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•The application of SR-AOPs for IWW treatment was systematically reviewed.•The theoretical (reactive species) and practical aspects (IWW composition) were analyzed.•SR-AOPs are vastly ...studied in landfill leachate and petrochemical IWW effluents.•Its advantages include the simultaneous HO/SO4− generation with non-radical pathways.•Limitations include the difficulty to apply heating, microwave and ultrasound activation.
Over the last years, Sulfate Radical-based Advanced Oxidation Processes (SR-AOPs) have received considerable attention due to their high versatility and efficacy in disinfection and decontamination. Their advantages over classical AOPs, the generation of sulfate radicals (SO4∙-) from peroxydisulfate (PDS, S2O82-), or joint sulfate and hydroxyl radicals (HO∙) production from peroxymonosulfate (PMS, HSO5-) and their abundant activation methods have facilitated their introduction into various remediation and effluent decontamination processes. In this review, we present the advances in the field of industrial wastewater (IWW) treatment by SR-AOPs, by activation of either PMS or PDS via any suitable method, in homogeneous or heterogeneous (photo)catalytic processes. This review aims to present the state of the art in SR-AOPs application for IWW treatment, and act as a guideline of the field advances, summarize the previous application experiences, hence avoid research pitfalls and empower better IWW treatment practices. After an integrated presentation of the dominant pathways towards IWW decontamination, we discuss the SR-AOPs application in the treatment of effluents such as landfill leachate, petrochemical and pharmaceutical WW, pulp or paper industry effluents, textile and winery WW, as well as less studied processes such as coking, olive mill or soil washing effluents. Finally, the advantages and shortcomings of SR-AOPs for IWW treatment, as well as their perspectives are discussed.
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•Fe3C@NCNTs/GNS is simply obtained by a direct pyrolysis of K4Fe(CN)6.•Fe3C@NCNTs/GNS exhibits excellent performance for Bisphenol A (BPA) degradation.•1O2 and O2− are responsible for ...BPA removal instead of classical OH and SO4−.•Graphitic carbon framework together with N doping induces the non-radical pathway.•Influences of anions, humic acid, and actual sewages are investigated in detail.
Developing novel carbocatalysts with available strategies for peroxymonosulfate (PMS) activation has become a popular topic in environmental remediation and protection fields. Herein, using commercial K4Fe(CN)6 as the precursor, Fe3C@nitrogen-doped carbon nanotubes/graphene nanosheets (Fe3C@NCNTs/GNS) is synthesized by a direct high-temperature pyrolysis. Characterization results prove that Fe3C@NCNTs/GNS has a relatively high graphitization degree and rich nitrogen doping content, which endow it with excellent catalytic efficiency in PMS activation for powerful removal of Bisphenol A (BPA). Influences of catalyst/oxidant dosages, some inorganic anions, humic acid, and practical sewages are investigated in detail. For mechanism studies, it is found that tert-butyl alcohol (TBA)/methanol fails to inhibit BPA degradation, and the primary reactive oxidative species (ROS) are superoxide radical (O2−) and singlet oxygen (1O2). Discussion on the origin of 1O2 confirms that moderate modification of N atoms in graphitic carbon frameworks plays an essential role in inducing the non-radical mechanism. This work will provide new insights for the preparation of high-performance carbocatalysts in PMS activation and exploring critical roles of N-doping during non-radical processes.
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•Sulfur-doped CN (CNS) is obtained by one-step heat treatment of trithiocyanuric acid.•CNS exhibits much higher surface area and catalytic activity than typical CN.•Effects ...influencing BPA degradation by CNS-activated PMS were investigated.•Mechanisms of BPA degradation and PMS activation by CNS were revealed.•CNS can be re-used to activate PMS for BPA degradation without efficiency loss.
While sulfate radical-generating Advanced Oxidation Processes (AOPs) are promising techniques to degrade Bisphenol A (BPA), transition metals are typically required as catalysts to activate peroxymonosulfate (PMS) to generate sulfate radicals for BPA degradation. To reduce environmental impact and associated costs from metallic catalysts, metal-free catalysts for activating PMS are more attractive and should be further developed. Here, we propose to employ a one-step prepared sulfur-doped carbon nitride (CNS) as a non-metal and easy-to-prepare catalyst to activate PMS for BPA degradation. The as-prepared CNS exhibited a significantly higher surface area and catalytic activity for activating PMS than undoped carbon nitride (CN). Under visible light irradiation, BPA degradation extent and kinetics by CNS-activated PMS were also much higher than CN-activated PMS. The more effectiveness of CNS-activated PMS can be attributed to the synergy of sulfur and nitrogen co-doping, which might enable CNS to exhibit higher catalytic and photo-catalytic activities. Factors influencing BPA degradation were also examined, including temperature, pH, and co-existing ions. CNS-activated PMS was much more favorable to degrade BPA at elevated temperatures and under neutral conditions. The effect of concentrated NaCl did not significantly inhibit PMS activation by CNS for BPA degradation. The mechanism and pathway of BPA degradation by CNS-activated PMS were also proposed by evaluating effects of radical scavengers and degradation intermediates. CNS was also reusable to activate PMS for BPA degradation over multiple cycles without significant efficiency loss. These features demonstrate that CNS is a conveniently-prepared and promisingly effective non-metal catalyst to activate PMS for BPA degradation.
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•ZIF-67 is a stable, hierarchical, and catalytic active substrate for supporting Ru.•Ru/ZIF-67 exhibits higher catalytic activities then Ru for HG from NaBH4 hydrolysis.•The optimal ...NaOH concentration for NaBH4 hydrolysis catalyzed by Ru/ZIF is 7.5%.•Ru/ZIF can be reused for multi-cyclic HG from NaBH4 hydrolysis without regeneration.
H2 generation (HG) from NaBH4 hydrolysis represents as a safe, mild and convenient method for storing and releasing H2. As Ru is the most effective metal for catalyzing NaBH4 hydrolysis, continuous efforts are being made to find suitable supports for immobilizing Ru nanoparticles (NPs) to form heterogeneous Ru catalysts. Since NaBH4 hydrolysis typically occurs in water and at high temperature, an ideal support necessitates high stability in water, high surface area, hierarchical structures and even synergy with Ru. In this study, ZIF-67 is particularly selected as a catalytic active support for immobilizing Ru species because ZIF-67 has proven to be highly stable in water and also hierarchically consists of Co, another catalytic active component for HG from NaBH4 hydrolysis. Compared to ZIF-8, ZIF-67 is validated to catalyze NaBH4 hydrolysis for HG, making Ru/ZIF-67 an enhanced Ru-based catalyst. Ru/ZIF also exhibited a higher catalytic activity than the equivalent Ru species, suggesting that the supporting of Ru on ZIF-67 enhanced catalytic activities of Ru species. As the effect of Ru loading on Ru/ZIF was evaluated, a higher Ru loading significantly boosted catalytic activities by substantially reducing Ea. HG from Ru/ZIF-catalyzed hydrolysis of NaBH4 could be optimized in the presence of 7.5 wt% of NaOH to exhibit a low Ea of 36.4 kJ mol−1, which is much lower than most of reported Ru-based catalysts. In addition, Ru/ZIF can be also re-used with consistent catalytic activities without regeneration. These results validate that Ru/ZIF67 composite is a promising and effective catalyst for H2 production from NaBH4 hydrolysis.
The global population growth demands intensification of anthropogenic processes, thus leading to inter alia pollution of both land and aquatic environments with toxic organic compounds. Particularly ...harmful synthetic compounds are classified as persistent organic pollutants (POPs). Their relatively high chemical resistance resulted in a worldwide ban or strict control on the use of POPs. The majority of POPs were commonly used as pesticides, and unfortunately, some of them are still utilized as an aid in agricultural practices. Therefore, environmental monitoring in terms of reliable detection and quantification of pesticidal POPs is an ever-increasing need. Chemical sensors and adsorption materials crafted for specific pesticide operate on host-guest interactions should provide selectivity and sensitivity, thus leading to the detection of target molecule down to the nanomolar range. This could be achieved with materials exhibiting a very large active surface area, well-defined structure, and high stability. The novel materials studied in that context are metal-organic frameworks (MOFs). The structure of various MOFs can be functionalized to provide desired host-guest interactions. In this mini-review, we critically discuss the application of MOFs for the detection and adsorption of selected pesticides that are classified as POPs according to the Stockholm Convention.
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•Metal-organic frameworks in the detection and adsorption of pesticides are reviewed.•Pesticides that are classified as persistent organic pollutants are discussed.•The need of new materials for persistent organic pollutants research is emphasized.
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•ZIF-67 as the first ZIF for adsorption of Malachite Green (MG) in water is investigated.•Kinetics, equilibrium, thermodynamics of the MG adsorption are determined.•ZIF-67 exhibits ...2430mgg−1 MG adsorption at 20°C and ∼3000mgg−1 at 40°C.•Regeneration efficiency of ZIF-67 for MG is>95% and remains up to 4 cycles.•Removal of MG from the aquaculture wastewater using ZIF-67 is demonstrated.
Zeolitic imidazole frameworks (ZIFs), a new class of adsorbents, are proposed to adsorb Malachite Green (MG) in water. Particularly, ZIF-67 was selected owing to its stability in water and straightforward synthesis. The as-synthesized ZIF-67 was characterized and used to adsorb MG from water. Factors affecting the adsorption capacity were investigated including mixing time, temperature, the presence of salts and pH. The kinetics, adsorption isotherm and thermodynamics of the MG adsorption to ZIF-67 were also studied. The adsorption capacity of ZIF-67 for MG could be as high as 2430mgg−1 at 20°C, which could be improved at the higher temperatures. Such an ultra-high adsorption capacity of ZIF-67 was almost 10-times of those of conventional adsorbents, including activated carbons and biopolymers. A mechanism for the high adsorption capacity was proposed and possibly attributed to the π–π stacking interaction between MG and ZIF-67. ZIF-67 also could be conveniently regenerated by washing with ethanol and the regeneration efficiency could remain 95% up to 4 cycles of the regeneration. ZIF-67 was also able to remove MG from the aquaculture wastewater, in which MG can be typically found. These features enable ZIF-67 to be one of the most effective and promising adsorbent to remove MG from water.
Food waste is one of the world’s most serious environmental issues, with waste and losses generated at every stage of the food supply chain. There are various waste management methods for the ...disposal of food waste, but these have several problems such as high costs, the generation of toxic by-products, and environmental pollution. Pyrolysis has recently attracted increased interest as a potentially sustainable and environmentally friendly solution for the valorization of food waste via the development of novel products. This review focuses on state-of-the-art non-catalytic and catalytic pyrolysis processes for a wide range of food waste types that can generate high-quality liquid, solid, and gas phase products. The aim of this study is to review the effect of the reaction parameters and catalyst selection on pyrolysis performance and the distribution of pyrolytic products. This is because the production of desired compounds such as bio-oil, syngas, and biochar primarily depends on these factors. Here, we highlight the results for several methods of food waste pyrolysis that utilize different materials, catalysts, and microwave irradiation settings. This review also discusses the drawbacks of current pyrolysis technology and suggests further research that needs to be conducted on the transformation of food waste into value-added products.
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•ZIF–MG shows a high adsorption capacity for benzotriazole (BTA) beyond 300mgg−1.•Adsorption kinetics, isotherm and thermodynamics are obtained and modeled.•Factors affecting the BTA ...adsorption are examined including pH, salts and surfactants.•ZIF–MG exhibits a higher selectivity toward BTA over benzimidazole in adsorption.•ZIF–MG is re-used and the regeneration efficiency remains above 98% over 4 cycles.
Benzotriazole (BTA) is extensively-used in industry and households, leading to the increasing detection of BTA in surface water and wastewater. The toxicity of BTA renders it harmful to aquatic organisms and even human; thus BTA has been recognized as an emerging pollutant. Although adsorption is preferable to remove BTA from water, adsorbents proposed for BTA adsorption are quite limited. Considering the positive surface charge and high BTA adsorption capacity of zeolitic imidazole frameworks (ZIFs), a self-assembly of ZIF-67 and negatively-charged magnetic reduced graphene oxide (MG) is prepared via the electrostatic attraction. The resultant ZIF–MG preserves chemical characteristics of ZIF-67 and magnetic property of MG. Thus, ZIF–MG not only shows a high adsorption capacity for BTA but also exhibits magnetic controllability, allowing ZIF–MG to be recovered easily by magnets. The adsorption kinetics, isotherms, and thermodynamics are also determined. With a maximal adsorption capacity of ∼300mgg−1, ZIF–MG is one of the most effective adsorbents when compared with reported adsorbents. ZIF–MG also exhibited relatively stable adsorption capacities at pH=4–9 and a higher selectivity over benzimidazole. Effects of salts and ionic surfactants are insignificant on the BTA adsorption to ZIF–MG. ZIF–MG can be also re-used for the BTA adsorption for multiple cycles and the regeneration efficiency remained 98%. The high adsorption capacity and the magnetically recoverable feature make ZIF–MG a promising and potent adsorbent for BTA in water.
Although perovskites are extensively investigated in many areas, studies using perovskites as catalysts to activate oxidants for chemical oxidations are still quite limited. While various transition ...metals can be inserted into perovskites to form different perovskites, it is critical to investigate the effects of various transition metallic substituents on the activation of oxidants in chemical oxidation reactions. In this study, we propose to evaluate various metallic substituents in Lanthanum (La)-based perovskites (LaMO3 (M: Co, Cu, Fe and Ni)) for activating a strong oxidant, peroxymonosulfate (POMS), in order to degrade organic contaminants. Rhodamine B (RB) decolorization is used as a model test to evaluate generation of sulfate radicals from activation of POMS by LaMO3. LaCoO3 was found to exhibit the highest catalytic activity, followed by LaNiO3, LaCuO3 and then LaFeO3. LaCoO3 was then selected as a representative LaMO3 to be further investigated for the behavior of POMS activation under various conditions. LaCoO3-activated POMS was favorable under neutral conditions and at high temperatures, but less effective in the presence of NaCl. The mechanism of RB decolorization by LaCoO3-activated POMS was elucidated by examining the effects of radical inhibitors and attributed primarily to sulfate radicals and hydroxyl radicals to a lesser extent. We also found that both La3+ and Co3+/Co2+ ions contribute to catalytic decomposition of POMS for yielding sulfate radicals. LaCoO3 was also shown to activate POMS for RB decolorization over multiple trials without losing efficiency. These results reveal that LaCoO3 is a recyclable and effective La-based perovskite for POMS activation, which can be used for degradation of organic contaminants.
•LaMO3 (M: Co, Cu, Fe, and Ni) are studied for activating peroxymonosulfate (POMS).•RB decolorization is used as a model test to evaluate POMS activation by LaMO3.•Kinetics and activation energies of RB decolorization by LaMO3 are determined.•LaCoO3 is the most effective LaMO3 to activate POMS for degrading RB dye.•Mechanisms of RB decolorization and activation of POMS by LaCoO3 are revealed.
Heteroatom-doped carbon materials have emerged as attractive catalysts for peroxymonosulfate (PMS) activation and environment remediation recently due to its low cost and non-toxicity. In this study, ...novel N, P, and S tri-doped hollow carbon shells (NPSC) are elaborately fabricated using ZIF-67 and poly (cyclotriphosphazene–co-4,4′- sulfonyldiphenol) (PZS) as precursors. NPSC obtained at 700 °C shows better performance than those at other temperature (600 and 800 °C), and it can effectively degrade 90.1% of Bisphenol A (BPA) in the presence of PMS, which totally exceeds the performance of several common catalysts. It is found that for used catalyst, surface oxidation of carbon networks and blockage of heteroatom-doping active sites are two main reasons for the deterioration of reusability. Electron paramagnetic resonance (EPR) measurements and radical quenching tests are conducted to reveal that hydroxyl, sulfate, and superoxide radicals are main reactive species for BPA degradation in NPSC/PMS systems. Finally, it is proposed that synergistic effects of N, P, and S doping may greatly break the electroneutrality of pristine carbon structures, promote the O-O breakage of PMS, and facilitate the generation of radicals. Such findings dedicate to enlighten new thoughts and deeper understanding for synthesis of heteroatom-doped porous carbon in PMS activation.
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