Humic Acid Removal Research Articles

Sustainable Activated Carbon from Agricultural Waste: A Study on Adsorption Efficiency for Humic Acid and Methyl Orange Dyes

In this study, porous activated carbon was produced from coffee waste and used as an effective adsorbent for the removal of humic acid (HA) from seawater and methyl orange (MO) dye from aqueous solutions. Phosphoric acid H3PO4 was used as an activating agent for the chemical activation of these agricultural wastes. The characterization of the activated carbon obtained using a scanning electron microscope (SEM), Fourier-transform infrared (FTIR) spectroscopy analysis, X-ray diffraction (XRD) and the Brunauer–Emmett–Teller (BET) method revealed that the activated carbon products exhibited high porosity and the formation of various functional groups. The effects of different parameters were examined using batch adsorption experiments, such as the adsorbent masses, pH, initial pollutant concentration and contact time. The results show that the performance increased with an increased adsorbent mass (up to 0.25 g/L) and decreased initial concentration of the adsorbent tested. On the other hand, this study clearly showed that the adsorption efficiency of the MO on the raw spent coffee grounds (SCGs) waste was around 43%, while no removal was observed for the humic acid. The experiments demonstrated that the activated carbon synthesized from the used coffee grounds (the efficiency was compared with commercial activated carbon (CAC) with a difference of 13%) was a promising alternative to commercially available adsorbents for the removal of humic acid from seawater. To understand and elucidate the adsorption mechanism, various isothermal and kinetic models were studied. The adsorption capacity was analyzed by fitting experimental data to these models. The experimental data for methyl orange dyes were analyzed using Langmuir and Freundlich isothermal models. The Freundlich isotherm model provided a superior fit to the equilibrium data, as indicated by a higher correlation coefficient (R2) than that of the Langmuir model. The maximum adsorption was observed at pH 3. The Freundlich adsorption capacity was found to be 333 mg/g adsorbent. The PAC showed a high adsorption capacity for the MO and HA. The PAC showed the highest adsorption capacities for the HA and MO compared with the other adsorbents used (SCGs and CAC) and would be a good material to increase the adsorption efficiency for humic acid removal in the seawater pretreatment process. In addition, the prepared AC BET surface area was 520.40 m2/g, suggesting a high adsorption capacity. This makes the material potentially suitable for various applications that require a high surface area. These results indicate that high-quality sustainable activated carbon can be efficiently produced from coffee waste, making it suitable for a wide range of adsorbent applications targeting various pollutants.

Surface-coated PVDF@TAPEG selective ultrafiltration membranes: an investigation on membranes’ hydrophilicity, and antifouling characteristics for effective humic acid removal from wastewater

This research aimed to synthesize polyvinyl fluoride membranes and coat them with tannic acid (TA) nanoparticles and polyethylene glycol (PEG) additives so that the membrane’s removal efficacy for humic acid (HA) pollutant from agricultural wastewater was investigated. Thus, six membranes with PEG:TA ratios of 0:0, 1:0, 0:1, 1:1, 4:1, and 1:4 were synthesized. Then, the membranes’ characteristics were identified by FTIR-ATR, FESEM, and AFM analysis, and HA’s particle size and zeta potential were also investigated. Based on optimizing effective parameters, the operating pressure of 1.5 bar and HA concentration of 80 ppm were selected as optimal values. The membrane with PEG:TA = 4:1, as the optimally modified membrane, had a pure water flux of 446.03 L/m2.h, effluent flux of 72.43 L/m2.h, and pollutant removal rate of 86.62% at pH = 7 after 60 min had passed. These values for the pristine membrane (PEG:TA = 0:0) were 265.64 L/m2.h, 89.39 L/m2.h, and 75.59%, respectively. The results showed that although the effluent flux was lower in the optimized modified membrane than in the pristine membrane, HA removal percentage was increased.

Fabrication and performance evaluation of polycarbonate/polyvinyl alcohol–titanium dioxide thin‐film nanocomposite membranes for water treatment

AbstractIn recent years, there has been growing interest in using polymer nanocomposite membranes as a more advanced method for removing pollutants from water and treating wastewater for various purposes. In this study, thin‐film nanocomposite (TFN) membranes of polycarbonate/polyvinyl alcohol–titanium dioxide thin‐film (PC/PVA–TiO2) were fabricated by dip‐coating a PC substrate in a PVA/TiO2 solution. Various methods, including attenuated total reflectance‐Fourier transform infrared (ATR‐FTIR) spectroscopy, field emission scanning electron microscopy (FE‐SEM), atomic force microscopy (AFM), and water contact angle were utilized to assess the structural characteristics of the produced membranes. The PC/PVA thin‐film composite (TFC) and PC/PVA–TiO2 TFN membranes were then examined in a submerged membrane system to evaluate their effectiveness in filtering humic acid (HA) under various vacuum transmembrane pressure (0.3 and 0.6 bar) condition. The FTIR‐ATR results confirmed the formation of the active layer of PVA/TiO2 nanoparticles (NPs). It was observed that adding 1 wt.% of TiO2 NPs to the active layer of PVA/TiO2 significantly enhanced the water contact angle from 77.5° for PC support to 55.3° for PC/PVA–TiO2 (0.1) TFN membranes. Furthermore, the FE‐SEM results confirmed the formation of an active layer of PVA/TiO2 with a thickness of 237.87 nm. The pure water flux increased from 101.64 L/m2h for the PC/PVA TFC membrane to 144.02 L/m2h and 199.09 L/m2h for the PC/PVA–TiO2 (0.05) and PC/PVA–TiO2 (0.1) TFN membranes, respectively. Also, the results revealed that at lower transmembrane pressure, all membranes showed higher value in HA removal as compared to when higher transmembrane pressure was used.

In-situ manganese-aluminum-iron biochar derived from waste flocs for enhanced peroxymonosulfate oxidation: Role of Fe/Mn drives active species based on aluminum adsorption and synergistic promoted electron transfer

Conventional coagulation or enhanced coagulation water treatment produced mass floc sludge, which contained plenty of metals and organic matter. Floc sludge disposal and resource recycling was vital relevance and urgently needed. Here, we reported on the waste flocs recycling through in-situ manganese-aluminum-iron biochar (MAFBC) synthesized via one-step pyrolysis using potassium permanganate (KMnO4) oxidation- aluminum-iron composite flocculant coagulation for humic acid removal floc sludge as raw material. Compared with ex-situ loaded or similar types of biochar, MAFBC showed faster and efficient activation effect of peroxymonosulfate (PMS) to degrade tetracycline (TC). TC was rapidly removed within 1 min in MAFBC/PMS system with degradation rate constant Kobs was 1.825 min−1, which mainly attributed to the multiple promoting effects of manganese-aluminum-iron. Aluminum oxides facilitated TC adsorption and synergistic Fe/Mn further significantly promoted electron transfer on the surface of the MAFBC. Additionally, bimetallic structure of Fe/Mn and the CO functional group on MAFBC accelerated the formation of reactive species. The redox cycles of Fe2+/Fe3+ and Mn2+/Mn3+/Mn4+ promoted the formation of free radicals OH and SO4−. Moreover, O2– and 1O2 also assumed an important role for TC removal during active species evolution drived by Fe/Mn. This research provides a new perspective for in-situ design of economical and stable metal carbon-based water treatment activator, and make contributions to the utilization of waste flocs in water treatment.

A review of advancements in humic acid removal: Insights into adsorption techniques and hybrid solutions

Humic acid (HA) is a prominent contaminant in wastewater, and its elimination is crucial to ensure purified drinking water. A variety of sources of HA in wastewater exist, ranging from agricultural runoff, industrial discharges, and natural decomposition. Adsorption is a technique that has been heavily investigated in this direction. The process complexities, technological advancements, and sustainable approaches are discussed in this review. A range of adsorbents can be employed for HA removal, including modified membranes, carbon nanotubes (CNTs), clay nanoparticles, and acid-modified natural materials. This work compares the effectiveness of the preceding adsorbents along with their advantages and limitations. This review also discusses the optimization of various process parameters, such as pH, ionic strength, and temperature, with an emphasis on response surface methodology for process optimization. Furthermore, the challenges and limitations associated with each removal technique are discussed, along with the potential areas for improvement and future directions in the field of wastewater treatment.

Harnessing different pre-treatment for production of Arundo Donax based Biochar for removal of humic acid from surface water, to meet the sustainable development goals

Harnessing different pre-treatment for production of Arundo Donax based Biochar for removal of humic acid from surface water, to meet the sustainable development goals

One-step electrospinning of cellulose acetate/chitosan/TiO2 fibrous membranes: efficient humic acid removal by synergistic adsorption and photocatalysis

One-step electrospinning of cellulose acetate/chitosan/TiO2 fibrous membranes: efficient humic acid removal by synergistic adsorption and photocatalysis

Co-activation of peroxymonosulfate activation with sunlight and tailored catalytic MnFe2O4/MWCNTs membrane to mitigate membrane fouling caused by NOM and synergistic oxidation mechanism analysis

Membrane fouling has been a major factor hindering the development of ultrafiltration membranes. Herein, a novel in situ oxidation system was constructed via introducing MnFe2O4/MWCNTs into polyvinylidene fluoride (PVDF) membranes, utilizing sunlight to synergistically activate persulfate (PMS) to mitigate ultrafiltration membrane fouling. The mechanism of mitigating membrane fouling in MnFe2O4/MWCNTs-PVDF ultrafiltration membranes was systematically explored under four system (single filtration, single sunlight irradiation, single PMS oxidation and sunlight co-activated PMS). The MnFe2O4/MWCNTs-PVDF membranes exhibited different fouling characteristics under the four systems, with the sunlight and MnFe2O4/MWCNTs membrane co-activated PMS filtration system showing the highest humic acid (HA) removal efficiency of 90.2 %, as well as the lowest Rr (0.2108 × 1012m−1) and Rir (0.4525 × 1012m−1). To further evaluate the practicality and effectiveness of the sunlight-MnFe2O4/MWCNTs-PMS system, the secondary effluent was selected to verify the treatment effect on natural organic matter (NOM) of actual water. By observing the microscopic morphology of the fouled membrane surface, it was evident that, compared with the other three filtration systems, the filter cake layer on the MnFe2O4/MWCNTs membrane surface of the sunlight co-activated PMS system was obviously reduced, and the structure of the cake layer was more loose. It can be concluded that the principle behind the synergistically activated system to alleviate the membrane fouling was to accelerate the mineralization rate of HA molecules, oxidize the HA into a smaller particle size that can pass through the membrane pores. The main reactive oxygen species and HA degradation mechanism in the synergistic activation system were further elucidated by electron paramagnetic resonance (EPR) analysis and density functional theory calculations (DFT). The results indicated that the degradation of HA by the synergistically activated PMS system involved a combination of free radicals (·O2−、SO4·− and ·OH) and non-free radicals (1O2). Overall, the in-situ oxidation system provided an alternative way to alleviate ultrafiltration membrane fouling.

Adsorption of Humic Acid from Water Using Metal-Organic Frameworks (MOFs): An Effective Removal Strategy

The escalating presence of humic acid (HA) in aquatic systems poses significant ecological and potable water treatment challenges, altering the color, taste, and odor of water and fueling algal blooms that deplete oxygen levels to the detriment of aquatic life. Traditional techniques like coagulation-flocculation, membrane filtration, oxidation fall short in efficiency due to its small fraction of HA, Humic acids (HAs) can interact with various organic and inorganic substances, affecting their characteristics and behavior in water. These interactions can influence the efficiency of water treatment processes like adsorption and coagulation. Specifically, HAs may compete with other contaminants for treatment sites or alter the chemical conditions of the treatment processes, impacting their effectiveness. This thesis confronts the pervasive issue of HA contamination by leveraging the advanced properties of metal-organic frameworks (MOFs). In this work, four representative MOFs are synthesized and well characterized. Then, their capability to enhance coagulation processes in water for HA and HA-kaolin treatment are detailed evaluated. The findings from this research extend beyond academic curiosity, offering actionable insights for water treatment facilities and environmental management agencies. The synthesis of MOFs which are UiO-66(Zr), MIL-100(Fe), ZIF-8, and Al-fum. Each MOFs have been applied to remove HA by adsorption under different condition, effect of contact time, effect of initial pH, effect of adsorbent dosage. After adsorption experiment, MOF samples prepared to dry and went through characterization. Removal of HA by MOF adsorption showed UiO-66(Zr) and MIL-100(Fe) examined shortest reaching equilibrium state with 10-15 min, however, ZIF-8 and Al-fum gradually reached equilibrium state after 60 min. Among various pH conditions, UiO-66(Zr) and MIL-100(Fe) showed the highest adsorption capacity under acidic conditions, while ZIF-8 excelled at neutral pH, and Al-fum exhibited the highest adsorption capacity under both acidic and basic conditions. ZIF-8 has the highest adsorption capacity among the MOFs with capacity of 754 mg/g. MOF after adsorption samples went through characterizations and their remained characteristics indicating the adsorption not affected the structure of the MOFs.

Preparation of a novel LC@MWCNTs membrane and its application for enhanced phosphate removal and fouling control

To control the eutrophication originating from phosphate discharge, a novel adsorptive membrane was prepared by vacuum filtrating lanthanum carbonate modified multi-walled carbon nanotubes (LC@MWCNTs) on the UF membrane. The LC@MWCNTs were firstly made using an in-situ method by adding MWCNTs to LaCl3·7H2O solution and forming lanthanum carbonate under alkaline conditions. The adsorption experiments exhibited that the maximum adsorption capacity of LC@MWCNTs was 77.58 mg P/g at pH 5. And the phosphate adsorption by LC@MWCNTs was not predominantly reliant on electrostatic interaction, but rather achieved through chemical interactions. Then, the prepared LC@MWCNTs membrane was systematically evaluated for its phosphate removal efficiency and anti-fouling performance during filtration. With the initial phosphate concentration of 1 mg P/L and membrane flux of 378 L·m−2 h−1, the phosphate removal by LC@MWCNTs membrane approached almost 100 %. Moreover, the LC@MWCNTs membrane exhibited higher permeability (281.6 L·m−2h−1bar−1) and effectiveness for humic acid (HA) removal (75 %), and LC@MWCNTs membrane mitigated the fouling caused by HA. XPS, FTIR and XRD elucidated that phosphate removal by LC@MWCNTs membrane primarily through the formation of La-O-P inner-sphere complexes via ligand exchange, resulting in the formation of adsorption product LaPO4·0.5H2O. Under strong alkaline conditions, the LC@MWCNTs membrane rapidly restored its phosphate removal performance (30 min) with no significant detachment of the LC@MWCNTs layer, indicating its good recovery and reusability performance. Additionally, the LC@MWCNTs membrane could continuously remove phosphate from actual water, confirming its potential for future practical applications.

An efficient Bi2MoO6 adsorbent with a positive surface and abundant oxygen vacancies for the removal of humic acid contaminants

Humic acids (HAs) in water react with chlorine disinfectants and form carcinogenic chemicals. These molecules also inhibit environmental engineering processes aiming at the removal of toxic metals and organic contaminants from wastewater. For these reasons, low-cost adsorption strategies are being developed to take out HAs from water. Here, the metal oxide Bi2MoO6 with either exposed [001] (BMO-001-Br) or [010] (BMO-010-Br) facets prepared with the cetyltrimethylammonium bromide (CTAB) surfactant was evaluated for the adsorption of HAs. With a maximal adsorption capacity for HAs of 63.1 mg/g, BMO-001-Br nanosheets constituted a superior adsorbent capable of removing contaminants over a large pH range. BMO-001-Br was reusable and could separate HAs from multiple solutions including tap water, synthetic wastewater, and real pharmaceutical wastewater. The adsorption capacity of BMO-001-Br can be explained by its suitable specific surface area and its positive surface charge related to the presence of CTAB molecules attracting negatively charged HA molecules. A third feature of BMO-001-Br involved in HAs removal is a high abundance of oxygen vacancies, which are easier to form on a BMO surface with exposed crystal [001] facets. The notable performance of BMO-001-Br indicates that it can serve efficiently for the extraction of HAs from different aqueous solutions.

Combining electrocoagulation process using aluminum electrodes with activated carbon on the removal of humic acid from synthetic and industrial wastewater

Combining electrocoagulation process using aluminum electrodes with activated carbon on the removal of humic acid from synthetic and industrial wastewater

Fabrication of 2D Vanadium MXene Polyphenylsulfone Ultrafiltration Membrane for Enhancing the Water Flux and for Effective Separation of Humic Acid and Dyes from Wastewater.

MXene, a new 2D transition metal carbide-based material, is gaining outstanding attention in recent days in the area of separation and purification. In this study, we have successfully synthesized vanadium-based MXene-V2CT x (where T represents functional groups such as -OH, O, and F) by etching an aluminum layer from V2AlC. For the first time, a vanadium-based MXene-V2CT x -embedded mixed matrix membrane was fabricated and utilized for removal of hazardous dye and humic acid from wastewater. With an increase in V2CT x loading, the hydrophilicity of the polyphenylsulfone (PPSU) membrane reasonably improved, and its water contact angle was reduced from 82.8 to 70.9°. V2CT x nanosheet-embedded PPSU membrane exhibited an excellent pure water permeability of 247 L m-2 h-1, which was 266% elevated than the pristine PPSU membrane. The V2CT x -PPSU membrane revealed a good antifouling nature, thermal stability, and 98.5% removal of humic acid. The optimal membrane exhibited 96.6 and 82.02% expulsion of Reactive Black 5 (RB 5) dye and Reactive Orange 16 (RO 16) dye, respectively. The flux for RO 16 and RB 5 dyes and humic acid were remarkable with a value of 202.02, 161.61, and 141.41 L m-2 h-1, respectively. This work provides a new V2CT x -incorporated PPSU ultrafiltration membrane to effectively treat humic acid and dye wastewater.

Effectiveness of cigarette butt filters as eco-friendly cellulose acetate membranes for organic contaminant removal

Abstract Cigarette waste is a persistent environmental problem that requires innovative solutions due to the inadequacy of traditional recycling methods. This paper explores the conversion of cigarette butt filters (CBFs) into raw material for cellulose acetate (CA) membrane production. This study prepared two types of membranes: 12% CBF and 12% CA as a control variable. The resulting material was evaluated for its properties and performance as an ultrafiltration membrane for organic contaminant removal. The result demonstrates that the CBF-based membrane exhibits superior characteristics to a CA-based membrane. This improvement is evident in the increased presence of hydroxyl (-OH) groups and enhanced porosity CA 18,37% and CBF 19,66%. Furthermore, the permeability of the CBF membrane has also increased, making it an efficient tool for maintaining humic acid removal CBF 79,02% and CA 66,18% while achieving a high flux ratio recovery CA 65,25 % and CBF 87,97%. The findings in this paper emphasize the promising potential of reusing cigarette waste as an eco-friendly membrane with high humic acid rejection and good antifouling properties.

Synthesis and evaluation of a novel cross-linked biochar/ferric chloride hybrid material for integrated coagulation and adsorption of turbidity and humic acid from synthetic wastewater: Implications for sludge valorisation

The deep removal of organic pollutants is challenging for coagulation technology in drinking water and wastewater treatment plants to satisfy the rising water standards. Iron (III) chloride (FeCl3) is a popular inorganic coagulant; although it has good performance in removing the turbidity (TB) in water at an alkaline medium, it cannot remove dissolved pollutants and natural organic matter such as humic acid water solution. Additionally, its hygroscopic nature complicates determining the optimal dosage for effective coagulation. Biochar (BC), a popular adsorbent with abundant functional groups, porous structure, and relatively high surface area, can adsorb adsorbates from water matrices. Therefore, combining BC with FeCl3 presents a potential solution to address the challenges associated with iron chloride. Consequently, this study focused on preparing and characterizing a novel biochar/ferric chloride-based coagulant (BC–FeCl3) for efficient removal of turbidity (TB) and natural organic matter, specifically humic acid (HA), from synthetic wastewater. The potential solution for the disposal of produced sludge was achieved by its recovering and recycling, then used in adsorption of HA from aqueous solution. The novel coagulant presented high TB and HA removal within 10 min of settling period at pH solution of 7.5. Furthermore, the recovered sludge presented a good performance in the adsorption of HA from aqueous solution. Adsorption isotherm and kinetics studies revealed that the Pseudo-second-order model best described kinetic adsorption, while the Freundlich model dominated the adsorption isotherm.

Removal of Humic Acid by UiO-66(Zr) and MIL-100(Fe) Metal-Organic Frameworks (MOFs) Adsorption

The escalating presence of humic acid (HA) in aquatic systems poses significant ecological and potable water treatment challenges, altering the color, taste, and odor of water and fueling algal blooms that deplete oxygen levels to the detriment of aquatic life. Traditional techniques like coagulation-flocculation, membrane filtration, oxidation fall short in efficiency due to its small fraction of HA. This study confronts the pervasive issue of HA contamination by leveraging the advanced properties of metal-organic frameworks (MOFs). In this work, two representative MOFs are synthesized and well characterized. Then, their capability for removal HA by adsorption process in water for HA treatment are detailed evaluated. The findings from this research extend beyond academic curiosity, offering actionable insights for water treatment facilities and environmental management agencies. The synthesis of MOFs which are UiO-66(Zr), MIL-100(Fe). Each MOFs have been applied to remove HA by adsorption under different condition. The effect of contacting time, initial pH, adsorbent dosage has been evaluated. After adsorption experiment, MOF samples prepared to dry and went through characterization. Removal of HA by MOF adsorption showed UiO-66(Zr) and MIL-100(Fe) examined rapid reaching equilibrium state with 10-15 min. Among various pH conditions, UiO-66(Zr) and MIL-100(Fe) showed the highest adsorption capacity under acidic conditions. MIL-100(Fe) achieves a higher maximum adsorption capacity than MIL-100(Fe). MOF after adsorption samples went through characterizations and their remained characteristics indicating the adsorption not affected the structure of the MOFs.

Removal of Humic Acid from Water by Adsorption Using Chitosan and Metal Organic Framework ZIF 8 Loaded Chitosan Adsorbents

Water is the most necessary need for life on the earth. There are a lot of organic pollutants in water. One of the organic pollutants is natural organic substances. Humic acid, a natural organic substance, turns into very harmful substances along with other pollutants. In this study, the humic acid removal from aqueous solution by adsorption using chitosan and chitosan/ZIF 8 composite spheres was examined. Chitosan spheres cross-linked with epichlorohydrin (ECH) and composite spheres consisting of metal organic framework ZIF8 and chitosan were prepared as adsorbents. Equilibrium, kinetic, and thermodynamic studies were investigated for humic acid adsorption by pristine chitosan-ECH and composite chitosan/ZIF 8 adsorbents. Chemical adsorption was found to be compatible with the Freundlich isotherm model and the pseudo-first-order kinetic model for pure chitosan adsorbents. Studies were carried out using chitosan/ZIF8 composite adsorbent, and the most suitable models for chemical adsorption were determined as Langmuir isotherm and pseudo-second order kinetic model. The response surface method was applied with the design expert program to determine the optimum experimental conditions. The adsorption tests were carried out using chitosan-ECH, ZIF 8 and chitosan/ZIF 8 adsorbents for specified optimum conditions, and the humic acid removal was determined as 95.1%, 98.3%, and 97.3%, respectively. In addition, desorption was performed using chitosan-ECH and chitosan/ZIF 8 spheres, and the desorption efficiency was found to be 20.9% and 82.5%, respectively. It has been observed that the developed adsorbents have potential in removing humic acid from water.

Electron beam radiation coupled to flocculation for advanced treatment of coking and dyeing wastewater: Performance and synergistic effect

Advanced treatment of industrial wastewater is a tough problem in the field of wastewater treatment. In this study, the electron beam radiation coupled to flocculation process was firstly developed and investigated for the advanced treatment of coking and dyeing wastewater. Three different coupled processes were studied, i.e. electron beam radiation followed by flocculation process (EBF), flocculation followed by electron beam radiation process (FEB), and simultaneous electron beam radiation and flocculation process (SEBF). It was found that different processes had various performances in the removal of targeted organic pollutants. For humic acid, FEB with poly aluminum ferric chloride (PAFC) as flocculants showed the best synergistic effect at 10 kGy, in which the removal of humic acid was 95.2%, while SEBF exhibited the inhibition effect under all the conditions. For Rhodamine B, EBF with PAFC had the highest synergistic effect at 10 kGy, in which the removal of Rhodamine B was 87.4%. For phenol, SEBF with PAFC as flocculants showed the highest synergistic effect at 10 kGy, in which the phenol removal was 64.2%. The transformation of organic pollutants, such as the polymerization was the main reason for the synergistic effect of EBF, while the dissolved iron ions and the enhanced oxidation made major contribution to the synergistic effect of FEB, and the structural change of flocculants and the transformation of organic pollutants during the process of electron beam radiation was mainly responsible for the synergistic effect of SEBF. EBF showed better performance in COD removal for actual coking and dyeing wastewater than FEB, indicating that electron beam radiation could promote the flocculation effect. Considering the operation procedure and treatment cost comprehensively, EBF with PAFC is recommended for the advanced treatment of actual coking and dyeing wastewater. This study could provide a novel and effective method for the advanced treatment of industrial wastewater.

Electroflocculation kinetics of humic acid removal from boiler make-up water using Al-base electrodes

Many coal-fired power plants have undergone a "heating transformation." This transformation measure significantly increases the boiler make-up water required by the power plant, and the make-up water source contains humic acid (HA) organic matter. HA will cause problems such as corrosion、scaling of thermal equipment and increaseing the difficulty of water treatment. The kinetics of electroflocculation were investigated in this study using an experimental device designed to treat HA from boiler make-up water, which is made of plexiglass and has a capacity of 1.2 L. The alloy plates are placed parallel to each other and perpendicular to the horizontal plane as the anode and cathode and are connected to the DC power supply through a wire. Three parameters were investigated: current density, initial pH, and electrode distance. The experimental results show that electroflocculation has a better removal effect on HA. The reaction rate constants of the three electrodes (Al–Zn–In, 6061 alloy, and Al) were 0.07994, 0.04282, and 0.03174 min−1. When the pH was 5, the current density was 100A·m−2, and the spacing between the electrodes was 3 cm, the highest rate constant of 0.10249 min−1 was observed for Al–Zn–In, and the removal rate of HA was 93.3% in 30 min. The SEM and EDS analyses were performed on the electrode and precipitated before and after electroflocculation. The doping of Al–Zn–In with In and Zn helps maintain the electrode surface's activation state during electroflocculation. The electroflocculation effect and anti-passivation ability of the three metals are Al–Zn–In＞6061 alloy＞Al. Al–Zn–In is expected to replace aluminum plates due to its resistance to passivation and superior electroflocculation effect.

Microcontaminants degradation in tertiary effluent by modified solar photo-Fenton process at neutral pH using organic iron complexes: Influence of the peroxide source and matrix composition

Peroxymonosulfate (HSO5–) and persulfate (S2O82–), both sources of sulfate radicals (SO4*–), were evaluated for the first time in modified solar photo-Fenton using Fe-chelating agents (nitriloacetic acid (NTA), ethylene diaminetetraacetic acid (EDTA), ethylenediamine-N,N′-disuccinic acid (EDDS) and citrate (Cit)) in comparison with hydrogen peroxide (H2O2) to degrade benzophenone-3 (BP-3), fipronil (FIP) and propylparaben (PPB) (100 µg L–1 each) in municipal tertiary effluent. Increasing HSO5– concentrations from 1.5 to 5.9 mmol L–1 reached ≥ 96 % removal for all iron complexes, while treatment efficiencies for all tested S2O82– concentrations (1.5–5.9 mmol L–1) were limited to 20 % to 55 %. This difference can be attributed to a pH decrease in the HSO5– system. The influence of pH and matrix composition upon treatment performance were also assessed in the FeNTA/S2O82– system, which was more efficient at pH < 7.0 due to higher availability of soluble iron, and partial removal of bicarbonate and humic acids caused by acidification. Matrix composition significantly influenced the process as higher degradation rates were achieved after isolated or combined removals of chloride, bicarbonate and sulfate. The comparison between naproxen (a high electron density compound) degradation and that of BP-3, FIP, and PPB by SO4*– - based advanced oxidation processes (SR-AOPs) was used to evaluate the influence of target compound structures upon treatment performance. S2O82− and HSO5– were ineffective for treatment at pH 7.0. Thus, H2O2 was the best peroxide source for target compounds degradation at neutral pH as this is the natural pH of municipal tertiary effluent and results indicated that the assessment and choice for SR-AOPs should consider the chemical structure of target compounds.