Carbon-doped CuFe_(2)O_(4) with C-O-M channels for enhanced Fenton-like degradation of tetracycline hydrochloride: From construction to mechanism

Carbon-doped copper ferrite(C–CuFe_(2)O_(4))was synthesized by a simple two-step hydrothermal method,which showed enhanced tetracycline hydrochloride(TCH)removal efficiency as compared to the pure CuFe_(2)O_(4) in Fenton-like reaction.A removal efficiency of 94%was achieved with 0.2 g L^(-1) catalyst and 20 mmol L^(-1) H_(2)O_(2) within 90 min.We demonstrated that 5%C–CuFe_(2)O_(4) catalyst in the presence of H_(2)O_(2) was significantly efficient for TCH degradation under the near-neutral pH(5–9)without buffer.Multiple techniques,including SEM,TEM,XRD,FTIR,Raman,XPS M€ossbauer and so on,were conducted to investigate the structures,morphologies and electronic properties of as-prepared samples.The introduction of carbon can effectively accelerate electron transfer by cooperating with Cu and Fe to activate H_(2)O_(2) to generate·OH and·O_(2)^(-).Particularly,theoretical calculations display that the p,p,d orbital hybridization of C,O,Cu and Fe can form C–O–Cu and C–O–Fe bonds,and the electrons on carbon can transfer to metal Cu and Fe along the C–O–Fe and C–O–Cu channels,thus forming electron-rich reactive centers around Fe and Cu.This work provides lightful reference for the modification of spinel ferrites in Fenton-like application.

Photo-Fenton和Photo-Fenton-like试剂对萘羟基化反应的影响

实验以H_2O_2,乙腈、Fe(NO_3)_3·9H_2O、FeSO_4·7H_2O,为试剂,以自制光催化反应器制备了萘酚。研究了Photo-Fenton和Photo-Fenton-like反应体系中萘的羟基化反应,考察了Fe^(2+)、Fe^(3+)浓度、H_2O_2浓度、反应时间等因素对两种反应体系的影响。对于Photo-Fenton反应体系中,在[Fe^(2+)]=1.5mmol/L、[H_2O_2]=0.8 mol/L条件下,萘的转化率达43%,1-萘酚的收率为2.8%。对于Photo-Fenton-like反应体系,在[Fe^(3+)]=4.5 mmol/L,[H_2O_2]=0.2 mol/L条件下,萘的转化率为17%,1-萘酚的收率达4.6%;同条件下[H_2O_2]提高至1.0 mol/L时,萘的转化率可达90%,但1-萘酚的收率却有所下降。

Exploitation of Fenton and Fenton-like reagents as alternative conditioners for alum sludge conditioning

The use of Fenton＇s reagent （Fe^2＋/H2O2） and Fenton-like reagents containing transition metals of Cu（Ⅱ）, Zn（Ⅱ）, Co（Ⅱ）, and Mn（Ⅱ） for an alum sludge conditioning to improve its dewaterability was investigated. The results obtained were compared with those obtained from conditioning the same alum sludge using cationic and anionic polymers. Experimental results show that Fenton＇s reagent was the best among the Fenton and Fenton-like reagents for the alum sludge conditioning. A considerable effectiveness of capillary suction time （CST） reduction efficiency of 47% can be achieved under test conditions of Fe^2＋/H2O2 = 20/125 mg/g DS （dry solid） and pH 6.0. The observation of floc-like particles after Fenton＇s reagent conditioning of alum sludge suggested that the mechanism of Fenton＇s reagent conditioning was different from that of polymer conditioning. In spite of the lower efficiency in the CST reduction of Fenton＇s reagent in alum sludge conditioning compared to that of polymer conditioning, Fenton＇s reagent offers a more environmentally safe option. Tiffs study provided an example of proactive treatment engineering, which is aimed at seeking a safe alternative to the use of polymers in sludge conditioning towards achieving a more sustainable sludge management strategy.

Augmenting Intrinsic Fenton-Like Activities of MOF-Derived Catalysts via N-Molecule-Assisted Self-catalyzed Carbonization

To overcome the ever-growing organic pollutions in the water system,abundant efforts have been dedicated to fabricating efficient Fenton-like carbon catalysts.However,the rational design of carbon catalysts with high intrinsic activity remains a long-term goal.Herein,we report a new N-molecule-assisted self-catalytic carbonization process in augmenting the intrinsic Fenton-like activity of metal-organic-framework-derived carbon hybrids.During carbonization,the N-molecules provide alkane/ammonia gases and the formed iron nanocrystals act as the in situ catalysts,which result in the elaborated formation of carbon nanotubes(in situ chemical vapor deposition from alkane/iron catalysts)and micro-/meso-porous structures(ammonia gas etching).The obtained catalysts exhibited with abundant Fe/Fe-Nx/pyridinic-N active species,micro-/meso-porous structures,and conductive carbon nanotubes.Consequently,the catalysts exhibit high efficiency toward the degradation of different organic pollutions,such as bisphenol A,methylene blue,and tetracycline.This study not only creates a new pathway for achieving highly active Fenton-like carbon catalysts but also takes a step toward the customized production of advanced carbon hybrids for diverse energy and environmental applications.

Boron carbide boosted Fenton-like oxidation: A novel Fe(Ⅲ)/Fe(Ⅱ) circulation

The sluggish kinetics of Fe(Ⅱ)recovery in Fenton/Fenton-like reactions significantly limits the oxidation efficiency.In this study,we for the first time use boron carbide(BC)as a green and stable promotor to enhance the reaction of Fe(Ⅲ)/H_(2)O_(2) for degradation of diverse organic pollutants.Electron paramagnetic resonance analysis and chemical quenching/capturing experiments demonstrate that hydroxyl radicals(·OH)are the primary reactive species in the BC/Fe(Ⅲ)/H_(2)O_(2) system.In situ electrochemical analysis indicates that BC remarkably boosts the Fe(Ⅲ)/Fe(Ⅱ)redox cycles,where the adsorbed Fe(Ⅲ)cations were transformed to more active Fe(Ⅲ)species with a higher oxidative potential to react with H_(2)O_(2) to produce Fe(Ⅱ).Thus,the recovery of Fe(Ⅱ)from Fe(Ⅲ)is facilitated over BC surface,which enhancesOH generation via Fenton reactions.Moreover,BC exhibits outstanding reusability and stability in successive cycles and avoids the secondary pollution caused by conventional organic and metalliferous promotors.Therefore,metal-free BC boosting Fe(Ⅲ)/H_(2)O_(2) oxidation of organics provides a green and advanced strategy for water decontamination.

Metal-doped(Cu,Zn)Fe2O4 from integral utilization of toxic Zn-containing electric arc furnace dust: An environment-friendly heterogeneous Fenton-like catalyst

Pure metal-doped(Cu,Zn)Fe2O4 was synthesized from Zn-containing electric arc furnace dust(EAFD)by solid-state reaction using copper salt as additive.The effects of pretreated EAFD-to-Cu2(OH)2CO3·6H2O mass ratio,calcination time,and calcination temperature on the structure and catalytic ability were systematically studied.Under the optimum conditions,the decolorization efficiency and total organic carbon(TOC)removal efficiency of the as-prepared ferrite for treating a Rhodamine B solution were approximately 90.0%and 45.0%,respectively,and the decolorization efficiency remained 83.0%after five recycles,suggesting that the as-prepared(Cu,Zn)Fe2O4 was an efficient heterogeneous Fenton-like catalyst with high stability.The high catalytic activity mainly depended on the synergistic effect of iron and copper ions occupying octahedral positions.More importantly,the toxicity characteristic leaching procedure(TCLP)analysis illustrated that the toxic Zncontaining EAFD was transformed into harmless(Cu,Zn)Fe2O4 and that the concentrations of toxic ions in the degraded solution were all lower than the national emission standard(GB/31574-2015),further confirming that the as obtained sample is an environment-friendly heterogeneous Fenton-like catalyst.

Green synthesis of bentonite-supported iron nanoparticles as a heterogeneous Fenton-like catalyst:Kinetics of decolorization of reactive blue 238 dye

This study aimed to synthesize green tea nano zero-valent iron(GT-NZVI)and bentonite-supported green tea nano zero-valent iron(BGT-NZVI)nanoparticles using green tea extracts in an environmentally sustainable way.Bentonite was used as a support material because it disperses and stabilizes GT-NZVI,and it helps to reduce the cost,increase the adsorption capacity of GT-NZVI,and decrease the optimum amount of GT-NZVI used in Fenton-like oxidation.A scanning electron microscope,an atomic force microscope,and a Fourier transform infrared spectroscope were used to characterize GT-NZVI and B-GT-NZVI,while the zeta potential was measured to evaluate the stability of iron nanoparticles.The decolorization kinetics of reactive blue 238(RB 238)dye in the aqueous phase in the Fenton-like oxidation process were investigated as well.The effects of various experimental conditions such as reaction time,dosages of catalysts,concentration of H2O2,temperature,addition of inorganic salts,and other parameters were investigated.The results show that the oxidative degradation efficiencies of RB 238 dye catalyzed by GT-NZVI and B-GT-NZVI were 93.5%and 96.2%,respectively,at the optimum reaction conditions as follows:c(H2O2)¼5 mmol/L,r(GT-NZVI)¼0.5 g/L or r(B-GT-NZVI)¼0.5 g/L,c(RB 238 dye)¼0.05 mmol/L,and pH¼2.5 at 180 min.The best catalytic performance was exhibited when B-GT-NZVI was used.Three kinetic models were employed,and the second-order model was found to be the best model representing the experimental kinetic data of RB 238 dye.The value of activation energy decreased from 38.22 kJ/mol for GT-NZVI to 14.13 kJ/mol for B-GT-NZVI.This indicates that the effect of B-GT-NZVI in decreasing the energy barrier is more pronounced than that of the GT-NZVI catalyst,leading to improved Fenton-like oxidation processes.©2020 Hohai University.Production and hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/).

Fenton-like/生物滤池一体化反应器的构建及其特性研究

针对典型印染废水,文章以蔗糖和四氧化三铁自制的催化剂颗粒作为生物滤床中填料的一部分,构建Fenton-like/生物滤池一体化反应器。通过比较Fenton-like/生物滤池一体化反应器与分离式反应器在高级氧化预氧化阶段以及反应器出水阶段的溶解氧浓度、AO7及COD去除效率,并对Fenton-like/生物滤池一体化反应器的运行条件进行优化。研究结果表明与分离式反应器相比,一体化反应器最终出水DO浓度高出69.9%;AO7的平均去除率为96.38%,无显著差别;COD的去除率达到59.38%,高出分离式反应器19.64%。实践表明,采用一体化反应器处理印染废水,可以克服分离式反应器的缺点,能有效利用液体双氧水沿着污水的升流方向渗透到生物滤池基质的每个区域进而分解为氧气,提高DO浓度及COD去除率。

Reactive species in resin supported heterogeneous Fenton-like oxidation of Malachite green solution

During the oxidative degradation of nonbiodegradable Malachite green (MG) by means of H2O2 /FeIIIR (iron supported on ion-exchage resin) in a dynamic column,the binding energy of the Fe(2p3/2) region for XPS spectra was found to be different between the top layer and the bottom layer in this column. Based on the data from XPS spectra and DMPO-OH·signal by EPR spectra,it is shown that the formation of ferryl (IV) is the key step for the oxidation of MG. The ferryl (IV) species can oxidize MG,and its redox potential is about 0. 739 - 0. 803 V measured by cyclic voltammograms (CV) . The catalytic capability of ferryl (IV) species was also evaluated,and it is found that it can promote the decomposition of H2O2 more efficiently than ferric iron. The removal rate of MG mainly depends on the adsorption of catalyst. Both ferryl (IV) and HO·radicals are the reactive species in the system. The oxidation of HO·is only a small part of the overall removal rate. Based on the obtained results,a possible mechanism for a resin-supported Fenton-like oxidation reaction is proposed.

Synthesis of Magnetically Modified Fe-Al Pillared Bentonite and Heterogeneous Fenton-like Degradation of Orange II

Magnetically modified Fe-Al pillared bentonite（Fe3O4/ Fe-Al-Bent） was prepared via chemical co-precipitation method and characterized by powder X-ray diffraction（XRD）, Brunauer-EmmettTeller（BET）, Fourier transform infrared spectroscopy（FTIR） and scanning electron microscopy（SEM）. A series of experiments were carried out to investigate the degradation of Orange II by the obtained heterogeneous catalysts in the presence of H2O2. The experimental result indicated that the synthetic materials had a high catalytic activity and good reusability.

Kinetic and Thermodynamic Study for Fenton-Like Oxidation of Amaranth Red Dye

Oxidation by Fenton like reactions (Fe3+/H2O2) is economically process for destructive hazardous pollutants in waste water. The effects of different parameters such as, amaranth red dye, ferric chloride, hydrogen peroxide concentrations, pH value of solution, temperature and the presence of inorganic ions (carbonate, nitrate, chloride) on oxidative decolorization of amaranth were investigated. Amaranth degradation by (Fe3+/H2O2) reagent was found to follow first order kinetic model. Under optimum condition, pH = 2.6 and [FeCl3] = 3.75 × 10-4 mol·dm-3, the amaranth in aqueous solution with an initial concentration of 5 × 10-5 mol·dm-3 was degraded by 95% within 6 minutes. Increasing temperature in the range of 298 - 308 K increases the rate of dye degradation. Thermodynamic constants, ΔH*, ΔS* and ΔG* were evaluated. The results implied that the oxidation process was favorable and endothermic.

Discarded Carbon-Zinc Batteries as Source of an Efficient Heterogeneous Fenton-Like Catalyst Employed to Degrade Organic Molecules in an Aqueous Medium

The present work evaluates the feasibility of using the raw material collected from discarded zinc-carbon batteries as heterogeneous catalyst to degrade the dye Indigo Carmine in an aqueous solution. Besides the evident environmental application, this work also presents an economic alternative for the production of new catalysts used to remediate polluted waters. For this, discarded carbon-zinc batteries were gathered, disassembled and their anodic paste collected. After acidic treatment and calcination at 500°C, characterization measurements, i.e. flame atomic absorption spectroscopy (FAAS), nitrogen sorption, X-ray diffraction (XRD) and scanning electron microscopy (SEM), revealed that the so-obtained material consisted mainly of ZnMn2O4. This material acts as a heterogeneous catalyst in a Fenton-like process that degrades the dye Indigo Carmine in water. That is probably due to the presence of Mn(III) (manganese in the +3 oxidation state) in this material that triggers the decomposition of hydrogen peroxide (H2O2) to yield hydroxyl radicals (HO·). Moreover, direct infusion electrospray ionization coupled to high resolution mass spectrometry (ESI-HRMS) was employed to characterize the main by-products resulting from such degradation process. These initial results thus indicate that raw materials from waste batteries can therefore be potentially employed as efficient Fenton-like catalysts to degrade organic pollutants in an aqueous solution.

多相Fenton-like催化剂Fe_2V_4O_(13)对AO Ⅱ的催化降解研究

含钒的化合物能够有效地催化H2O2,因此可作为多元Fenton-like催化剂中的有效组份之一,Fe2V4O13中存在Fe(Ⅲ)和V(V)同时和协同活化H2O2的可能性。通过液相合成法制备了Fe2V4O13,并对其对AOⅡ的催化活性进行了研究,研究表明,Fe2V4O13是一种新型高效稳定的多相Fenton-like催化剂。

Degradation of n-butyl xanthate using fly ash as heterogeneous Fenton-like catalyst

Heterogeneous Fenton-like process using fly ash as a catalyst was studied to degrade n-butyl xanthate form aqueous solution. The different reaction parameters on the degradation efficiency of the process were investigated. The fly ash/H2O2 catalyst possesses a high oxidation activity for n-butyl xanthate degradation in aqueous solution. It is found that both the dosage of catalyst and initial solution pH significantly affect the n-butyl xanthate conversion efficient. The results indicate that by using 1.176 mmol/L H2O2 and 1.0 g/L fly ash catalyst with mass fraction of 4.14% Fe(III) oxide at pH 3.0, almost 96.90% n-butyl xanthate conversion and over 96.66% COD removal can be achieved within 120 min with heterogeneous catalysis by fly ash. CS2 as an intermediate of n-butyl xanthate oxidation. Finally, it is demonstrated that the fly ash/H2O2 catalytic oxidation process can be an efficient method for the treatment of n-butyl xanthate containing wastewater.

Microwave-assisted Fenton-like decolorization of methyl orange solution using chromium compounds

Azo dyes discharged in the environment are persistent organic pollutants (POPs),which are very difficult to remove. We developed a microwave-assisted Fenton-like process to degrade methyl orange (MO),an azo dye,with hydrogen peroxide (H2O2) catalyzed by chromium compounds coexisting with MO in the solution. Comparison between the Cr(Ⅲ)-H2O2 and Cr(VI)-H2O2 systems shows that Cr(VI) has a stronger and more stable catalytical activity than Cr(Ⅲ),and Cr(Ⅲ) is more susceptible to a change in the acidity or alkalinity of the reaction system. With a Cr(VI) concentration of 10 mmol L-1 or a Cr(Ⅲ) concentration of 12 mmol L?1 in the solution under the microwave irradiation of a power larger than 300 W for 3 min,10 mmol L-1 H2O2 can degrade more than 95% of 1 000 mg L-1 methyl orange; when the microwave power is increased to 700 W,the same amount of H2O2 can degrade all methyl orange in the solution with the same amount of Cr(VI) catalyst. Ultraviolet-visible spectrography indicates the cleavage of the azo bond in methyl orange after treatment,suggesting the potential of this Fenton-like process to degrade azo dye POPs. Reusing waste chromium compounds coexisting with dyestuff in wastewater to catalyze the degradation of azo dyes could be a cost-effective technique for azo dyes and chromate manufacturers and/or users to treat their wastewater and prevent POPs from endangering the environment. This is of particular importance to controlling the water quality of the Three Gorges Reservoir.

Iron single-atom/clusters catalysts derived from iron-rich Enteromorpha after urea-saturation for Fenton-like reaction

Fabrication of single atom catalysts(SACs)by a green and gentle method is important for their practical Fenton-like use.In this work,a high effective iron-based catalyst was prepared from the iron-rich Enteromorpha for NPX degradation via peroxymonosulfate(PMS).Both Fe-SACs and iron-clusters was fabricated from the intrinsic iron element in Enteromorpha after the urea saturation.The Fe-SACs/clusters can achieve 100%of NPX oxidation within 20 min with the k_(obs)of 0.282 min^(-1).Quenching tests indicated that the radical pathways were not dominated in the catalytic systems,and strong electron transfer process can be induced in the Fe-SACs/clusters+PMS system by using the NPX as electron donor and FeSACs/clusters/PMS^*complexes as electron acceptor.This result was consistent with the phenomenon observed in the galvanic oxidation system.In addition,the Fe-SACs/clusters was deposited onto the ceramic membrane(CM)by the spraying-crosslinking process to form a Fe-SACs/clusters@CM,which showed an effective and continuous NPX degradation in a heterogeneous PMS system.

Synergy enhancement of Co single atoms and asymmetric subnanoclusters for Fenton-like activation

As a new water treatment technology,Fenton-like reaction has great potential.In this study,we successfully prepared an excellent Fenton-like catalyst,which is composed of cobalt monoatoms and asymmetric subnanoclusters(labeled CoSA/Clu-C_(2)N),and exhibits excellent peroxymonosulfate(PMS)activation reactivity.By directly comparing the catalytic properties of CoSA-C_(2)N and CoSA/Clu-C_(2)N,the synergistic effects of coasymmetric Co subclusters and Co atoms on the activation of PMS and degradation of organic micropollutants were investigated.The results showed that CoSA/Clu-C_(2)N had higher degradation rates of carbamazepine(CBZ),antipyrine(AT)and chlorobenzoic acid(CA)when combined with active oxidant PMS.The cyclic frequency of CBZ was 5.4 min^(-1),which was twice as high as the catalytic constant of CoSA-C_(2)N(2.4 min^(-1)).The results show that CoSA/Clu-C_(2)N cobalt subnanoclusters and cobalt single atom can synergistically improve the catalytic performance of activated PMS oxidation of micropollutants in water.In addition,electron paramagnetic resonance(EPR)technology has proved that the introduction of Co subnano clusters in CoSA/Clu-C_(2)N is conducive to the production of singlet oxygen(1O2),thereby improving the efficiency of pollutant oxidation.This work lays a solid foundation for the future design of advanced multifunctional catalysts by carefully regulating and combining monmetallic atoms and metal subnanoclusters.

Amino acids modified nanoscale zero-valent iron:Density functional theory calculations,experimental synthesis and application in the Fenton-like degradation of organic solvents

To improve the adsorption and catalytic performance of heterogeneous Fenton-like catalysts for oil wastes,amino acids were used to modify nanoscale zero-valent iron(AA@Fe^(0)),which were applied in the Fenton-like degradation of organic solvents(tributyl phosphate and n-dodecane,named TBP and DD).Twelve amino acids,i.e.,glycine(Gly),alanine(Ala),leucine(Leu),proline(Pro),phenylalanine(Phe),methionine(Met),cysteine(Cys),asparagine(Asn),serine(Ser),glutamic acid(Glu),lysine(Lys)and arginine(Arg),were selected and calculated by density functional theory(DFT).The optimized structure,charge distribution,the highest occupied molecular orbital(HOMO),the lowest unoccupied molecular orbital(LUMO),interaction region indicator(IRI)isosurface map and adsorption energy of AA@Fe^(0),AA@Fe^(0)-TBP and AA@Fe^(0)-DD were studied,which indicated that Fe is more likely to approach and charge transfer with-COO and-NH_(3) on theα-carbon of amino acids.There is strong attraction between Fe and–COO,and Van der Waals force between Fe and-NH_(3),respectively.In the interaction of AA@Fe^(0)with TBP and DD,Van der Waal force plays an important role.AA@Fe^(0)was synthesized in laboratory and characterized to investigate physicochemical properties.In Fenton-like degradation of organic solvents,the change of COD in water phase during the degradation process as well as the volume of the organic phase after the reaction were investigated.The results of calculations combined with experiments showed that Ser-modified Fe^(0)performed the best in these amino acids,with 98%removal of organic solvents.A possible catalytic mechanism was proposed in which amino acids acted a linking role between Fe and organic solvents,activating H_(2)O_(2)to generate hydroxyl radicals for the degradation of organic solvents.

Confinement of Fe atoms between MoS_(2) interlayers drives phase transition for improved reactivity in Fenton-like reactions

Phase manipulation of MoS_(2) from thermodynamically stable 2H phase to the unstable but more reactive 1T phase represents a crucial strategy for improving the reactivity in many reactions.The widely adopted wet chemistry approach uses intercalating entities especially alkali metal ions to achieve the phase transition;however,these entities are normally inert for the target reaction.Here,we describe the first use of iron atoms for the intercalation of 2H-MoS_(2) layers,driving the partial transition from 2H to 1T phase.Interestingly,in the peroxymonosulfate(PMS)-based Fenton-like reactions,the interlayered confinement of Fe atoms not only activates the inert basal plane,but also adds more reactive Fe sites for the formation of metal-PMS complex as primary reactive species for pollutant removal.In the degradation of a model pollutant carbamazepine(CBZ),the Fe-intercalated MoS_(2) exhibits a first order rate constant 13.3 times higher than 2H-MoS_(2).This strategy is a new direction for manipulating the phase composition and boosting the catalytic reactivity of MoS_(2)-based catalysts in various scenarios,including environmental remediation and energy applications.

Enhanced Fenton-like process over Cu/L(+)-ascorbic acid co-doping mesoporous silica for toxicity reduction of emerging contaminants

Effective removal of emerging contaminants(ECs)to minimize their impacts on human health and the natural environment is a global priority.For the removal of ECs in water,we fabricated a seaweed spherical microsphere catalyst with Cu cation-πstructures by in situ doping of Cu species and ascorbic acid in mesoporous silica(Cu-C-MSNs)via a hydrothermal method.The results indicate that bisphenol A(BPA)is substantially degraded within 5 min under natural conditions,with its biological toxicity considerably weakened.Moreover,industrial wastewater could also be effectively purified by Cu-C-MSNs/H_(2)O_(2) system.The presence of metal sites and the complexation of ECs via cation-πinteraction andπ-πstacking on the catalyst surface were directly responsible for the polarization distribution of electrons,thus activating H_(2)O_(2) and dissolved oxygen(DO).The removal of contaminants could be attributed primarily to 1)the activation of H_(2)O_(2) into ^(·)OH to attack the contaminants and 2)self-cleavage because of the transfer of electrons from the contaminants to the catalysts.This study provides an innovative solution for the effective treatment of ECs and has positive implications for easing global environmental crises.