Evaluation of advanced oxidation processes for water and wastewater treatment - A critical review

Numerical simulation of the bifurcation-remerging process and intermittency in an undriven direct current glow discharge

As a complex nonlinear medium, gas discharge plasma can exhibit various nonlinear discharge behaviors. In this study, in order to investigate the chaos phenomenon in the subnormal glow region of an undriven direct current glow discharge, a two-dimensional plasma fluid model is established coupled with a circuit model as a boundary condition. Using the applied voltage as control parameter in the simulation, the complete period-doubling bifurcation and inverse period-doubling bifurcation processes in the oscillation region are found, and the influence of the applied voltage on the spatiotemporal distribution of plasma parameters during the bifurcation-remerging process is examined. In addition, the spatial distribution of the plasma parameters of the bifurcation-remerging process is also examined. Also, a series of periodic windows are present in the chaotic region, where the positions and relative order are generally consistent with the universal sequence. Additionally, this study showed that the intermittent chaos appears near the period-3 window, and the bursts appearing in the approximate periodic motion becomes more and more frequent as the control parameters move away from the saddle-node bifurcation point, which shows the typical type-I intermittent chaos characteristics.

Activation of periodate using ultrasonic waves and UV radiation for landfill leachate treatment

In the present work, saline leachate of the Bushehr coastal city (Iran) was purified using the ultraviolet/ultrasonication wave/periodate process. The initial TDS and TOC values of the leachate studied were 7390 mg/L and 975 mg/L, respectively. During the effect of various parameters on leachate purification, the experiments were optimized at pH 3, oxidizer concentration of 4 mM, and treatment time of 120 min. The initial BOD₅/COD ratio of 0.66 was reduced to 0.42 at the end of the purification time (120 min). After leachate treatment under optimal conditions, the amount of BOD₅, COD, and UV₂₅₄ were 451.5 mg/L, 1072 mg/L, and 12.69 cm^-1, respectively. Concentrations of heavy metals in crude leachate by ICP-OES were checked. Also, the concentration of organic compounds before and after purification was determined using GC-Mass. The leachate purification kinetics followed the first-order model using the designed method. Based on the COD factor, the system energy consumption for leachate treatment was calculated to be 11.4 kWh/m³. The results showed that the system explored (UV/US/IO₄^-) can effectively purify high salinity waste leachate.

The calcium alginate-immobilized Co-g-C3N4 composite microspheres as an efficient mediator to activate peroxymonosulfate for degrading organic pollutants

Poor water stability and difficult separation severely limited the application of Co-based catalysts in persulfate activation. Herein, for the first time, the calcium alginate-immobilized Co-g-C₃N₄-2 composite microspheres were prepared by a feasible method. Notably, embedding Co ion into g-C₃N₄ can improve its specific surface area and electrochemical activities. More significantly, as-prepared Co-g-C₃N₄-2 microsphere presented excellent catalytic performance in PMS activation for the degradation of TC. For the activation mechanisms of PMS over Co-g-C₃N₄-2 microspheres, the calcium alginate microspheres could mediate the direct electron transfer between TC and PMS, while both radical and nonradical pathways were involved in the activation of PMS over Co-g-C₃N₄-2. Meanwhile, SO₄^•-, OH^•, O₂^•- and ¹O₂ were major reactive oxygen species formed in the Co-g-C₃N₄-2 microsphere/PMS system. Proposed Co-g-C₃N₄-2 microsphere/PMS system still exhibited great degradation ability towards TC over a wide pH range, and co-existing anions had weak influence on TC degradation over Co-g-C₃N₄-2 microsphere/PMS system. Moreover, the construction of Co-g-C₃N₄-2 microspheres not only avoided the release of metal ion from catalyst, but also provided convenience for the recovery of catalyst. In short, current work shared some novel insights into the application of heterogeneous catalysis in persulfate activation for wastewater treatment.

Efficient degradation of tetracycline under the conditions of high-salt and coexisting substances by magnetic CuFe2O4/g-C3N4 photo-Fenton process

For the effective degradation of tetracycline (TC), a facilely prepared magnetic CuFe₂O₄/g-C₃N₄ (CFO/g) photocatalyst was successfully constructed. The structure, morphology, composition, optical, and magnetic properties of CFO/g were characterized. CFO/g demonstrated excellent photo-Fenton performance of TC in the presence of high-Cl^-, NO₃^-, HCO₃^-, HPO₄^2-, SO₄^2- and humic acid. Ten cycles of experiments with the removal rate of TC only decreasing by 2.8% confirmed the stability and high activity of CFO/g. The dissolved concentrations of Fe and Cu ions were 0.013 and 0.009 mg L^-1, respectively. Its excellent magnetic properties made CFO/g easier to be recycled than traditional catalysts. ·OH and O₂·^- were proposed to be the main active species in the photo-Fenton system. The CFO/g heterojunction enhanced the separation of photogenerated electron-hole pairs and visible light absorption range. Furthermore, the identification of intermediates suggested that TC degradation was classified into two pathways, and the most critical and rapid degradation was achieved within the first 30 min. The TC and its intermediates did not significantly inhibit the growth activity of Escherichia coli. This research provided a promising application of magnetic photocatalysts in wastewater treatment of pharmaceuticals and personal care products.

A detailed review on advanced oxidation process in treatment of wastewater: Mechanism, challenges and future outlook

The presence of several contaminants in waterbodies raises global pollution and creates major risks to mankind, wildlife, as well as other living organisms. Development of an effective, feasible, cost-effective and eco-friendly approach for treating wastewater that is discharged from various industries is important for bringing down the deposition of contaminants into environment. Advanced oxidation process is an efficient technique for treating wastewater owing to its advantages such as high oxidation efficacy and does not produce any secondary pollutants. Advanced oxidation process can be performed through various methods such as ozone, Fenton, electrochemical, photolysis, sonolysis, etc. These methods have been widely utilized for degradation of emerging pollutants that cannot be destroyed using conventional approaches. This review focuses on wastewater treatment using advanced oxidation process. A brief discussion on mechanism involved is provided. In addition, various types of advanced oxidation process and their mechanism are explained in detail. Challenges faced during wastewater treatment process using oxidation, electrochemical, Fenton, photocatalysis and sonolysis are discussed elaborately. Advanced oxidation process can be viewed as potential approach for treating wastewater with certain modifications and solving challenges.

The Effect of Magnetic Composites (γ-Al2O3/TiO2/γ-Fe2O3) as Ozone Catalysts in Wastewater Treatment

Using municipal sewage as a source of reclaimed water is an important way to alleviate the shortage of water resources. At present, advanced oxidation technology (AOPs), represented by ozone oxidation, is widely used in wastewater treatment. In this study, γ-Al₂O₃, a low-cost traditional ozone catalyst, was selected as the matrix. By modifying magnetic γ-Fe₂O₃ with a titanate coupling agent, in situ deposition, and calcination, the final formation of a γ-Al₂O₃/TiO₂/γ-Fe₂O₃ micrometer ozone catalyst was achieved. A variety of material characterization methods were used to demonstrate that the required material was successfully prepared. The catalyst powder particles have strong magnetic properties, form aggregates easily, and have good precipitation and separation properties. Subsequently, ibuprofen was used as the degradation substrate to investigate the ozone catalytic performance of the prepared catalyst, and this proved that it had good ozone catalytic activity. The degradation process was also analyzed. The results showed that in the ozone system, some of the ibuprofen molecules will be oxidized to form 1,4-propanal phenylacetic acid, which is then further oxidized to form 1,4-acetaldehyde benzoic acid and p-phenylacetaldehyde. Finally, the prepared catalyst was applied to the actual wastewater treatment process, and it also had good catalytic performance in this context. GC-MS detection of the water samples after treatment showed that the types of organic matter in the water were significantly reduced, among which nine pollutants with high content, such as bisphenol A and sulfamethoxazole, were not detected after treatment.

Ultrasound-enhanced catalytic degradation of simulated dye wastewater using waste printed circuit boards: catalytic performance and artificial neuron network-based simulation

Recent developments of heterogeneous advanced oxidation for refractory organic contaminants and catalysts made of solid waste have attracted much attention. In this work, waste printed circuit board (wPCB) was used for catalytic degradation of simulated textile wastewater enhanced by ultrasound. Catalytic degradation of rhodamine B (RhB) and methylene blue (MB) was conducted in the presence of H₂O₂. Effect of ultrasound, wPCB, H₂O₂, pH, and dye concentration was investigated by single factor experiments. The growing catalytic efficiency was determined by ultrasound. The removal efficiency of MB and RhB are influenced by wPCB, H₂O₂, pH, and dye concentration. Degradation efficiency is accelerated with increasing wPCB dosage and H₂O₂ and decreasing dye concentration. Effective degradation of MB and RhB is obtained under broader pH region, attractively at neutral pH. Under optimal conditions, MB removal reaches 98.83% at 90 min while RhB removal reaches 99.57% at 80 min. Hydroxyl radicals play an important role in catalytic process. Tentative mechanism for catalytic degradation of MB and RhB are discussed based on multiple characterizations. Superior reusability of wPCB proves that wPCB is highly durable catalyst. Due to low cost and high efficiency, wPCB is attractive as effective catalyst for treatment of organic wastewater. Artificial neuron network-based (ANN) simulation, as a widely used artificial intelligence algorithm, was one of preferred methods for the wastewater treatment due to its unique properties in solving complex processes. An ANN model was designed for the prediction of the performance of ultrasound-enhanced catalytic degradation with a high R value (0.99).

On-Site Application of Solar-Activated Membrane (Cr-Mn-Doped TiO2@Graphene Oxide) for the Rapid Degradation of Toxic Textile Effluents

Solar-activated water treatment has become an emerging research field due to its eco-friendly nature and the economic feasibility of green photocatalysis. Herein, we synthesized promising, cost-effective, and ultralong-semiconductor TiO₂ nanowires (NW), with the aim to degrade toxic azo dyes. The band gap of TiO₂ NW was tuned through transition metals, i.e., chromium (Cr) and manganese (Mn), and narrowed by conjugation with high surface area graphene oxide (GO) sheets. Cr-Mn-doped TiO₂ NWs were chemically grafted onto GO nanosheets and polymerized with sodium alginate to form a mesh network with an excellent band gap (2.6 eV), making it most suitable to act as a solar photocatalytic membrane. Cr-Mn-doped TiO₂ NW @GO aerogels possess high purity and crystallinity confirmed by Energy Dispersive X-ray spectroscopy and X-ray diffraction pattern. A Cr-Mn-doped TiO₂ NW @GO aerogels membrane was tested for the photodegradation of Acid Black 1 (AB 1) dye. The synthesized photocatalytic membrane in the solar photocatalytic reactor at conditions optimized by response surface methodology (statistical model) and upon exposure to solar radiation (within 180 min) degraded 100% (1.44 kg/m³/day) AB 1dye into simpler hydrocarbons, confirmed by the disappearance of dye color and Fourier transform infrared spectroscopy. An 80% reduction in water quality parameters defines Cr-Mn-doped TiO₂ NW @GO aerogels as a potential photocatalytic membrane to degrade highly toxic pollutants.

Removal of Pharmaceuticals and Personal Care Products (PPCPs) by Free Radicals in Advanced Oxidation Processes

As emerging pollutants, pharmaceutical and personal care products (PPCPs) have received extensive attention due to their high detection frequency (with concentrations ranging from ng/L to μg/L) and potential risk to aqueous environments and human health. Advanced oxidation processes (AOPs) are effective techniques for the removal of PPCPs from water environments. In AOPs, different types of free radicals (HO·, SO₄·^-, O₂·^-, etc.) are generated to decompose PPCPs into non-toxic and small-molecule compounds, finally leading to the decomposition of PPCPs. This review systematically summarizes the features of various AOPs and the removal of PPCPs by different free radicals. The operation conditions and comprehensive performance of different types of free radicals are summarized, and the reaction mechanisms are further revealed. This review will provide a quick understanding of AOPs for later researchers.

Emerging technologies for enhanced removal of residual antibiotics from source-separated urine and wastewaters: A review

Antibiotic residues are of significant concern in the ecosystem because of their capacity to mediate antibiotic resistance development among environmental microbes. This paper reviews recent technologies for the abatement of antibiotics from human urine and wastewaters. Antibiotics are widely distributed in the aquatic environment as a result of the discharge of municipal sewage. Their existence is a cause for worry due to the potential ecological impact (for instance, antibiotic resistance) on bacteria in the background. Numerous contaminants that enter wastewater treatment facilities and the aquatic environment, as a result, go undetected. Sludge can act as a medium for some chemicals to concentrate while being treated as wastewater. The most sewage sludge that has undergone treatment is spread on agricultural land without being properly checked for pollutants. The fate of antibiotic residues in soils is hence poorly understood. The idea of the Separation of urine at the source has recently been propagated as a measure to control the flow of pharmaceutical residues into centralized wastewater treatment plants (WWTPs). With the ever increasing acceptance of urine source separation practices, visibility and awareness on dedicated treatement technologies is needed. Human urine, as well as conventional WWTPs, are point sources of pharmaceutical micropollutants contributing to the ubiquitous detection of pharmaceutical residues in the receiving water bodies. Focused post-treatment of source-separated urine includes distillation and nitrification, ammonia stripping, and adsorption processes. Other reviewed methods include physical and biological treatment methods, advanced oxidation processes, and a host of combination treatment methods. All these are aimed at ensuring minimized risk products are returned to the environment.

Boosting the photocatalytic properties of NaTaO3 by coupling with AgBr

AgBr/NaTaO3 composites, with different molar % of NaTaO3 (Br/NTO(X%)), have been synthesized by simple precipitation methods; bare NaTaO3 was synthesized by hydrothermal procedure, while AgBr was synthesized by a precipitation procedure using cetyl-tri-methyl-ammonium bromide (CTAB) and AgNO3. Samples have been characterized by X-ray diffraction (XRD), N2 adsorption, UV–vis diffuse reflectance spectroscopy (DRS), Fourier-transform infrared spectroscopy (FT-IR), Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Photocatalytic activity of the as-prepared photo-catalysts was evaluated through photocatalytic degradation of rhodamine B (RhB), methyl orange (MO) and caffeic acid (CAFA) under UV and visible illumination. Single AgBr material and Br/NTO(X%) composites displayed the ability to absorb light in the visible region, while NaTaO3 is only photoactive under UV irradiation. Based on the position of conduction and valence bands of AgBr and NaTaO3, the heterojunction between these two photo-catalysts corresponds to a type II junction. In the case of photocatalytic degradation of RhB and CAFA, Br/NTO(x%) composites have highest photocatalytic activity than that obtained by both parental materials under the same operational conditions. AgBr and Br/NTO(x%) composites achieve a fast degradation of MO, together with a considerable adsorption capacity, attributed to the presence of a remaining amount of residual CTAB on the AgBr surface. In summary, coupling AgBr with NaTaO3 improves the photocatalytic activity under both UV and visible illumination with respect to the parental components, but the performance of the composites is highly dependent on the type of substrate to be degraded and the illumination conditions.

State-of-the-Art on the Sulfate Radical-Advanced Oxidation Coupled with Nanomaterials: Biological and Environmental Applications

Sulfate radicals (SO₄^-·) play important biological roles in biomedical and environmental engineering, such as antimicrobial, antitumor, and disinfection. Compared with other common free radicals, it has the advantages of a longer half-life and higher oxidation potential, which could bring unexpected effects. These properties have prompted researchers to make great contributions to biology and environmental engineering by exploiting their properties. Peroxymonosulfate (PMS) and peroxydisulfate (PDS) are the main raw materials for SO₄^-· formation. Due to the remarkable progress in nanotechnology, a large number of nanomaterials have been explored that can efficiently activate PMS/PDS, which have been used to generate SO₄^-· for biological applications. Based on the superior properties and application potential of SO₄^-·, it is of great significance to review its chemical mechanism, biological effect, and application field. Therefore, in this review, we summarize the latest design of nanomaterials that can effectually activate PMS/PDS to create SO₄^-·, including metal-based nanomaterials, metal-free nanomaterials, and nanocomposites. Furthermore, we discuss the underlying mechanism of the activation of PMS/PDS using these nanomaterials and the application of SO₄^-· in the fields of environmental remediation and biomedicine, liberating the application potential of SO₄^-·. Finally, this review provides the existing problems and prospects of nanomaterials being used to generate SO₄^-· in the future, providing new ideas and possibilities for the development of biomedicine and environmental remediation.

Degradation of micropollutants in flow-through UV/chlorine reactors: Kinetics, mechanism, energy requirement and toxicity evaluation

The degradation of three micropollutants (i.e., atrazine (ATZ), sulfamethoxazole (SMX) and metoprolol (MET)) was comprehensively investigated in flow-through UV/chlorine reactors. Results showed that the micropollutants degradation fitted well with pseudo-first-order kinetics (R² > 0.92) with the order of rate constants following SMX > MET > ATZ. The developed steady-state approximation (SSA) model was roughly applicable in flow-through UV/chlorine reactors with the predictions deviated within 44%. UV photolysis here stood as the major degradation pathway for ATZ while the contribution of non-radical processes (UV photolysis and chlorination) to SMX degradation increased as the reactor internal diameter enlarged. The degradation rates were reduced to varying extents with complex water matrices (chloride, bicarbonate and dissolved organic matter (DOM)) where the inhibition from the DOM was most prominent (up to 73.6%). Although reactors with a larger internal diameter resulted in reduced degradation rate constants, the energy requirements were also lowered. The E_EO values of micropollutants degradation by UV/chlorine fell mostly within 1.0 kWh m^-3 order^-1 in deionized water and under different water matrices. The acute toxicity was observed to be higher after UV/chlorine treatment in tap water, but still stayed low in general. This study revealed the different kinetics and mechanisms of micropollutants degradation in flow-through reactors and demonstrated the potential of the UV/chlorine process in terms of low energy consumption and acute toxicity.

UVA-irradiated dual photoanodes and dual cathodes photocatalytic fuel cell: mechanisms and Reactive Red 120 degradation pathways

To enhance dye removal and energy recovery efficiencies in single-pair electrode photocatalytic fuel cell (PFC-AC), dual cathodes PFC (PFC-ACC) and dual photoanodes PFC (PFC-AAC) were established. Results revealed that PFC-AAC yielded the highest decolorization rate (1.44 h-1) due to the promotion of active species such as superoxide radical (•O2-) and hydroxyl radical (•OH) when the number of photoanode was doubled. The results from scavenging test and UV-Vis spectrophotometry disclosed that •OH was the primary active species in dye degradation of PFC. Additionally, PFC-AAC also exhibited the highest power output (17.99 μW) but the experimental power output was much lower than the theoretical power output (28.24 μW) due to the strong competition of electron donors of doubled photoanodes to electron acceptors at the single cathode and its high internal resistance. Besides, it was found that the increments of dye volume and initial dye concentration decreased the decolorization rate but increased the power output due to the higher amount of sacrificial agents presented in PFC. Based on the abovementioned findings and the respective dye intermediate products identified from gas chromatography-mass spectrometry (GC-MS), the possible degradation pathway of RR120 was scrutinized and proposed.

Separation of emulsified crude oil from produced water by gas flotation: A review

The development and production of oil and gas fields would eventually result in a considerable amount of oily generated water, posing serious risks to humans and the environment. Nowadays, the oil concentration in the drainage stream of the produced water is strictly regulated, and many countries have established strict emission standards. As an indispensable oily wastewater treatment technology, flotation technology has attracted much attention because of its maturity, economy, practicality, and relative efficiency. Firstly, this paper summarizes and compares flotation techniques, such as dissolved gas flotation, induced gas flotation, electroflotation, and compact flotation units widely used in produced water treatment offshore in recent years. Considering the complexity of the mechanism of oil removal by air flotation, the mechanism of the oil droplet-bubble interaction is further discussed. The effects of flocculant, PH, and salinity on the oil droplet-bubble interaction in the flotation process were summarized from the perspective of the microscopic colloidal interface, which has a specific guiding role in improving the oil removal efficiency in the gas flotation process. Finally, the research status of produced water treatment by air flotation is summarized, and the feasible research direction is put forward.

Degradation of geosmin and 2-methylisoborneol in UV-based AOPs for photoreactors with reflective inner surfaces: Kinetics and transformation products

Geosmin (GSM) and 2-methylisoborneol (2-MIB) are representative musty/earthy odor compounds commonly present in surface water. In present study, the degradation of GSM and 2-MIB subject to different UV-based advanced oxidation processes (AOPs), including UV/H₂O₂, UV/S₂O₈^2-, UV/chlorine, and UV/chloramine, in a phosphate-buffered saline (PBS) was conducted in a photoreactor with reflective inner surfaces and compared with that in an environmental water sample. A dynamic model to predict the degradation of GSM and 2-MIB in the photoreactor with reflective inner surfaces in the four UV-based AOPs was developed applying the second-order rate constants for the GSM and 2-MIB with primary reactive species (i.e., •OH, •Cl, and •SO₄^-) determined in this study. The model was proven to successfully simulate the degradation of GSM and 2-MIB. In addition, 8, 7, 8, and 11 degradation intermediates were detected from UV/H₂O₂, UV/S₂O₈^2-, UV/chlorine, and UV/chloramine in this study, and possible degradation pathways were proposed. This study is the first to report the degradation kinetics and formation products of GSM and 2-MIB in UV/chloramine. Research based on photoreactors with reflective inner surfaces may provide some guidance for eliminating GSM and 2-MIB in UV-based AOPs for full-scale engineering applications.

TiO2-immobilized porous geopolymer composite membrane for removal of antibiotics in hospital wastewater

This experimental research proposes an environment-friendly and low-cost porous geopolymer composite membrane (PGCM) to treat antibiotics in hospital wastewater. The proposed PGCM consisted of two layers: a porous support layer and a dense coating layer. The dense coating layer was synthesized by incorporating variable TiO₂ content (0, 2, 6, and 10 wt%) into the geopolymer matrix. The dense coating layer was of hierarchical mesoporous structure with 700 μm in thickness and adhered to the porous support layer. The average pore size, total pore volume, and open porosity of the dense coating layer decreased with an increase in TiO₂, resulting in reduced water permeability. The PGCM was applied to remove six target antibiotics including amoxicillin, ciprofloxacin, norfloxacin, sulfamethoxazole, tetracycline, and trimethoprim in real hospital wastewater. By comparison, the PGCM with 10 wt% TiO₂ achieved the highest antibiotic removal efficiencies, with the adsorption and combined adsorption/photodegradation removal efficiencies for the target antibiotics of 38-75% and 74-86%, respectively. The novelty of this research lies in the use of a tailor-made porous geopolymer composite membrane incorporated with TiO₂ photooxidation as a single-step treatment of recalcitrant antibiotics contained in hospital wastewater.

Decontamination of wastewater containing contaminants of emerging concern by electrooxidation and Fenton-based processes - A review on the relevance of materials and methods

In recent years, there has been an increasingly growing interest regarding the use of electrochemical advanced oxidation processes (EAOPs) which are considered highly promising alternative treatment techniques for addressing environmental issues related to pollutants of emerging concern. In EAOPs, electrogenerated oxidizing agents, such as hydroxyl radical (HO^•), can react non-selectively with a wide range of organic compounds, degrading and mineralizing their structures to unharmful molecules like CO₂, H₂O, and inorganic ions. To this date, a broad spectrum of advanced electrocatalysts have been developed and applied for the treatment of compounds of interest in different matrices, specifically aiming at enhancing the degradation performance. New combined methods have also been employed as alternative treatment techniques targeted at circumventing the major obstacles encountered in Fenton-based processes, such as high costs and energy consumption, which still contribute significantly toward inhibiting the large-scale application of these processes. First, some fundamental aspects of EAOPs will be presented. Further, we will provide an overview of electrode materials which have been recently developed and reported in the literature, highlighting different anode and cathode structures employed in EAOPs, their main advantages and disadvantages, as well as their contribution to the performance of the treatment processes. The influence of operating parameters, such as initial concentrations, pH effect, temperature, supporting electrolyte, and radiation source, on the treatment processes were also studied. Finally, hybrid techniques which have been reported in the literature and critically assess the most recent techniques used for evaluating the degradation efficiency of the treatment processes.

Removal assessment of disinfection by-products (DBPs) from drinking water supplies by solar heterogeneous photocatalysis: A case study of trihalomethanes (THMs)

Solar heterogeneous photocatalysis was used to remove trihalomethanes (THMs) from drinking water. THMs, mainly trichloromethane (TCM), tribromomethane (TBM), bromodichloromethane (BDCM) and dibromochloromethane (DBCM) are one of the main class of disinfection by-products (DBPs). THMs were determined by HSGC-MS with detection limits (LODs) ranging from 0.5 μg L^-1 to 0.9 μg L^-1 for TCM and BDCM, respectively. Results show that a great proportion of THMs present in water are finally transferred to air as a result of their high volatility in the order TCM > BDCM > DBCM > TBM. The use of band-gap semiconductor materials (TiO₂ and mainly ZnO) used as photocatalysts in combination with Na₂S₂O₈ as electron acceptor and sulfate radical anion (SO₄^•-) generator enhanced the photooxidation of all THMs as compared to photolytic test. The time required for 50% of THMs to disappear (DT₅₀) from water calculated for the most effective treatment (ZnO/Na₂S₂O₈) were 12, 42, 57 and 61 min for TCM, TBM, BDCM, and DBCM, respectively. Therefore, solar heterogeneous photocatalysis can be considered as an interesting strategy for THMs removal, especially in sunny areas like Mediterranean basin.

Investigation of black phosphorus anodic catalyst for electrolysis: Degradation of organics via a perchlorate-free oxidant activation

This study investigated the potential of a novel fabricated black phosphorus (BP) nanoparticle electrode as an alternative to noble metal-based catalysts for application in electrolysis. The BP electrode was compared with other conventional catalysts (boron-doped diamond (BDD) and a dimensional stable electrode (DSA)) under different electrolyte conditions for the generation of specific oxidants (e.g., OH^•, HOCl, OCl^-, SO₄^{• -}) in the bulk phase during electrolysis. In the presence of sulfate-based electrolyte, results on the electrochemical oxidation showed that the BP not only resulted in an 8-fold increase in the current efficiency compared to DSA, but also reduced energy consumptions by approximately 30-fold. Moreover, electrolysis using certain electrodes (i.e., BDD) under high current densities in the presence of chlorine-based electrolyte has been reported to be hazardous to the water system due to the generation of toxic chlorine oxyanions (i.e., perchlorate), which necessitates the operation of a post-treatment process. Likewise, application of the BDD electrode was confirmed to produce perchlorate under high current densities, while no by-product was generated by electrolysis with the BP electrode. Finally, multiple degradation pathways for selective water treatment was monitored under oxidation with the BP electrode. To the best of our knowledge, this study is the first to apply the novel fabricated BP electrode as the anodic catalyst for the treatment of a water system.

Kitchen-waste-derived biochar modified nanocomposites with improved photocatalytic performances for degrading organic contaminants

Kitchen-waste-derived biochar (KBC) was produced by thermal treatment at 400 °C, and a series of KBC/BiOX (X = Br, Cl) photocatalysts were developed using ultrasonication and solvothermal treatment. The as-prepared photocatalysts were characterized by several tests and investigated by photocatalytic reactions towards methyl orange (MO) and tetracycline (TC). The best photocatalysts, 0.15KBC/BiOBr and 0.15KBC/BiOCl separately achieved complete MO photodegradation in 20 min and 35 min. Further study confirmed that 0.15KBC/BiOBr and 0.15KBC/BiOCl possessed excellent photocatalytic efficiency that was 17.9 and 14.8 times higher than BiOBr and BiOCl, respectively. In addition, 0.15KBC/BiOX showed higher activity removal of TC than pure BiOX in 60 min. Notably, 0.15KBC/BiOX maintained a reproducible high photocatalytic efficiency after five recycles. Estimated band gap energy for 0.15KBC/BiOBr (2.40 eV) and 0.15KBC/BiOCl (3.00 eV) was considerably lower than that of BiOBr (2.73 eV) and BiOCl (3.30 eV), indicating a delocalized state was created when forming electronic pathways on the interface. Besides, visible-light harvesting of photocatalysts got promoted by the modification of KBC. Active species trapping experiments and electron paramagnetic resonance (EPR) tests illustrated that photogenerated holes were the principal active species, while ∙OH was involved in the reaction. The successful synthesis of 0.15KBC/BiOX catalyst provided a new approach on simultaneously degrading organic contaminants in water and disposing of excessive kitchen waste.

Degradation of phenol using Fe(II)-activated CaO2: effect of ball-milled activated carbon (ACBM) addition

In-situ chemical oxidation (ISCO) based on peroxide activation is one of the most promising technologies for removing organic contaminants from natural groundwater (NGW). However, use of the most common form of hydrogen peroxide (H₂O₂) is limited owing to its significantly rapid reaction rate and heat generation. Therefore, in the present study, the activation of calcium peroxide (CaO₂), a slow H₂O₂ releasing agent, by Fe(II) was proposed (CaO₂/Fe(II)), and the phenol degradation mechanisms and feasibility of NGW remediation were investigated. The optimum molar ratio of [phenol]/[CaO₂]/[Fe(II)] (phenol = 0.5 mM) was 1/10/10, resulting in 87.0-92.5% phenol removal within 120 min under a broad initial pH range of 3-9. HCO₃^-, PO₄^3-, and humic acid significantly inhibited degradation, whereas the effects of Cl^-, NO₃^-, and SO₄^2- were negligible. Reactive oxygen species (ROS) were identified based on the results of phenol degradation in the presence of scavengers and electron spin resonance (ESR) spectroscopy, which demonstrated that ¹O₂ played the dominant role, supported by ^•OH, in CaO₂/Fe(II). Phenol removal in NGW (67.81%) was less than that in distilled and deionized water (DIW, 92.5%) at a [phenol]/[CaO₂]/[Fe(II)] ratio of 1/10/10. However, phenol removal was significantly improved (∼100%) by increasing the CaO₂ and Fe(II) doses to 1/20/20-40. Furthermore, when 125-250 mg L^-1 of ball-milled activated carbon (AC_BM) was added (CaO₂/Fe(II)-AC_BM), phenol removal was enhanced from 67.81% to 90.94-100% in the NGW. CaO₂/Fe(II)-AC_BM exhibited higher total organic carbon (TOC) removal than CaO₂/Fe(II). In addition, no notable by-products were detected using CaO₂/Fe(II)-AC_BM, whereas the polymerisation products of hydroxylated and/or ring-cleaved compounds, that is, aconitic acid, gallocatechin, and 10-hydroxyaloin, were found in the reaction with CaO₂/Fe(II). These results strongly suggest that CaO₂/Fe(II)-AC_BM is highly promising for groundwater remediation, minimizing degradation byproducts and the adverse effects caused by the NGW components.

Elimination efficiency of synthetic musks during the treatment of drinking water with ozonation and UV-based advanced oxidation processes

This study investigated the reaction kinetics and elimination efficiency of eleven synthetic musks during ozonation and UV_254nm-based, advanced oxidation processes. The synthetic musks containing olefin moieties with electron-donating alkyl substituents such as octahydro tetramethyl naphthalenyl ethanone (OTNE) and ambrettolide (AMBT) showed high reactivity toward ozone (k ≥ 3.7 × 10⁵ M^-1 s^-1) and free available chlorine (FAC) (k = 9.2 - 88 M^-1 s^-1), while all other synthetic musks were less ozone reactive (k = 0.3 - 560 M^-1 s^-1) and FAC-refractory. All synthetic musks showed high ^•OH reactivity (k > 5 × 10⁹ M^-1 s^-1), except musk ketone (MK) (k = 2.3 × 10⁹ M^-1 s^-1). In concordance with the kinetic information, OTNE and AMBT were efficiently eliminated (>97%) in simulated ozone treatments of drinking water at a specific ozone dose of 0.5 gO₃/gDOC. The elimination levels of the other synthetic musks were below 50% at 0.5 gO₃/gDOC. The fluence-based UV photolysis rate constant of the synthetic musks was determined to be (0.2 - 2.7) × 10^-3 cm²/mJ. The elimination levels of synthetic musks during UV alone treatment ranged from 7 to 81% at a UV fluence of 500 mJ/cm². The addition of 10 mg/L H₂O₂ (UV/H₂O₂) significantly enhanced the elimination of most synthetic musks (achieving >90% elimination at 500 mJ/cm²), indicating that the ^•OH reaction was mainly responsible for their elimination. The addition of 10 mg/L FAC (UV/FAC) also significantly enhanced the elimination of olefinic and aromatic synthetic musks (>90%), for which the reaction with ClO^• was mainly responsible. For MK and two alkyl synthetic musks, their elimination during UV/FAC treatment was still limited (28 - 64%) and was mainly achieved by UV photolysis or reaction with ^•OH. In summary, this study substantiates the chemical kinetics approach as a helpful tool for predicting or interpreting the elimination of micropollutants during oxidative water treatment.

Impact of water matrices on oxidation effects and mechanisms of pharmaceuticals by ultraviolet-based advanced oxidation technologies: A review

The binding between water components (dissolved organic matters, anions and cations) and pharmaceuticals influences the migration and transformation of pollutants. Herein, the impact of water matrices on drug degradation, as well as the electrical energy demands during UV, UV/catalysts, UV/O₃, UV/H₂O₂-based, UV/persulfate and UV/chlorine processes were systemically evaluated. The enhancement effects of water constituents are due to the powerful reactive species formation, the recombination reduction of electrons and holes of catalyst and the catalyst regeneration; the inhibition results from the light attenuation, quenching effects of the excited states of target pollutants and reactive species, the stable complexations generation and the catalyst deactivation. The transformation pathways of the same pollutant in various AOPs have high similarities. At the same time, each oxidant also can act as a special nucleophile or electrophile, depending on the functional groups of the target compound. The electrical energy per order (EEO) of drugs degradation may follow the order of EEO_UV > EEO_UV/catalyst > EEO_UV/H2O2 > EEO_UV/PS > EEO_UV/chlorine or EEO_UV/O3. Meanwhile, it is crucial to balance the cost-benefit assessment and toxic by-products formation, and the comparison of the contaminant degradation pathways and productions in the presence of different water matrices is still lacking.

Hybridizing electron-mediated H5PMo10V2O40 with CdS/g-C3N4 for efficient photocatalytic performance of Z-scheme heterojunction in wastewater treatment

Photocatalytic technology has been considered as a promising method to alleviate environmental pollution owing to the dual characteristics of redox. The novel V-based H₅PMo₁₀V₂O₄₀ (HPA-2) photocatalyst with Z-scheme heterostructure was constructed. The energy level of HPA-2 matches well with CdS and g-C₃N₄ (CN) according to Mott-Schottky and UV-Vis diffused reflectance tests, which allows the efficient separation of photogenerated electrons. The optimized CdS/HPA-2/CN showed superior ability in Rhodamine B (RhB) degradation and reduction of Cr (Ⅵ) under visible light irradiation. The maximum rate constant reached 0.092 min^-1 for RhB degradation at 60 min and 0.260 min^-1 for Cr (Ⅵ) reduction at 20 min, respectively. The photocatalytic mechanism was analyzed by adding scavengers. The effect of active species for RhB degradation was determined as h⁺ > ·O₂^- > ·OH, while ·O₂^- and e^- were essential for the reduction of Cr (Ⅵ). Besides, cyclic tests exhibit excellent repeatability and stable structure of CdS/HPA-2/CN after four cycles. Meanwhile, the detailed degradation process of RhB involving de-ethylation, hydroxylation, substitution and decarboxylation was determined according to LC-MS and evaluated by Fukui function calculation. Furthermore, total organic carbon content decreased to 6.2% of the initial value. In this work, as an electron mediator, HPA-2 provides the inspiration for construction of Z-scheme heterojunction, and CdS/HPA-2/CN exhibits enormous potential in the environmental remediation by photocatalysis.

Metal-free graphene-based catalytic membranes for persulfate activation toward organic pollutant removal: a review

Owing to their ultrathin two-dimensional structure and efficient catalytic ability for persulfate activation, graphene-based nanocarbons exhibit considerable application potential in fabricating carbonaceous composite membranes for in situ catalytic oxidation to remove organic pollutants. This approach offers significant advantages over conventional batch systems. However, the relationships between the physicochemical properties of carbon mats and performance of graphene-based catalytic membranes in water purification remain ambiguous. Herein, we summarize the main mechanisms of in situ catalytic oxidation and the facile fabrication strategies of carbonaceous composite membranes. Different factors influencing the performance of graphene-based catalytic membranes are comprehensively discussed. The defective level, heteroatom doping, and stacking morphology of carbon mats and operational conditions during filtration play critical roles in the oxidative degradation of target pollutants. Long-term operation leads to the deterioration of catalytic activity and transmembrane pressure, especially in the complex water matrix. Finally, the present challenges and future perspectives are presented to improve the anti-fouling performance and catalytic stability of membranes and develop scalable fabrication methods to promote the engineering applications of in situ catalytic oxidation in real water purification.

Evaluation of a liquid-phase plasma discharge process for ammonia oxidation in wastewater: Process optimization and kinetic modeling

Removing ammonia-nitrogen (NH₃N) from wastewater is of paramount importance for wastewater treatment. In this study, a novel continuous liquid plasma process (CLPD) was evaluated to remove NH₃N from synthetic wastewater. The Box-Behnken experimental design was used to optimize the main process parameters, including the initial NH₃N concentration (50-200 mg/L), power input (150-300 W), and gas-flow rate (1.5-2.5 L/min), for efficient NH₃N removal from wastewater. The gas-flow rate and power input were found to be significant factors affecting the removal efficiency of NH₃N, whereas the initial concentration of NH₃N played a vital role in determining the energy efficiency of the process. Under the optimal conditions of an initial NH₃N concentration of 200 mg/L, applied power of 223 W, and gas-flow rate of 2.4 L/min, 98.91% of NH₃N could be removed with a N₂ selectivity of 92.91%, and the corresponding energy efficiency was 0.527 g/kWh after 2 hrs of treatment. A small fraction of undesirable NO₃^--N (7.05 mg/L) and NO₂^--N (2.83 mg/L) were also produced. Kinetic modeling revealed that NH₃N degradation by the CLPD followed a pseudo-first-order reaction model, with a rate constant (k) of 0.03522 min^-1. Optical emission spectroscopy (OES) was used to gather information about the active chemical species produced during the plasma discharge. The obtained spectra revealed the presence of several highly oxidative radicals, including ‧OH, ‧O, and ‧O₂⁺. These results demonstrate the potential of liquid phase plasma discharge as a highly efficient technology for removing ammonia from aqueous solutions.

Comparative study of UV/H2O2 and UV/PMS processes for treating pulp and paper wastewater

Pulp and paper wastewater (PPWW) contains numerous refractory and harmful contaminants that require advanced treatment to meet the discharge criteria. This study compared the efficacy of two PPWW treatments: ultraviolet/peroxymonosulfate (UV/PMS) and ultraviolet/H₂O₂ (UV/H₂O₂) working under similar circumstances. The initial pH value, oxidant dosage, UV radiation intensity, and pseudo-first-order constant k_obs were systematically studied in both systems. Optimally, the UV/PMS process produced an effluent of higher quality than the UV/H₂O₂, as measured by the removal efficiencies of chemical oxygen demand (COD) in 60 min, which were 48.2 and 64.3% for the respective UV/H₂O₂ and UV/PMS processes and corresponding k_obs values of 0.0102 and 0.0159 min^-1, respectively. Radical scavenging experiments demonstrated that •OH was the primary reactive oxygen species in UV/H₂O₂ process, and •OH and SO₄^-• in the UV/PMS process. Moreover, ultraviolet-visible spectroscopy and gas chromatography coupled mass spectroscopy analyses showed that deep treatment of petroleum hydrocarbons with carbon chain lengths greater than 18 and macromolecular semi-volatile organic compounds in paper wastewater is difficult, whereas the UV/PMS process can significantly improve the removal of amides, esters, phenols, and other aromatic compounds.

Nanomaterials photocatalytic activities for waste water treatment: a review

Water is necessary for the survival of life on Earth. A wide range of pollutants has contaminated water resources in the last few decades. The presence of contaminants incredibly different dyes in waste, potable, and surface water is hazardous to environmental and human health. Different types of dyes are the principal contaminants in water that need sudden attention because of their widespread domestic and industrial use. The toxic effects of these dyes and their ability to resist traditional water treatment procedures have inspired the researcher to develop an eco-friendly method that could effectively and efficiently degrade these toxic contaminants. Here, in this review, we explored the effective and economical methods of metal-based nanomaterials photocatalytic degradation for successfully removing dyes from wastewater. This study provides a tool for protecting the environment and human health. In addition, the insights into the transformation of solar energy for photocatalytic reduction of toxic metal ions and photocatalytic degradation of dyes contaminated wastewater will open a gate for water treatment research. The mechanism of photocatalytic degradation and the parameters that affect the photocatalytic activities of various photocatalysts have also been reported.

Endocrine disrupting chemicals in the environment: Environmental sources, biological effects, remediation techniques, and perspective

Endocrine disrupting chemicals (EDCs) have been identified as emerging contaminants, which poses a great threat to human health and ecosystem. Pesticides, polycyclic aromatic hydrocarbons, dioxins, brominated flame retardants, steroid hormones and alkylphenols are representative of this type of contaminant, which are closely related to daily life. Unfortunately, many wastewater treatment plants (WWTPs) do not treat EDCs as targets in the normal treatment process, resulting in EDCs entering the environment. Few studies have systematically reviewed the related content of EDCs in terms of occurrence, harm and remediation. For this reason, in this article, the sources and exposure routes of common EDCs are systematically described. The existence of EDCs in the environment is mainly related to human activities (Wastewater discharges and industrial activities). The common hazards of these EDCs are clarified based on available toxicological data. At the same time, the mechanism and effect of some mainstream EDCs remediation technologies (such as adsorption, advanced oxidation, membrane bioreactor, constructed wetland, etc.) are separately mentioned. Moreover, our perspectives are provided for further research of EDCs.

Recent advances in aqueous virus removal technologies

The COVID-19 outbreak has triggered a massive research, but still urgent detection and treatment of this virus seems a public concern. The spread of viruses in aqueous environments underlined efficient virus treatment processes as a hot challenge. This review critically and comprehensively enables identifying and classifying advanced biochemical, membrane-based and disinfection processes for effective treatment of virus-contaminated water and wastewater. Understanding the functions of individual and combined/multi-stage processes in terms of manufacturing and economical parameters makes this contribution a different story from available review papers. Moreover, this review discusses challenges of combining biochemical, membrane and disinfection processes for synergistic treatment of viruses in order to reduce the dissemination of waterborne diseases. Certainly, the combination technologies are proactive in minimizing and restraining the outbreaks of the virus. It emphasizes the importance of health authorities to confront the outbreaks of unknown viruses in the future.

Application of visible light active photocatalysis for water contaminants: A review

Organic water pollutants are ubiquitous in the natural environment arising from domestic products as well as current and legacy industrial processes. Many of these organic water pollutants are recalcitrant and only partially degraded using conventional water and wastewater treatment processes. In recent decades, visible light active photocatalyst has gained attention as a non-conventional alternative for the removal of organic pollutants during water treatment, including industrial wastewater and drinking water treatment. This paper reviews the current state of research on the use of visible light active photocatalysts, their modified methods, efficacy, and pilot-scale applications for the degradation of organic pollutants in water supplies and waste streams. Initially, the general mechanism of the visible light active photocatalyst is evaluated, followed by an overview of the major synthesis techniques. Because few of these photocatalysts are commercialized, particular attention was given to summarizing the different types of visible light active photocatalysts developed to the pilot-scale stage for practical application and commercialization. The organic pollutant degradation ability of these visible light active photocatalysts was found to be considerable and in many cases comparable with existing and commercially available advanced oxidation processes. Finally, this review concludes with a summary of current achievements and challenges as well as possible directions for further research. PRACTITIONER POINTS: Visible light active photocatalysis is a promising advanced oxidation process (AOP) for the reduction of organic water pollutants. Various mechanisms of photocatalysis using visible light active materials are identified and discussed. Many recent photocatalysts are synthesized from renewable materials that are more sustainable for applications in the 21st century. Only a small number of pilot-scale applications exist and these are outlined in this review.

Removal of emerging organic micropollutants via modified-reverse osmosis/nanofiltration membranes: A review

Hazardous micropollutants (MPs) such as pharmaceutically active compounds (PhACs), pesticides and personal care products (PCPs) have emerged as a critical concern nowadays for acquiring clean and safe water resources. In the last few decades, innumerable water treatment methods involving biodegradation, adsorption and advanced oxidation process have been utilized for the removal of MPs. Of these methods, membrane technology has proven to be a promising technique for the removal of MPs due to its sustainability, high efficiency and cost-effectiveness. Herein, the aim of this article is to provide a comprehensive review regarding the MPs rejection mechanisms of reverse osmosis (RO) and nanofiltration (NF) membranes after incorporation of nanomaterials and also surface modification atop the PA layer. Size exclusion, adsorption and electrostatic charge interaction mechanisms play important roles in governing the MP removal rate. In addition, this review also discusses the state-of-the-art research on the surface modification of thin film composite (TFC) membrane and nanomaterials-incorporated thin film nanocomposite (TFN) membrane in enhancing MPs removal performance. It is hoped that this review can provide insights in modifying the physicochemical properties of NF and RO membranes to achieve better performance in water treatment process, particularly for the removal of emerging hazardous substances.

Recent Developments in Activated Carbon Catalysts Based on Pore Size Regulation in the Application of Catalytic Ozonation

Due to its highly developed pore structure and large specific surface area, activated carbon is often used as a catalyst or catalyst carrier in catalytic ozonation. Although the pore structure of activated carbon plays a significant role in the treatment of wastewater and the mass transfer of ozone molecules, the effect is complicated and unclear. Because different application scenarios require catalysts with different pore structures, catalysts with appropriate pore structure characteristics should be developed. In this review, we systematically summarized the current adjustment methods for the pore structure of activated carbon, including raw material, carbonization, activation, modification, and loading. Then, based on the brief introduction of the application of activated carbon in catalytic ozonation, the effects of pore structure on catalytic ozonation and mass transfer are reviewed. Furthermore, we proposed that the effect of pore structure is mainly to provide catalytic active sites, promote free radical generation, and reduce mass transfer resistance. Therefore, large external surface area and reasonable pore size distribution are conducive to catalytic ozonation and mass transfer.

Electrodeposited Fe on Cu foam as advanced fenton reagent for catalytic mineralization of methyl orange

In many countries, the textile industry remains the major contributor to environmental pollution. Untreated textile dyes discharged into water negatively impact the performance of aquatic organisms and may cause a variety of serious problems to their predators. Effective wastewater treatment is a key to reducing environmental and human health risks. In this work, the Fe/Cu catalysts were used in heterogeneous Fenton’s reaction for the degradation of high concentrations of methyl orange (model azo dye) in aqueous solutions. For the first time, the catalysts were prepared onto commercial copper foams by potentiostatic electrodeposition of iron using an environmentally friendly electrolyte. The influence of electrodeposition conditions, H₂O₂ concentration, dye concentration and temperature on the model dye degradation was investigated. It was revealed that both the surface area and the catalyst loading play the major role in the effective dye degradation. The experimental results involving spectrophotometric measurements coupled with total carbon and nitrogen quantification suggest that a solution containing up to 100 mg/L of methyl orange can be successfully decolorized within 90 s at 50°C using porous Fe/Cu catalyst in the presence of hydrogen peroxide that largely surpasses the current state-of-the-art performance. Already within the first 10°min, ∼ 30% of total methyl orange concentration is fully mineralized. The described process represents a cost-efficient and environmentally friendly way to treat azo dyes in aqueous solutions.

Evaluation of global research trends in photocatalytic degradation of dye effluents using scientometrics analysis

Photocatalysis technology is observed to be an effective approach for its outstanding performance to eliminate wide range of organic pollutants including dyes in textile effluent. Despite growing number of studies, there is no scientometric perspective addressing the research topic "photocatalytic degradation of dye effluents". In this regard, a total of 954 documents were extracted from the Web of Science (WoS) database using keywords search to cover all the published documents during the period 1996-2020. Publications in this area started to increase exponentially from year 2007. The most dominant subject categories were Engineering, Chemistry and Environmental Science & Ecology. Applied Catalysis B-Environmental and Desalination & Water Treatment were identified as the most-impactful and productive journals respectively. Authors based in India accounted for 29.6% of total publications followed by China (14.2%); but in terms of citations Spain and Italy were more influential. Based on keyword analysis, azo dyes, TiO2, nanoparticles, adsorption, methylene blue, visible light, ZnO and kinetics are the most studied, and visible light mediated photocatalysis, hybrid treatment systems, nano based photocatalysis and more recently, metal based photocatalysis, have received most attention. Studies on cost and energy analysis, recovery of value-added products, development of more efficient photocatalytic materials and new photocatalyst regeneration approaches should be considered for future research. This study therefore, provides a comprehensive understanding about the trends and patterns of the specified research field worldwide.

Photothermal Localization in an Optofluidic Microreactor for Rapid Pretreatment toward Online Pollutant Analysis

The realization of high-efficient digestion in a microfluidic reactor is considered to be advantageous for pretreatment toward online pollutant detection. However, it is difficult to achieve satisfactory device performance due to the gap between the low digestion reaction efficiency and the demand for rapid pretreatment for online detection. Herein, we design and manufacture an optofluidic microreactor combined with a MnO₂ nanofilm localizing the heat inside the reaction chamber under solar irradiation, which contributes a lot to the on-chip nutrient digestion efficiency enhancement. The overall temperature of the water sample in the reactor chamber can be dramatically increased in a fleeting time of less than 1 s and maintained at 78 °C. The digestion rate constant of the microreactor is improved by about 100 times compared with that obtained by the traditional method in the national standard, which is attributed to temperature enhancement and various oxidation reactions in the heated reaction chamber. Notably, when pretreating the actual total phosphorus water samples, the digestion efficiency is demonstrated to be higher than 95% within 12 s under solar light irradiation. The optofluidic platform brings many benefits to accelerate the various photochemically enhanced reactions using solar light and is extremely adapted for rapid pretreatment of biochemical samples to further develop their online analysis.