published articles about persulfate activation has steadily increased during this time, reflecting extensive international collaboration. Furthermore, this review introduces the most widely employed strategies for persulfate activation reported in the past 10years, including carbon material activation, photocatalysis, transition metal activation, electrochemical activation, ultrasonic activation, thermal activation, and alkali activation. Next, the potential activation mechanisms and influencing factors, such as persulfate dosage during activation, are discussed. Finally, the application of PS-AOPs in wastewater treatment and in situ groundwater treatment is examined. This review summarizes the previously reported experiences of persulfate-based advanced oxidation technology and presents the current application status of PS-AOPs in organic pollution removal, with the aim of avoiding misunderstandings and providing a solid foundation for future research on the removal of organic pollutants.