Controlled Radical Polymerization of Methyl Methacrylate Catalyzed by Hybrid Supported Iron Catalyst

A supported iron catalyst, which was prepared by anchoring FeCl2/FeCl3 on the cross-linking macroporous polyacrylate ion exchange resin, was evaluated via the controlled radical polymerization. When a small amount of CuCl2/ Me6TREN was added, the controllability of the polymerization over the iron-mediated catalyst was significantly improved（Mw/Mn = 1.23-1.73 ）, affording a polymer with a low residual metal via a simple catalyst separation procedure. After suitable regeneration, the supported iron catalyst could also he recycled. UV-Vis analysis showed that the additional copper catalyst could facilitate the radical deactivation process.

Effect of catalyst on formation of poly(methyl methacrylate) brushes by surface initiated atom transfer radical polymerization

Poly(methyl methacrylate)(PMMA) brushes were synthesized from silicon wafers via surface initiated atom transfer radical polymerization(SI-ATRP).Energy disperse spectroscopy(EDS) and atomic force microscopy(AFM) confirmed that PMMA brushes were successfully prepared on the silicon wafers,and the surface became more hydrophobic according to the contact angle of 69°.It is found that CuCl/1,1,4,7,10,10-hexamethyl triethylenetetramine(HMTETA) system is more suitable than CuBr/N,N,N′,N″,N″-pentamethyl diethylenetriamine(PMDETA) system to control the free radical polymerization of MMA in solution.Nevertheless,better control on the thickness of PMMA brushes was achieved in CuBr/PMDETA than in CuCl/HMTETA due to higher activity and better reversibility of the former system.

Preparation of sodium alginate gel microspheres catalysts and its high catalytic performance for treatment of ciprofloxacin wastewater

The discharge of the antibiotic wastewater has increased dramatically in our country with the development of medical science and wide application of antibiotic,resulting in serious harm to human body and ecological environment.In this work,ciprofloxacin(CIP)was selected as one of typical antibiotics and heterogeneous Fenton-like catalysts were prepared for the treatment of ciprofloxacin wastewater.The sodium alginate(SA)gel microspheres catalysts were prepared by polymerization method using double metal ions of Fe^(3+)and Mn^(2+)as cross-linking agents.Preparation conditions such as metal ions concentration,mass fraction of SA,polymerization temperature and dual-metal ions as crosslinking agent were optimized.Moreover,the effects of operating conditions such as initial concentration of CIP,pH value and catalyst dosage on CIP removal were studied.The kinetic equation showed that the effect of the initial concentration of CIP on the degradation rate was in line with second-order kinetics,and the effects of catalyst dosage and pH value on the degradation rate of CIP were in line with first-order kinetics.The SA gel microspheres catalysts prepared by dual-metal ions exhibited a high CIP removal and showed a good reusability after six recycles.The SA gel microspheres catalysts with an easy recovery performance provided an economical and efficient method for the removal of antibiotics in the future.

Fluorescence detection of hydroxyl radical generated from oxygen reduction on Fe/N/C catalyst

Pyrolyzed Fe/N/C catalyst has been considered as the most promising candidate to replace Pt for oxygen reduction reaction(ORR) in fuel cells.However,poor stability of Fe/N/C catalyst,mainly attributed to the oxidation corrosion by aggressive ·OH radical,severely hampers its applications.However,the exact mechanism for generation of ·OH is unclear yet.Herein,we developed a fluorescent method to effectively detect ·OH generated from ORR on Fe/N/C catalyst by using coumarin as a fluorescent probe.A great difference in potential dependence between ·OH and H2O2 generated from the ORR was observed,which suggests that ·OH is not generated from the decomposition of H2O2 as traditional viewpoint.

One-pot synthesis of network supported catalyst using supramolecular gel as template

A simple and general strategy is described for preparing network supported catalyst through a one-pot synthetic procedure using supramolecular gel as template.This procedure directly attaches ligand to support during fabricating the support.Using this strategy,supported CuBr/di-（2-picolyl） amine catalyst with U-shaped fibrillar network was prepared and used in atom transfer radical polymerization of methyl methacrylate.XPS and SEM characterization of the catalyst revealed homogeneous distribution of ligand,sufficient reactive sites,adequate mechanical strength and macroporosity.The polymerization results demonstrated high activity and reusability of such catalyst.This strategy might be extended to other supported catalysts used in column reactors.

Determination of hydroxyl radicals in TiO2/Ti photoelectrocatalytic oxidation system using Fe（phen）3^2＋ spectrophotometry

A new method of determining the cumulate concentration of hydroxyl radicals in the TiO2/Ti photoelectrocatalytic（PEC） oxidation system was established by o-phenanthroline-Fe（Ⅱ）（Fe（phen）3^2＋） spectrophotometry and using anion exchange membrane. Fe （phen）3^2＋ can be oxidized to o-phenanthroline-Fe（Ⅲ）（Fe（phen）3^3＋） by strong oxidization of hydroxyl radicals（·OH）. Then the cumulate concentration of hydroxyl radicals can be calculated through determining the change of the Fe（phen）3^3＋ absorbency at 509 nm. In addition, the research results showed the production rate of hydroxyl radicals was affected obviously by pH of solution, the cumulate concentration of hydroxyl radicals was the largest at nearby the initial pH 6.3 （isoelectric point）, and the change direction of pH after illumination tended to nearby isoelectric point.

Superoxide-like Cu/GO single-atom catalysts nanozyme with high specificity and activity for removing superoxide free radicals

Although nanozyme has become an emerging area of research attracting extensive attention recently,the activity and specificity of currently reported nanozymes are generally lower than those of natural enzymes.Developing highly active and specific nanozymes is therefore extremely necessary and also remains a great challenge.Superoxide dismutase(SOD)catalyzes the disproportionation of cytotoxic O_(2)·^(−)into hydrogen peroxide and oxygen,and plays an important role in reducing human oxidative stress.In this work,we prepare Cu single-atom catalysts(Cu/GO SACs,GO=graphene oxide)through a simple and low-cost strategy at room temperature using Cu foam and graphene oxide.Cu/GO SACs can maintain excellent catalytic activity under harsh environment.Compared with the natural enzyme,SOD-like Cu/GO SAC nanozyme has higher catalytic activity and meanwhile,it does not possess the common properties of other mimic enzymes often existing in nanomaterials.Based on the excellent SOD-like enzyme activity of Cu/GO SACs,it successfully eliminates the active oxygen in cigarette smoke.This work not only provides a new idea for the design and synthesis of nanozymes with excellent SOD mimetic properties,but also is promising in the treatment of lung injury and inflammatory diseases related to free radical production.

Synthesis of End Functional Polymers via Atom Transfer Radical Polymerization in Immobilized Catalytic System

Cross-linked polystyrene with azo-crown ether functional side chain (PSt-1, 10-dicarbonyl-3,6,9-trizaoeylcode-cane) was prepared under microwave irradiation and the structure was characterized through FT-IR and element analysis. The functionalized cross-linked polystyrene (cross-link degree, 3.5%) combining with immobilized catalyst system (CuBr and ethylα-bromo-isobutyrate) can catalyze atom transfer radical polymerization of Styrene. Neat polymer products can be obtained then. Complex of La and the polymer end group (EBiB) was synthesized. The third order nonlinear optical property of the polymer-La complex was investigated and the structure was also characterized by FT-IR and XPS.

Stable and efficient metal-biochar supported catalyst:degradation of model pollutants through sulfate radical-based advanced oxidation processes

This study focuses on the synthesis of metal-based biochar catalysts and their catalytic activation of peroxymonosulfate(PMS,HSO5−)for the degradation of three different wastewater model pollutants employing advanced oxidation processes(AOP).Iron,copper,and two different cobalt-based catalysts were prepared and evaluated.The catalysts were supported on a biochar obtained from the pyrolysis of woody pruning wastes.They were characterized by C,H,and N elemental analysis,X-Ray diffraction(XRD),Fourier-transform infrared spectroscopy(FTIR),and scanning electron microscope(SEM).The metal content in each catalyst was determined by means of atomic absorption spectroscopy(AAS).The degradation reac-tions of benzoic acid(BA),catechol(C),and cinnamic acid(CA)were carried out in a lab scale batch glass reactor and were followed by UV-Visible spectroscopy(UV-Vis).A colorimetric technique was employed to verify the presence of oxidant during the reaction progress.The catalyst/oxidant optimal ratio was determined for the cobalt catalysts.The mineralization degree of the pollutants after the degradations was verified by means of total organic carbon(TOC)content in the residual liquids.After 4 h of reaction,the maximum mineralization was reached when C was treated with a cobalt-based catalyst(>80%),and its stability was evaluated through successive cycles of use.

Enhanced persulfate activation process by magnetically separable catalysts for water purification:A review

In recent years,persulfate(PS)-based advanced oxidation processes(AOPs)have become a hot research topic for degrading environmental pollutants due to their excellent oxidation capacity,selectivity,and stability.PS-AOPs can generate sulfate radicals(SO^(·-)_(4))with strong oxidation ability,but single PS produces limited or no radicals.Therefore,activation of PS by energy input or catalyst dosing is used to improve its oxidation performance.However,the addition of disposable catalyst not only causes a waste of resources,but also may lead to secondary pollution.Therefore,magnetically separable catalysts for activating PS have received widespread attention due to their reusability.Although there are few literature reviews on the activation of PS by carbon-or iron-based magnetic materials,the mechanism analysis of the activation of PS by magnetic materials to degrade pollut-ants is not deep enough,and the discussion of material types is not comprehensive and detailed.Moreover,the discussion of magnetic materials in terms of recycling properties is lacking.Therefore,this review firstly sum-marizes and analyzes the mechanism of magnetically separable catalysts activating PS to degrade pollutants.Then,the research progress of zero-valent iron(ZVI,Fe^(0))-based,iron oxide-based,bimetallic oxide-based,and other magnetically separable catalyst is introduced,and the tailoring engineering approaches and reusability of magnetically separable catalysts are discussed.Finally,some possible material optimization suggestions are proposed in this paper.In conclusion,this review is expected to provide useful insights for improving the per-formance and reusability of magnetically separable materials activated PS in the future.

Enhanced activation of peroxymonosulfate by Fe/N co-doped ordered mesoporous carbon with dual active sites for efficient removal of m-cresol

The novel Fe-N co-doped ordered mesoporous carbon with high catalytic activity in m-cresol removal was prepared by urea-assisted impregnation and simple pyrolysis method.During the preparation of the Fe-NC catalyst,the complexation of N elements in urea could anchor Fe,and the formation of C3N4during urea pyrolysis could also prevent migration and aggregation of Fe species,which jointly improve the dispersion and stability of Fe.The FeN4sites and highly dispersed Fe nanoparticles synergistically trigger the dual-site peroxymonosulfate (PMS) activation for highly efficient m-cresol degradation,while the ordered mesoporous structure of the catalyst could improve the mass transfer rate of the catalytic process,which together promote catalytic degradation of m-cresol by PMS activation.Reactive oxygen species (ROS) analytic experiments demonstrate that the system degrades m-cresol by free radical pathway mainly based on SO_(4)^(-)·and·OH,and partially based on·OH as the active components,and a possible PMS activation mechanism by 5Fe-50 for m-cresol degradation was proposed.This study can provide theoretical guidance for the preparation of efficient and stable catalysts for the degradation of organic pollutants by activated PMS.

Fe-Mn-sepiolite as an effective heterogeneous Fenton-like catalyst for the decolorization of reactive brilliant blue

A study of the decolorization of reactive brilliant blue in an aqueous solution using Fe-Mn-sepiolite as a heterogeneous Fenton-like catalyst has been performed. The Fourier transform infrared （FTIR） spectra of the catalyst showed bending vibrations of the Fe-O. The Xray diffraction （XRD） patterns of the catalyst showed characteristic diffraction peaks of α-Fe203, γ-Fe203 and MnO. A four factor central composite design （CCD） coupled with response surface methodology （RSM） was applied to evaluate and optimize the important variables （catalyst addition, hydrogen peroxide dosage, initial pH value and initial dye concentration）. When the reaction conditions were catalyst dosage = 0.4 g, [H202]= 0.3 mL, pH= 2.5, [reactive brilliant blue]o = 50mg·L-1, and volume of solution = 500 mL at room temperature, the decolorization efficiency of reactive brilliant blue was 91.98% within 60min. Moreover, the Fe-Mn-sepiolite catalyst had good stability for the degradation of reactive brilliant blue even after six cycles. Leaching of iron ions （ 〈 0.4 mg·L-l） was observed. The decoloring process was reactive brilliant blue specific via a redox reaction. The benzene ring and naphthalene ring were first oxidized to open ring; these were then oxidized to the alcohol and carboxylic acid. The reactive brilliant blue was decom- posed mainly by the attack of .OH radicals including surface-bound .OH radicals generated on the catalyst surface.

Hydroxyl radical-involved cancer therapy via Fenton reactions

The tumor microenvironment features over-expressed hydrogen peroxide(H_(2)O_(2)).Thus,versatile therapeutic strategies based on H_(2)O_(2) as a reaction substrate to generate hydroxyl radical(•OH)have been used as a prospective therapeutic method to boost anticancer efficiency.However,the limited Fenton catalysts and insufficient endogenous H_(2)O_(2) content in tumor sites greatly hinder•OH production,failing to achieve the desired therapeutic effect.Therefore,supplying Fenton catalysts and elevating H_(2)O_(2) levels into cancer cells are effective strategies to improve•OH generation.These therapeutic strategies are systematically discussed in this review.Furthermore,the challenges and future developments of hydroxyl radical-involved cancer therapy are discussed to improve therapeutic efficacy.

g-C_(3)N_(4)锚定Cu(Ⅰ)高选择性催化CCl_(4)合成2,4,4,4-四氯丁腈

以尿素和Cu(NO_(3))_(2)·3H_(2)O为前体,采用热缩合法制备了不同Cu负载量的氮化碳(g-C_(3)N_(4))基催化剂Cu/CNn(n=1、2、3),采用X射线衍射仪、傅里叶变换红外光谱、X射线光电子能谱、比表面积测试、扫描电子显微镜及透射电子显微镜对其结构和形貌进行了表征,比较了不同Cu负载量的Cu/CNn催化CCl_(4)与丙烯腈(AN)的原子转移自由基加成(ATRA)反应合成2,4,4,4-四氯丁腈(TBN)的催化性能。结果表明,Cu/CN1呈现优异的催化性能,以乙腈(MeCN)为溶剂,n(Cu/CN1)∶n(AN)=1∶1000,120℃反应12h,TBN的选择性可达96.5%,产率可达83.3%,Cu/CN作为多相催化剂,经过滤处理便可重复利用,使用7次其催化活性仍能稳定保持。基于相关的实验结果,提出了Cu/CN催化CCl_(4)和AN的ATRA反应的氧化-还原循环机理。实验结果揭示了Cu与g-C_(3)N_(4)载体的协同作用机制,为CCl_(4)深加工开发高效的催化体系提供了新的思路。

Successive Free-Radical C(sp^(2))-C(sp^(2)) Coupling Reactions to Form Graphene

Graphene is of great interest because of its exciting properties and potential applications,but its production on a large-scale still presents considerable challenges.Herein,we report the synthesis of predominately few-layer graphene,due toπ–πstacking,and single-layer graphene from reaction between hexabromobenzene and Na metal,followed by annealing to improve crystallinity.The reaction proceeds via a free-radical C(sp^(2))–C(sp^(2))coupling mechanism,which is supported by theoretical calculations.The graphene can host unpaired spin electrons,leading to a short acquisition time for a solidstate nuclear magnetic resonance 13C spectrum from unlabeled graphene,which is ascribed to the very short spin-lattice relaxation time.High catalytic activity for transforming amine to imine with a conversion of>99%and a yield of∼97%is demonstrated,and high electronic conductivity of∼105 S·m^(−1) is found by terahertz spectroscopy.The reaction delivers a method for synthesizing graphene with a high spin concentration from perbrominated benzene molecules by using an active metallic agent,such as Na,Li,or Mg.

Mechanochemically sulfured FeS1.92 as stable and efficient heterogeneous Fenton catalyst

Fenton reaction is one of most promising approaches for efficient removal of various robust organic pollutants in wastewater,however it faces several intrinsic challenges such as acidic condition,sludge waste and sensitive to sulfide-containing compound.Here we reported a novel FeS1.92 as an efficient and sulfide resistant heterogeneous Fenton catalyst under mild condition.This novel FeS1.92 was facilely prepared through a mechanochemical synthesis of mackinawite(FeS) with sulfur powder(S) by ball milling.The sulfured mackinawite(FeS1.92) exhibits high performance in activating H2 O2 to generate hydroxyle radicals for organic waste remediation.Furthermore,this FeS1.92 based heterogeneous Fenton catalyst is highly sulfide resistant and shows improved performance for degrading sulfide-containing organic pollutants.This study provides an effective mechanochemical approach to fabricate heterogeneous Fenton catalysts for sulfide-containing wastewater treatment.

External Photocatalyst-Free Visible Light-Promoted 1,3-Addition of Perfluoroalkyl Iodides to Vinyldiazoacetates

Alkenes and alkynes are typical substrates used in atom transfer radical addition(ATRA)reactions,resulting in the formation of vicinal disubstituted products.In this report,vinyldiazoacetates were first developed as the radical acceptors in an ATRA reaction of RfI,leading to 1,3-difunctional adducts.The reaction is driven by visible light,without the need for external photocatalysts and additives.A series of control experiments and density functional theory(DFT)calculations indicate the 1,3-addition proceeds via a radical-chain process and the initial Rf radical was generated by homolytic dissociation of a radical pair complex of triplet free vinylcarbene and perfluoroalkyl iodide.After postreaction isomerization,various 1-iodo-3-perfluoroalkyl-alkenes were obtained in good yields with high Z selectivity.The synthetic utility of the ATRA 1,3-adduct was demonstrated by cross-coupling reactions and defluorination of perfluoroalkyl groups.

镍催化可控/活性自由基聚合反应研究进展

可控/活性自由基聚合是近年来发展的温和、聚合反应进程可控、分子结构可设计性强的自由基聚合反应技术,其核心在于活性自由基中间体与催化剂/链转移剂的可逆活化/失活过程,常用于极性单体聚合制备结构多样的有机高分子材料。镍催化剂具有多变的中心金属价态及多样的聚合反应机理,在可控/活性自由基聚合领域存在独特的优势。对近年来原子转移自由基聚合(ATRP)和有机金属控制的活性自由基聚合(OMRP)中的镍催化剂结构、聚合反应机理、反应行为和产物结构特征进行了综述,并对镍催化的可控/活性自由基聚合未来发展方向和应用前景进行了展望。

生物碳基纳米钯铜催化剂的优化制备及脱硝研究

针对目前高效处理水体硝酸盐污染的技术瓶颈,以毛竹生物碳为载体基材,通过湿化学-浸渍还原的手段制备生物碳基纳米钯铜双金属催化剂(Nano-PdCu-BC),并以其为粒子电极,协同传统的二维电化学反应器,搭建三维粒子电催化反应体系去除水体中的硝酸盐污染物.探究了催化剂制备的前驱液浓度、初始硝酸盐氮浓度、电流强度、催化剂投加量和初始pH值对电催化还原NO_(3)-N的影响.结果显示,通过浸渍还原的方法可以将钯铜双金属成功负载在毛竹生物碳载体上,获得纳米钯铜双金属催化剂.在前驱液为0.60g/LPdCl_(2)和0.15g/LCuCl_(2)的溶液组合,初始硝酸盐氮(NO_(3)-N)浓度为100mg/L、电流强度为220mA、初始pH值为7,催化剂投加量为0.80g/L的条件下,反应180min后硝酸盐氮去除率可达99.68%,N_(2)选择性约为44.25%;Nano-PdCu-BC电催化还原NO_(3)-N的反应符合一级反应动力学,反应动力学常数k值为0.034/min;经3次循环使用后,NO_(3)-N去除率仍维持在95%以上,N_(2)选择性保持在40%以上;揭示了纳米钯铜双金属催化剂电催化还原硝酸盐的机理,纳米零价Cu位点吸附NO_(3)-N后被氧化为CuO,提供电子促进NO_(3)-N还原为NO_(2)-N,协同纳米零价Pd,通过为吸附激活原子氢H*间接还原NO_(3)-N,达到将NO_(3)-N还原为NH_4和N_(2)的目的.

水性油墨污泥基炭材料活化过硫酸盐降解活性染料

以水性油墨污泥为原料,通过高温煅烧法制备了污泥基炭材料(AC)及改性炭材料(AC1),利用SEM、BET、FTIR和XPS对材料的形貌、结构及官能团进行了表征。考察了水性油墨污泥与碳酸钾(K_(2)CO_(3))质量比、炭材料投加量、过硫酸钠(PS)投加量、活性艳蓝X-BR初始浓度及温度对染料脱色的影响,并探讨了污泥基炭材料用于活化过硫酸钠(PS)降解染料的性能和活化机制。结果表明:改性炭材料AC1比AC具有大的比表面积和更丰富的孔道结构;AC1活化PS对活性艳蓝X-BR脱色效果优于AC;在AC1投加量0.8 g/L、PS投加量0.8 g/L、反应时间120 min、温度25℃、水浴振荡频率140 r/min条件下对40 mg/L染料溶液的降解效果最优,脱色率可达94.1%;炭材料的缺陷和表面的氧官能团是导致活化的原因,促进了活性染料的脱色;发挥作用的自由基主要为SO_(4)^(-·)和·OH。