Metronidazole degradation mechanism by sono-photo-Fenton processes using a spinel ferrite cobalt on activated carbon catalyst.

A heterogeneous catalyst was prepared by anchoring spinel cobalt ferrite nanoparticles on porous activated carbon (SCF@AC). The catalyst was tested to activate hydrogen peroxide (HP) in the Fenton degradation of metronidazole (MTZ). SCF nanoparticles were produced through the co-precipitation of iron and cobalt metal salts in an alkaline condition. Elemental mapping, physico-chemical, morphological, structural, and magnetic properties of the as-fabricated catalyst were analyzed utilizing EDX mapping, FESEM-EDS, TEM, BET, XRD, and VSM techniques. The porous structure of AC enhanced the catalytic activity of SCF by a significant decrease in the agglomeration of SCF nanoparticles. The effectiveness of SCF@AC in Fenton degradation improved substantially when UV light and ultrasound (US) irradiations were induced, most likely due to the strong synergistic effect between the catalyst and these irradiation sources. The photo-Fenton system was more efficient than the Fenton, sono-, and sono-photo-Fenton processes eliminating both MTZ and TOC. It was found that AC not only dispersed SCF nanoparticles and improved the stability of the catalyst, but also provided a high adsorption capacity of MTZ, resulting in a faster degradation. After 60 min of the photo-Fenton reaction, the elimination efficiencies of MTZ (30 mg L-1) and TOC were 97 and 42.1% under optimum operational conditions (pH = 3.0, HP = 4.0 mM, SCF@AC = 0.3 g L-1, and UV = 6 W). SCF@AC showed excellent stability with low leaching of metal ions during the reaction. Radical and non-radical (O2•-, HO•, and 1O2 species), alongside adsorption and photocatalysis mechanisms, were responsible for MTZ decontamination over the SCF@AC/HP/UV system. A comprehensive study on the HP activation mechanism and MTZ degradation pathway was obtained through scavenging tests. The findings demonstrate that SCF@AC is an effective, reusable, and environmentally sustainable catalyst for advanced oxidation processes that can effectively remove organic pollutants from wastewater. This study offers valuable insights into the feasibility of employing SCF@AC catalysts in Fenton-based processes for the degradation of MTZ.

Spinel cobalt ferrite-based porous activated carbon in conjunction with UV light irradiation for boosting peroxymonosulfate oxidation of bisphenol A.

Developing heterogeneous catalysts with high performance for peroxymonosulfate (PMS) activation to decontaminate organic pollutants from wastewater is of prominent importance. In this study, spinel cobalt ferrite (CoFe2O4) materials were coated on the surface of powdered activated carbon (CoFe2O4@PAC) via the facile co-precipitation method. The high specific surface area of PAC was beneficial for the adsorption of both bisphenol A (BP-A) and PMS molecules. The CoFe2O4@PAC-mediated PMS activation process under UV light could effectively eliminate 99.4% of the BP-A within 60 min of reaction. A significant synergy effect was attained between CoFe2O4 and PAC towards PMS activation and subsequent elimination of BP-A. Comparative tests demonstrated that the heterogeneous CoFe2O4@PAC catalyst had a better degradation performance in comparison with its components and homogeneous catalysts (Fe, Co, and, Fe + Co ions). The formed by-products and intermediates during BP-A decontamination were evaluated using LC/MS analysis, and then a possible degradation pathway was proposed. Moreover, the prepared catalyst exhibited excellent performance in recyclability with slight leaching amounts of Co and Fe ions. A TOC conversion of 38% was obtained after five consecutive reaction cycles. It can be concluded that the PMS photo-activation process via the CoFe2O4@PAC catalyst can be utilized as an effective and promising method for the degradation of organic contaminants from polluted-water resources.

Peroxymonosulfate assisted pesticide breakdown: Unveiling the potential of a novel S-scheme ZnO@CoFe2O4 photo-catalyst, anchored on activated carbon.

A ternary hetero-junction was prepared by anchoring ZnO@CoFe2O4 (ZCF) on activated carbon (AC) and employed as a UV-assisted peroxymonosulfate (PMS) activator to boost the degradation of diazinon (DZN) pesticide. The structure, morphology, and optical properties of the ZCFAC hetero-junction were characterized through a series of techniques. The highest degradation efficiency of DZN (100% in 90 min) was achieved by the PMS-mediated ZCFAC/UV system, superior to other single or binary catalytic systems due to the strong synergistic effect between ZCFAC, PMS, and UV. The operating reaction conditions, synergistic effects, and the possible pathways of DZN degradation were investigated and discussed. Optical analysis showed that the band-gap energy of the ZCFAC hetero-junction not only enhanced the absorption of UV light but also reduced the recombination of photo-induced electron/hole pairs. Both radical and non-radical species (HO•, SO4•-, O2•-, 1O2, and h+) took part in the photo-degradation of DZN, assessed by scavenging tests. It was found that AC as a carrier not only improved the catalytic activity of CF and ZnO nanoparticles and conferred high stability for the catalyst but also played a crucial role in accelerating the catalytic PMS activation mechanism. Moreover, the PMS-mediated ZCFAC/UV system showed good reusability, universality, and practical applicability potential. Overall, this work explored an efficient strategy for the best use of hetero-structure photo-catalysts towards PMS activation to achieve high performance in decontaminating organic compounds.

Synergetic Photocatalytic Peroxymonosulfate Oxidation of Benzotriazole by Copper Ferrite Spinel: Factors and Mechanism Analysis.

The development of oxidation processes with the efficient generation of powerful radicals is the most interesting and thought-provoking dimension of peroxymonosulfate (PMS) activation. This study reports the successful preparation of a magnetic spinel of CuFe2O4 using a facile, non-toxic, and cost-efficient co-precipitation method. The prepared material exhibited a synergetic effect with photocatalytic PMS oxidation, which was effective in degrading the recalcitrant benzotriazole (BTA). Moreover, central composite design (CCD) analysis confirmed that the highest BTA degradation rate reached 81.4% after 70 min of irradiation time under the optimum operating conditions of CuFe2O4 = 0.4 g L-1, PMS = 2 mM, and BTA = 20 mg L-1. Furthermore, the active species capture experiments conducted in this study revealed the influence of various species, including •OH, SO4•-, O2•-, and h+ in the CuFe2O4/UV/PMS system. The results showed that SO4•- played a predominant role in BTA photodegradation. The combination of photocatalysis and PMS activation enhanced the consumption of metal ions in the redox cycle reactions, thus minimizing metal ion leaching. Additionally, this maintained the reusability of the catalyst with reasonable mineralization efficiency, which reached more than 40% total organic carbon removal after four batch experiments. The presence of common inorganic anions was found to have a retardant effect on BTA oxidation, with the order of retardation following: HCO3- > Cl- > NO3- > SO42-. Overall, this work demonstrated a simple and environmentally benign strategy to exploit the synergy between the photocatalytic activity of CuFe2O4 and PMS activation for the treatment of wastewater contaminated with widely used industrial chemicals such as BTA.

Putting the electro-bugs to work: A systematic review of 22 years of advances in bio-electrochemical systems and the parameters governing their performance.

Wastewater treatment using bioelectrochemical systems (BESs) can be considered as a technology finding application in versatile areas such as for renewable energy production and simultaneous reducing environmental problems, biosensors, and bioelectrosynthesis. This review paper reports and critically discusses the challenges, and advances in bio-electrochemical studies in the 21st century. To sum and critically analyze the strides of the last 20+ years on the topic, this study first provides a comprehensive analysis on the structure, performance, and application of BESs, which include Microbial Fuel Cells (MFCs), Microbial Electrolysis Cells (MECs) and Microbial Desalination Cells (MDCs). We focus on the effect of various parameters, such as electroactive microbial community structure, electrode material, configuration of bioreactors, anode unit volume, membrane type, initial COD, co-substrates and the nature of the input wastewater in treatment process and the amount of energy and fuel production, with the purpose of showcasing the modes of operation as a guide for future studies. The results of this review show that the BES have great potential in reducing environmental pollution, purifying saltwater, and producing energy and fuel. At a larger scale, it aspires to facilitate the path of achieving sustainable development and practical application of BES in real-world scenarios.

Establishing the relationship between Polycyclic Aromatic Hydrocarbons (PAHs) exposure and male infertility: A systematic review.

It has been demonstrated that human exposure to environmental chemicals may have sperm genotoxic potentiality. Among the different classes, Polycyclic Aromatic Hydrocarbons (PAHs) have been receiving attention in recent years due to reports of sperm geno-toxicity, a series of reproductive defects and male infertility. This review aims to substantiate the effects of PAHs exposure on male infertility, with focus on the sperm characteristics (count, concentration, volume, motility, DNA damage, and morphology). To this end, international databases such as Cochrane Library, PubMed, Web of Science, Embase Ovid, Scopus, and Google Scholar were used to conduct a systematic search for papers on the subject, based on PRISMA guidelines, published up to 24 March 2022. The Newcastle-Ottawa Scale was subsequently used to assess the quality of the studies. The results showed that there is a significant negative relationship between PAHs metabolites and sperm volume, concentration, motility, morphology, as well as an observed DNA degeneration. Also, the CYP1A1 genotype polymorphisms were considered as a representative of PAHs exposure to infertility; the review highlights that polymorphisms of this genotype were more common in the infertile people. In overall, this work provides a solid summary of the existing works correlating PAHs exposure and male infertility, which could impulse further protective measures and informative campaigns on users, workers, and general population.

Anchoring ZnO on spinel cobalt ferrite for highly synergic sono-photo-catalytic, surfactant-assisted PAH degradation from soil washing solutions.

In this study, the photocatalytic activity of ZnO was effectively improved via its combination with spinel cobalt ferrite (SCF) nanoparticles. The catalytic performance of ZnO@SCF (ZSCF) was investigated in coupling with UV irradiation and ultrasound (US), as a heterogeneous sono-photocatalytic process, for the decontamination of phenanthrene (PHE) from contaminated soil. Soil washing tests were conducted in a batch environment, after extraction assisted by using Tween 80. Several characterization techniques such as XRD, FESEM-EDS, BET, TEM, UV-vis DRS, PL and VSM were utilized to determine the features of the as-prepared catalysts. ZSCF showed an excellent catalytic activity toward degradation of PHE in the presence of US and UV with a significant synergic effect. It was found that more than 93% of PHE (35 mg/L) and 87.5% of TOC could be eliminated by the integrated ZSCF/US/UV system under optimum operational conditions (pH: 8.0, ZSCF: 1.5 g/L, UV power: 6.0 W and US power: 70 W) within 90 min of reaction. After five times of use, ZSCF illustrated good reusability in the decontamination of PHE (87%) and TOC (79%). Quenching tests revealed the contribution of h+, HO• and e- species during PHE degradation over ZSCF/UV/US and an S-scheme photocatalytic mechanisms was proposed for the possible charge transfer routes under the ZSCF system. This study provides the important role of SCF in enhancing the ZnO photocatalytic activity due to its high performance, easy recovery and excellent durability, which it make an efficient and promising catalyst in environmental clean-up applications.

Improved catalytic performance of ZnO via coupling with CoFe2O4 and carbon nanotubes: A new, photocatalysis-mediated peroxymonosulfate activation system, applied towards Cefixime degradation.

In this study, a ternary ZnO@spinel cobalt ferrite@carbon nanotube magnetic photocatalyst (ZSCF@CNT) was successfully synthesized and used to activate peroxymonosulfate (PMS) for Cefixime (CFX) antibiotic degradation under UVC irradiation. The morphology, optical, structural, and physicochemical properties of ZSCF@CNT were characterized and analyzed by XPS, XRD, FESEM-EDX, TEM, BET, VSM, UV-vis DRS and PL analysis. The results indicated that the ternary ZSCF@CNT photocatalyst exhibited superior catalytic activity on CFX elimination than that of individual components and binary composite catalysts, in which CFX with was rapidly removed under UVC irradiation and PMS. The effect of operational parameters including initial PMS, catalyst, and CFX concentrations and solution pH on the catalytic activity was investigated in detail; the optimal conditions were: pH: 7.0, catalyst: 0.3 g/L, PMS: 3.0 mM, leading to total CFX (10 mg/L) elimination in ∼20 min. Based on the radical scavenger tests, various radicals and non-radical species including sulfate, hydroxyl and superoxide radicals, singlet oxygen and electrons were involved in the ZSCF@CNT/PMS/UVC system. The high surface area, reduced agglomeration formation and excellent separation of photogenerated electron-hole pairs embodied in ZSCF@CNT photocatalyst conferred its superior catalytic activity and stability. The results from the tests in real water matrices revealed that ZSCF@CNT could be a promising photocatalyst to activate PMS for actual aqueous matrices' treatment.

A novel, Z-scheme ZnO@AC@FeO photocatalyst, suitable for the intensification of photo-mediated peroxymonosulfate activation: Performance, reactivity and bisphenol A degradation pathways.

In this study, the intensification of a UVC-based PMS activation treatment is performed by a novel photocatalyst. Using ZnO nanoparticles coupled with activated carbon (AC), impregnated by ferroferric oxides (FO, magnetite), as an effective Z-scheme photocatalyst (ZACFO), the effective Bisphenol A (BP-A) removal was attained. Several techniques were applied for the characterization of the as-prepared catalyst and proved the successful preparation of ZACFO. The photocatalytic activity of pristine ZnO was significantly improved after its combination with ACFO. It was found that the fabrication of ZACFO heterostructures could inhibit the charge carriers recombination and also accelerate the charge separation of photo-induced e-/h+ pairs. Under this UVC-based photocatalysis-mediated PMS activation system, ZACFO showed an excellent potential as compared to the single constituent catalysts. The complete degradation of 20 mg/L concentration of BP-A was attained in just 20 min with excellent reaction rate constant of 27.3 × 10-2 min-1. Besides, over 60% of TOC was eliminated by the integrated ZACFO/PMS/UV system within 60 min of reaction. The minor inhibition by most matrix components, the high recycling capability with minor metals' leaching and the effectiveness in complex matrices, constitute this composite method an efficient and promising process for treating real wastewater samples. Finally, based on the photo-produced reactive intermediates and by-products identified, the Z-scheme photocatalytic mechanism and the plausible pathway of BP-A degradation were proposed comprehensively. The presence and role of radical and non-radical pathways in the decontamination process of BP-A over ZACFO/PMS/UV system was confirmed.

Exploring the visible light-assisted conversion of CO2 into methane and methanol, using direct Z-scheme TiO2@g-C3N4 nanosheets: synthesis and photocatalytic performance.

The rapid growth of carbon dioxide (CO2) emissions raises concern about the possible consequences of atmospheric CO2 increase, such as global warming and greenhouse effect. Photocatalytic CO2 conversion has attracted researchers' interests to find a sustainable route for its elimination. In the present study, a direct Z-scheme TiO2/g-C3N4 composite (T-GCN) was fabricated via a facile hydrothermal route for the photocatalytic reduction of CO2 into methane (CH4) and methanol (CH3OH), under visible light irradiation without an electron mediator. The microstructure of the as-obtained TiO2/g-C3N4 nanocomposites was fully characterized for its physicochemical, structural, charge separation, electronic, and photo-excited carrier separation properties. The effect of CO2 and H2O partial pressure was studied to find the best operational conditions for obtaining maximum photocatalytic efficiency; the PCO2 and PH2O were 75.8 and 15.5 kPa, respectively, whereas, by increasing the light intensity from 20 to 80 mW/cm2, a remarkable improvement in the reduction rate takes place (from 11.04 to 32.49 µmol.gcat-1.h-1 methane production, respectively). Finally, under the most favorable light, PCO2 and PH2O conditions, high methanol and methane rates were obtained from the CO2 photocatalytic reduction through T-GCN (1.44 µmol.gcat.-1.h-1 and 32.49 µmol.gcat.-1.h-1, respectively) and an integrated proposition for the Z-scheme mechanism of photocatalytic reduction was proposed. This study offers a promising strategy to synthesize a Z-scheme T-GCN heterojunction with high photocatalytic performance for effective CO2 conversion.

Effective promotion of g-C3N4 photocatalytic performance via surface oxygen vacancy and coupling with bismuth-based semiconductors towards antibiotics degradation.

In this research, the potential of bismuth chromate (BCO), a new bismuth-based semiconductor belongs to the family of Bi2XO6 (X = Mo, W, or Cr), was introduced by a novel 1D/2D structure consist of BCO nanobelts and N2-freezed ultra-wrinkled graphitic carbon nitride (N-CN) nanosheets. To enhance intimate contact between BCO and N-CN (BCO/N-CN composite), surface oxygen vacancy (VO) was created as an efficient electron transfer highway using a simple alkaline-treatment-assisted method. Various characterization techniques, including XRD, FT-IR, EPR, FE-SEM, TEM, BET, DRS, PL, EIS, and photocurrent transient analyses were conducted to elucidate the physicochemical aspects of catalysts. The synthesized catalysts were subjected to levofloxacin (LVFX) photodegradation and optimum conditions were found under LED irradiation. Under optimum conditions, about 92.5% of LVFX was catalytically degraded over VO-rich BCO/N-CN heterojunction after 120 min of reaction, which was 2.3 folds higher than that of VO-free composite. The obtained heterojunction maintained superior performance after five consecutive runs with no noticeable changes in the XRD and FT-IR patterns, demonstrating the high stability of synthesized nanocomposite. Thus, the proposed interfacial engineering in this study opens new insight for ameliorating the insufficient interfacial contact between components of heterojunctions. This study not only presents a new bismuth-based photocatalyst for antibiotic degradation but also sheds light on the charge migration behavior in favor of efficient Z-type heterojunction.

Encapsulation of spinel CuCo2O4 hollow sphere in V2O5-decorated graphitic carbon nitride as high-efficiency double Z-type nanocomposite for levofloxacin photodegradation.

In this study, spinel CuCo2O4 (CCO) with a hierarchical hollow sphere morphology was encapsulated in V2O5-decorated ultra-wrinkled graphitic carbon-nitride (VO-UCN) for the first time via a facile glycerol-assisted solvothermal method in the interest of developing a novel high-efficiency double Z-type nano-photocatalyst (denoted as VO-UCN@CCO). The remarkable physicochemical features of the as-prepared nano-photocatalysts were verified using diverse characterization techniques including TGA, XRD, FT-IR, FE-SEM, TEM, BET, UV-vis DRS, PL, EIS, and transient photocurrent techniques. Herein, VO-UCN@CCO nanocomposite was employed for the photodisintegration of levofloxacin (LVOF) antibiotic under visible-light irradiation and the impact of certain operative reaction system variables was explored in an effort to optimize the photocatalytic capability. The 40% loading of CCO in VO-UCN@CCO nanocomposite was found to display maximum photocatalytic performance (about 95%) for LVOF photodecomposition, which was 9.3, 6.6, and 13.8 times greater when compared with pristine VO, UCN, and CCO, respectively. A high capability was observed for as-prepared photocatalyst during reusability tests and near 90% degradation efficiency was obtained in the sixth run. The complete mineralization of LVOF was achieved by the VO-UCN@CCO photocatalyst process after 300 min of reaction. An excellent synergy factor towards the degradation of LVOF was obtained for VO-UCN@CCO compared to each of its components alone. This peculiar design is envisaged to provide new inspirations for ameliorating the photocatalytic decontamination of tenacious and non-biodegradable species present in real wastewater.

Bisphenol A degradation by peroxymonosulfate photo-activation coupled with carbon-based cobalt ferrite nanocomposite: Performance, upgrading synergy and mechanistic pathway.

Cobalt ferrite (CoFe2O4, CF) nanoparticles were anchored on the multiwalled carbon nanotube (MWCNT) for synthesis of CF@MWCNT nanocomposite and enhancing the catalytic activity of CF. After well characterization, it was applied as a catalyst towards photo-activation peroxymonosulfate (PMS) for degradation of bisphenol A (BPA). Based on the identified intermediates, a possible degradation pathway was proposed for BPA. CF@MWCNT coupled with PMS and UV (i.e., CF@MWCNT/PMS/UV) exhibited a better performance than homogeneous UV-assisted PMS processes under Fe and Co ions. A significant synergy on the degradation of BPA was observed in the simultaneous application of catalyst, UV light and PMS. Under optimum conditions, the removal efficiencies of 100 and 72.6% were attained respectively for BPA and TOC by CF@MWCNT/PMS/UV within 60 min reaction. These efficiencies were decreased to 88 and 61% after five times use of catalyst, respectively. The leaching of metal ions dissolved from the catalyst was slight during cyclic utilization of catalyst, confirming high stability of CF@MWCNT. In this process, the participation of radical mechanisms was approximately 60%, which SO4•- and HO• species contributed as predominant oxidizing reactive species. It also showed the excellent catalytic performance towards decomposition of persulfate and hydrogen peroxide. Overall, UV-assisted PMS catalyzed by CF@MWCNT exhibited a good catalytic performance and so it can be potentially introduced as a promising method for efficient treatment of water contaminated by BPA.

Sono-photocatalytic degradation of tetracycline and pharmaceutical wastewater using WO3/CNT heterojunction nanocomposite under US and visible light irradiations: A novel hybrid system.

In this paper, in-situ fabrication of tungsten oxide (WO3) on carbon nano-tube (CNT) was performed via sol-gel/hydrothermal method to prepare WO3/CNT nanocomposites and then coupled with visible light and ultrasound (US) irradiations for sono-photocatalytic removal of tetracycline (TTC) and pharmaceutical wastewater treatment. The as-prepared catalysts were characterized by FT-IR, XRD, TEM, UV-VIS DRS, FESEM, EDS, TGA, BET, BJH, EIS, and EDX techniques. The characterization tests, indicated successful incorporation of CTNs into the WO3 framework and efficient reduction of charge carries recombination rate after modifying with CNT. The investigation of experimental parameters verified that 60 mg/L TTC could be perfectly degraded at optimum operational parameters (WO3/CNT: 0.7 g/L, pH: 9.0, US power: 250 W/m2, and light intensity: 120 W/m2 over 60 min treatment. Trapping experiments results verified that HO radicals and h+ were the main oxidative species in degradation of TTC. The as-prepared photocatalysts could be reused after six successive cycles with an approximately 8.8 % reduction in removal efficiency. Investigation of the effect of real pharmaceutical wastewater revealed that this system is able to eliminate 83.7 and 90.6 % of TOC and COD, respectively after 220 min of reaction time. Some compounds with lower toxic impact and molecular weight, compared to raw pharmaceutical wastewater, were detected after treatment by sono-photocatalysis process. The biodegradability of real pharmaceutical wastewater was improved significantly after treatment by WO3/CNT sono-photocatalysis.

Efficient clean-up of waters contaminated with diazinon pesticide using photo-decomposition of peroxymonosulfate by ZnO decorated on a magnetic core/shell structure.

In the present study, ZnO nanoparticles were anchored on a magnetic core/shell structure (SiO2@Fe3O4) to perpetrate ZnO@SiO2@Fe3O4 and then coupled with UV light as a heterogeneous nanocatalyst for activating peroxymonosulfate (PMS) into diazinon (DZ) degradation. Several techniques like XRD (X-ray diffraction), BET (Brunaeur, Emmett and Teller), TEM (Transmission electron microscope), FESEM (Field emission-scanning electron microscope) coupled with EDS (Energy Dispersive X-ray Spectrometer), PL (photoluminescence), VSM (Vibrating Sample Magnetometer) and UV-vis diffuse reflectance spectroscopy (DRS) were applied for identification of catalyst features. A possible mechanism for PMS activation and DZ degradation was proposed in details. The effect of solution pH, various concentrations of catalyst, PMS and DZ, quenching agents, different chemical oxidants and co-existing anions was assessed as operating factors to determine the optimum conditions. PMS decomposed effectively in coupling with ZnO@SiO2@Fe3O4 and UV. At optimal conditions, over 95 and 56% of DZ and TOC were removed during 60 min reaction, respectively. The complete degradation of DZ was confirmed using its absorption peak in UV-vis spectra analysis over 60 min treatment. A wide variety of free radicals was identified during quenching tests. HO• and h+ played a pivotal role in the degradation process of DZ. Decreasing the degradation efficiency in the presence of anions was as Cl- > CO32- > NO3- > PO43- > SO42- > HCO3-. A negligible amount of leaching Fe (<0.2 mg/L) was found for ZnO@SiO2@Fe3O4, indicating that the catalyst possesses a high stability in oxidation systems. In addition, a significant potential was achieved in reusing of catalyst within five consecutive runs. In conclusion, ZnO@SiO2@Fe3O4/PMS/UV hybrid system can be utilized as a promising advanced oxidation process into efficient degradation of pesticides, thanks to easy recovery, high catalytic activity, co-production of different reactive species and high durability and recyclability potential.

Photo-assisted catalytic degradation of acetaminophen using peroxymonosulfate decomposed by magnetic carbon heterojunction catalyst.

Catalytic oxidative degradation of acetaminophen (ACT) was evaluated using magnetic mesoporous carbon (MNPs@C) coupled with UV light and peroxymonosulfate (PMS). The performance of hybrid system (i.e., MNPs@C/UV/PMS) was assessed as a function of some operational factors (e.g., reaction time and different concentrations of catalyst, PMS and ACT) in a batch system. MNPs@C represented a high magnetic response and was easily recovered from aqueous solution via an external magnet. A significant synergistic effect was observed among the applied techniques in MNPs@C/UV/PMS system for ACT degradation. After 40 min reaction, the removal efficiencies of 97.4 and 63.5% were obtained for ACT and TOC, respectively. Both adsorption and oxidation mechanisms were responsible simultaneously for ACT removal in MNPs@C/UV/PMS system. Under optimum conditions, the removal rates of ACT and TOC were reduced slightly to 91.7 and 49.4% after five consecutive catalyst uses, which indicates the excellent reusing potential of MNPs@C. In addition, a high stability was detected for as-prepared catalyst during recycling tests, since the quantity of leached Fe was <0.2 mg/L. Methanol and tert-butyl alcohol showed a strong quenching effect on the performance of MNPs@C/UV/PMS system, demonstrating the dominant role of SO4•- and HO radicals in ACT degradation process. MNPs@C in comparison with ferrous ions, as a homogeneous catalyst, showed a better performance in the activation of PMS and ACT degradation. Integration of MNPs@C, UV and PMS exhibited an excellent performance into ACT removal over 40 min reaction, which can be utilized as an effective and promising technique for the efficient decontamination of polluted waters.

Enhanced sono-photocatalysis of tetracycline antibiotic using TiO2 decorated on magnetic activated carbon (MAC@T) coupled with US and UV: A new hybrid system.

A combined system including sonocatalysis and photocatalysis was applied for catalytic degradation of tetracycline (TC) antibiotic using TiO2 decorated on magnetic activated carbon (MAC@T) in coupling with ultraviolet (UV) and ultrasound (US) irradiations. MAC was fabricated via magnetization of AC using Fe3O4 nanoparticles. FESEM, EDS, TEM, BET, XRD, PL, VSM and UV-visible DRS techniques were used to characterize the catalyst features. The performance of MAC@T/UV/US system was examined under impact of different input variable such as catalyst loading, solution pH, initial TC concentration, US power, scavenging agents, chemical oxidants and co-exiting anions. The degradation rate was enhanced substantially when MAC@T coupled with US and UV irradiations. At optimal conditions, over 93% TC and 50% TOC were removed under 180 min reaction. Whereas, the complete removal of TC was obtained after 60 min treatment, when MAC@T/UV/US coupled with oxidants. Decreasing sequence of the inhibitory effect of anions was chloride > bicarbonate > phosphate > nitrate > sulfate. Both Fe leaching and loss of the decontamination were slight with reused times, indicating MAC@T has a high stability and reusability. According to trapping tests, holes, OH and 1O2 were contributed in the degradation process. In conclusion, integration of MAC@T composite and US/UV for enhancing catalytic degradation efficiency can be introduced as a successful and promising technique, owing to excellent catalytic activity, easy recovery, good adsorption capacity and high durability and recycling potential.

Efficient treatment of saline recalcitrant petrochemical wastewater using heterogeneous UV-assisted sono-Fenton process.

An effective hybrid system was applied as a first report for successful treatment of recalcitrant petrochemical wastewater (PCW). In this regards, magnetic powdered activated carbon (MPAC), as a heterogeneous catalyst, was coupled with ultrasound (US) and UV irradiations for activation of H2O2 (marked as MPAC/US/UV/H2O2). Chemical oxygen demand (COD) removal ratio was evaluated with various influencing operating factors including solution pH, MPAC and H2O2 concentrations, US power and quenchers. A possible mechanism for catalytic degradation and generation of reactive species was proposed. To evaluate the biodegradability of both raw and treated PCWs, the activated sludge inhibition experiments were performed based on Zahn-Wellens test. MPAC indicated high catalytic activity, reusability and stability in the studied system. Over 87% of COD was removed under optimum conditions within 80 min treatment and the residual COD concentration reached 82.9 mg/L, which was permissible to discharge surface water sources based on the environmental standards. Leaching of transition metals from catalyst textural was negligible. Compared to homogeneous system (Fe2+/US/UV/H2O2), heterogeneous system (MPAC/US/UV/H2O2) represented a better performance in COD removal. Identification of intermediates by GC-MS showed that a wide range of recalcitrant compounds was removed and/or degraded into small molecular compounds effectively after treatment. A biodegradability ratio of 64% and the residual COD of 28 mg/L for treated PCW, indicating that the biodegradability was improved and refractory organic matters removed effectively. As conclusion, MPAC/US/UV/H2O2 hybrid system can be introduced as a successful advanced treatment process for efficient remediation of refractory PCWs.

Removal of vanadium and palladium ions by adsorption onto magnetic chitosan nanoparticles.

Chitosan (CS), synthesized from chitin chemically extracted from shrimp shells, was used for the synthesis of magnetic chitosan nanoparticles (Fe3O4-CSN), which makes the adsorbent easier to separate. Fe3O4-CSN was used for the removal of toxic metals such as vanadium (V(V)) and palladium (Pd(II)) ions from aqueous solutions. Influencing factors on the adsorption process such as pH, contact time, adsorbent dosage, and agitation speed were investigated. A competitive adsorption of V(V) and Pd(II) ions for the active sites was also studied. The monolayer maximum adsorption capacities (Qm) of 186.6 and 192.3 mg/g were obtained for V(V) and Pd(II) ions, respectively. The pseudo-second-order equation gave the best fit for the kinetic data, implying that chemisorption was the determining step. Freundlich model yielded a much better fit than the other adsorption models assessed (Langmuir, Temkin and Dubinin-Radushkevich). Thus, the adsorption of V(V) and Pd(II) ions onto Fe3O4-CSN is a combination of physical and chemical adsorption, as based on the kinetics and equilibrium study. Generally, physical adsorption is the mechanism that governs the system, while chemical adsorption is the slowest adsorption step that takes place. Thermodynamic studies displayed that the adsorption process was exothermic and spontaneous. Removal efficiencies of 99.9% for V(V) and 92.3% for Pd(II) ions were achieved, implying that Fe3O4-CSN adsorbent had an excellent ability for the removal of the metal ions from real industrial wastewaters without remarkable matrix effect. Graphical abstract ᅟ.

Photocatalytic activation of peroxymonosulfate by TiO2 anchored on cupper ferrite (TiO2@CuFe2O4) into 2,4-D degradation: Process feasibility, mechanism and pathway.

A thorough study of photo-oxidation efficiency of TiO2@CuFe2O4 dissociating peroxymonosulfate (PMS) is reported in detail. The origin of high catalytic activity was discussed as evidence by numerous controlled trials and several operational parameters. Based on quenching tests, possible mechanism and pathway of degradation were proposed. 2,4-dichlorophenoxyacetic acid (2,4-D) degradation in TiO2@CuFe2O4/UV/PMS system could abide pseudo-first-order kinetics. Moreover, reaction rate constant (Kobs) showed a linear increasing trend as PMS and catalyst concentrations increased. Over 97.2% of 2,4-D (20 mg/L) was degraded within 60 min at 0.3 mM PMS and 0.1 g/L TiO2@CuFe2O4. However, the water matrix species inhibited 2,4-D degradation to different amounts and the inhibiting effect was as follows: HCO3- > NO3-  > Cl- > SO42-. As-prepared catalyst showed a high ability of PMS activation, compared to other studied oxidants. Particularly, sulfate radicals were accounted for 2,4-D degradation in the catalytic oxidation reaction. TiO2@CuFe2O4 catalyst displayed the excellent recyclability and durability. Identification of intermediates and end-products brought about the conclusion that enhanced degradation involving dechlorination, dehydrogenation, hydroxylation, and ring cleavage, through SO4-, OH, O2- and holes attack during TiO2@CuFe2O4/PMS photocatalysis of 2,4-D. As conclusion, integration of TiO2, CuFe2O4 and UV light to efficient activation of PMS can be proposed as a successful and promising method to wastewater treatment effectively, because of the cogeneration of different reactive oxidizing species, simple and easy recovery of catalyst and good catalytic activity.