Materials For Water Treatment Research Articles

Characteristics and Sonophotocatalytic Activity of Natural Sphalerite under Ultrasonic (1.7 MHz) and UVA LED (365 nm) Irradiation.

Naturally occurring sono- and photoactive minerals, which are abundant on Earth, represent an attractive alternative to the synthesized sonophotocatalysts as cost-effective materials for water and wastewater treatment. This study focuses on characterizing and evaluating the sonophotocatalytic activity of natural sphalerite (NatS) from Dovatka deposit (Siberia) under high-frequency ultrasonic (US, 1.7 MHz) and ultraviolet light-emitting diodes (UVA LED, 365 nm) irradiation towards degradation of 4-chlorophenol as a model organic pollutant. Since raw natural sphalerite did not exhibit a measurable photocatalytic activity, it was calcined at 500, 900 and 1200 °C. The natural sphalerite after calcination at 900 °C (NatS*) was found to be the most effective for sonophotocatalytic degradation of 4-chlorophenol, attaining the highest efficiency (55%, 1 h exposure) in the following row: UV < US ≈ UV/US ≈ US/NatS* < UV/NatS* < UV/US/NatS*. Addition of 1 mM H2O2 increased the removal to 74% by UV/US/NatS*/H2O2 process. An additive effect between UV/NatS* and US/NatS* processes was observed in the sonophotocatalytic system as well as in the H2O2-assisted system. We assume that the sonophotocatalytic hybrid process, which is based on the simultaneous use of high-frequency ultrasound, UVA light, calcined natural sphalerite and H2O2, could provide a basis of an environmentally safe and cost-effective method of elimination of organic pollutants from aqueous media.

Multifunctional porous β-cyclodextrin polymer for water purification

Keeping water clean is of vital significance for human health and environmental protection. In order to remove organic micro-pollutants and natural organic substances in water bodies and kill pathogenic microorganisms simultaneously, this study synthesized a multifunctional porous β-cyclodextrin polymer with a high specific surface area by introducing quaternary ammonium groups and rigid benzene rings, respectively, which was then polymerized with crosslinking agent-4,4′-bis (chloromethyl)-1,1′-biphenyl (BCMBP) in an ionic liquid system. The grafting of quaternary ammonium groups was beneficial for the removal of negative-charged humic acid (HA) and sterilization. The introduction of numerous rigid structures during benzylation and Friedel-Crafts alkylation reaction could significantly improve the porosity and specific surface area of the polymer, conducive to the exposure of cyclodextrin binding sites and contaminant adsorption. By changing the proportions of quaternization and benzylation, the structure and surface properties of the polymer could be adjusted, thus further regulating the adsorption performance. Compared with activated carbon, the polymer named BQCD-BP with a huge surface area of 1133 m2 g−1 prepared under optimized conditions showed outstanding adsorption performance and sterilization ability. The pseudo-second-order kinetic constant of BQCD-BP reached 1.2058 g·mg−1·min−1, which was approximately 50 times greater than that of activated carbon (0.0256 g·mg−1·min−1) under the same experimental condition. The adsorption capacity of BQCD-BP to HA was twice as high as that to AC, and the antibacterial ability of BQCD-BP was significant, achieving 90% at the dosage of 1g L−1. Moreover, the adsorption process was hardly affected by the hydrochemical conditions, and the polymer was easy to regenerate. In addition, the excellent adsorption and antibacterial performance of the polymer were also identified by natural water treatment. COD was almost completely removed, and the removal efficiency of TP reached 92% after contact with BQCD-BP. The sterilization rate of BQCD-BP to viable bacteria in complex water bodies reached 82%. Undoubtedly, BQCD-BP is a potential multifunctional water treatment material with reasonable design in the actual water purification.

A Comparative Study on Optofluidic Fenton Microreactors Integrated with Fe-Based Materials for Water Treatment.

The catalysts employed in catalytic reactors greatly affect the reaction efficiency of the reaction system and the reactor’s performance. This work presents a rapid comparative study on three kinds of Fe-based materials integrated into an optofluidic Fenton reactor for water treatment. The Fe-based sheets (FeSiB, FeNbCuSiB, and FeNi) were respectively implanted into the reaction chamber to degrade the organic dyes with the assistance of H2O2. In the experiment, by adjusting the hydrogen peroxide concentration, flow rate, and light irradiation, the applicable conditions of the Fe-based materials for the dye degradation could be evaluated quickly to explore the optimal design of the Fenton reaction system. The results indicated that FeNi (1j85) exhibits excellent degradability in the microreactor, the reaction rate can reach 23.4%/s at the flow rate of 330 μL/min, but its weak corrosion resistance was definitely demonstrated. Although the initial degradability of the microreactor by using FeNbCuSiB (1k107) was not as good as that of 1j85, it increased after being reused several times instead, and the degradation efficiency reached >98% after being reused five times. However, the FeSiB (1k101) material shows the worst degradability and recycling. Therefore, in contrast, 1k107 has the greatest potential to be used in Fenton reactors for practical water treatment.

Efficient adsorption of heavy metals from wastewater on nanocomposite beads prepared by chitosan and paper sludge

Chitosan was commonly used with inorganic salt and organic compounds to prepare adsorption material for water treatment. Different materials were mixed for the preparation, leading to a high cost for water treatment. Sludge from papermaking has abundant fiber and inorganic salt, which can reduce the addition of raw materials in preparing the adsorption material and thus lower the cost. This work used recycled industrial paper sludge to prepare adsorption material to remove heavy metals from wastewater. The adsorption properties of the prepared sludge-chitosan material for Cu2+ and Cr3+ in wastewater were investigated. The impacts of adsorption time, pH, and initial concentrations of Cu2+ and Cr3+ on adsorption amount were studied and optimized. The saturated adsorption capacity of sludge-chitosan material for Cu2+ and Cr3+ can reach 114.6 and 110.3 mg/g. The adsorption kinetics satisfied the pseudo-second-order model, indicating two modes, physical diffusion, and chem-sorption, in the heavy metal adsorption by the sludge-chitosan materials. Physical distribution has little Effect on chemical adsorption. The materials can be applied to treating Cu2+ and Cr3+ containing wastewater with the proposed cheap and readily available sludge-chitosan material. The results confirmed that sludge-chitosan material possessed good regeneration performance and was an ideal adsorbent.

Removal of heavy metals and dyes from wastewater using graphene oxide-based nanomaterials: A critical review

Water has always been one of the most important and precious natural resources. However, due to the rapid growth of the population and industrial progress, the available resources of freshwater are decreasing in an alarming manner. The contamination of water by hazardous pollutants has prompted researchers to develop new, efficient and low-cost methods and materials for water treatment. Adsorption is one of the most effective ways to remove many pollutants, even at very low concentrations. Recently, new adsorbent nanomaterials, whose efficiency can be improved when exposed to external influences such as pH, agitation, and temperature have been used in research on wastewater treatment. Graphene oxide based nanomaterials and their composites are considered as promising adsorbents for the removal of heavy metals, dyes, and other hazardous pollutants from aqueous environments due to its distinctive physicochemical properties, such as chemical stability, huge surface area, high adsorption capacity and recyclability. The present review, with 198 articles included, summarizes the methods of synthesis and characterization of graphene oxide-based adsorbents, as well as their adsorption characteristics, mechanisms and kinetics of pollutants removal processes, the experimental parameters to be optimized, and the adsorption–desorption recycling processes. Several representative examples are reported in details. Also, the main challenges, treatment system economic, and future perspectives in the field are also highlighted.

Application of Dragon Fruit Peel’s Mucilage in Coagulation – Flocculation Process to Remove Turbidity from Water

The study determined flocculation activity of mucilage extracted from dragon fruit peel (Hylocereus undatus) and its ability in reducing synthetic coagulant polyaluminium chloride (PAC) used in coagulation – flocculation process to remove turbidity of different types of water. Investigated waters were turbid waters made from kaolin suspension (KS), suspension of river water with hill soil (FW), and To Lich river water (TL). Turbidity removal was assessed in a sequent coagulation and flocculation model using PAC and mucilage extracted from dragon fruit peel in Jar-tests. Optimal coagulation conditions of PAC with PAC dosage of 20-50 mg/L and pH range of 6-8 regardless of water types and resulted in maximum turbidity removal of about 98%. In order to obtain a comparable turbidity removal, 50%-68% of the required PAC was reduced if mucilage was used. The presence of mucilage enhanced turbidity removal of PAC by 13-22% total efficiency. Mucilage extracted from dragon fruit peel has shown its flocculation ability and its potential as a green material in water treatment.&#x0D; &#x0D; &#x0D;

System and eco-material design based on slow-release ferrate(vi) combined with ultrasound for ballast water treatment

Abstract Background The problem of ballast water is caused by microorganisms. The solution to solve this problem is ballast water disinfection. Until the recent day, there have not been many practical solutions. Usually, ozone, chlorine, and UV treatments were used for disinfection. However, these methods still have many weaknesses in treating ballast water. Methods The ferrate(vi) system proposed in this paper is liquid ferrate(vi) produced on-site using a slow-released system and combined with ultrasound. This paper investigated the optimum time to produce liquid ferrate(vi), pH, and temperature. Results The optimum synthesis time has been observed to be 10 min with the produced ferrate(vi) of 42,000 ppm. The optimal pH and temperature to make ballast water harmless have been observed to be the neutral pH condition at 25°C, respectively. The design of ballast water treatment using ferrate(vi) combined with ultrasound has also been proposed in this paper. Conclusions Ferrate(vi), as the primary material in ballast water treatment, has been successfully synthesized. The process of ballast water treatment using ferrate(vi) combined with ultrasound can be performed automatically using a time sensor and a mass sensor. With the proposed design, it can be a promising solution to solve the problems related to ballast water.

Nitrogen and Phosphorus Removal Efficiency and Denitrification Kinetics of Different Substrates in Constructed Wetland

Constructed wetlands (CWs) are generally used for wastewater treatment and removing nitrogen and phosphorus. However, the treatment efficiency of CWs is limited due to the poor performance of various substrates. To find appropriate substrates of CWs for micro-polluted water treatment, zeolite, quartz sand, bio-ceramsite, porous filter, and palygorskite self-assembled composite material (PSM) were used as filtering media to treat slightly polluted water with the aid of autotrophic denitrifying bacteria. PSM exhibited the most remarkable nitrogen and phosphorus removal performance among these substrates. The average removal efficiencies of ammonia nitrogen, total nitrogen, and total phosphorus of PSM were 66.4%, 58.1%, and 85%, respectively. First-order continuous stirred-tank reactor (first-order-CSTR) and Monod continuous stirred-tank reactor (Monod-CSTR) models were established to investigate the kinetic behavior of denitrification nitrogen removal processes using different substrates. Monod-CSTR model was proven to be an accurate model that could simulate nitrate nitrogen removal performance in vertical flow constructed wetland (VFCWs). Moreover, PSM demonstrated significant pollutant removal capacity with the kinetics coefficient of 2.0021 g/m2 d. Hence, PSM can be considered as a promising new type of substrate for micro-polluted wastewater treatment, and Monod-CSTR model can be employed to simulate denitrification processes.

Study on treatment of acid red G with bio-carbon compound immobilized white rot fungi.

Corn straw biochar was used as a carrier to immobilize white rot fungi and the removal performance of immobilized pellets for acid red G (ARG) dye was studied. The results showed that the removal rate of ARG could reach 96.17% under the best preparation conditions of immobilized pellets (3% sodium alginate concentration, 0.7% corn straw biochar, 5% white rot fungus mycelium suspension, 4% CaCl2, and 36 h immobilization time). The orthogonal test results showed that the best combination was the immobilized pellets dosage of 200/100 mL, pH of 4.5, rotation speed of 150 r/min, and initial concentration of 20 mg/L dye at 30 °C. The degradation pathway of ARG by immobilized microspheres was studied by ultraviolet-visible spectrometer, Fourier transform infrared spectroscopy, and liquid chromatography-mass spectrometry. The results showed that ARG was degraded into aniline and 5-(acetamino)-4-hydroxy-3-amino-2,7-naphthalene disulfonic acid. Aniline was further deaminated to form benzene, and benzene was ring opened to form other organic compounds; 5-(acetylamino)-4-hydroxy-3-amino-2,7-naphthalene disulfonic acid was dehydroxylated to form 5-(acetylamino)-3-amino-2,7-naphthalene disulfonic acid. This study shows that the prepared biochar immobilized pellets can be used as an efficient water treatment material to remove ARG dye from wastewater.

A mini-review on rare earth metal doped ZnO nanomaterials for photocatalytic remediation of waste water

The mineralization and degradation of organic compounds present in waste water by heterogeneous photocatalysis has gained wide attention due to its effectiveness and tenancy to utilize UV-Visible solar light spectrum. The chemical stability, non-toxic character, magnificent electrical and optical properties have been recognized the ZnO as useful material for waste water treatment in environmental remediation technology. However, photocatalytic activity of ZnO limited to ultraviolet region because of its wide band gap (3.37eV). ZnO wide band gap obstruct photo-excitation for actual photocatalytic applications under abundant, safe and clean solar energy source. Many methods have been evolved in last decades to overcome this barrier. ZnO surfaces have been tailored with rare-earth metals to enhance its optical, surface and photocatalytic properties by different research groups. The doping with rare-earth metal ions enhanced the efficiency of ZnO photocatalyst by reducing band gap and shifted the absorbed wavelength to the visible region. This review paper compiles the attempts on modification of ZnO and their effect on photocatalytic activities by using rare earth metals.

Super-bridging fibrous materials for water treatment

To deal with issues of process sustainability, cost, and efficiency, we developed materials reengineered from fibers to serve as super-bridging agents, adsorbents, and ballast media. These sustainable fiber-based materials considerably increased the floc size (~6,630 µm) compared to conventional physicochemical treatment using a coagulant and a flocculant (~520 µm). The materials also reduced coagulant usage (up to 40%) and flocculant usage (up to 60%). These materials could be used in synergy with coagulants and flocculants to improve settling in existing water treatment processes and allow facilities to reduce their capital and operating costs as well as their environmental footprint. Moreover, the super-sized flocs produced using fiber-based materials (up to ~13 times larger compared to conventional treatment) enabled easy floc removal by screening, eliminating the need for a settling tank, a large and costly process unit. The materials can be effective solutions at removing classical (e.g., natural organic matter (NOM) and phosphorus) and emerging contaminants (e.g., microplastics and nanoplastics). Due to their large size, Si- and Fe-grafted fiber-based materials can be easily recovered from sludge and reused multiple times.

Synthesis of covalent organic frameworks via Kabachnik-Fields reaction for water treatment

Providing safe and clean domestic water for people is currently one of the greatest worldwide issues. In this context, heavy metal ions and pathogenic microbes are the two major factors in water pollution. The conventional water treatment methods, however, are generally high-energy and high-resource consumptive. Herein, we report, the first of its kind, the room-temperature synthesis of α-aminophosphonate-linked COFs via three-component one-pot in situ Kabachnik-Fields reaction (KF-3CR). Due to the coexistent bioactive α-aminophosphonate and photosensitive porphyrin, the obtained APCOF-1 exhibits highly efficient solar-powered bactericidal and heavy metal ion removal abilities, which allows it to be a promising COF-based multifunctional material for water treatment in an energy- and resource-saving way. Specifically, by incorporating APCOF-1 (up to 50 wt%) with eco-friendly and low-cost chitosan, an APCOF-1 @chitosan aerogel-based helical setup is fabricated via a facile templated freeze-drying approach and it can be a continuous flow-through water purifier model to achieve scaled-up water treatment through adsorptive removal of heavy metal ions and sunlight-driven sterilization. We believe that this research not only can significantly enrich the synthetic methodology of COFs, but also will hopefully bring COFs one step closer to the practical application.

In situ growth of ZIF-8 on carboxymethyl chitosan beads for improved adsorption of lead ion from aqueous solutions.

In this study, a method for the in situ growth of zeolitic imidazolate framework-8 (ZIF-8) on carboxymethyl chitosan beads (BCMC) to produce a composite adsorbent (BCMC@ZIF-8) for the removal of Pb2+ from water is proposed. The results revealed that the utilization of the BCMC as a framework enhanced the stability of ZIF-8, and the presence of the latter in the composite improved the removal efficiency of Pb2+ from water. Data from X-ray photoelectron spectroscopy analysis and adsorption kinetics revealed that the adsorption mechanism included diffusion and the sharing/transfer of electrons between BCMC@ZIF-8 and Pb2+. The maximum adsorption capacity of BCMC@ZIF-8 fitted using the Langmuir model was 566.09mg/g. Results of the experiments on the regeneration of the adsorbent and its stability in water further indicated that BCMC improved the stability of ZIF-8. This study demonstrated that the stability of metal-organic framework (MOF) materials, which exhibited high efficiencies for the removal of heavy metals in water can be improved through fixation of the polymer skeleton. Thus, the present study offers practical and theoretical guidance for the application of MOF materials in water treatment.

Malachite green dye removal using ceramsite-supported nanoscale zero-valent iron in a fixed-bed reactor

Abstract In this study, we prepared and characterized ceramsite-supported nanoscale zero-valent iron (nZVI). Malachite green (MG) dye removal from aqueous solutions using a fixed-bed reactor packed with the above composite material was investigated. This research was carried out according to the prophase study of the preparation and characterization of ceramsite material for water treatment using sintering method from solid wastes. The results indicated that ceramsite could be loaded with nZVI, mainly because of its magnetic property. With the decrease in the initial concentration and influent flow rate or the increase in the reaction temperature, the breakthrough curve became less steep. Meanwhile, the breakthrough and saturation points gradually shifted rightward. When the initial concentration was 10 mg·L−1, the reaction temperature was 25°C, and the influent flow rate was 5 mL·min−1, the breakthrough curve presented an irregular “S” shape, the breakthrough and saturation times were 230 and 515 h, respectively. The characterization of MG dye-containing wastewater treatment using ceramsite-supported nZVI in a fixed-bed reactor by employing the Yoon-Nelson kinetic model was superior to those using the Thomas and Adams-Bohart kinetic models, with R 2 &gt; 0.96.

Insights into the electrooxidation of florfenicol by a highly active La-doped Ti4O7 anode

In this study, a novel active La-doped Ti4O7 (La-Ti4O7) electrode was fabricated through a simple one-step spark plasma sintering method. Characterization results revealed that La was successfully incorporated into the crystal lattice of Ti4O7, leading to an increase in the surface oxygen vacancy content (from 26% to 31%), oxygen evolution potential (from 2.24 to 2.75 V vs SCE), hydroxyl radical yield [•OH, from 0.123 to 0.205 μmol/(min·cm2)] and interfacial charge-transfer rate compared to pristine Ti4O7. La-Ti4O7 electrodes achieved efficient anodic oxidation of florfenicol (FLO, one of the most widely used antibiotics), which mainly due to the indirect oxidation mediated by electro-generated •OH. The degradation of FLO by La-Ti4O7 electrodes fitted well with the pseudo-first-order kinetic model, and the optimal degradation rate constant (kFLO, 0.021 min−1) was achieved by 1.60% La-Ti4O7 electrode. In addition, the degradation efficiency of FLO increased with the increasing current density, decreasing pH and co-existing Cl-, while an opposite pattern was observed with co-existing NO3–. Seven degradation products of FLO were identified by UPLC-MS/MS. The main degradation pathways included hydrolysis, hydroxylation, dechlorination and C-N bonds cleavage. The energy consumption (EC) for FLO degradation ranged from 1.91 to 29.53 Wh/L, and the optimal practical conditions were obtained by the analysis of the calculated ratios of kFLO and EC. Moreover, La-Ti4O7 electrode maintained excellent removal efficiency of FLO (>93.5%) within 20 degradation cycles. This study suggested that La-Ti4O7 is a promising anodic material for the efficient treatment of FLO-polluted water.

Ecological floating bed for decontamination of eutrophic water bodies: Using alum sludge ceramsite

In this study, a combined ecological floating bed (C-EFB) with alum sludge ceramsite (ASC) was designed to improve the water purification effect of traditional ecological floating beds (T-EFBs). During the ASC preparation stage, alum sludge was shaped into a ball, air-dried, and fired under 600 °C. The physical and chemical properties of the ASC meet the requirements of Artificial Ceramsite Filter Materials for Water Treatment (CJ/T229-2008). This study investigated the increased capability of this new-type artificial substrate (ASC) on the removal of chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), total phosphorus (TP), and total nitrogen (TN) from eutrophic landscape water. Compared with the T-EFB, the C-EFB owns a higher purification efficiency. The highest average efficiency of COD, NH4+-N, TN and TP removals during the four operating stages was 78.2%, 58.1%, 46.7% and 53.2%, respectively, in the C-EFB, which were all higher than those of 53.5%, 32.4%, 27.2% and 25.8%, respectively, for the T-EFB. Among them, the C-EFB showed a higher advantage in the removal of TP. The results showed that the potential benefits of utilizing ASC in seriously eutrophic bodies of water.

Recent progress of functional metal–organic framework materials for water treatment using sulfate radicals

Human health is being threatened by the ever-increasing water pollution. Sulfate radical (SO4•−)-based advanced oxidation processes (SR-AOPs) are rapidly being developed and gaining considerable attention due to their high oxidation potential and selectivity as a way to purify water by degrading organic contaminants in it. Among the catalytic materials that can activate the precursor to generate SO4•−, metal–organic frameworks (MOFs) are the most promising heterogeneous catalytic material in SR-AOPs because of their various structure possibilities, large surface area, ordered porous structure, and regular activation sites. Herein, an in-depth overview of MOFs and their derivatives for water purification with SR-AOPs is provided. The latest studies on pristine MOFs, MOF composites, and MOF derivatives (metal oxides, metal–carbon hybrids, and carbon materials) are summarized. The mechanisms of decomposition of pollutants in water via radical and non-radical pathways are also discussed. This review suggests future research directions for water purification through MOF-based SR-AOP.

Synthesis of an Environmentally Friendly Boron Nitride/Dye Composite Photocatalytic Material and Study on Degradation Mechanism of Tetracycline Wastewater

AbstractHerein, a boron nitride‐dye composite photocatalytic material is synthesized by a simple and environmentally friendly method. In this method, boron nitride (BN) is added to Methylene blue (MB), Congo red (CR), Rhodamine B (RhB), methyl orange (MO) solution respectively, the formed composites (BN‐RhB, BN‐MB, BN‐MO and BN‐CR) can further work as photocatalyst to degrade tetracycline (TC) under visible light irradiation. The degradation rate of TC are 278.5, 303.3, 89 and 115.5 times by BN‐RhB, BN‐MB, BN‐MO and BN‐CR higher than that of BN. This is from the sensitization of dyes for BN and these dyes have different absorption ranges for visible light. After the adsorption of BN for RhB‐MO, RhB‐CR, MB‐MO and MB‐CR mixed solutions, BN‐RhB‐MO, BN‐RhB‐CR, BN‐MB‐MO and BN‐MB‐CR composites are formed. Compared with BN, their photodegradation rate for TC are improved by about 102.75, 118, 388 and 460.75 times, respectively. The photodegradation rate of BN‐MB‐CR (k=0.01843) is better than that of BN‐MB (k=0.01213), being from that binary dyes are more conducive to improve the electron transfer efficiency than single dyes. The involved photo‐active species during photodegradation process and the photodegradation intermediate products of TC have detected as well. The photodegradation rate (k=0.01213) of BN‐MB for TC is also higher than that of g‐C3N4 (k=0.00599), g‐C3N4‐MB (k=0.01027), TiO2 (k=0.01061) and TiO2‐MB (k=0.01163). This work is helpful to develop an environment‐friendly water treatment material.

Biosynthesis of zinc oxide nanoparticles from Phyllanthus Niruri plant extract for photocatalytic and antioxidant activities

ABSTRACT The lack of access to hygienic conditions and clean water is a serious issue in developing countries. Eco-friendly, bio-synthesised nanomaterials-based catalyst will be potential candidate material for waste water treatment. In this study, Phyllanthus niruri plant extract was used to make non-toxic, cost-effective ZnO NPs. The X-ray diffraction pattern was shown that the bio-synthesised ZnO NPs were in hexagonal wurtzite structure. The SEM image was used to analyse the surface morphology of the NPs, and the chemical purity of the NPs was analysed by EDAX spectrum. The various functional groups that exist in the NPs and purity of the prepared samples were analysed by Fourier-transform infrared (FTIR) spectroscopy. The bio-synthesised ZnO NPs decolourised the methylene blue dye and Reactive Red 120. The larger surface area of ZnO nanoparticles (NPs) and wide absorption band of the NPs led to superior photocatalytic activity under the sunlight irradiation. The bio-synthesised ZnO NPs prevented or slowed down the oxidative damage of cells by controlling the generation of reactive oxygen species (ROS).

Ozonation of phenol in the presence of biochar and carbonaceous materials: The effect of surface functional groups and graphitic structure on the formation of reactive oxygen species

To develop a novel oxidation process using ozone and carbonaceous materials for water treatment and groundwater remediation, the effect of carbonaceous materials on the ozonation of phenol was investigated via batch experiments. Anode carbonaceous material (ACM) recovered from spent Li-ion batteries, graphite, granular activated carbon (GAC), and rice straw-derived biochar were evaluated as catalysts to enhance the ozonation of phenol. Compared with direct ozonation (28% removal in 2 h), the addition of carbonaceous materials enhanced the oxidation of phenol by ozone, showing 47%, 45%, 81%, and 74% removal with ACM, graphite, GAC, and biochar, respectively. According to the quenching experiments with chemical reagents and electron paramagnetic resonance analysis, reactive oxygen species, such as hydroxyl radicals (·OH), superoxide radicals (O2·-), and singlet oxygen (1O2), as well as electron transfer in the mediated-reaction, are included in the ozonation of phenol in the presence of carbonaceous materials. The oxygen-containing surface functional groups and graphitic structure are responsible for the reactive oxygen species and electron transfer reactions, respectively. Our results suggest that carbonaceous materials may be effectively used as catalysts to promote the ozonation of recalcitrant contaminants in water.