Environmental pollution due to humankind’s often irresponsible actions has become a serious concern in the last few decades. Numerous contaminants are anthropogenically produced and are being ...transformed in ecological systems, which creates pollutants with unknown chemical properties and toxicity. Such chemical pathways are usually examined in the laboratory, where hours are often needed to perform proper kinetic experiments and analytical procedures. Due to increased computing power, it becomes easier to use quantum chemistry computation approaches (QCC) for predicting reaction pathways, kinetics, and regioselectivity. This review paper presents QCC for describing the oxidative degradation of contaminants by advanced oxidation processes (AOP, i.e., techniques utilizing •OH for degradation of pollutants). Regioselectivity was discussed based on the Acid Blue 129 compound. Moreover, the forecasting of the mechanism of hydroxyl radical reaction with organic pollutants and the techniques of prediction of degradation kinetics was discussed. The reactions of •OH in various aqueous systems (explicit and implicit solvation) with water matrix constituents were reviewed. For example, possible singlet oxygen formation routes in the AOP systems were proposed. Furthermore, quantum chemical computation was shown to be an excellent tool for solving the controversies present in the field of environmental chemistry, such as the Fenton reaction debate main species were determined to be: •OH < pH = 2.2 < oxoiron(IV). An ongoing discussion on such processes concerning similar reactions, e.g., associated with sulphate radical-based advanced oxidation processes (SR-AOP), could, in the future, be enriched by similar means. It can be concluded that, with the rapid growth of computational power, QCC can replace most of the experimental investigations related to the pollutant’s remediation in the future; at the same time, experiments could be pushed aside for quality assessment only.
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•UVA-LED/CFO-rGO/PMS system was highly effective for BPA degradation.•The effect of reaction parameters for BPA degradation was completely studied.•Degradation intermediates were ...determined and degradation pathway was proposed.•CFO-rGO had high stability and low metal leaching.•Ecotoxicity of BPA and intermediates were evaluated by ECOSAR.
In this work, CoFe2O4-reduced graphene oxide (CFO-rGO) nanocomposite was synthesized to activate peroxymonosulfate (PMS) under UVA-LED irradiation. Bisphenol A (BPA) was selected as an emerging pollutant to evaluate the performance of the UVA-LED/CFO-rGO/PMS system. CFO-rGO was characterized by several advanced methods including XRD, FTIR, FESEM, EDX-mapping, TEM, XPS, BET-BJH, Raman spectrometry, VSM, PL, and EIS analyses. The operating factors, the determination of reactive species, and the mechanism were studied and discussed. During 30 min reaction time, more than 99% of BPA was removed by 150 mg/L PMS and 400 mg/L CFO-rGO under mild conditions (pH = 3–9). Bicarbonate ions could inhibit the BPA degradation by scavenging the free radicals. The trapping experiments exhibited that sulfate (SO4•-) and hydroxyl (•OH) radicals were prevailing agents for BPA degradation. Humic acid (HA) and sodium dodecyl sulfate (SDS) had a hindering effect on BPA degradation. CFO-rGO showed a high potential for recyclability up to six cycles. Moreover, the leaching of metals was approximately null for CFO-rGO, indicating that the current nanocomposite is highly stable. We also examined UVA-LED/CFO-rGO/PMS system on other pollutants, as well as real conditions. The results showed high efficiency for all conditions. The UVA-LED/CFO-rGO/PMS process could mineralize 67% of BPA during 80 min reaction time. Intermediates of BPA degradation were identified and their toxicity was also estimated. This work enlightened the ferrite catalysts' importance in activating PMS under UVA-LED irradiation for emerging pollutants wastewater remediation.
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•Chemical and physical properties of persulfates were described in detail.•Up-to-date list of persulfates activation and determination methods was created.•Direct oxidation, radical ...oxidation and matrix effects were discussed.•Recent developments in the use of persulfates in waters and wastewaters were shown.
Persulfate decontamination technologies either utilizing radical driven processes or direct electron transfer are very powerful tools for the treatment of a broad range of impurities, including halogenated olefins, BTEXs (benzene, toluene, ethylbenzene and xylenes), perfluorinated chemicals, phenols, pharmaceuticals, inorganics and pesticides. Furthermore, the reactivity of persulfates is extremely dependent on the related activation techniques and the composition of the treated water matrix. Direct reactions of peroxydisulfate (PDS) or peroxymonosulfate (PMS) are rather slow and mostly unsuitable for pollutant degradation. However, PDS or PMS decompose at elevated temperatures under UV radiation, and radiolysis treatment as well as in presence of reduced metal ions to form sulfate radicals (SO4−). (SO4−)-based oxidation can also form secondary oxidants for instance carbonate radicals, hydroxyl radicals, superoxide radicals or singlet oxygen which can influence both transformation efficiency and product formation. The formation of such species is extremely subjected on the water matrix composition and can hardly be predicted. One important aspect in dealing with PDS or PMS is their analysis, which is often prone for interference by other matrix components and hampered by the low stability of PDS and PMS in aqueous systems. Numerous methods for analysis of PDS and PMS are available. The present work also provides an overview on these methods.
In recent years, there has been growing interest on the application of advanced oxidation processes (AOPs) based on sulfate radical in the elimination of organic contaminants. In such processes, ...sulfate radical is typically generated from the activation of peroxymonosulfate (PMS) or peroxydisulfate (PDS). In this paper, generation of sulfate radical by various methods and mechanism of activation processes for PMS or PDS were discussed. Moreover, certain applications of sulfate radical-based AOPs in wastewater, groundwater, and soil remediation were also summarized. More strategies, such as developing stable and highly efficient metal oxide activators, fabricating efficient carbonaceous-based materials, and combining with other treatment technologies, should be considered in further applications of sulfate radical-based advanced oxidation processes (SR-AOPs). In addition, more attention should be paid to elucidate the underlying mechanisms by coupling experimental analysis with theoretical models. The generation of toxic byproducts, high level of sulfate ion, and complex quenching reactions are pointed out as main limitations. Finally, further studies on mechanistic aspects of the chemistry involved and evaluation of the potential for on-site applications are desired to further explore implementation of such SR-AOPs.
UV-E-chlorination/hematite nanoparticles (UV/E-Cl/HNs) as a heterogeneous photocatalytic activation of electrogenerated chlorine was assessed for the degradation of bisphenol A (BPA) as a new ...approach based on the generation of reactive chlorine and oxygen species. The prepared sample was characterized using multiple techniques, such as XRD, FTIR, FESEM, EDS, and BET-BJH. An excellent decontamination efficiency of 99.4% was achieved within 40 min of electrolysis under optimum conditions (pH of 5, HNs dosage 100 mg/L, current density of 20 mA/cm2, and NaCl concentration of 50 mM). The HOCl content was reduced more swiftly in the presence of ultraviolet (UV) irradiation and hematite, resulting in the production of oxidative radicals (i.e., •OH, Cl•, and Cl2•−). The scavenging experiments also verified the vital role of these radicals in oxidative treatment. The UV/E-Cl/HNs process is readily supplied with hydroxyl radicals through several mechanisms. Bicarbonate ions showed a noticeable inhibitory impact, whereas nitrate and sulfate anions only slightly affected BPA degradation. The HNs were a recoverable and stable catalyst for six cycles. Furthermore, the ECOSAR program predicted that the UV/E-Cl/HNs can be labeled as an environmental-friendly process. Eventually, reasonable degradation pathways were proposed based on the identified by-products through experimental and theoretical approaches.
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•Electrogenerated chlorine was activated by UV and Fe2O3 (HNs) simultaneously.•BPA was completed degraded by E-Cl/UV/HNs during 40 min electrolysis time.•Hydroxyl radicals (•OH) and dichlorine radical (Cl2•-) were the main responsible for BPA degradation.•The pathway of BPA degradation was evaluated and the toxicity of by-products was assessed.
Contaminated water with landfill leachate (CWLL) with high salinity and high organic content (total organic carbon (TOC) = 649 mg/L and Chemical Oxygen Demand (COD) = 1175 mg/L) is a toxic and ...non-biodegradable effluent. The present research aimed to assess the treatment effectiveness of CWLL by electrocoagulation (EC)/oxidant process. The ferrous ions generated during the process were employed as coagulant and catalyst for the activation of different oxidants such as peroxymonosulfate (PMS), peroxydisulfate (PDS), hydrogen peroxide (HP), and percarbonate (PC) to decrease TOC in CWLL. Removal of ammonia, color, phosphorous, and chemical oxygen demand (COD) from CWLL effluent was explored at various processes. EC/HP had the best performance (∼73%) in mineralization of organic pollutants compared to others under the condition of pH 6.8, applied current of 200 mA, oxidant dosage of 6 mM, and time of 80 min. The oxidation priority was to follow this order: EC/HP > EC/PMS > EC/PDS > EC/PC. These processes enhanced the biodegradability of CWLL based on the average oxidation state and biochemical oxygen demand (BOD)/COD ratio. SUVA254 and E2/E3 indices were also investigated on obtained effluents. The phytotoxicity evaluation was carried out based on the germination index, indicating that the electro-activated oxidant was an effective system to reduce the toxicity of polluted waters. EC/HP showed supremacy compared to others in terms of efficiency, cost, and detoxification. Therefore, the electro-activated oxidant system is a good means for removing organic pollutants from real wastewater.
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•PC, HP, PDS, and PMS were used in EC to treat CWLL.•COD, ammonia, TOC, color, and phosphorous were monitored in different processes.•Phytotoxicity, biodegradability, and humification of each effluent were evaluated.•Economic analysis showed that EC/HP is the best option for the treatment.
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•US-assisted heterogeneous electro-Fenton (SEF) was evaluated for the first time.•SEF-HNPs is a novel EAOP with ~99% PCT degradation during 60 min.•Sonocatalysis of HNPs improved ...considerably SEF performance.•SEF-HNPs outperforms other processes in the detoxification of the PCT solution.
Pharmaceuticals are one of the most reported categories of anthropogenic micropollutants, which often require a specific remediation type to be eliminated from the environment. This study aimed to address the potential of degrading the pharmaceutical pollutant paracetamol (PCT) in the aqueous environment under ultrasound (US) assisted electro-Fenton by Fe2O3 (hematite) nanoparticles (HNPs) as a catalyst. The synthesized sample was characterized by various techniques including XRD, FESEM, EDS, X-ray dot-mapping, and FTIR. The performance of the electro-Fenton (EF) and US processes was evaluated separately and in combination under optimum conditions. The results showed that the sonoelectro-Fenton (SEF) process under optimum conditions, including pH of 5, HNPs dosage 0.15 g/L, applied current 230 mA, initial PCT concentration 20 mg/L, resulted in a PCT degradation of 98.9% within 60 min of electrolysis time. PCT degradation was well-fitted to the pseudo-first-order kinetic model. Meanwhile, scavenging experiments indicated the vital role of OH in the decomposition of PCT compared to the negligible role of O2∙-. The nitrate ions had a strong inhibitory effect, whereas chloride anions affected PCT elimination slightly. The reusability test of HNPs revealed that almost a 14% drop occurred at the end of the fourth cycle. The HNPs showed high catalytic activity for degradation of PCT compared to other conventional homogeneous transition metals. Besides, SEF-HNPs can successfully detoxify the PCT solution based on the bioassay test. The by-products of PCT degradation by SEF-HNPs were determined and degradation pathway was also proposed. Conclusively, the SEF-HNPs process could be an appropriate system for the removal of various contaminants from aqueous solutions.
•A smart energy-comfort system was presented for green roofs in building.•Green roof parameters optimised for energy conservation and thermal comfort.•Optimised green roofs increase comfort by 12.8% ...and reduce energy by 14%.•ANFIS used for Energy-Comfort prediction with correlation coefficient >0.97.•There are potential total greenhouse gas emissions reduction of 89,360 tCO2.
The rise in greenhouse gas emissions in cities and the excessive consumption of fossil energy resources has made the development of green spaces, such as green roofs, an increasingly important focus in urban areas. This study proposes a novel smart energy-comfort system for green roofs in housing estates that utilises integrated machine learning (ML), DesignBuilder (DB) software and Taguchi design computations for optimising green roof design and operation in buildings. The optimisation process maximises energy conservation and thermal comfort of the green roof buildings for effective parameters of green roofs including Leaf Area Index (P1), leaf reflectivity (P2), leaf emissivity (P3), and stomatal resistance (P4). The optimal solutions can result in a 12.8% increase in comfort hours and a 14% reduction in energy consumption compared to the base case. The ML analysis revealed that the adaptive network-based fuzzy inference system is the most appropriate method for predicting Energy-Comfort functions based on effective parameters, with a correlation coefficient greater than 97%. This novel smart framework for the optimal design of green roofs in buildings offers an innovative approach to achieving energy conservation and thermal comfort in urban areas.
The food packaging industry explores economically viable, environmentally benign, and non-toxic packaging materials. Biopolymers, including chitosan (CH) and gelatin (GE), are considered a leading ...replacement for plastic packaging materials, with preferred packaging functionality and biodegradability. CH, GE, and different proportions of silver nanoparticles (AgNPs) are used to prepare novel packaging materials using a simple solution casting method. The functional and morphological characterization of the prepared films was carried out by using Fourier transform infrared spectroscopy (FTIR), UV–Visible spectroscopy, and scanning electron microscopy (SEM). The mechanical strength, solubility, water vapor transmission rate, swelling behavior, moisture retention capability, and biodegradability of composite films were evaluated. The addition of AgNPs to the polymer blend matrix improves the physicochemical and biological functioning of the matrix. Due to the cross-linking motion of AgNPs, it is found that the swelling degree, moisture retention capability, and water vapor transmission rate slightly decrease. The tensile strength of pure CH–GE films was 24.4 ± 0.03, and it increased to 25.8 ± 0.05 MPa upon the addition of 0.0075% of AgNPs. The real-time application of the films was tested by evaluating the shelf-life existence of carrot pieces covered with the composite films. The composite film containing AgNPs becomes effective in lowering bacterial contamination while comparing the plastic polyethylene films. In principle, the synthesized composite films possessed all the ideal characteristics of packaging material and were considered biodegradable and biocompatible food packaging material and an alternate option for petroleum-based plastics.
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