Biocatalytic enhancement of laccase immobilized on ZnFe_(2)O_(4) nanoparticles and its application for degradation of textile dyes

Efficient and convenient treatment of industrial dyeing wastewater is of great significance to guarantee human and animal health.This work presented the enhanced catalytic activity at pH 3.0 of laccase immobilized on amino-functionalized ZnFe_(2)O_(4) nanoparticles(ZnFe_(2)O_(4)-laccase)and its application for the degradation of textile dyes.Due to the existence of a large number of oxygen vacancies on the surface of the ZnFe_(2)O_(4) nanoparticles,negative ions accumulated on the magnetic carriers,which resulted in a harsh optimal pH value of the ZnFe_(2)O_(4)-laccase.Laccase activity assays revealed that the ZnFe_(2)O_(4)-laccase possessed superior pH and thermal stabilities,excellent reusability,and noticeable organic solvent tolerance.Meanwhile,the ZnFe_(2)O_(4) laccase presented efficient and sustainable degradation of high concentrations of textile dyes.The initial decoloration efficiencies of malachite green(MG),brilliant green(BG),azophloxine,crystal violet(CV),reactive blue 19(RB19),and procion red MX-5B were approximately 99.1%,95.0%,93.3%,87.4%,86.1%,and 85.3%,respectively.After 10 consecutive reuses,the degradation rates of the textile dyes still maintained about 98.2%,92.5%,83.2%,81.5%,79.8%and 65.9%,respectively.The excellent dye degradation properties indicate that the ZnFe_(2)O_(4)-laccase has a technical application in high concentrations of dyestuff treatment.

Photocatalytic Degradation of Water-Soluble Dyes by LaCoO_3

Perovskite type oxides LaCoO 3 was prepared by citrate method in granula of 20～30 nm. Using a fluorescent Hg lamp or sunlight as irradiator, the degradation experiments of various water soluble dyes were carried out in the suspension system of LaCoO 3. The results show that the perovskite type oxide LaCoO 3 has good photocatalytic activity. With the study of X ray photoelectron spectroscopy and photoacoustic spectra, its photocatalytic activity is mainly related with the factors such as the d electron structure of ion Co 3+ , Co O binding energy and adsorbed oxygen on the surface etc.

Catalytic degradation of methylene blue by Fenton like system: model to the environmental reaction

To develop more efficient chemical methods for the demineralization of organic pollutants from water bodies, which one was also mimic to the nature, a degradation of methylene blue by Fe(Ⅲ) and H 2O 2 in the absence of light instead of Fe(Ⅱ) and H 2O 2 was studied. Results showed that use of Fe (Ⅲ) is more promising than Fe(Ⅱ). The present study reflects that Fenton reaction is more efficient, in the presence of a small amount of salicylic acid is added which is a one of the priority pollutant.

Photocatalytic degradation of textile dyeing wastewater through microwave synthesized Zr-AC,Ni-AC and Zn-AC

The novel zirconium oxide, nickel oxide and zinc oxide nanoparticles supported activated carbons（Zr-AC, Ni-AC, Zn-AC） were successfully fabricated through microwave irradiation method. The synthesized nanoparticles were characterized using XRD, HR-SEM, XPS and BET. The optical properties of Zr-AC, Ni-AC and Zn-AC composites were investigated using UV–Vis diffuse reflectance spectroscopy. The photocatalytic efficiency was verified in the degradation of textile dyeing wastewater（TDW） in UV light irradiation. The chemical oxygen demand（COD） of TDW was observed at regular intervals to calculate the removal rate of COD. Zn-AC composites showed impressive photocatalytic enrichment, which can be ascribed to the enhanced absorbance in the UV light region, the effective adsorptive capacity to dye molecules, the assisted charge transfer and the inhibited recombination of electron-hole pairs. The maximum TDW degradation（82% COD removal） was achieved with Zn-AC. A possible synergy mechanism on the surface of Zn-AC was also designed. Zn-AC could be reused five times without exceptional loss of its activity.

Structure relationship of nitrochlorobenzene catalytic degradation process in water over palladium-iron bimetallic catalyst

Two isomers ofnitrochlorobenzene （o- andp-NCB） were treated by a Pd/Fe catalyst in aqueous solutions through catalytic amination and dechlorination. Nitrochlorobenzenes are rapidly converted to form chloroanilines （CAN） first through an amination process, and then rapidly dechlorinated to become aniline （AN） and CI^-, without the involvement of any other intermediate reaction products. The amination and dechlorination reaction are believed to take place predominantly on the surface site of the Pd/Fe catalysts. The dechlorination rate of the reductive degradation of the two isomers of nitrochlorobenzene （o-, and p-NCB） in the presence of Pd/Fe as a catalyst was measured experimentally. In all cases, the reaction rate constants were found to increase with the decrease in the Gibbs free energy （correlation with the activation energy） of NCBs formation; the activation energy of each dechlorination reaction was measured to be 95.83 and 77.05 kJ/mol, respectively for o- and p-NCB. The results demonstrated that p-NCBs were reduced more easily than o-NCBs.

A New Property of Conjugated Polymer PFP: Catalytic Degradation of Methylene Blue Aqueous Solution

A new property of conjugated polymer poly（furancarbinol-co-phenol）（PFP） was studied. The target copolymer was used as a catalyst after proper heating treatment. And dye methylene blue （MB） could be fully degraded and largely mineralized on PFP, under natural light or even in dark, in a few minutes. Furthermore, the catalytic activity could be preserved after several runs and the catalyst was readily separated. The effect of calcination temperature was also observed.

MESOPOROUS ACID SOLID AS A CARRIER FOR METALLOCENE CATALYST IN ETHYLENE POLYMERIZATION AND A CATALYST IN CATALYTIC DEGRADATION OF POLYETHYLENE

The possibility of mesoporous acid solid as a carder for metallocene catalyst in ethylene polymerization and catalyst for polyethylene （PE） catalytic degradation was investigated. Here, HMCM-41 and AIMCM-41, and mesoporous silicoaluminophosphate molecular sieves （SAPO1 and SAPO2） were synthesized and used as acid solid. Much more gases were produced during catalytic degradation in PE/acid solid mixtures via in situ polymerization than those via physical mixing. The particle size distribution results exhibited that the particle size of SAPO1 in the PE/SAPOI mixture via in situ polymerization was about 1/14 times of that of the original SAPO1 or SAPO1-supported metallocene catalyst. This work shows a novel technology for chemical recycling of polyolefin.

Facile Preparation of PVA-AA/TiO2 Composite Gel Particles and Their Tunable Photo-catalytic Property for the Degradation of Methyl Orange

In the presence of titanium dioxide powder, cross-linking reaction between commercial polyvinyl alcohol(PVA)-based macromonomer and acrylic acid(AA) was initiated with potassium persulfate in an emulsifying system. As a result, PVA-AA/TiO2 composite gel particles were obtained. The morphology and composition of the particles were analyzed with scanning electron microscopy(SEM), energy scattering x-ray spectroscopy(EDS), Fourier infrared spectroscopy(FTIR), and thermogravimetric analysis(TGA). The analysis results confirmed that the particles were the expected ones. TiO2 was dispersed homogeneously within the spheroidal particles. Compared to the control gel, the composite gel particles not only contained Ti element but also showed higher thermal stability. In addition, the photo-catalytic behavior of the particles for the degradation of methyl orange contained in aqueous solution was examined. The particles exhibited photocatalytic characteristic for the degradation of the model dye, which could be modulated by simply varying the amount of cross-linking agent or TiO2. The photo-catalytic degradation percentage of methyl orange maintained at 91%-96% after using the particles three times, which indicated that TiO2 could played its role repeatedly via being fixated within polyvinyl alcohol-based gel.

Peak-like three-dimensional CoFe_(2)O_(4)/carbon nanotube decorated bamboo fabrics for simultaneous solar-thermal evaporation of water and photocatalytic degradation of bisphenol A

Catalytic CoFe_(2)O_(4) and solar-thermal carbon nanotube decorated bamboo fabrics(CCBF)are fabricated for integrating efficient solar steam generation from wastewater with catalytic degradation of its organic con-taminants.Thanks to the numerous porous channels and polar groups of bamboo fabric and the efficient solar-thermal energy conversion of black carbon nanotubes,the porous and hydrophilic CCBF exhibits fast upward transport of water,efficient solar light absorption,and high solar-thermal energy conversion effi-ciency.The decorated CoFe_(2)O_(4) not only enhances the solar-thermal energy conversion efficiency of CCBF but also activates potassium peroxymonosulfate to generate abundant highly active species for catalytic degradation of bisphenol A(BPA).Furthermore,folding the CCBF into a peak-like 3D evaporator can en-hance solar energy utilization,and gain environmental energy for promoting solar-thermal water evapo-ration and catalytic degradation performances.The 3D CCBF evaporator achieves a water evaporation rate of 2.72 kg m^(-2) h^(-1) under 1-sun irradiation.Meanwhile,100%of the BPA in the seawater can be degraded within 10 min.An exceptional high purification efficiency of 27.72 kg m^(-2) h^(-1) is achieved with the 3D evaporator during a long-term treatment of BPA-containing seawater under 1-sun irradiation.This work demonstrates efficient purification of seawater/wastewater with both metal ions and organic pollutants by simultaneous solar-thermal evaporation of water and catalytic degradation of organic pollutants.

Dual-functional MnS_(2)/MnO_(2) heterostructure catalyst for efficient acidic hydrogen evolution reaction and assisted degradation of organic wastewater

The design and synthesis of non-precious metal dual-functional electrocatalysts through the modulation of electronic structure are important for the development of renewable hydrogen energy.Herein,MnS_(2)/MnO_(2)-CC heterostructure dual-functional catalysts with ultrathin nanosheets were prepared by a twostep electrodeposition method for efficient acidic hydrogen evolution reaction(HER) and degradation of organic wastewater(such as methylene blue(MB)).The electronic structure of Mn atoms at the MnS_(2)/MnO_(2)-CC heterostructure interface is reconfigured under the joint action of S and O atoms.Theoretical calculations show that the Mn d-band electron distribution in MnS_(2)/MnO_(2)-CC catalyst has higher occupied states near the Fermi level compared to the MnO_(2) and MnS_(2) catalysts,which indicates that MnS_(2)/MnO_(2)-CC catalyst has better electron transfer capability and catalytic activity.The MnS_(2)/MnO_(2)-CC catalysts require overpotential of only 66 and 116 mV to reach current density of 10 and 100 mA cm^(-2)in MB/H_(2)SO_(4) media.The MnS_(2)/MnO_(2)-CC catalyst also has a low Tafel slope(26.72 mV dec^(-1)) and excellent stability(the performance does not decay after 20 h of testing).In addition,the MB removal efficiency of the MnS_(2)/MnO_(2)-CC catalyst with a better kinetic rate(0.0226) can reach 97.76%,which is much higher than that of the MnO_(x)-CC catalyst(72.10%).This strategy provides a new way to develop efficient and stable non-precious metal dual-functional electrocatalysts for HER and organic wastewater degradation.

Dynamic Regulation of Hydrogen Bonding Networks and Solvation Structures for Synergistic Solar‑Thermal Desalination of Seawater and Catalytic Degradation of Organic Pollutants

Although solar steam generation strategy is efficient in desalinating seawater,it is still challenging to achieve continuous solar-thermal desalination of seawater and catalytic degradation of organic pollutants.Herein,dynamic regulations of hydrogen bonding networks and solvation structures are realized by designing an asymmetric bilayer membrane consisting of a bacterial cellulose/carbon nanotube/Co_(2)(OH)_(2)CO_(3)nanorod top layer and a bacterial cellulose/Co_(2)(OH)_(2)CO_(3)nanorod(BCH)bottom layer.Crucially,the hydrogen bonding networks inside the membrane can be tuned by the rich surface–OH groups of the bacterial cellulose and Co_(2)(OH)_(2)CO_(3)as well as the ions and radicals in situ generated during the catalysis process.Moreover,both SO_(4)^(2−)and HSO_(5)−can regulate the solvation structure of Na^(+)and be adsorbed more preferentially on the evaporation surface than Cl^(−),thus hindering the de-solvation of the solvated Na^(+)and subsequent nucleation/growth of NaCl.Furthermore,the heat generated by the solar-thermal energy conversion can accelerate the reaction kinetics and enhance the catalytic degradation efficiency.This work provides a flow-bed water purification system with an asymmetric solar-thermal and catalytic membrane for synergistic solar thermal desalination of seawater/brine and catalytic degradation of organic pollutants.

Synthesis of Hierarchically Porous CaFe204/Carbon Fiber Hybrids and Microwave Induced Catalytic Activity

Hierarchically porous CaFe204/carbon fiber hybrids with enhanced microwave induced cat- alytic activity for the degradation of methyl violet （MV） from water were synthesized from kapok by a novel two-step process coupling pore-fabricating and nanoparticles assembling. The as-prepared samples exhibited characteristic hollow fiber morphology, CaFe204 nanopar- ticles dispersed uniformly on the surface of hollow carbon fibers （HCF）. The effects of various factors such as CaFe204 loading, microwave power, catalyst doses, initial concen- tration of MV solution and pH value on the microwave induced degradation of MV over CaFe204/HCF were evaluated. It was found that the microwave induced degradation of MV over CaFe204/HCF had high reaction rate and short process time. The kinetic study indicated that the degradation of MV over CaFe204/HCF followed pseudo-first-order kinet- ics model. The high catalytic activity of CaFe204/HCF was facilitated by the synergistic relationship between microwave induced catalytic reaction and adsorption characteristics.

Degradation analysis of A^2/O combined with AgNO3 + K2FeO4 on coking wastewater

In this work, a coking wastewater was selected and a biochemical Az/O treatment device for fractional degradation was designed and employed. After each stage of the treatment, the products were analyzed through gas chromatography-mass spectroscopy （GC-MS） to determine their composition. Finally, AgNO3 ＋ K2FeO4 was used as an advanced deep catalytic oxidation treatment. It was concluded from the analysis that cyclic organics could be degraded and the chemical oxygen demand （COD） was controlled within 50 mg. L-1, in line with the target value, Meanwhile, the spectra obtained from the GC-MS were in accordance with the conclusions reached based on the COD. The research results showed that all hard-degradable organics in coking wastewater could be eliminated through the A2/O bio-membrane treatment and the advanced treatment of making use of K2FeO4 as an oxidant and Ag＋ as a catalyst, the catalytic efficiency with Ag＋ as a catalyst of K2FeO4 was very high. Ag＋ could evidently improve the oxidation capacity of K2FeO4 to wastewater in its short stability time, and this is an important innovation.

Integration of Ru/C and base for reductive catalytic fractionation of triploid poplar

Lignin,which is the most recalcitrant component of lignocellulosic biomass,is also the most abundant renewable aromatic resource.Herein,reductive treatment of triploid poplar sawdust by the integration of catalytic Ru/C and a base,which afforded high yields of phenolic monomers from the lignin component and a solid carbohydrate pulp,is reported.The introduction of Cs_(2)CO_(3) led to the generation of C2 side‐chained phenols through the cleavage of C_(β)–O and C_(β)–C_(γ) bonds inβ–O–4 units in addition to C3 side‐chained phenols;the relationship between C2 and C3 was dependent on the base dosage.The reaction conditions,including base species,temperature,time,and H_(2) pressure,were optimized in terms of phenolic product distribution,delignification degree,and carbohydrate retention.The carbohydrate pulps generated from reductive catalytic fractionation in the presence of Cs_(2)CO_(3) were more amenable to enzymatic hydrolysis,indicating that this treatment of biomass constituted the fractionation of biomass components together with the breakdown of biomass recalcitrance.

One-pot synthesis of poly vinyl alcohol(PVA) supported silver nanoparticles and its efficiency in catalytic reduction of methylene blue

Stable silver nanoparticles were synthesized using polyvinyl alcohol （PVA） as reducing and capping agent. The method of steric stabilization was adopted for the incorporation of silver nanoparticles in the polymer matrix. The successful incorporation of silver nanoparticles in a PVA matrix was confirmed by UV–Visible spectroscopy, transmission electron microscopy （TEM） and Fourier transform infrared （FT-IR） spectroscopy. The synthesized silver nanoparticles were characterized by a peak at 426 nm in the UV–Vis spectrum. TEM studies showed the formation of spherical shaped silver nanoparticles of 10-13 nm, following the reduction by UV irradiation. Catalytic properties were studied by means of UV-Visible spectroscopic analysis. The synthesized silver nanoparticles exhibited good catalytic properties in the reduction of methylene blue.

Degradation of Residual Formaldehyde in Fabric by Photo-catalysis

The residual formaldehyde （HCHO） in fabric was degraded using photo-catalysis assisted by the compound catalyst of nano-TiO2 and nano-ZnO. The effects of several factors on the degradation, such as the composing of catalyst, irradiation time, pH value and the H2CHO concentration of the immersed solution were investigated. Results showed that H2CHO of the immersed solution had degraded 93% after 5 h irradiation, and the degradation ratio of formaldehyde could be improved and the aging of the fabric can be avoided with the addition of ZnO nanoparticles and pH value of the immersed-fibric solution. The fabric with residual formaldehyde about 1 800 μg/g can be efficiently treated to satisfy the China National Standard （GB/2912.1-1998） with the photo-catalytic degradation.

Oil Pollutants Degradation of Nano-MgO in Micro-Polluted Water

The removal of oil pollutants from water and purifying process of oil-polluted water are studied through catalytic degradation method with nano-MgO. The results indicated that catalytic degradation effect of nano-MgO on the oil pollutants was associated with dosage of nano-MgO, pH and water temperature. When oil content was 1.8 mg/L, 0.17 g nano-MgO was used and the removal rate of oil was 93.92%. Furthermore, nano-Mgo was a non-photosensitive catalyst. GC/MS analysis showed that the amount of petroleum-based pollutants in water was reduced 73.77% from the previous 61 kinds to 16 kinds, and the total peak area was reduced 96.05% after catalytic degradation of nano-MgO. Therefore, nano-MgO has an excellent effect on the catalytic degradation of oil pollutants and can be applied in the treatment of oil wastewaters.

Effects of Cu(Ⅱ) or Zn(Ⅱ) on photodegradation of some toxic organic compounds in wastewater by using TiO_2 as catalyst

The effects of Cu (Ⅱ) or Zn (Ⅱ) on the photo-catalytic degradation of some organic chemicals in water, such as acetone, phenol, dyes, and tea saponin were studied. Dyes in wastewater from a textile factory can be effectively degraded by photo-catalysis with TiO 2 and ultraviolet light or sunshine, but the reaction rate could be slowed down if copper or zinc salt exists in the solution.

多羧酸镍配合物催化降解罗丹明B的活性与机理

由于纺织、印刷等工业规模的迅速扩张,生产过程中产生的染料废水对人类生存环境造成巨大压力。目前,在染料废水修复处理领域,基于SO_(4)^(·-)的高级氧化技术由于其氧化优势备受关注。通常,过一硫酸盐(PMS)可自分解产生SO_(4)^(·-),然而其生成效率很低,因此,探寻有效的PMS催化剂成为研究热点。本研究以5,5′-二苯醚间苯二甲酸(H 4odip)和Ni(NO_(3))_(2)·6H_(2)O为原料,采用溶剂热法制得一种三维结构配合物Ni 4(odip)2-(μ2-OH_(2))2(H_(2)O)8,该材料水稳定性较好且能够在弱酸弱碱环境下稳定存在。采用X射线单晶和粉末衍射、红外光谱、热重及元素分析对配合物的结构和组成进行了表征。利用紫外-可见分光光度计研究其催化降解罗丹明B的活性与机理,系统探讨了配合物和PMS用量、溶液反应温度和pH对罗丹明B降解性能的影响。与不加催化剂相比,配合物的加入可使罗丹明B的降解速率提高两倍。研究表明,在中性环境中,PMS/配合物催化体系具有更强的降解能力,降解率可达92.3%。活性氧物种(ROS)捕获实验和电子顺磁共振波谱结果表明该催化体系降解罗丹明B的ROS有SO_(4)^(·-)、·OH、1O_(2)和O_(2)^(·-),且此四种ROS在降解罗丹明B时的贡献作用相近。综合分析实验结果,该配合物在催化PMS用于染料废水修复处理领域可作为一种有效且能循环使用的新型多相催化剂。

Co-MOFs衍生的钴基化合物催化氧化典型VOCs研究进展

基于催化氧化技术在挥发性有机化合物(VOCs)末端治理方面有极高的效率,以及近年来金属有机骨架(MOFs)衍生的钴基化合物在催化氧化VOCs中的优异表现,文章总结了4种典型的钴基MOFs(ZIF-67,ZSA-1,Co-MOF-71和Co-MOF-74)及其衍生的钴基催化剂的组成与制备方法,并综述了其衍生物催化氧化几种典型VOCs(甲苯、邻二甲苯、甲醛和丙酮)的研究进展。最后归纳了反应过程中空速和湿度等因素对钴基化合物催化氧化VOCs的影响,探讨了MOFs衍生的钴基催化剂的反应机理,并对MOFs衍生的钴基催化剂在VOCs氧化中的研究进行了展望。