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Weak interaction between flocculants and oil is a main bottleneck in the treatment of oil-containing wastewater. To solve this problem, a novel flocculant PAB with cationic micro-block structure and hydrophobic groups of benzene rings was synthesized by ultrasound initiated polymerization technique and applied to remove turbidity and oil from water. To avoid unnecessary addition of reagents in traditional template and micellar copolymerization, surface-active monomer benzyl(methacryloyloxyethyl)dimethylammonium chloride (BMDAC) with self-assembly ability in aqueous solution was employed to synthesize flocculants. The critical association concentration of BMDAC measured by conductivity and surface tension methods was 0.014 mol·L −1 . The results of reactivity ratio, statistical analysis of sequence-length distribution and 1 H NMR provided evidence for the synthesis of copolymer with cationic micro-block. In addition, the apparent viscosity measurement indicated that PAB had an obvious hydrophobic association property. Finally, flocculation tests demonstrated that flocculation performance was greatly improved by adding PAB and the removal rate of oil and turbidity both reached the maximum (87.5% and 92%) at dosage of 40 mg·L −1 and pH of 7.0. Flocculation mechanism investigation demonstrated that the cooperation of charge neutralization, adsorption bridging, and hydrophobic association effect played an important role. The formed flocs by PAB was large, compact, difficult to break, and easy to regrow because of the enhanced interaction between flocculants and oil. In summary, this study can provide important reference in the design of organic flocculants in oily wastewater treatment applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Combining PM and 3D electrode process showed a remarkable synergy for DCF removal. • GAC and organic contaminants promoted the conversion of MnO 2 and PM to Mn(III) aq. • GAC act as a mediator transferring electrons from organic contaminants to PM. • Mn(III) aq and colloidal MnO 2 mainly contributed to ECs removal. • GAC particles exhibited a stable catalytic performance after 10 cycles. Currently, the electro-activated permanganate (PM) process, as one of the reactive manganese species (RMnS)-based advanced oxidation processes, has shown great potential for environmental remediation. However, the activation efficiency of PM in the electro-activated PM (E-PM) process is limited due to the poor mass transfer and electron transfer efficiency in the two-dimensional (2D) process. In this study, to overcome these drawbacks, granular activated carbon (GAC) was introduced as particle electrodes, establishing an efficient three-dimensional (3D) electrode process (E-GAC-PM), which promoted the generation of RMnS. Comparative experiments exhibited the significant synergy between PM and the 3D electrode process, resulting in the highest diclofenac (DCF) removal (90.2 %) with the lowest energy consumption. Electrochemical impedance spectroscopy and Tafel curve showed that the addition of GAC greatly attenuated the electrochemical impedance, facilitating the activation of PM. Further studies revealed that GAC can serve as an electron mediator, transferring electrons from contaminants to PM, thereby generating Mn2+ and promoting Mn(III) aq formation. Meanwhile, in-situ generated Mn2+ can also be oxidized by the anode and particle electrodes into Mn(III) aq. Besides, the in-situ generated MnO 2 facilitates the performance via oxidation and catalysis effects. Under the protection of the electric field, GAC showed a relatively stable performance which could be regenerated and maintain active after 10 cycles. All these results demonstrated that the E-GAC-PM process was an efficient, energy-saving, and sustainable method for refractory organic contaminants removal, which showed potential for practical application. [ABSTRACT FROM AUTHOR]

[Display omitted] • Abundant electron-rich Co centers generated by Mg doping enhanced PMS activation. • MCO@PES membrane/PMS system achieved instant contaminants elimination. • The highly accessible SO 4 −, OH, and 1O 2 were the responsible reactive species. • Catalyst recovery and enhanced mass transfer in membrane provided the application value. The practical application of heterogeneous Fenton-like processes in wastewater treatment is limited by inadequate catalyst recovery and limited mass transfer in traditional batch mode. Consequently, a catalytic membrane composed of inert magnesium (Mg)-doped Co 3 O 4 spinel (MCO) was crafted to activate peroxymonosulfate (PMS) for the elimination of organic contaminants. The incorporation of the less electronegative Mg induced electronic polarization on the MCO surface, resulting in the generation of sufficient electron-rich Co centers, thereby amplifying its electron-donating properties in PMS activation and enhancing the inherent catalytic activity of the spinel. Regarding the catalytic membrane, the stacked porous structure of the MCO layer achieved reactive sites exposure, mass transfer enhancement, and reactive species availability. Remarkably, the MCO@polyethersulfone (PES) membrane/PMS system instantaneously activated PMS, displaying an elimination kinetic constant of 0.039 ms−1 for tetracycline. The MCO@PES membrane exhibited exceptional catalytic performance and stability in long-term operational studies. Mechanistic investigations elucidated that the highly accessible SO 4 −, OH, and 1O 2 within the catalytic membrane facilitated the immediate elimination of contaminants. This study serves as a valuable reference for the application of transition metal spinel-based catalytic membranes in wastewater treatment. [ABSTRACT FROM AUTHOR]

• Captured SO 2 reutilization and water remediation were simultaneously achieved. • An EC/CoSi/sulfite system for efficient sulfate radical production was developed. • Insights for synergy mechanism of EC/CoSi/sulfite system were provided. • Influencing factors were investigated and operating conditions were optimized. The desulfurization by-product (e.g. sulfite) treatment and water pollution are two widespread concerns, while the sulfite activation by transition metals can be adopted to solve both of them simultaneously. In this study, a silica-supported cobalt catalyst (CoSi) was used to activate sulfite for the degradation of organic pollutants in an electrochemical system (the EC/CoSi/sulfite system), which demonstrated remarkable water treatment efficiencies due to sulfate radical oxidation. The synergy mechanisms of the EC/CoSi/sulfite system were revealed. (i) The as-prepared CoSi played the dual roles as an electro-adsorbent and a catalyst for sulfite activation. (ii) The electrolytic oxygenation supported the conversion of cobalt species and the chain reactions of oxysulfur radicals. (iii) The anodic oxidation of sulfite also generated oxysulfur radicals. The influencing factors and operating parameters were investigated and optimized systematically. Moreover, the efficient degradation of highly concentrated X-3B and non-selective oxidation of various organic compounds confirmed the promising application of the EC/CoSi/sulfite system in practical water treatment. Overall, the EC/CoSi/sulfite system created new value of the industrial waste (e.g. sulfite) for further application in the environmental remediation. [ABSTRACT FROM AUTHOR]

Co–Zn–N–C catalyst (MCZC) with neighboring Co and Zn pairs anchored on hollow carbon nitride was constructed by the direct etching of zeolitic imidazolate frameworks assembled with Co and Zn. Adequate characterizations and density functional theory (DFT) studies confirmed the successful construction of non-bonding Co and Zn pairs with enhanced electron transfer on Co sites by adjacent Zn sites. Based on the synergy of adjacent Co and Zn atom pairs, the MCZC/Perxymosulfate (PMS) system achieved 99.6% Tetracycline (TC) degradation in 24 min with a mineralization rate of 55.8% and PMS decomposition efficiency of 73.1%. DFT calculation based on the Fukui index identified the sites susceptible to attack by the active species. TC degradation pathways could be inferred, and reduced toxicity of intermediates was observed. This work provides new insights into the design of MOF-derived bimetallic catalysts and the importance of the interaction between adjacent metal active sites to catalytic performance. [Display omitted] • Co, Zn doped hollow carbon nitride catalyst was synthesized by etching Co 0.5 Zn 0.5 -ZIF. • Co sites were highly activated by adjacent Zn atoms via non-bonding interaction. • MCZC/PMS system achieved efficient tetracycline degradation and risk control. • The unique structure provides MCZC catalyst with high stability and low metal leaching. [ABSTRACT FROM AUTHOR]

Environmentally friendly magnetic sodium alginate beads with glutaraldehyde cross-linking catalyzed by acetic acid-hydrochloric acid were successfully designed (FSSi@SA), and the magnetic bio-sorbents after amide reaction (FSSi@SA-sula) were utilized to absorb fluoroquinolone antibiotics in water. After amidation, FSSi@SA-sula exhibited strong pH adaptability (pH = 6.0–12.0). Langmuir and pseudo-first-order models can better describe the isotherm and kinetic process well, respectively. Under the optimization conditions with pH = 7 and temperature of 318.15 K, the maximum adsorption capacities of FSSi@SA-sula on the third-generation FQs ciprofloxacin (CIP) and the fourth-generation FQs moxifloxacin (MOX) respectively reached 365.66 and 149.57 mg g−1. The thermodynamics research indicated that the as-prepared FSSi@SA-sula is spontaneous and feasible. And after five adsorption cycles, the loss of adsorption capacity was less than 20% for both CIP and MOX, demonstrating the fine reusability and stability of the designed magnetic bio-sorbent. This study provides some ideas for facile synthesis of acid-catalyzed sodium alginate-glutaraldehyde cross-linking, which has promising applications in grafting various types of groups onto the retained carboxyl groups of sodium alginate spheres for the various contaminants removal in wastewater. [Display omitted] • FSSi@SA-sula beads were prepared by acid-catalyzed glutaraldehyde cross-linking. • FSSi@SA-sula showed excellent adsorption and reusability for CIP and MOX. • Langmuir and pseudo-first-order models better fitted adsorption process. • The mechanisms include electrostatic interactions, hydrogen bonding and n-π EDA. • Provided new ideas for facile synthesis of functional sodium alginate adsorbents. [ABSTRACT FROM AUTHOR]

Among homogeneous catalysts, cobalt ions exhibit ultra-high persulfate activation performance. In this work, an electrically supported medium Co(II) activated peroxydisulfate synergistic process was established to eliminate organic contaminants in water. The synergistic catalytic effect was verified by comparing the oxidative degradation performance and reaction rate constant of different coupling systems. The decolorization ability of E-Co(II)-PDS on reactive black 5 (RB5) was explored, and the results showed that the removal rate of RB5 can reach 93.21% under the optimized conditions of current density of 5.71 mA/cm2, initial pH of 4, Co(II) concentration of 0.2 mM and PDS concentration of 5 mM. The effect of water matrix on the removal of RB5 was studied, and it was found that HCO 3 − and humic acid significantly inhibited the degradation of RB5, while Cl− and H 2 PO 4 − could effectively promote it at a certain concentration. Notably, the degradation of RB5 in E-Co(II)-PDS system achieved lower energy consumption, with an energy consumption per unit volume (EE/O) value of 0.4304 kWh·m−3. EPR test, quenching experiments and contribution rate analysis showed that the oxidation active species in E-Co(II)-PDS process were Co(III), sulfate radicals and hydroxyl radicals, and their oxidation contribution rates were 15.72%, 12.69% and 53.25%, respectively. Finally, the decomposition process of RB5 was proposed by the mass spectrometry results. The electric current promotes cobalt ion cycling and PDS activation through electron transfer, and induces Co(II) to promote the activation of PDS, which is the main mechanism of E-Co(II)-PDS system to achieve the robust degradation ability of RB5. • Co(II) greatly improved the activation effect of electroactivated persulfate system. • The current promotes Co(II)/Co(III) cycling and peroxydisulfate activation. • Low energy consumption was achieved by E-Co(II)-PDS system. • Co(III), SO 4.•– and •OH contributed to RB5 removal in E-Co(II)-PDS process. • E-Co(II)-PDS could robustly degrade organic contaminants in water. [ABSTRACT FROM AUTHOR]

The low specific surface area, poor porosity, and weak charge transport caused by the disordered morphology of metal-N-site catalysts are the main factors limiting their environmental applications. Therefore, a hollow-nanotube carbon nitride (Cu-HNCN) catalyst with CuN x sites dispersed in a hollow nanotube-like CN was constructed and used for the degradation of organic pollutants via the photo-Fenton (PF) process. The high specific surface area, rich porosity, and good visible-light trapping capability of the Cu-HNCN nanotubes were identified. The Cu-HNCN/PF system achieved 96.0% degradation efficiency of tetracycline within 50 min and showed efficient degradation of various antibiotic contaminants. Moreover, the short Cu-N bonds contributed to the improved stability and decreased copper leaching in the Cu-HNCN/PF system. Cu-HNCN, with its enhanced photogenerated charge generation, separation, and transport, was the key to the generation of abundant active species and efficient degradation of pollutants. In addition, frontier electron density theory successfully distinguished the roles of different types of active species in the degradation process. This work provides new insights into the development of catalysts with high stability and accelerated electron transfer to enhance the application of the PF process in practical wastewater purification. [Display omitted] • Hollow-nanotube carbon nitride catalyst were designed for antibiotics degradation. • CuN x sites are highly dispersed for effectively avoiding the loss of Cu ions. • Degradation process was contributed by the abundance of active species and nanotube properties. • It provides catalyst with high stability and accelerated electron transfer for photo-Fenton process. [ABSTRACT FROM AUTHOR]