Dye decolorization with hybrid advanced oxidation processes comprising sonolysis/Fenton-like/photo-ferrioxalate systems: A mechanistic investigation

In situ formation of red/black phosphorus-modified SiO2@g-C3N4 multi-heterojunction for the enhanced photocatalytic degradation of organic contaminants

A new heterojunction material BP/RP-g-C₃N₄/SiO₂ was obtained by a one-step ball milling method, and its photocatalytic capacity was researched by the degradation of Rhodamine B (RhB) and ofloxacin (OFL) in simulated sunlight. The construction of an in situ BP/RP heterojunction can achieve perfect interface contact between different semiconductors and effectively promote the separation of photogenerated carriers. The composite material was well characterized, which proved that the multi-heterogeneous structure was prepared. Furthermore, the type II heterojunction was formed between the g-C₃N₄ and BP/RP interface, playing an important role in the degradation and promoting electron transfer. The degradation effect of BP/RP-g-C₃N₄/SiO₂ on RhB reached 90% after 26 min of simulated solar irradiation, which was 1.8 times that of g-C₃N₄/SiO₂. The degradation of OFL by BP/RP-g-C₃N₄/SiO₂ reached 85.3% after illumination for 50 min, while the degradation of g-C₃N₄/SiO₂ was only 35.4%. The mechanisms were further discussed, and ˙O₂ ^- and h⁺ were found to be the main active substances to degrade RhB. The catalyst also revealed distinguished stability of catalyst and recyclability, and the degradation effect of RhB can still realize 85% after 4 runs of experiment. Thus, this study provided a novel method for the design and preparation of multi-heterojunction catalysts in the removal of organic pollutants from wastewater.

Synthesis of bismuth oxyhalide (BiOBrzI(1-z)) solid solutions for photodegradation of methylene blue dye

Background: The removal of textile wastes is a priority due to their mutagenic and carcinogenic properties.  In this study, bismuth oxyhalide was used in the removal of methylene blue (MB) which is a textile waste. The main objective of this study was to develop and investigate the applicability of a bismuth oxyhalide (BiOBr _zI _(1-z)) solid solutions in the photodegradation of MB under solar and ultraviolet (UV) light irradiation.

Methods: Bismuth oxyhalide (BiOBr _zI _(1-z)) (0 ≤ z ≤ 1) materials were successfully prepared through the hydrothermal method. Brunauer-Emmett-Teller (BET), transmission electron microscope (TEM), X-ray diffractometer (XRD), and scanning electron microscope (SEM) were used to determine the surface area, microstructure, crystal structure, and morphology of the resultant products. The photocatalytic performance of BiOBr _zI _(1-z) materials was examined through methylene blue (MB) degradation under UV light and solar irradiation.

Results: The XRD showed that BiOBr _zI _(1-z) materials crystallized into a tetragonal crystal structure with (102) peak slightly shifting to lower diffraction angle with an increase in the amount of iodide (I ^-). BiOBr _0.6I _0.4 materials showed a point of zero charge of 5.29 and presented the highest photocatalytic activity in the removal of MB with 99% and 88% efficiency under solar and UV irradiation, respectively. The kinetics studies of MB removal by BiOBr _zI _(1-z) materials showed that the degradation process followed nonlinear pseudo-first-order model indicating that the removal of MB depends on the population of the adsorption sites. Trapping experiments confirmed that photogenerated holes (h ⁺) and superoxide radicals ( ^•O ₂⁻) are the key species responsible for the degradation of MB.

Conclusions: This study shows that bismuth oxyhalide materials are very active in the degradation of methylene blue dye using sunlight and thus they have great potential in safeguarding public health and the environment from the dye’s degradation standpoint. Moreover, the experimental results agree with nonlinear fitting.

Prediction of degradability of micropollutants by sonolysis in water with QSPR - a case study on phenol derivates

The increasing quantity and variety of organic contaminants discharged into surface and groundwater increase the necessity of additional and suitable water treatment methods, which can be incorporated into existing wastewater treatment plants. The huge variety of micropollutants and local variability of the composition of the organic load or matrix effects paired with multiple possible degradation processes lead to the requirement of a recommendation tool for the best possible water treatment method under given local conditions. Due to the diversity of physicochemical properties of micropollutants, such predictions are challenging. In this study, a quantitative correlation between the structural properties of certain micropollutants and their degradability using high-frequency sonolysis has been investigated. Therefore, Quantitative Structure-Property Relationship (QSPR) has been applied on a set of phenol derivates. To obtain the kinetic data, all experiments have been conducted in standardized, constant conditions for all 32 investigated phenol derivates. QSPR modelling was then executed using the software PaDEL for descriptor calculation and the software QSARINS for the overall modelling process including genetic algorithm (GA) and multiple linear regression (MLR). The final model consisting of 5 molecular descriptors was selected using a multi-criteria decision-making method based on extensive statistical parameters. The predictive power and robustness of the model was evaluated by means of internal cross validation and external validation using an independent validation set. The final selected model showed very good values for regression abilities, predictive power as well as stability (R²_adj = 0.9455, CCC_tr = 0.9777, Q²_loo = 0.9285, CCC_ext = 0.9797 and Q²_ext-F1 = 0.9711). The applicability domain of the QSPR model was defined based on the Williams plot and Insubria plot. The five OECD principles for the application of QSPR/QSAR modelling in industry and regulation were fulfilled in the whole process to the best of our knowledge, including the collection of the underlying experimental data as well as the entire modelling process. The final QSPR model included the molecular polarity and occurrence of hydrogen bonds as major influences on the reaction rate constants in accordance with previous studies. Nevertheless, potential biases in the selection of these descriptors due to the small size of the dataset were highlighted.

Synthesis of bismuth oxyhalide (BiOBr zI (1- z)) solid solutions for photodegradation of methylene dye

Background: The removal of textile wastes is a priority due to their mutagenic and carcinogenic properties.  In this study, bismuth oxyhalide was used in the removal of methylene blue (MB) which is a textile waste. The main objective of this study was to develop and investigate the applicability of a bismuth oxyhalide (BiOBr _zI _(1-z)) solid solutions in the photodegradation of MB under solar and ultraviolet (UV) light irradiation. Methods: Bismuth oxyhalide (BiOBr _zI _(1-z)) (0 ≤ z ≤ 1) materials were successfully prepared through the hydrothermal method. Brunauer-Emmett-Teller (BET), transmission electron microscope (TEM), X-ray diffractometer (XRD), and scanning electron microscope (SEM) were used to determine the surface area, microstructure, crystal structure, and morphology of the resultant products. The photocatalytic performance of BiOBr _zI _(1-z) materials was examined through methylene blue (MB) degradation under UV light and solar irradiation. Results: The XRD showed that BiOBr _zI _(1-z) materials crystallized into a tetragonal crystal structure with (102) peak slightly shifting to lower diffraction angle with an increase in the amount of iodide (I ^-). BiOBr _0.6I _0.4 materials showed a point of zero charge of 5.29 and presented the highest photocatalytic activity in the removal of MB with 99% and 88% efficiency under solar and UV irradiation, respectively. The kinetics studies of MB removal by BiOBr _zI _(1-z) materials showed that the degradation process followed nonlinear pseudo-first-order model indicating that the removal of MB depends on the population of the adsorption sites. Trapping experiments confirmed that photogenerated holes (h ⁺) and superoxide radicals ( ^•O ₂ ^-) are the key species responsible for the degradation of MB. Conclusions : This study shows that bismuth oxyhalide materials are very active in the degradation of methylene blue dye using sunlight and thus they have great potential in safeguarding public health and the environment from the dye's degradation standpoint. Moreover, the experimental results agree with nonlinear fitting.

A critical analysis of sono-hybrid advanced oxidation process of ferrioxalate system for degradation of recalcitrant pollutants

The emerging contaminants in wastewater discharged from numerous chemical process industries, pharmaceutical industries, textile, and wineries have attracted the attention of the scientific community due to their toxicity and persistence in the environment. The conventional techniques are incompetent to treat many of such recalcitrant toxic pollutants. To achieve high mineralization, advanced oxidation processes (AOPs) are found to be more efficient for the degradation of these organic pollutants without producing secondary pollutants with no/less amount of sludge. The primary oxidation agents for AOPs are in-situ generated free radicals, which are highly reactive and effective oxidants for degrading any type of organic molecules present in the wastewater. In the past decades, the combination of AOPs or simultaneous application of more than one AOP has been investigated extensively for wastewater treatment and these hybrid-AOPs have been reported to be beneficial for high-level mineralization of organic pollutants. This paper presented the characteristics, properties and influence of parameters in sono-photo-ferrioxalate system. The primary operating parameters in sono-photo-ferrioxalate system that affect the kinetics are defined as the solution pH, temperature, molar ratio of Fe³⁺/C₂O₄^2-, H₂O₂ concentration, source of light, ultrasound intensity, dissolved gases, and size of cavitation bubble. In this process, several oxidizing radicals are generated such as HO^•, HO₂^•, C₂O₄^•-, CO₂^•- and O₂^•- which are also responsible for degradation. In this review, we have mainly addressed the degradation of recalcitrant pollutants using the sono-photo-ferrioxalate system and a critical analysis of process parameters that influence mineralization efficiency.

Experimental and theoretical study of deep oxidative desulfurization of Dibenzothiophene using Oxalate-Based catalyst

The present study reports the experimental and theoretical investigation for production of ultra-low sulfur liquid fuels through estimation of various reactive species formed during the reaction with the help of simulation. All the experiments were performed using an ultrasound bath which operates at a frequency of 37 kHz and a theoretical power of 95 W. The presented oxalate-based technique is found to be more efficient with > 93% DBT oxidation within 15 min of reaction time at 25 °C due to formation of reactive species like Fe^IIC₂O₄ and [Formula: see text] which accelerate the reaction kinetics. Moreover, we have also investigated the influence of process parameters such as molar ratio of C₂O₄^2-/Fe^{2 +}, oxidant concentration, volume ratio of organic to aqueous phase, sulfur concentration, and activation methods of oxidant. The results revealed that catalyst can be reused for several runs without decrease in catalytic activity. The experimental and simulation of cavitation bubble dynamics results revealed that sonochemical effect assists to accelerate the reaction kinetics through formation of free radicals (^•O, ^•H, ^•OH and HO₂^∙) and other reactive species like O₃ and H₂O₂ generated during transient cavitation. The sono-physical effects of cavitation help to create a fine emulsion in the liquid-liquid heterogeneous system leading to enhanced mass transfer rate by providing more interfacial surface area for occurring chemical reaction.

Sonochemical synthesis of amphoteric Cu0-Nanoparticles using Hibiscus rosa-sinensis extract and their applications for degradation of 5-fluorouracil and lovastatin drugs

Recent studies reported the detection of numerous emerging and active pharmaceutical constituents in the ground and surface water. To address these issues, the present study reported the ultrasound-assisted synthesis of zero-valent copper (Cu⁰) nanoparticles using Hibiscus rosa-sinensis extract as reducing and stabilizing agent. The catalyst was characterized using XRD, SEM, EDX, PSA, BET, etc., and the results revealed that sonochemical synthesis technique influenced the crystallinity with controlled growth of Cu⁰. While the hard ligand hydroxyl group (-OH) reduces the Cu²⁺ to Cu⁰ and soft ligand carbonyl group (CO) present in the oxidized polyphenols helps in capping and stabilizing the Cu⁰-nanoparticles. During the ultrasound application, continuous release of Cu⁺ from Cu⁰ promoted the degradation by producing OH and O₂^•- radicals. Approx. 91.3 % and 93.2 % degradation efficiencies were achieved for 5-fluorouracil and lovastatin. The results showed that Cu⁰ nanoparticles were amphoteric in nature and the synergy calculation revealed that ultrasound has a direct influence on degradation of drugs which are difficult to degrade/mineralize using conventional techniques. Based on the results, a possible degradation mechanism of drug molecules in the presence of oxidants, zero-valent copper and ultrasound has been proposed.

Mechanistic insight into ultrasound-induced enhancement of electrochemical oxidation of ofloxacin: Multi-response optimization and cost analysis

In this paper, a hybrid advanced oxidation process of sonoelectrochemical, in which ultrasound and electrochemical are applied simultaneously, has been used for the degradation of ofloxacin (bio-recalcitrant pharmaceutical pollutant). Response surface methodology based central composite design was applied to understand the parametric effects of ultrasonic power, current density, initial pH, and electrolyte dose. Enhanced ofloxacin degradation was obtained using sonoelectrochemical (≈95%) process in comparison to the electrochemical (≈60.6%) and sonolysis alone (≈7.2%) after 120 min treatment time. Multi-response optimization was used so as to maximize COD removal (70.12%) and minimize specific energy consumption (11.92 kWh (g COD removed)^-1)at the optimized parametric condition of pH = 6.3 (natural pH), ultrasonic power = 54 W, current density = 213 A m^-2, and Na₂SO₄ electrolyte dose = 2.0 g L^-1. It was revealed that ^•OH radicals contribute major to the ofloxacin degradation reaction among the other oxidizing agents. Degradation of the ofloxacin followed pseudo-first-order kinetics with a higher reaction rate, which confirmed the synergistic effect of 34% between ultrasound and electrochemical approaches. The degradation pathway of ofloxacin removal was elucidated at optimum condition by the temporal evolution of the intermediate compounds and final products using gas chromatography coupled with mass spectroscopy (GC-MS), liquid chromatography-mass spectroscopy (LC-MS), high-resolution mass spectroscopy (HR-MS), and Fourier transform infrared spectroscopy (FTIR). Atomic force microscopy (AFM) and field emission scanning electron microscope (FE-SEM) coupled with energy dispersed X-ray (EDX) were used to determine the morphology of electrodes. Operational cost analysis was done based on the reactor employed in the present study.

Feasibility of industrial-scale treatment of dye wastewater via bio-adsorption technology

This review emphasizes the importance of costs in industrial-scale treatment of dye wastewater and provides a way to assess the cost-based feasibility of bio-adsorption technologies. Dye wastewater is one of the major contributors to environmental pollution. Bio-adsorption has attracted considerable attentions in dye wastewater treatment due to its technical feasibility, flexibility and operation simplicity. However, industrial-scale treatment of dye wastewater via bio-adsorption technologies remains stagnant, mainly due to high costs. So far, no review or research articles have systematically discussed the criteria for successful utilization of bio-adsorption technologies on a large scale. This review discusses the major factors affecting adsorption and desorption performance based on basic chemical and physical structures of bio-adsorbents available in literatures. A quantitative relationship has been summarized based on previous studies to assess the cost to utilize a bio-adsorption technology and serve as an access threshold for quality bio-adsorbents to be taken into real applications.

Photocatalytic and Photo-Fenton Catalytic Degradation Activities of Z-Scheme Ag₂S/BiFeO₃ Heterojunction Composites under Visible-Light Irradiation

Z-scheme Ag₂S/BiFeO₃ heterojunction composites were successfully prepared through a precipitation method. The morphology and microstructure characterization demonstrate that Ag₂S nanoparticles (30⁻50 nm) are well-decorated on the surfaces of polyhedral BiFeO₃ particles (500⁻800 nm) to form Ag₂S/BiFeO₃ heterojunctions. The photocatalytic and photo-Fenton catalytic activities of the as-derived Ag₂S/BiFeO₃ heterojunction composites were evaluated by the degradation of methyl orange (MO) under visible-light irradiation. The photocatalytic result indicates that the Ag₂S/BiFeO₃ composites exhibit much improved photocatalytic activities when compared with bare Ag₂S and BiFeO₃. The optimum composite sample was observed to be 15% Ag₂S/BiFeO₃ with an Ag₂S mass fraction of 15%. Furthermore, the addition of H₂O₂ can further enhance the dye degradation efficiency, which is due to the synergistic effects of photo- and Fenton catalysis. The results of photoelectrochemical and photoluminescence measurements suggest a greater separation of the photoexcited electron/hole pairs in the Ag₂S/BiFeO₃ composites. According to the active species trapping experiments, the photocatalytic and photo-Fenton catalytic mechanisms of the Ag₂S/BiFeO₃ composites were proposed and discussed.

Mechanistic investigation in degradation mechanism of 5-Fluorouracil using graphitic carbon nitride

The present study reports the synthesis of metal-free polymeric catalyst, graphitic carbon nitride (g-C₃N₄), through sonochemical method followed by thermal treatment. The synthesized g-C₃N₄ was characterized using XRD, DRS, FESEM, TGA, EDX, etc. and the characterization results revealed that it possesses medium band-gap energy, high thermal and chemical stability. The photo-activity of the catalyst was also evaluated using degradation of 5-Fluorouracil under different experimental conditions. The results revealed that the addition of H₂O₂ during sonolysis process did not show any significant synergy. This is attributed to the low vapor pressure of H₂O₂ that does not allow it to diffuse into the cavitation bubble to produce OH radicals through sonolysis process. Using sono-hybrid process, more than 90% degradation was seen within 5 min of treatment with a rate constant of 3.95 × 10^-2 s^-1. In alkaline medium, 5-Fluorouracil degradation occurred through defluorination and subsequently substitution of -OH group to the aromatic ring leading to formation of intermediates such as 2-fluoro-3-oxopropanoic acid and urea. While sono-hybrid advanced oxidation processes (AOPs) helped towards complete mineralization through formation of smaller molecular compounds such as maleic acids, lactic acids, propanol, etc. On the other hand, the maximum synergy effect of ∼2.4 was seen for sonocatalysis process followed by hybrid-AOPs of (US + g-C₃N₄ + H₂O₂ + UVC) with a synergy factor of ∼2.2. Also, the synthesized catalyst exhibited the same catalytic activity even after 5 runs of sono-photocatalysis process for degradation of 5-Fluorouracil.

Wastewater cleanup using Phlebia acerina fungi: An insight into mycoremediation

The scarcity of available drinking water has led the researchers to develop novel and cost-effective ways of bioremediation process for wastewater treatment. Bioremediation is a cost-effective and environmentally sound method for the removal of toxic compounds. Such approach is not only a chemical-less effort but also an energy savior. In the present work Phlebia acerina, a white rot wood rotting fungi have been used to degrade the toxic wastewater pollutants. Congo Red (CR) and Eriochrome Black T (EBT) have been selected as model pollutants to test the wastewater cleaning ability of the fungus. The Lignin modifying enzyme (LME) and Cellulolytic enzyme assays (CMC) potential of Phlebia acerina helped in understanding the dye degradation mechanism. Under the optimum conditions, the fungi was able to degrade as high as 92.4% CR while the EBT was degraded to a maximum of 50%. Phlebia acerina was found to show first-order kinetics of dyes degradation. Further, the seed germination and antimicrobial assay of treated and untreated water were carried out in order to establish the formation of non-toxic end product after degradation.

Degradation of organic pollutants by photoelectro-peroxone/ZVI process: Synergistic, kinetic and feasibility studies

In this study a novel hybrid process was employed for the degradation of Metanil Yellow (MY). The operational parameters of photoelectro-peroxone/zero valent iron (PEP/ZVI) process were studied and the complete decoloration was found at pH = 3.0, 100 mg/L ZVI, 33.2 mg/L ozone, 300 mA applied current and 25 min reaction time. The combination of UV, ozone, electrogenerated H₂O₂ and ZVI showed high synergistic effect for MY degradation. ZVI showed high reusability in PEP/ZVI process. Among anions, nitrite ion demonstrated high inhibitory effect while chloride ions had no significant effect on MY degradation. Scavenging tests depicted that hydroxyl radical and singlet oxygen were the main agents of MY degradation. PEP/ZVI process was tested for several emerging pollutants (benzotriazole, 4-chlorophenol, carmoisine and tetracycline); the results presented the effectiveness of the process for the degradation of pollutants in a way that complete degradation occurred at only 30 min. Moreover, the performance of PEP/ZVI was examined for the treatment of two actual wastewaters. PEP/ZVI demonstrated an excellent function in terms of the removal of organic compounds to achieve discharging standards.

Novel magnetically separable Fe3O4–WSe2/NG photocatalysts: synthesis and photocatalytic performance under visible-light irradiation

Visible light responsive Fe₃O₄–WSe₂/NG (nitrogen doped graphene oxide) heterojunction nanocomposites were synthesized by a hydrothermal synthesis route, in which Fe₃O₄ and WSe₂ particles were coated on the surface of NG.

Photo-Fenton and Fenton-like processes for the treatment of the antineoplastic drug 5-fluorouracil under simulated solar radiation

In the present study, photo-Fenton and Fenton-like processes were investigated for the degradation and mineralization of the antineoplastic drug 5-fluorouracil (5-FU). For the optimization of photo-Fenton treatment under simulated solar light (SSL) radiation, the effects of several operating parameters (i.e., 5-FU concentration, Fe³⁺, and oxidant concentration) on the treatment efficiency were studied. According to the results, SSL/[Fe(C₂Ο₄)₃]^3-/Η₂Ο₂ process was the most efficient, since faster degradation of 5-FU and higher mineralization percentages were achieved. All the applied processes followed quite similar transformation routes which include defluorination-hydroxylation as well as pyrimidine ring opening, as demonstrated by the transformation products identified by high resolution mass spectrometry analysis. The toxicity of the treated solutions was evaluated using the Microtox assay. In general, low toxicity was recorded for the initial solution and the solution at the end of the photocatalytic treatment, while an increase in the overall toxicity was observed only at the first stages of SSL/Fe³⁺/Η₂Ο₂ and SSL/Fe³⁺/S₂O₈^2- processes.

Production of pyrite nanoparticles using high energy planetary ball milling for sonocatalytic degradation of sulfasalazine

Sonocatalytic performance of pyrite nanoparticles was evaluated by the degradation of sulfasalazine (SSZ). Pyrite nanoparticles were produced via a high energy mechanical ball milling (MBM) in different processing time from 2h to 6h, in the constant milling speed of 320rpm. X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FT-IR) analysis and Brunauer-Emmett-Teller (BET) confirmed the production of pyrite nanoparticles during 6h of ball milling with the average size distribution of 20-80nm. The effects of various operational parameters including pH value, catalyst amount (mg/L), SSZ concentration (mg/L), ultrasonic frequency (kHz) and reaction time on the SSZ removal efficiency were examined. The obtained results showed that the maximum removal efficiency of 97.00% was obtained at pH value of 4, catalyst dosage of 0.5g/L, SSZ concentration of 10mg/L and reaction time of 30min. Experimental results demonstrated that the kinetic of the degradation process can be demonstrated using Langmuir-Hinshelwood (L-H) kinetic model. The effect of different inorganic ions such as Cl^-, CO₃^2- and SO₄^2- was investigated on the L-H reaction rate (k_r) and adsorption (K_s) constants. Results showed that the presence of the mentioned ions significantly influenced the L-H constants. The impact of ethanol as a OH radical scavenger and some enhancers including H₂O₂ and K₂S₂O₈ was investigated on the SSZ removal efficiency. Accordingly, the presence of ethanol suppressed SSZ degradation due to the quenching of OH radicals and the addition of K₂S₂O₈ and H₂O₂ increased the SSZ removal efficiency, due to the formation of SO₄^- and additional OH radicals, respectively. Under the identical conditions of operating parameters, pyrite nanoparticles maintained their catalytic activity during four consecutive runs.

Polymer-grafted magnetic microspheres for enhanced removal of methylene blue from aqueous solutions

Chitosan/magnetite composite microspheres were grafted with polymer by graft polymerization of 2-acrylamido-2-methylpropane sulfonic acid and acrylic acid onto their surface and then applied for the removal of methylene blue from aqueous solutions.

The mechanism study of efficient degradation of hydrophobic nonylphenol in solution by a chemical-free technology of sonophotolysis

Nonylphenol is a hydrophobic endocrine disrupting compound, which can inhibit the growth of sewage bacteria in biological processes. This study investigated the degradation of 4-n-nonylphenol (NP) in water by a chemical-free technology of sonophotolysis with emphasis on the impacts of several important parameters, including light intensity, solution pH, two commonly seen inorganic ions (i.e. NO3(-) and HCO3(-)), and principally on the examination of degradation mechanisms. It was found that, solution pH could significantly influence both NP degradation efficiency and the synergistic effect of sonophotolytic process, where higher synergistic effect was obtained at more acidic condition. In addition, the presence of NO3(-) accelerated NP degradation by both acting as a photosensitizer and providing NO2˙ radicals, while HCO3(-) had little effect on NP degradation. Identification of intermediates of NP degradation indicated that NP sonophotolysis was mainly initiated by the formation of hydroxy-NP, and a new intermediate di-hydroxy-NP was identified for the first time ever in this study. Through thermodynamic analysis, results indicated that both ortho- and meta-hydroxy-NP species can coexist in the solution but the ortho-4-NBZQ (4-nonyl-benzoquinone) is dominant. In addition, the mechanism of ortho-hydroxy-NP formation was suggested by the addition of HO˙ and H˙ radicals.

Development of an advanced chemical oxidation wastewater treatment system for the batik industry in Malaysia

Symmetric representation of the Fenton oxidation batch system for the treatment of highly recalcitrant batik wastewater.