Reagent Dosage Research Articles

Analysis of the Interrelationship between Water Color and Coagulant Dose and the Possibility of Taking it into Account in Mathematical Modeling

The character of water chromaticity change in a water source, which is the main one for organizing water supply of a large urban agglomeration, is analyzed. It is shown that the correlation analysis characterizes the interrelationship between the coagulant dose and water chromaticity as noticeable (on the Cheddock scale), which predetermines the necessity to take into account water chromaticity as a parameter influencing the choice of coagulant dose. Variation series were constructed, empirical and theoretical functions of water chromaticity distribution by months were obtained. The possibility of modeling the reagent dose on the change of chromaticity taking into account specific conditions of practically constant influence of seasonal and random factors in the selected periods has been achieved. It is concluded that the chromaticity index makes a significant contribution to the value of the predicted value of coagulant dose.

Influence of surface oxidation rate on the flotation of sphalerite and galena inhibited by gum arabic

Differences in the flotation behavior of galena and sphalerite using potassium permanganate (KMnO4) and gum arabic (GA) alone and using a mixture of KMnO4 and GA were investigated. The single mineral flotation tests revealed that when KMnO4 and GA were used individually, galena and sphalerite flotation were inhibited, but the reagent dosages required were large. Sphalerite was strongly inhibited by the addition of a tiny amount of GA after oxidation with KMnO4 while galena was not inhibited under the same conditions. Following oxidation by KMnO4, galena and sphalerite exhibited a significant 83 % difference in flotation recovery when 10 mg/L GA was used, which clearly showed the potential for the combined use of KMnO4 and GA to achieve flotation separation of galena from mixed lead-zinc ores. The inhibitory effect of GA on sphalerite was investigated through a combination of analytical techniques, including Microcalorimetry, Fourier Transform Infrared (FTIR) Spectroscopy, contact angle measurements, X-ray Photoelectron Spectroscopy (XPS), and Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray (EDS) analysis. The results displayed that sphalerite had a much higher oxidation rate than galena, resulting in more oxides and hydroxides. As a result, the sphalerite surface exhibits an increased availability of active sites favorable to GA adsorption, thereby impeding Butyl xanthate (PBX) adsorption. However, the galena surface was able to absorb PBX, resulting in mineral separation.

Fluorescence sensor enabled control of contaminants of emerging concern in reclaimed wastewater using ozone-based treatment processes

Contaminants of emerging concern (CEC) pose significant challenges to environmental and human health. The development of the wastewater reuse sector, coupled with progressively stringent regulations, needs innovative systems that integrate advanced treatment processes with in-situ and real-time monitoring of CEC. This study investigates the use of a tryptophan-like fluorescence sensor for real-time and online monitoring of CEC within a pilot plant employing O3-based advanced oxidation processes (AOPs). Two tertiary wastewater effluents (WW-1 and WW-2) were tested, placing the pilot system downstream of two different wastewater treatment plants (WWTPs). Priority substances and micropollutants detected in the investigated water matrixes such as pharmaceuticals, per- and polyfluoroalkyl substances (PFAS) were selected as targeted compounds in this study. Fluorescence degradation was detected in real-time by the sensor, showing a high capability to detect fast changes in water quality induced by oxidation. Furthermore, the real-time fluorescence showed better sensitivity than lab-scale fluorescence in detecting the fast action of hydroxyl radicals (·OH) during the O3/H2O2 process, highlighting the importance of online monitoring. Selected CEC were degraded by AOPs with different percentages of removal efficiency (RE) (0%<RE<100% in WW-1 and 15%<RE<90% in WW-2) depending on oxidant doses and the reactivity of compounds with O3 and ·OH. Fluorescence data by online sensor enabled accurate prediction of the removal of a wide spectrum of CEC during O3 and O3/H2O2 processes (R2≥0.93). Furthermore, real-time fluorescence data were successfully used to predict observed pseudo-first-order rate constants of CEC with O3 or O3/H2O2. Obtained results suggest that real-time fluorescence monitoring is an excellent tool to control CEC removal during O3-based AOPs and monitor the transferred ozone in wastewater (R2≥0.94), contributing to the optimization of reagent dose, energy and costs.

Synergistic enhancement of dewatering of montmorillonite-containing coal slime by novel combined filter aid: an experimental and simulation study

ABSTRACT The efficient dewatering of montmorillonite (Mt)-containing coal slime is still an urgent problem to be solved in coal preparation plant. In this study, the dewatering effect of poly(o-phenylenediamine)/Poly dimethyl diallyl ammonium chloride (POPD/PDADMAC) combined filter aid on Mt-containing coal slime was studied. The dewatering performance of combined filter aid was investigated by vacuum filtration test. The action mechanism of combined filter aid was revealed by contact angle, zeta potential, cake pore and atomic force microscope (AFM). The co-adsorption principle of the combined filter aid was elucidated based on density functional theory (DFT) and molecular dynamics simulation (MD). Compared to PDADMAC, the combined filter aid has better performance for dewatering of Mt-containing coal slime, and has the advantage of low reagent dosage. The combined filter aid can greatly reduce the Mt potential, increase the Mt contact angle, and increase the porosity of the filter cake. There was a co-adsorption effect between the combined filter aid. Specifically, there were ion–dipole interaction, cation–π interaction and Cl ions bridged electrostatic interaction between POPD and PDADMAC. This study has developed a novel combined filter aid, which provides theoretical and technical support for the high-efficiency pressure filtration dewatering of Mt-containing coal slime in coal preparation plants.

Preparation, characteristics and antioxidant activity of mung bean peel polysaccharides

The mung bean peel polysaccharide (MBP) extracted by hot water was chemically modified. By changing the dosage of phosphorylation reagent and acetylation reagent, three kinds of phosphorylated MBP ( P-MBP-1, P-MBP-2, P-MBP-3 ) and acetylated MBP ( AC 0.6-MBP, AC 1-MBP, AC 1.4-MBP ) with different degrees of substitution were prepared. By measuring the sugar content and substitution degree of the modified products, it was found that the amount of reagent had a certain effect on both of them. The modified products were determined by infrared spectrum and nuclear magnetic resonance. The results showed that the chemical modification was successful. The in vitro antioxidant capacity (·OH scavenging ability, O2−·clearing ability, reducing capacity, resistance to lipid peroxidation) of seven polysaccharide were measured, which manifested that chemical modification could enhance the antioxidant ability of MBP to varying degrees, and the DS also had a certain impact on their antioxidant activity. This promoted the development of mung bean peel polysaccharide functional products and the utilization of mung bean peel resources.

Influence of the Use of Ammonium Sulfate and Citric Acid on the Buoyancy of Minerals in Copper-cobalt Plant Process (Case of 635 Deposit Fed at Kambove

The objective pursued in this work is testing the performance of two new reagents namely ammonium sulfate and citric acid, on buoyancy of Kamfundwa ore currently treated at Kambove Concentrator. Optimization tests were conducted in order to determine the optimal doses of reagents commonly used, in this case Sodium hydrosulfide (NaSH), the amylxanthate potassium (KAX), Sodium silicate (Na2SiO3), and the mixture fuel-fatty acid. Metallurgical results obtained with these tests were used as reference for further work. Tests with citric acid alone could not improve the metallurgical results obtained under standard conditions, the same finding was observed in tests with ammonium sulfate alone and that performance seemed to be much closer to those of reference tests. We finally realized flotation tests by combining citric acid and ammonium sulfate in order to streamline the synergy of these two reagents. It appears from these tests that at the dose of 600 g / t of citric acid and 400 g / t of ammonium sulfate, metallurgical performance obtained are better than previously. The following results were achieved during the batch flotation tests: 18.87% as copper content of the head concentrate, with a recovery rate of 55.34%, and 10.81% as copper content of the global concentrate; for a copper recovery corresponding to 80.94%. This mixture of citric acid and ammonium sulfate has allowed good selectivity and a reduction of gangue trained to the concentrate.

The application and adsorption selectivity of a novel collector 4-butoxy-N-hydroxybenzamide in cassiterite flotation

In cassiterite flotation, the superior selectivity of benzohydroxamic acid (BHA) leads to its common use as a collector. However, its weak collecting ability necessitates the synthesis of 4-butoxy-N-hydroxybenzamide (BHBA) by introducing a butoxy group at the para-position of the N-hydroxyamide group in BHA molecular structure. BHBA, when functioning as a collector in the flotation separation of cassiterite and calcite, retains BHA selectivity while enhancing its collecting ability. Zeta potential experiments show that under same reagent dosage and slurry pH conditions, BHBA is adsorbed in larger amounts on cassiterite surface than on calcite, conferring its stronger collecting ability in cassiterite flotation. X-ray photoelectron spectroscopy reveals that BHBA donates more electrons to Sn4+ ions on cassiterite surface versus Ca2+ ions on calcite surface, resulting in the intensified adsorption affinity of BHBA on cassiterite. First-principles calculations indicate that BHBA achieves higher recoveries of cassiterite relative to BHA, attributed to its longer hydrophobic carbon chain and the electron-donating nature of the butoxy group, which enhances the reactivity of the N-hydroxy amide group in BHBA.

Boron removal from wastewater via coordinative adsorption assisted by Fenton-Induced Oxoprecipitation/Flocculation

Chemical precipitation is widely used for boron removal from water in industrial-scale processes, though a following post treatment is generally required to meet the concentration set by current international standards.In this work, chemical precipitation of boron (B) in water by different precipitating agents was combined with Fenton treatment to enhance the boron removal effectiveness. This approach achieved residual boron concentration of less than 0.5 mg/L, hard to achieve through conventional precipitation methods.Batch tests were performed at different dosage of Fenton reagents, and selected Fe2+/H2O2 weight ratios were evaluated with or without adding precipitating agents. The effect of pH on the process was also investigated, to assess the optimal conditions to maximize boron removal. At the end of the process, barium hydroxide was used to remove effectively excess sulfate ions.The sludge produced was characterized by XRD, SEM and FTIR analysis, and the mechanism of boron removal was investigated.An oxoprecipitation mechanism was induced by the Fenton process: boron-based species were converted into borate ion, thus predisposing them to a coordination-type adsorption on the surface of iron and calcium hydroxide, assisted by aluminum sulfate at pH 12.5.The process was then successfully tested on real boron −contaminated wastewater, thus confirming the effectiveness of the process while simultaneously decreasing the organic content.

The promotional role of peroxydisulfate in Arsenic(III) oxidation by Fe(III)/Sulfite: Boosting and regulating the generation of radical and non-radical species

The Fe(III)-activated sulfite (S(IV)) process to yield powerful SO4•−/HO• radicals is increasingly recognized as an appealing advanced oxidation process (AOP). However, its application is constrained by its heavy reliance on dissolved oxygen and the low selectivity of these short-lived radicals. In this work, peroxydisulfate (PDS) was found to indeed amplify the capacity of the Fe(III)/S(IV) system for arsenite (As(III)) oxidation, with increasing the oxidation efficiency and rate constant from 47 % to 95 % and 0.165 min−1 to 0.455 min−1, respectively. The mechanistic study revealed that the predominant reactive species were identified as both radicals (SO4•−/HO•) and non-radical (Fe(IV)O2+ instead of 1O2), with HO• primarily originating from Fe(IV)O2+. Herein, PDS not only acted as an electron acceptor to react with the in-situ formed Fe(II), thus accelerating the Fe(II) ↔ Fe(III) cycle and producing Fe(IV)O2+, but also functioned as a substitute for dissolved oxygen to facilitate SO4•− generation even under anaerobic conditions. Moreover, the generation efficiency and distribution of these oxidizing reactive species were significantly influenced by adjusting experimental parameters (i.e., reagents dosage and solution pH). Overall, this work unveiled an enticing strategy to fine-tune the oxidative prowess and precision of the Fe(III)/S(IV)/PDS system for oxidizing specific contaminants by orchestrating the relative distribution of radicals (SO4•−/HO•) and non-radical (Fe(IV)O2+).

A Sweet Synthesis of MXenes.

Two-dimensional transition metal carbides/nitrides (MXenes) have shown great promise in various applications. However, mass production of MXenes suffers from the excessive use of toxic fluorine-containing reagents. Herein, a new method was validated for synthesizing MXenes from five MAX ceramics. The method features a minimized (stoichiometric) dosage of F-containing reagent (NaBF4) and polyols (glycerol, erythritol, and xylitol) as the reaction solvent. Due to the sweetness of polyols and the low environmental impact, we refer to this method as a "sweet" synthesis of MXenes. An in-depth molecular dynamics simulation study, combined with experimental kinetic parameters, further revealed that the diffusion of F- in the confined interplanar space is rate-determining for the etching reaction. The expansion of interlayer spacing by polyols effectively reduces the diffusion activation energy of F- and accelerates the etching reaction.

Separation of copper-lead using 2,5-dimercapto-1,3,4-thiadiazole as chalcopyrite depressant: Adsorption and hydrophilicity studies

Galena separation from chalcopyrite poses a notable challenge in mineral processing, owing to the involvement of high dosages of traditional process reagents and substantial environmental impact. This study addresses this challenge by introducing 2,5-dimethoxy-1,3,4-thiadiazole (DMTD) as a chalcopyrite depressant using sodium ethyl xanthate (NaEX) as a collector. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) analyses showed that DMTD can be adsorbed on the surfaces of chalcopyrite and galena, but the adsorption on chalcopyrite is stronger than that on galena. UV–vis, zeta potential and time-of-flight secondary ion mass spectrometry (ToF-SIMS) analyses revealed that DMTD impeded the adsorption of NaEX on chalcopyrite; moreover, NaEX could desorb the DMTD adsorbed on galena and re-adsorb it on galena. Surface hydrophilicity tests revealed that DMTD significantly enhanced the hydrophilicity of chalcopyrite in the presence of NaEX, and galena was selectively separated from chalcopyrite using 1×10− 4 mol/L DMTD at pH exceeding 5. The recovery of galena remained >90 %, while that of chalcopyrite drastically decreased to <5 %. Furthermore, artificial-mixing experiments confirmed the separation effect of DMTD as a chalcopyrite depressant. Notably, this study avoids environmental pollution caused by traditional depressants, offering a potential green approach to achieve effective flotation separation of copper–lead sulfide ore.

Influence of Carbonated Pyrolysis Oil Recycled from Scrap Tires on Metallurgical Efficiency of Coal Flotation

This research assesses the effect of carbonated pyrolysis oil (CPO) derived from scrap car tires on the metallurgical efficiency of coal flotation as a flotation additive. Using a statistical experimental design, the influence of various operational variables, including solid percent of feed pulp and dosages of reagents, i.e., CPO as an additive, diesel oil as a collector, and pine oil as a frother, on the ash content and yield of the final concentrate were investigated. Experimental data vary significantly based on operational conditions, ranging from 6.6% ash content with a 15% yield to 19.1% ash content with a 76.8% yield. The composition of the pyrolysis oil was identified by using Fourier transform infrared spectroscopy (FTIR). The analysis of variance (ANOVA) of experimental results demonstrated that almost all variables had a substantial effect on the flotation responses, positive or negative, depending on the variable or variable interaction. It was discovered that the usage of CPO intensified the total yield and ash content of concentrate in a nonlinear fashion in a range of 15% and 4%, respectively. The results revealed a non-selective interaction effect between CPO and pine oil, as well as competitive adsorption between diesel oil and CPO, which contributed to the curved behavior of flotation measurements. The detrimental effect of CPO on the flotation response of the studied coal sample was also related to the interaction of the hydrophilic groups in the CPO structure and the oxide groups of ash material in coal particles. This work shows the potential of carbonated pyrolysis oil to enhance coal flotation performance and sheds light on the underlying mechanisms.

Untargeted metabolomics reveals the mechanism for leaching rare earth elements from ion-adsorption rare earth ores using a composite lixiviant

Rare earth elements (REEs) are an important strategic scarce resource, and how to mine and utilise them efficiently and greenly is a difficult problem. In this study, to reduce the use of chemical reagents in the leaching process, Bacillus thuringiensis fermentation broth and magnesium acetate were used as composite lixiviants to leach REEs from ionic rare earth ores via biochemical synergy. The effectiveness of composite lixiviant for leaching REEs was studied, and the optimum leaching conditions were determined. In addition, untargeted metabolomics was used to explore metabolite differences and metabolic pathway profiles before and after leaching with the composite lixiviant. The interaction between the composite lixiviant and the rare earth minerals was also investigated by combining various characterisation tools. The results showed that the leaching rate was 96.3 % when the concentration of magnesium acetate in the composite lixiviant was 0.3 mol/L, the pH was 4, and the liquid–solid ratio was 2:1. Metabolomics analysis showed that lipids and lipid-like molecules, benzenoids, and organic acids, and derivatives contained in the fermentation broth of the complex leach play an important role in the leaching process. This study provides a new composite lixiviant for leaching ionic REEs, which can reduce the dosage of chemical reagents, provide a reference for the biochemical synergistic leaching of ionic rare earth ores, and help guide environmentally friendly and efficient leaching of ionic rare earth ores in the future.

Obtention of Suitable Pregnant Leach Solution (PLS) for Copper Solvent Extraction Plants from Copper Concentrate Using Hydrogen Peroxide and Iodine in a Sulfuric Acid–Chloride Medium

Copper leaching presents an environmentally friendly alternative to traditional sulfide ore processing methods. This study investigates an efficient leaching process for copper concentrate, utilizing a solution of sulfuric acid (H2SO4) and potassium iodide (KI) in a chloride medium (NaCl), enhanced by hydrogen peroxide (H2O2) at room temperature. A significant aspect of this research was optimizing the KI concentration to minimize iodide sublimation into iodine gas (I2). Through the experimental design, the optimal dosages of reagents were determined, leading to maximized copper extraction of approximately 27% in 45 min of testing at room temperature. The results showed that it is possible to obtain a suitable pregnant leach solution (PLS) (i.e., in the range of 3 to 8 g/L of Cu) for treatment in available copper solvent extraction (SX) plants with a cost of less than 4.5 USD/t Cu, according to the economic analysis carried out. The results of this study determine the most effective operational conditions for leaching and ensure a suitable PLS for SX plants in a cost-effective and environmentally friendly manner. This approach could significantly contribute to more sustainable practices in the mining and processing of copper ores.

Depth dewatering of kaolinite cake by SDBS/PEI synergy and a mesoscopic mechanism study

The objective of this study was to elucidate the synergistic dewatering mechanism of mixed sodium dodecylbenzene sulfonate (SDBS) and polyethyleneimine (PEI) on kaolinite filter cakes and to test the dewatering effectiveness of a custom-built pressure dewatering device. The dewatering experiments showed that while the reagent dose was reduced by 50%, the dewatering rate decreased to 19.78%, surpassing the optimal dose of a single reagent. During the natural compression stage of the filter cake, the deformation reached its maximum under the same pressure difference. During the transitional period, the closure of the filter cake pores occurred at a slower rate, facilitating better moisture drainage. Under strong compression, the ultimate deformation reached its maximum. PEI acted as a bridging agent for kaolin flocculation and served as a medium for SDBS on the kaolin surface. A small amount of PEI reduced the electrostatic repulsion of SDBS, increasing its adsorption capacity. PEI adsorbed on the kaolin surface through electrostatic and hydrogen bonding, while SDBS could adsorb onto the PEI reagent layer through electrostatic and polar interactions, exposing its alkyl chains on the surface and thereby facilitating flocculation and generating a hydrophobic reagent layer. This study could provide a new method and insights for the efficient pressurized dewatering of kaolin.

Mechanistic study on the significant difference in flotation collector consumption of different coal gasification fine slag

ABSTRACT Froth flotation, a prevalent technique for the separation of fine materials, is employed in the decarburization process of coal gasification fine slag (CGFS). This process is known to consume significant quantities of reagents. This study investigates the pronounced variance in collector consumption during the flotation decarbonization of two distinct CGFS samples, where a tenfold difference was observed when the tailings ash content surpassed 95%. A comprehensive set of analyses, including XPS, BET, SEM, wettability tests, LF-NMR and IGC-SEA, was conducted on the residual charcoal from CGFS to elucidate the mechanism behind reagent consumption. The findings reveal that the reagent’s ability to alter the surface hydrophobicity of residual charcoal is contingent upon the adsorption saturation of micropores and transition pores. Furthermore, variations in porosity and surface energy significantly impact collector consumption, independent of differences in the type and quantity of oxygen-containing functional groups. This investigation aims to provide a theoretical framework for reducing the dosage of reagents in the flotation decarburization of CGFS.

Enhanced scavenger-free photocatalysis-self-Fenton degradation performance over B-doped NVs modified g-C3N4 via promoting Fe(II)/Fe(III) cycle

As an advanced oxidation method, Fenton oxidation has been extensively studied in industrial wastewater treatment. However, its drawbacks such as high reagent dosage, costliness, and the generation of secondary pollutants have limited its application in urban sewage treatment. Photocatalytic in-situ hydrogen peroxide (H2O2) generation and the construction of photocatalysis-self-Fenton oxidation system (PSFs) is considered a potential approach for applying Fenton oxidation in the sewage treatment industry. In this paper, a nitrogen vacancy-modified B-doped g-C3N4 photocatalyst with high efficiency of H2O2 production without adding a scavenger was prepared based on ion-doping and defect construction. Combined with both characterization analysis and theoretical calculation, it was clarified that the modified catalyst enhanced the photo-generated charge separation and transfer. A PSFs was constructed by adding Fe2+ for the degradation of tetracycline (TC). The system produced H2O2 in-situ through photocatalytic action and promoted the Fe2+/Fe3+ cycle under the action of photo-generated electrons. The system achieved almost complete degradation of TC under the joint action of hydroxyl radicals and superoxide radicals, and maintained more than 90 % degradation efficiency after five cycles. And the efficiency of PSFs was significantly improved compared with that of single photocatalysis and photo-Fenton oxidation.

Droplet array with microfluidic concentration gradient (DA-MCG) for 2-dimensional reaction condition screening

Droplet microfluidic technology can use each microdroplet as a microreactor, which has the advantages of low reagent dosage, less cross contamination, and fast reaction time. Combining concentration gradient generation with droplet formation and capture to form a two-dimensional reaction condition screening platform (including reactant concentration and reaction time) is expected to broaden the application range of microfluidic screening. In this work, a microfluidic chip that can dynamically generate and capture microdroplets and form static microdroplet array was designed and fabricated. An optimized Christmas tree structure by adjusting the horizontal channel length ratio was used to generate a chemical concentration gradient while obtaining a uniform outlet flow rate, forming a droplet array with different concentrations. The performance of droplet array with microfluidic concentration gradient (DA-MCG) was verified using sodium fluorescein as a model reagent. The chromogenic reaction of NaOH and phenolphthalein, and luminol chemiluminescence reaction were used to verify the two-dimensional screening ability of DA-MCG. The results indicated that the DA-MCG has the potential to be applied in the field of multi-dimensional drug screening.

Engineering sulfur vacancies on Mo-doped FeS2 nanosheets grown on activated carbon fibers enhances peroxymonosulfate activation for efficient elimination of sulfamethazine, antibiotic resistant bacteria and antibiotic resistance genes: The dominant role of singlet oxygen

The widespread of antibiotics will induce the generation of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs), causing threats to human health. Therefore, developing a green and efficient synchronous removal technology for the removal of antibiotics, ARB and ARGs is urgent. In this study, Mo doped FeS2 nanosheet with rich sulfur vacancies (SVs) grown on activated carbon fibers was successfully synthesized and employed as a PMS activator to remove sulfamethazine (SMT), ARB and ARGs in aqueous solution. Mo-FeS2/ACFs-0.1 (MFAs-0.1, the molar ratio of Mo/Fe is 0.1) showed high performance for PMS activation, and 99.7 % SMT was removed in 60 min (250 mg/L MFAs-0.1, 0.3 g/L PMS, initial pH = 5.5). In addition, low reagent doses of MFAs-0.1 catalyst (250 mg/L) and PMS (0.5 g/L) were found to be efficient for removing 7.25-log of ARB within 30 min and restraining conjugative transfer of ARGs. Singlet oxygen (1O2) was identified as the primary reactive oxygen species for SMT degradation and ARB inactivation. Meanwhile, the integration of Mo-doping with SVs could optimize the electronic structure, generating electron-rich and highly active regions. This facilitates the adsorption of PMS onto the Fe site and boosts electrons transfer from FeS2 to PMS, as indicated by density functional theory (DFT) calculations. Overall, this study demonstrated that the MFAs-0.1 based heterogeneous system was an economically “one stop” treatment process for the removal of biological and chemical contaminants. In addition, it would provide a new insight into the fabrication of FeS2 composites-based PMS activator.

Unintended polyhalogenated carbazole production during advanced oxidation of coking wastewater

Polyhalogenated carbazoles (PHCZs) are emerging as dioxin-like global pollutants, yet their environmental origins are not fully understood. This study investigates the application of the Fenton process in coking wastewater treatment, focusing on its dual role in carbazole removal and unintended PHCZ formation. The common halide ions (Cl– and Br–) in coking wastewater, especially Br– ions, exerted a notable impact on carbazole removal. Particularly, the influence of Br– ions was more significant, not only enhancing carbazole removal but also shaping the congener composition of PHCZ formation. Elevated halide ion concentrations were associated with the heightened formation of higher halogenated carbazoles. The Fenton reagent dosage ratio was identified as a crucial factor affecting the congener composition of PHCZs and their toxic equivalency value. The coexisting organic substance (i.e., phenol) in coking wastewater was observed to inhibit PHCZ formation, likely through competitive reactions with carbazole. Intriguingly, ammonium (NH4+) facilitated the generation of higher and mixed halogenated carbazoles, possibly due to the generation of nitrogen-containing brominating agents with stronger bromination capacity. This study underscores the importance of a comprehensive assessment, considering both substrate removal and potential byproduct formation, when employing the Fenton process for saline wastewater treatment.