改性PAN纤维负载hemin催化降解染料的研究

使用含有偕胺肟基团的改性聚丙烯腈(PAN)纤维作为载体材料,通过轴向配位作用负载氯化血红素(hemin)制备了非均相催化剂hemin-PAN,重点对其在有机染料氧化降解反应中的催化性能进行研究。结果表明,hemin-PAN能够通过活化H2O2催化染料的氧化降解反应,其催化活性与纤维中偕胺肟基团数量密切相关,PAN增重率为14.9%时,hemin-PAN有最高的催化活性;增加催化剂hemin负载量或提高反应温度都有利于染料的氧化降解反应,hemin-PAN(增重率为14.9%,hemin负载量为0.026 mmol/g)催化罗丹明B染料氧化降解反应的活化能为63.83 k J/mol。     

改性PAN纤维负载hemin催化剂的制备及应用

分别使用盐酸羟胺及其与水合肼的混合物对聚丙烯腈(PAN)纤维进行改性,得到偕胺肟改性PAN纤维(AO-PAN)和含有偕胺肟、氨基腙两种基团的混合改性PAN纤维(M-PAN)。然后分别将其与氯化血红素(hemin)进行反应制备了仿生催化剂hemin-AO-PAN、hemin-M-PAN,并应用于染料的氧化降解反应中,探讨了改性PAN纤维的增重率对hemin负载量及脱色率的影响,分析了纤维形态结构的变化及催化条件对催化剂降解染料的影响。结果表明,引入氨基腙基团会降低AO-PAN负载hemin的能力,但会明显改善其负载hemin后纤维的表面形貌和机械性能;hemin-AO-PAN、hemin-M-PAN都能够通过活化H2O2氧化降解罗丹明B染料,且相似条件下hemin-M-PAN比hemin-AO-PAN具有更高的催化活性,而且还具有较强的活化H2O2的能力以及较宽的p H适用范围。     

FePc/TiO2负载纳米纤维膜制备及光催化性能

使用静电纺丝技术制备聚丙烯腈(PAN)纳米纤维,通过对其化学改性引入偕胺肟基团,然后借助配位作用同时负载酞菁铁(FePc)和二氧化钛(TiO₂)制备了光催化剂,在对其形态结构和光吸收特性进行表征的基础上,考察其在有机染料氧化降解中的光催化性能。结果表明,FePc和TiO₂能够有效负载于改性PAN纳米纤维表面,并使其形貌发生明显变化。FePc能够作为光敏剂拓宽TiO₂催化剂的光谱响应范围,使其在可见光区显示出较强吸收,从而能够在可见光辐射下对染料的氧化降解反应显示出较高的光催化活性。此外,当改性PAN纳米纤维增重率为30.4%时,制备的光催化剂显示出最佳活性,而且其催化活性与可见光强度呈正相关性。     

PAN纤维表面原位合成BiOCl及光催化降解性能

使用含有偕胺肟基团的改性聚丙烯腈纤维作为基材，通过溶剂热法在纤维表面原位合成了氯氧化铋（BiOCl）光催化剂，并对其表面形貌、结晶性能和分子结构进行表征分析，考察其在可见光下对染料废水氧化降解的催化作用。结果表明，BiOCl能够通过Bi离子与偕胺肟基团的配位作用与纤维载体进行结合，并在纤维表面形成结晶度较高的层状结构。所制备的纤维光催化剂能够在可见光下有效催化染料的降解反应，而且制备过程中有机溶剂的选择对其光催化活性影响显著。此外，纤维光催化剂在可见光强度为80 m W/cm2时显示出最高的光催化活性，该体系对不同结构的染料均具有一定的光催化降解性能。     

PAN纤维增强hemin/TiO_2可见光催化性能研究

使用偕胺肟改性聚丙烯腈(PAN)纤维作为载体,通过配位作用同时负载氯化血红素(hemin)和二氧化钛(TiO_2)制备了复合光敏催化材料,在对其表面形貌和光吸收特性进行表征的基础上,考察其在有机染料降解反应中的可见光催化性能。结果表明,hemin/TiO_2能够有效负载于改性PAN纤维表面,而且所制备的催化剂在可见光区显示出较强的吸收性能。通过对染料光催化降解试验发现,纤维载体能够大幅提升hemin/TiO_2的光催化活性,而且其活性与催化剂中hemin含量相关;该复合光敏催化材料具有较宽的pH适用范围,而且增加可见光强度能够提升其光催化活性。     

改性PAN纤维铁配合物暗态催化偶氮染料降解反应

利用偕胺肟改性聚丙烯腈（PAN）纤维和三氯化铁的配位反应制备改性PAN纤维铁配合物（Fe-AO-PAN）,然后将其作为非均相Fenton反应催化剂应用于不同结构偶氮染料的降解反应中,重点考察Fe-AO-PAN的添加量（M）和铁离子含量（CFe-PAN）与暗态时染料的脱色率（D）和初始反应速率常数（k）之间的关系。此外还研究了暗态时偶氮染料的降解反应过程以及无机盐的影响。结果表明：Fe-AO-PAN暗态时能够催化偶氮染料的降解,并且使活性染料的k值明显高于酸性染料;暗态时Fe-AO-PAN的M和CFe-PAN与染料降解反应50min时的D和k值之间存在着线性关系,可通过定量增加Fe-AO-PAN的M和CFe-PAN来促进暗态时染料的降解反应,达到其在辐射光时的降解效果。     

改性聚丙烯腈纤维与金属离子的配位反应及其应用进展

为解决聚丙烯腈（PAN）纤维在产业用纺织品应用中存在的问题,介绍了腈基通过多种化学反应在PAN纤维表面引入偕胺肟基、胺基、羧基以及其他配位基团的改性方法,比较了不同改性PAN 纤维与过渡金属离子或稀土金属离子的配位反应模式及其所生成配合物的分子结构和特性,评述了多种改性PAN纤维在重金属离子去除、微量金属离子检测、稀有金属和贵金属离子浓缩富集以及绿色催化剂制备等领域中的应用进展,最后指出引入新型配位基团、纤维材料重复利用性的提高和纳米纤维膜的应用是目前促进PAN纤维在产业用纺织品中发展的主要方向。     

东华大学科研成果展示

正项目名称:高效广谱纳米纤维吸附材料项目简介:纤维形态的偕胺肟材料具有比表面积大、吸附容量高、吸附速度快、选择性好、易洗脱、再,生性能好等优点作为一种高性能吸附材料,在工业废水处理以及金属离子富集、回收等方面有着广阔的应用前景,并被认为是吸附和分离材料的主要发展方向。以PAN纳米纤维材料为基础原料,通过在纳米纤维中引入偕胺肟功能基团,成功开发了可同时吸附多种重金属离子的高性能偕胺肟化纳米纤维吸附材料。本研究中偕胺肟基转化比例可达50%以上,高于其     

偕胺肟化SiO2/聚丙烯腈复合纤维膜的制备及其性能

为构筑具有特殊表/界面性能的膜材料,利用静电纺丝技术制备SiO₂/聚丙烯腈(PAN)复合纤维膜,然后经盐酸羟胺偕胺肟化处理赋予其超亲水及水下超疏油性能。借助场发射扫描电子显微镜、X射线能谱仪、傅里叶变换光谱仪及接触角测试仪等分析了纤维膜的微观形貌、结构和表/界面性质。结果表明:偕胺肟化改性后纤维膜表面有絮状物包覆,盐酸羟胺改性液最佳质量浓度为35~40 g/L,最佳改性温度为60 ℃,偕胺肟化SiO₂/PAN纤维的平均直径为275 nm;改性后纤维膜表面Si和O元素质量分数为2.13%和6.60%,SiO₂锚固在PAN纤维膜表面,且SiO₂/PAN偕胺肟化成功;相比PAN纤维膜,SiO₂/PAN纤维膜在60 ℃偕胺肟化后水润湿时间由5.4 s缩短到0.5 s,且水下油接触角达到(165.2±1)°;偕胺肟化纤维膜断裂强度达4.1 MPa,可满足油水分离的基本要求。     

液喷纺微纳米纤维在重金属废水处理中的应用

以液喷纺聚丙烯腈(PAN)微纳米纤维为研究对象,通过对其进行化学改性,制备偕胺肟基PAN(APAN)微纳米纤维吸附剂,研究溶液p H值、反应时间、金属离子初始浓度和反应温度对其吸附废水中Cd(Ⅱ)和Pb(Ⅱ)的影响。并通过吸附-解吸实验,探讨了APAN纤维吸附剂的解吸和可重复利用性能。该研究可为废水中重金属污染物的去除提供方法和实用材料。     

铁改性腈纶纤维催化剂在偶氮染料降解反应中的应用

使用水合肼和盐酸羟胺对腈纶纤维进行表面改性,然后将其与铁离子反应制得铁改性腈纶纤维催化剂（PAN-Fe）。在过氧化氢存在条件下将PAN-Fe催化剂应用于2种水溶性阴离子偶氮染料的光催化氧化降解反应中,考察了催化剂添加量、催化剂表面铁离子含量、染料浓度和pH值对染料降解反应的影响。结果表明,尽管PAN-Fe催化剂在暗态能催化染料降解反应,但是光辐射可促进其催化作用的提高;催化剂添加量及其表面铁离子含量的增加能够明显提高染料的脱色率。在PAN-Fe催化剂存在下染料降解反应可在碱性条件下进行,但是染料浓度的增加会使其脱色率降低。     

Mechanism of the photocatalytic degradation of C.I. Reactive Black 5 at pH 12.0 using SrTiO3/CeO2 as the catalyst

The photocatalytic degradation mechanism of an azo dye, C.I. Reactive Black 5 (RB5), has been investigated in an aqueous suspension of SrTiO3/CeO2 composite under 250 W UV irradiation at pH 12.0. The process was studied by monitoring the change in RB5 concentration and the intermediate products employing UV-visible spectrophotometry, ion chromatography (IC), and gas chromatography/ mass spectrometry (GC/MS) techniques and depletion in total organic carbon (TOC) content as a function of irradiation time. The adsorption peaks at wavelengths of 600, 312, and 254 nm were identified as the chromophore structure, and the naphthalene and benzene components of RB5, respectively. Little influence of iodide ion, tert-butyl alcohol, fluoride ion, or persulfate ion as h(vb)+, *OH, or e(cb)- scavengers on the decolorization proved that the decolorization of RB5 primarily proceeded by photolysis and/or O2*- in the bulk solution. After the decolorization, the process could shift progressively from the bulk solution to the surface of the catalysts and cleavage of the naphthalene and benzene rings was mainly attributed to the h(vb)+ pathway and *OH(ads) reactions, which was further verified by the effect of scavengers.     

Enhanced sonocatalytic degradation of azo dyes by Au/TiO2

Au-loaded TiO2 (Au/TiO2) has been reported for the first time as a sonocatalyst. It was found that the catalyst Au/TiO2, with a low Au loading 0.5 wt % and under common and commercial frequency (40 kHz) ultrasonic irradiation, greatly accelerated both the discoloration and total organic carbon (TOC) removal of azo dyes such as orange II (Org II), ethyl orange (EO), and acid red G (ARG), as compared to bare TiO2 and nano-Au catalyst. About 80% TOC removal was achieved after complete discoloration of 2.5 x 10(-4) M Org II. H2O2 and H2 formation as well as their accumulation was greatly enhanced due to Au loading on TiO2. Both oxidative and reductive degradation intermediates have been detected, and thus the mechanism involves both enhanced oxidation and enhanced reduction via the accelerated formation of active *OH and *H radicals due to Au loading on TiO2, which is supported by electron spin resonance (EPR) and other evidence. The study provides an admirable way to raise the efficiency of sonication and to treat azo dye-containing wastewaters with sonocatalytic processes.     

Environmental remediation by an integrated microwave/UV illumination method. V. Thermal and nonthermal effects of microwave radiation on the photocatalyst and on the photodegradation of rhodamine-B under UV/Vis radiation

The photocatalyzed degradation (PD) of the cationic rhodamine-B (RhB) dye was examined in aqueous TiO2 dispersions using UV/Vis illumination assisted by microwave radiation (PD/MW). The initial degradation by the PD/MW method is compared to the PD method and to the thermally assisted PD method using conventional heating (PD/TH). Total organic carbon (TOC) assays show that the efficiency of complete mineralization of the dye follows PD/MW > PD/TH > PD > MW. In all cases, microwave radiation alone had no effect on the loss of TOC. The degradation involving microwave radiation was especially efficient when coupled to UV irradiation. By contrast, the extent of degradation of RhB involving suitable excited states through visible irradiation of the dye was rather inefficient when coupled to microwave radiation. Contact angle measurements on the TiO2 photocatalyst particles indicate that microwave radiation also causes an increase in the hydrophobic character of the TiO2 surface, with consequences on the adsorption mode of the dye substrate and thus on the overall mechanism of degradation. Deethylated RhB intermediates were identified by an electrospray ESI ionization mass spectral technique in the positive ion mode and subsequently confirmed by HPLC/absorption spectroscopy. Computer simulations led to estimates of frontier electron densities of all atoms of the RhB structure, affording inferences as to the position of radical attack on RhB. The nitrogen atoms of the dye were all converted to NH4+ ions. The major difference between the thermally assisted PD/TH method and the microwave-assisted PD/MW method showed that nonthermal effects from the microwave radiation impact significantly on the nature of the photocatalyst surface. These effects led to a more efficient photodegradation and mineralization of the dye substrate.     

改性聚丙烯腈纤维负载MoSx/TiO2光催化材料制备及其降解染料性能

为提升MoS_x/TiO₂异质结的光催化性能,使用偕胺肟改性的聚丙烯腈(PAN)纤维作为载体,先通过静电结合及原位转化负载MoS_x,再通过配位作用结合TiO₂合成了复合光催化剂。分析了该催化剂的表面形貌、化学结构和光吸收性能,并考察了其在可见光下对印染废水的处理效果。结果表明:MoS_x和TiO₂可均匀分布于PAN纤维表面,且MoS_x的引入大幅提升了催化剂的光吸收性能,并能够在波长大于500 nm的可见光下快速氧化降解染料废水,其反应速率常数达到单独负载TiO₂纤维催化剂的4.7倍;该催化剂具有优异的重复使用性能,其高活性主要来源于MoS_x对污染物的强吸附能力及其在可见光下对TiO₂的敏化作用。     

Effect of surface chemistry of Fe-Ni nanoparticles on mechanistic pathways of azo dye degradation

The degradation of Orange G, a monoazo dye, in aqueous solutions was investigated using as-synthesized and stored Fe-Ni bimetallic nanoparticles. Batch experiments with a nanocatalyst loading of 3 g/L showed complete dye degradation (150 mg/L) after 10 min of reaction time. HPLC-MS analysis of the degradation products showed that as-synthesized nanoparticles reductively cleaved the azo linkage to produce aniline as the major degradation product. However, 1-year-stored nanoparticles showed an oxidative degradation of Orange G through a hydroxyl-radical induced coupling of parent and/or product molecules. XPS analysis in corroboration with HPLC-MS data showed that the surface chemistry between Fe and Ni in as-synthesized and stored nanoparticles play a crucial role in directing the mode of degradation. Reductive dye degradation using as-synthesized nanoparticles proceeded through hydride transfer from nickel, whereas formation of a Fe2+ -Ni(0) galvanic cell in stored nanoparticles generated hydroxyl radicals from water in a nonFenton type reaction. The latter were responsible for the generation of radical centers on the dye molecule, which led to a coupling-mediated oxidative degradation of Orange G. The generation of hydroxyl radicals is further substantiated with radical quenching experiments using ascorbic acid indicating that stored nanoparticles degrade Orange G through a predominantly oxidative mechanism. HPLC-MS and XPS analysis of dye degradation using as-synthesized nanoparticles exposed to air and water confirmed that the reductive or oxidative degradation capability of Fe-Ni nanoparticles is decided by the time and type of catalyst aging process.     

氯离子协同增强十六氯铁酞菁/聚丙烯腈复合纳米纤维光催化降解性能

为提升粉末催化剂的催化活性及重复使用性能,高效去除高盐废水中的有机污染物,采用静电纺丝技术制备十六氯铁酞菁/聚丙烯腈(FePcCl₁₆/PAN)复合纳米纤维。借助扫描电子显微镜、透射电子显微镜、X射线衍射仪等表征了纳米纤维的微观形貌、结晶结构等特性。选取卡马西平(CBZ)作为模型污染物,研究了氯离子存在下,FePcCl₁₆/PAN复合纳米纤维光活化过一硫酸盐的催化降解活性。结果表明:FePcCl₁₆可有效分散于PAN纳米纤维中,从而避免因FePcCl₁₆分子团聚而影响催化活性;在模拟太阳光照射下,随着氯离子质量浓度的增加,FePcCl₁₆/PAN复合纳米纤维催化活性逐渐增强;在较高氯离子质量浓度(6.0～18.0g/L)下,CBZ及其降解产物(包括具有潜在毒性的氯代有机副产物)都能降解完全,FePcCl₁₆/PAN复合纳米纤维循环降解5次后仍具有良好的催化降解性能。     

Photocatalytic degradation of acid blue 80 in aqueous solutions containing TiO2 suspensions

The photocatalytic degradation of the anthraquinonic dye Acid Blue 80 in aqueous solutions containing TiO2 dispersions has been investigated. The process has been monitored by following either the disappearance of the dye (via HPLC) and the formation of its end-products (via IC, GC, and TOC analysis). Although a relatively fast decolorization of the solutions has been observed, the mineralization is slower, and the presence of residual organic compounds was evidenced even after long term irradiation, confirming the relevant stability of anthraquinone derivatives. The identification of various unstable intermediates formed after low irradiation times was performed by HPLC-MS, allowing us to give insight into the early steps of the degradation process which mainly involve C-N bonds breaking and substrate hydroxylation. Complete and relatively fast mineralization of the substrate was achieved by irradiating the semiconductor dispersions in the presence of added K2S2O8.