Construction of Hierarchical Nanostructured N-doped TiO2 Immobilized Activated Carbon Fiber Porous Composites for Toluene Removal

The hierarchical nanostructured N-doped TiO2 immobilized activated carbon fiber(N-TiO2/ACF)porous composites are fabricated to removal dynamic toluene gas.The results show that nitrogen ions doping and ACF modification can decrease the band gap of TiO2,leading to red shift toward visible light region.Interestingly,N-TiO2/ACF exhibits strongly synergistic effect owing to high surface area,good crystallinity,enhanced bandgap structure and light harvesting.The toluene removal rate of N-TiO2/ACF composites is 2.29 times higher than that of TiO2.The N-TiO2/ACF for toluene degradation followed the Langmuir-Hinshelwood kinetic model,and the rate constant is enhanced 8 times compared with TiO2.The possible photodegradation pathway and mechanisms are proposed.

Preparation of spherical activated carbon-supported and Er^(3+):YAlO_3-doped TiO_2 photocatalyst for methyl orange degradation under visible light

In order to develop the high photocatalytic activity of TiO2 under visible light as that under ultraviolet light and make it easy to be separated from treated liquor, a visible light response and spherical activated carbon （SAC） supported photocatalyst doped with upconversion luminescence agent Er3＋：YAlO3 was prepared by immobilizing Er3＋：YAlO3/TiO2, which was obtained by combination of Er3＋：YAlO3 and TiO2 using sol-gel method, on the surface of SAC. The crystal phase composition, surface structure and element distribution, and light absorption of the new photocatalysts were examined by X-ray diffraction （XRD）, energy dispersive X-ray spectra （EDS） analysis, scanning electron microscopy （SEM） and fluorescence spectra analysis （FSA）. The photocatalytic oxidation activity of the photocatalysts was also evaluated by the photodegradation of methyl orange （MO） in aqueous solution under visible light irradiation from a LED lamp （λ400 nm）. The results showed that Er3＋：YAlO3 could perform as the upconversion luminescence agent which converts the visible light up to ultraviolet light. The Er3＋：YAlO3/TiO2 calcinated at 700 °C revealed the highest photocatalytic activity. The apparent reaction rate constant could reach 0.0197 min-1 under visible light irradiation.

Photocatalytic degradation of L- acid by TiO_2 supported on the activated carbon

TiO2 sol was prepared by sol-gel technique with tetrabutyl titanate as precursor. Supported TiO2 catalysts on activated carbon were prepared by soak and sintering method. The aggregation of nano-TiO2 particles can be effectively suppressed by added polyethylene glycol （PEG） as a surface modifier. The average particle diameter of TiO2, specific surface area and absorbability of catalyst can be modified. Based on characteristics of the TiO2 photocatalyst with XRD, specific surface area, adsorption valves of methylene blue and the amount of TiO2 supported on the activated carbon, the photocatalytic degradation of L-acid was studied. The effect of the factors, such as pH of the solution, the initial concentration of L-acid on the photocatalytic degradation of L-acid, were studied also. It was found that when the pH of the solution is 1.95, the amount of photocatalyst is 0.5 g, the concentration of the L-acid solution is 1.34×10^3 mol/L and the illumination time is 7 h, the photocatalytic degradation efficiency of L-acid can reach 89,88%, The catalyst was reused 6 times and its degradation efficiency hardly changed.

Plasma Modification of Activated Carbon Fibers for Adsorption of SO_2

Viscose-based activated carbon fibers （VACFs） were treated by a dielectric-barrier discharge plasma under the feed gas of N2. The surface functional groups of VACFs were modified to improve the adsorption and catalysis capacity for SO2. The surface properties of the untreated and plasma-treated VACFs were diagnosed by SEM, BET, FTIR, and XPS, and the adsorption capacities of VACFs for SO2 were also compared and discussed. The results show that after the plasma treatment, the external surface of VACFs was etched and became rougher, while the surface area and the total pore volume decreased. FTIR and XPS revealed that nitrogen atoms were introduced onto the VACFs surface and the distribution of functional groups on the VACFs surface was changed remarkably. The adsorption characteristic of SO2 indicates that the plasmatreated VACFs have better adsorption capacity than the original VACFs due to the nitrogen functional groups and new functional groups formed in modification, which is beneficial to the adsorption of SO2.

Catalytic Pyrolyses of Rayon and the Effect on Activated Carbon Fiber

The catalytic pyrolyses of rayon have been studied respectively by thermo-gravimetric analysis (TGA) when rayon was treated with phosphoric acid (PA), three ammonium phosphate salts and ammonium sulfate (AS). The air is favorable to the catalysis of dibasic ammonium phosphate (DAP), but not to those of ADP, PA, AP, and AS obviously. It is put forward that a peak’s shape character can be described with the ratio of height to half-height-width (H/W /2) of the peak on a differential thermo-gravimetric (DTG) curve. A flat cracking peak, presenting a more moderate dehydration reaction, has a smaller ratio and could lead to higher carbonization and activation yields. The experimental results prove this view. According to expectation, the order of catalysis is: DAP≥ADP>PA> APAS no catalyst.

STUDIES ON THE PREPARATION OF ZINC-CONTAINING ACTIVATED CARBON FIBERS AND THEIR ANTIBACTERIAL ACTIVITY

Several kinds of activated carbon fibers, using sisal fiber as precursors, were prepared with steam activation or with ZnCl2 activation. Zinc or its compounds were dispersed in them. The antibacterial activities of these activated carbon fibers were determined and compared. The research results showed that these sisal based activated carbon fibers supporting zinc have stronger antibacterial activity against Escherichia coli and S. aureus. The antibacterial activity is related to the precursors, the pyrolysis temperature, and the zinc content. In addition, small quantity of silver supported on zinc-containing ACFs will greatly enhance the antibacterial activity of ACFs.

Photocatalytic activity and kinetics for acid yellow degradation over surface composites of TiO_2-coated activated carbon under different photocatalytic conditions

TiO2-coated activated carbon surface （TAs） composites were prepared by a sol-gel method with supercritical pretreatment. The photocatalytic degradation of acid yellow （AY） was investigated under UV radiation to estimate activity of catalysts and determine the kinetics. And the effects of parameters including the initial concentration of AY, light intensity and TiO2 content in catalysts were examined. The results indicate that TAs has a higher efficiency in decomposition of AY than P25, pure TiO2 particles as well as the mixture of TiO2 powder and active carbon. The photocatalytic degradation rate is found to follow the pseudo-first order kinetics with respect to the AY concentration. The new kinetic model fairly resembles the classic Langmuir-Hinshelwood equation, and the rate constant is proportional to the square root of the light intensity in a wide range. However, its absorption performance depends on the surface areas of catalysts. The model fits quite well with the experimental data and elucidates phenomena about the effects of the TiO2 content in TAs on the degradation rate.

Preparation and Photocatalytic Activity of Ce, H3PW12O40 co-doped TiO2 Hollow Fibers

A series of Ce, H3PW12O40 co-doped TiO2 hollow fibers photocatalysts have been prepared by sol-gel method using ammonium ceric nitrate, H3PW12O40 and tetrabutyltitanate as precursors and cotton fibers as template, followed by calcination at 500 ℃ in N2 atmosphere for 2 h. Scanning electron microscopy, X-ray diffraction, nitrogen adsorption-desorption mea- surements, and UV-Vis spectroscopy are employed to characterize the morphology, crystal structure, surface structure, and optical absorption properties of the samples. The photo- catalytic performance of the samples has been studied by photodegradation phenol in water under UV and visible light irradiation. The results show that the TiO2 fiber materials have hollow structures, and the co-doped TiO2 hollow fibers exhibit higher photocatalytic activities for the degradation of phenol than un-doped, single-doped TiO2 hollow fibers under UV and visible light. In addition, the recyclability of co-doped TiO2 fibers is also confirmed that the TiO2 fiber retains ca. 90% of its activity after being used four times. It is shown that the co-doped TiO2 fibers can be activated by visible light and may be potentially applied to the treatment of water contaminated by organic pollutants. The synergistic effect of Ce and H3PW12O40 co-doping plays an important role in improving the photocatalytic activity.

Photocatalytic Characterization of TiO_2 Supported on Active Carbon

The Photocatalytic characterization of TiO2 supported on active carbon was investigated for photocatalytic decomposition of dichloroacetic acid. It was found that TiO2 / AC exhibited a higher photocatalytic activity than pure TiO2. The reason is that active carbon acting as powerful adsorbent supports makes high concentration environments of organic pollutant molecules around TiO2 particles.

Influence of H-Type and L-Type Activated Carbon in the Photodegradation of Methylene Blue and Phenol under UV and Visible Light Irradiated TiO₂

Photodegradation of methylene blue (MB) and phenol (Ph) on TiO2 in presence of H-type and L-type activated carbons (AC) was studied. Photodegradation of MB and Ph were studied under two different lamps and results were compared against those obtained on a commercial TiO2. Apparent first order rate constant for the degradation of MB was higher in presence of any AC in comparison of TiO2 alone while only in presence of ACco2-800phenol was photodegradated in shorter irradiation time than that required by TiO2. It can be concluded that TiO2 enhances its photoactivity by a factor up to 8.7 in the degradation of MB in presence of AC and this effect is associated to the specific surface properties of AC.

Computational Study on Interactions between CO2 and （TiO2）n Clusters at Specific Sites

The energetic pathways of adsorption and activation of carbon dioxide (CO2) on low-lying compact (TiO2)n clusters are systematically investigated by using electronic structure calculations based on density-functional theory (DFT). Our calculated results show that CO2 is adsorbed preferably on the bridge O atom of the clusters, forming a "chemisorption" carbonate complex, while the CO is adsorbed preferably to the Ti atom of terminal Ti-O.The computed carbonate vibrational frequency values are in good agreement with the results obtained experimentally, which suggests that CO2 in the complex is distorted slightly from its undeviating linear configuration. In addition, the analyses of electronic parameters, electronic density, ionization potential, HOMO-LUMO gap, and density of states(DOS) confirm the charge transfer and interaction between CO2 and the cluster. From the predicted energy profiles, CO2 can be easily adsorbed and activated, while the activation of CO2 on (TiO2)n clusters are structure-dependent and energetically more favorable than that on the bulk TiO2. Overall, this study critically highlights how the small (TiO2)n clusters can influence the CO2 adsorption and activation which are the critical steps for CO2 reduction the surface of a catalyst and subsequent conversion into industrially relevant chemicals and fuels.

构筑TiO2/碳纤维多级增强树脂基复合材料研究

为了改善碳纤维/酚醛复合材料的界面性能,可以通过溶胶-凝胶法和水热法在碳纤维与树脂之间引入了TiO 2薄膜层、纳米线层,来实现多级增强.本文系统研究了不同厚度的薄膜层对复合材料力学性能和摩擦学性能的影响.结果表明,当溶胶-凝胶法涂覆3次并水热生长纳米线时,薄膜层的厚度为0.1μm时,复合材料具有最大的弯曲强度,较原始样品增加了32.8%.而且,其平均摩擦系数为0.17,磨损率最小且相较于原始样品降低了39.8%.

活性炭负载的TiO2对蔬菜中残留乐果的光催化降解作用

探讨了活性炭(AC)负载的TiO2对蔬菜中残留的农药乐果的光催化降解作用。采用Sol-Gel法在酸性条件下制备TiO2和AC负载的TiO2(TiO2/AC),并用钼酸铵分光光度法测定光催化降解前后乐果溶液的浓度。结果表明,室温下TiO2降解乐果的最适时间为4 h,最适TiO2质量浓度为1000 mg/L,最适降解pH为11。AC负载的TiO2复合物显著提高了TiO2对乐果的降解率;在复合物中,每30 mL TiO2溶胶中AC的最佳加入量为1 g;负载型复合物的降解作用对蔬菜的营养成分影响不大。由此得出结论:负载型AC/TiO2复合物能更有效地降低乐果的残留。

TiO_2-loaded activated carbon fiber:Hydrothermal synthesis,adsorption properties and photo catalytic activity under visible light irradiation

TiO2-loaded activated carbon fibers （ACF） were prepared by a hydrothermal method. The samples were characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, Fourier transform infrared （FTIR） spectrometry and UV-vis diffuse reflectance spectra （DRS）. SEM images showed that the TiO2 nanoparticles were deposited on the surface of ACF, and the particle size and loading amount of TiO2 were varied by changing the initial concentration of tetrabutyl titanate （TBOT）. The results of an ash experiment showed that the loading amounts of TiO2 were 18.4%, 43.3%, 52.5%, 75.1%, and 91.1% for initial concentrations of TBOT of 0.07,014, 0.21,0.28, and 0.35 tool/L, respectively, Physical interactions played an important role in the formation of TiO2/ACF composite fibers that absorb UV and visible light. Compared with those of ACF, improved adsorption and photocatalytic activity toward Rhodamine B （RhB） were observed for TiO2/ACF composite fiber. The Rhodamine B could be removed efficiently by TiO2/ACF composite fibers, and the TiO2 loading amount had a significant effect on the photocatalytic activity of TiO2/ACF composite fibers.

Removal of Volatile Organic Compounds by Adsorption and Photocatalytic Oxydation

Based on the study of equilibrium adsorption on viscose rayon-based activated carbon fiber （ACF） by gravimetric method, mounting of TiO2 on PAN-based activated carbon cloth （ACC） and their photocatalytic activity as well as adsorption performance for benzene were investigated. The crystallinity of TiO2 and pore structure were characterized by XRD and N2 adsorption. The results show that crystallinity of TiO2 and pore structure could be postulated by heat treatment condition. Both crystallinity of TiO2 and pore structure of hybrid have effects on photocatalytic performance of TiO2-mounted ACC. It would be more attractive and prospective for the combination of TiO2 photocatalytic activity and adsorption ability of porous materials.

Enhanced photoelectrocatalytic decomplexation of Ni-EDTA and simultaneous recovery of metallic nickel via TiO_(2)/Ni-Sb-SnO_(2) bifunctional photoanode and activated carbon fiber cathode

In order to enhance Ni-EDTA decomplexation and Ni recovery via photoelectrocatalytic (PEC)process,TiO_(2)/Ni-Sb-SnO_(2)bifunctional electrode was fabricated as the photoanode and activated carbon fiber (ACF) was introduced as the cathode.At a cell voltage of 3.5 V and initial solution pH of 6.3,the TiO_(2)/Ni-Sb-SnO_(2)bifunctional photoanode exhibited a synergetic effect on the decomplexation of Ni-EDTA with the pseudo-first-order rate constant of 0.01068 min^(-1)with 180 min by using stainless steel (SS) cathode,which was 1.5 and 2.4times higher than that of TiO_(2)photoanode and Ni-Sb-SnO_(2)anode,respectively.Moreover,both the efficiencies of Ni-EDTA decomplexation and Ni recovery were improved to 98%from 86%and 73%from 41%after replacing SS cathode with ACF cathode,respectively.Influencing factors on Ni-EDTA decomplexation and Ni recovery were investigated and the efficiencies were favored at acidic condition,higher cell voltage and lower initial Ni-EDTA concentration.Ni-EDTA was mainly decomposed via·OH radicals which generated via the interaction of O_(3),H_(2)O_(2),and UV irradiation in the contrasted PEC system.Then,the liberated Ni^(2+)ions which liberated from Ni-EDTA decomplexation were eventually reduced to metallic Ni on the ACF cathode surface.Finally,the stability of the constructed PEC system on Ni-EDTA decomplexation and Ni recovery was exhibited.

Activated carbon fiber mediates efficient activation of peroxymonosulfate systems:Modulation of manganese oxides and cycling of manganese species

Manganese oxides show a strong catalytic activity in the peroxymonosulfate(PMS)advanced oxidation process but have poor chemical stability and a propensity to cause the aggregation of nanoparticles.Here,a novel composite material(abbreviated as MnO_(x)@ACF)was synthesized,characterized,and applied.Activated carbon fiber(ACF)was selected as a carrier,which modulated the composition of manganese oxides.The results showed that MnO_(x)@ACF had a strong adsorption ability and successfully activated PMS to degrade tetracycline hydrochloride(TCH),with a removal eficiency of 89.0%in 30 min.Influencing factors such as pH and coexisting ion species were investigated,and a five-cycle test was conducted.Singlet oxygen(^(1)O_(2))was predominated in the MnO_(x)@ACF/PMS system.A possible explanatory pathway of TCH was proposed based on the results of the high performance liquid chromatography-mass spectrometry.It was concluded that this study provides a novel insight into the activation of PMS for the degradation of organic matter by carbon-loaded multivalent manganese oxides.

Support effect and confinement effect of porous carbon loaded tin dioxide nanoparticles in high-performance CO_(2) electroreduction towards formate

Leveraging the interplay between the metal component and the supporting material represents a cornerstone strategy for augmenting electrocatalytic efficiency,e.g.,electrocatalytic CO_(2)reduction reaction(CO_(2)RR).Herein,we employ freestanding porous carbon fibers(PCNF)as an efficacious and stable support for the uniformly distributed SnO_(2)nanoparticles(SnO_(2)PCNF),thereby capitalizing on the synergistic support effect that arises from their strong interaction.On one hand,the interaction between the SnO_(2)nanoparticles and the carbon support optimizes the electronic configuration of the active centers.This interaction leads to a noteworthy shift of the d-band center toward stronger intermediate adsorption energy,consequently lowering the energy barrier associated with CO_(2)reduction.As a result,the Sn O_(2)PCNF realizes a remarkable CO_(2)RR performance with excellent selectivity towards formate(98.1%).On the other hand,the porous carbon fibers enable the uniform and stable dispersion of SnO_(2)nanoparticles,and this superior porous structure of carbon supports can also facilitate the exposure of the SnO_(2)nanoparticles on the reaction interface to a great extent.Consequently,adequate contact between active sites,reactants,and electrolytes can significantly increase the metal utilization,eventually bringing forth a remarkable7.09 A/mg mass activity.This work might provide a useful idea for improving the utilization rate of metals in numerous electrocatalytic reactions.

硝酸铜改性活性炭纤维吸附材料制备及性能研究

以不同浓度的Cu(NO_(3))_(2)溶液对活性炭纤维表面进行修饰改性制备SO_(2)、NO_(x)腐蚀气氛吸附材料。通过红外光谱、X射线衍射仪、X射线光电子能谱仪等多种表征方式,揭示了Cu(NO_(3))_(2)改性对活性炭纤维孔隙结构、表面物理化学性质、吸附性能的影响。结果表明,经硝酸铜改性后,活性炭纤维表面官能团发生变化,比表面积、孔容、孔径等结构参数均呈减小趋势。改性后活性炭纤维表面活性位点有所增加,对应的吸附性能显著增加,10%Cu(NO_(3))_(2)改性活性炭纤维对SO_(2)、NO_(2)、NO的饱和吸附量分别为110、102、67mg/g,与改性前相比分别提高了80%、88%、24%。将装有10%Cu(NO_(3))_(2)改性活性炭纤维的防护包装长贮于海洋大气环境下,验证控制效果。