胶原纤维对水中Cr(Ⅵ)的吸附性能研究

胶原纤维(CF)作为吸附剂去除水中Cr(Ⅵ),研究了CF去除Cr(Ⅵ)时溶液pH值、温度、吸附剂用量和Cr(Ⅵ)初始浓度对去除效率的影响。结果显示,CF对Cr(Ⅵ)的去除率随溶液pH值降低而升高,在pH值为2.0时达到最大,随吸附剂用量增大而增大,随Cr(Ⅵ)初始浓度增加而减小,CF对Cr(Ⅵ)的吸附量随吸附剂用量增加而减小;随Cr(Ⅵ)初始浓度增加而增加,最后趋于稳定。吸附平衡时间为6h,最佳吸附温度为40℃。测定了吸附等温线和吸附动力学曲线,结果表明,Freundlich等温方程能更好地描述CF对Cr(Ⅵ)的吸附,吸附动力学符合伪二级吸附速率方程。FT-IR和SEM-EDS分析表明,CF表面含有大量氨基羧基及羟基等活性官能团,CF对Cr(Ⅵ)的吸附过程存在铬酸根阴离子与质子化活性官能团的静电吸附作用和离子交换作用。     

埃洛石纳米管/聚间苯二胺复合材料去除Cr(Ⅵ)的性能

为了获得一种去除重金属Cr（Ⅵ）的高性能吸附材料,在原位化学聚合过程中滴加Na₂CO₃对产物的氧化态进行调节,室温条件下成功制备了埃洛石纳米管/聚间苯二胺（HNTs/PmPD）复合材料。采用SEM、TGA、EDS、Brunauer-Emmett-Teller比表面积分析（BET）、电感耦合等离子体质谱分析（ICP-MS）、FTIR和Zeta电位分析（Zeta）等对HNTs/PmPD复合材料性能和表面结构进行表征。同时,还研究了pH值、时间、初始浓度和温度等实验参数对HNTs/PmPD复合材料的去除Cr（Ⅵ）效果的影响。通过动力学和等温线模型对HNTs/PmPD复合材料吸附Cr（Ⅵ）的实验数据进行了拟合评估。HNTs/PmPD复合材料具有优异的Cr（Ⅵ）去除能力及良好的沉降分离和循环再生性能,室温下的Cr（Ⅵ）吸附容量可达到855.66 mg·g-1以上。研究表明,存在于HNTs/PmPD复合材料表面的大量氨基和亚胺基是去除Cr（Ⅵ）的主要活性位点。HNTs/PmPD复合材料性能优异,在含Cr（Ⅵ）废水治理领域具有广阔的应用前景。      

交联淀粉微球的制备及其对Cr(Ⅵ)的吸附性能研究

以可溶性淀粉为主要原料,N,N’-亚甲基双丙烯酰胺(MBAA)为制备反应的交联剂,环己烷为油相,过硫酸钾-亚硫酸氢钠(K_2S_2O_8-Na HSO_3)氧化还原体系为引发剂,Span80、Tween60为乳化剂,采用反向悬浮法制备交联淀粉微球,并利用红外光谱仪对交联淀粉微球的结构进行表征。以交联淀粉微球作为吸附剂,研究了吸附时间、淀粉微球的质量及Cr(Ⅵ)的初始浓度对Cr(Ⅵ)的吸附性能的影响并考察了淀粉微球吸附Cr(Ⅵ)的热力学特性。吸附实验发现,在淀粉微球质量为0.05 g、吸附时间为70 min、初始浓度为50 mg/L时交联淀粉微球对Cr(Ⅵ)的吸附量较高。热力学实验表明,交联淀粉微球对Cr(Ⅵ)吸附行为符合Langmuir热力学方程,相关系数为0.989 0。     

氨基化石墨烯气凝胶的制备及其对Cr(Ⅵ)吸附性能研究

以四乙烯五胺(TEPA)为氮源和改性剂,对氧化石墨烯(GO)进行氨基化改性,通过一步水热法制备四乙烯五胺-石墨烯气凝胶(TEPA-GA),采用FT-IR、XRD、拉曼光谱、SEM、XPS、TG等方法对产品的化学结构与形貌进行表征及性能检测。结果表明,通过TEPA成功将GO进行氨基化改性,并制备出具有多孔互穿网络结构的TEPA-GA,其具有超轻、密度小及热性能优异等特点。再将TEPA-GA用于对Cr(Ⅵ)的吸附研究,发现在最佳吸附条件下,吸附容量高达342.48mg/g。     

ACFs对溶液中Cr(Ⅵ)的吸附性能研究

利用比表面分析仪、扫描电镜和红外光谱仪对活性炭纤维(ACFs)的性能进行表征。选择一定浓度的六价铬[Cr(Ⅵ)]溶液进行吸附研究,考察接触时间、溶液pH值以及溶液中Cr(Ⅵ)的初始质量浓度对吸附行为的影响。结果表明,最佳接触时间为125 min;Cr(Ⅵ)的去除率随着pH值的减小而增大,当pH=2.0时达到最大;Cr(Ⅵ)的吸附量随着Cr(Ⅵ)初始质量浓度的增加而增大,而去除率随着Cr(Ⅵ)初始质量浓度的增加而减小。此外,对材料的吸附机制进行了简要的分析。     

氨化烟末生物碳吸附剂的制备及其对Cr(Ⅵ)的吸附行为

以卷烟废弃烟末为原材料,对其进行碳化处理后再引入氨基功能团制备氨化烟末生物碳吸附剂(NH₂/TPB),研究p H、投加量、温度、吸附时间对NH₂/TPB吸附Cr(Ⅵ)的影响。通过扫描电镜(SEM)、傅里叶红外光谱(FTIR)、X射线光电子能谱(XPS)等技术进行机制分析。结果表明:初始浓度为210 mg/L、pH=4、投加量为0.8 g/L、温度为45℃、吸附时间为120 min时,NH₂/TPB对Cr(Ⅵ)的最大吸附量为103.627 mg/g。吸附过程符合准二级动力学模型和Langmuir吸附等温模型。Cr(Ⅵ)吸附去除机制主要包括静电相互作用、还原反应以及与-NH₂、-OH、-COOH的配位络合,与Si-O-Si的"π-π"相互作用。通过5次吸附-解吸试验发现,Cr(Ⅵ)去除率在82.88%以上。研究表明氨化烟末生物碳具备处理与修复酸性含Cr(Ⅵ)废水污染的潜力。     

改性壳聚糖吸附Cr(Ⅵ)的研究进展

壳聚糖是一种来源丰富、无毒无害的天然吸附材料,对污水中Cr(Ⅵ)有较好的吸附效果。介绍了Cr(Ⅵ)在水溶液中的存在形式、分析了壳聚糖吸附Cr(Ⅵ)的机理,综述了化学改性和复合改性两类壳聚糖的研究进展。详细介绍了交联改性壳聚糖、接枝改性壳聚糖、有机材料复合改性壳聚糖、磁性材料改性壳聚糖、复合载体材料改性壳聚糖的结构、活性官能团类别、吸附原理和应用。最后对改性壳聚糖的新材料研发、制备工艺优化、应用拓展等研究方向进行了展望。     

钡改性污泥陶粒对废水中Cr(Ⅵ)的吸附性能研究

以污水厂污泥、粉煤灰为主要原料制备污泥陶粒,并采用BaCl2浸泡、焙烧的方法对其进行改性,制得钡改性污泥陶粒(Ba-SC),考察了其对水中Cr(Ⅵ)的吸附性能、动力学及吸附等温线,并采用扫描电子显微镜(SEM)对其进行了表征。结果表明:Ba-SC对Cr(Ⅵ)的去除效果远高于SC,且吸附效果受pH影响较大,在pH≥7时对Cr(Ⅵ)的去除率可达90%以上。SEM结果显示,负载在污泥陶粒表面的Ba可吸附Cr(Ⅵ)并与之反应形成正交晶型的结晶体。Ba-SC对Cr(Ⅵ)的吸附过程符合准二级动力学模型及Langmuir等温吸附模型,吸附反应为单分子层化学吸附过程。     

改性壳聚糖吸附Cr(Ⅵ)的应用研究进展

Cr(Ⅵ)是一种对生物和人体高度有毒的重金属离子。改性壳聚糖对Cr(Ⅵ)的吸附是去除含Cr(Ⅵ)废水中Cr(Ⅵ)的一种有效方法。壳聚糖通过分子中的氨基和羟基等功能团与Cr(Ⅵ)离子发生吸附作用。通过改性可以提高壳聚糖的物理稳定性和吸附容量等。综述了壳聚糖的化学和复合改性在吸附Cr(Ⅵ)方面的研究进展。     

聚吡咯对Cr(Ⅵ)离子的吸附性能研究

目前有关纯聚吡咯(PPy)用于吸附处理含Cr(Ⅵ)废水的研究不多。为了考察聚吡咯对铬离子污水的吸附性能,在超声条件下原位氧化聚合制备了PPy微/纳米球。用红外光谱仪、X射线衍射仪、扫描电子显微镜、透射电子显微镜和紫外-可见光谱仪分别表征了样品的结构、形貌和吸附性能。以聚吡咯为吸附剂研究了吸附时间、pH值、初始浓度及温度对Cr(Ⅵ)离子吸附性能的影响。结果表明:对于含Cr(Ⅵ)500 mg/L的溶液,吸附5 min的去除率已超过94.6%;pH值对PPy吸附性能影响不大;随着温度的升高,吸附率逐渐升高。其等温吸附行为较好地符合Freudlich吸附模型。PPy动力学吸附拟合满足准二级动力学模型,通过计算得到聚吡咯对Cr(Ⅵ)的理论最大单位吸附量为47.6 mg/g(试验值为49.7 mg/g)。     

Synthesis of Cr(VI)-imprinted poly(4-vinyl pyridine-co-hydroxyethyl methacrylate) particles: its adsorption propensity to Cr(VI)

The aim of this study is to prepare ion-imprinted polymers, which can be used for the selective removal of Cr(VI) anions from aqueous media. 4-Vinyl pyridine (4-VP) was used as functional monomer. The Cr(VI)-imprinted poly(4-vinyl pyridine-co-2-hydroxyethyl methacrylate), poly(VP-HEMA), particles were prepared by bulk polymerization. The Cr(VI)-imprinted polymer particles were grained from the bulk polymer, and the template ions (i.e., Cr(VI)) were removed using thiourea (0.5%, v/v) in 0.5M HCl. The Cr(VI)-imprinted polymer contained 21.4 μmol 4-VP/g polymers. The specific surface area of the IIP2 particles was found to be 34.5m(2)/g (size range of 75-150 μm), and the swelling ratio was about to 108%. The effect of initial concentration of Cr(VI) anions, the adsorption rate and the pH of the medium on adsorption capacity of Cr(VI)-imprinting polymer were studied. The maximum experimental adsorption capacity was 3.31 mmol Cr(VI)/g polymer. Under competitive condition, the adsorption capacity of Cr(VI)-imprinted particles for Cr(VI) is 13.8 and 11.7 folds greater than that of the Cr(III) and Ni(II) ions, respectively. The first- and second order kinetics models were estimated on the basis of comparative analysis of the corresponding rate parameters, equilibrium capacity and correlation coefficients. The Langmuir adsorption isotherm model was well described the Cr(VI)-imprinted system and the maximum adsorption capacity (Q(max)) was found to be 3.42 mmol/g. Moreover, the reusability of the poly(VP-HEMA) particles was tested for several times and no significant loss in adsorption capacity was observed.     

Mechanism of Cr(VI) adsorption by coir pith studied by ESR and adsorption kinetic

The oxidation state of chromium in coir pith after Cr(VI) adsorption from aqueous solution was investigated using electron spin resonance (ESR). To elucidate the mechanism of chromium adsorption on coir pith, the adsorption studies of Cr(VI) onto lignin, alpha-cellulose and holocellulose extracted from coir pith were also studied. ESR signals of Cr(V) and Cr(III) were observed in coir pith adsorbed Cr(VI) at solution pH 2, while ESR spectra of lignin extracted from coir pith revealed only the Cr(III) signal. In addition, ESR signal of Cr(V) was observed in alpha-cellulose and holocellulose extracted from coir pith adsorbed Cr(VI). These results confirmed that lignin in coir pith reduced Cr(VI) to Cr(III) while alpha-cellulose and holocellulose extracted from coir pith reduced Cr(VI) to Cr(V). The Cr(V) signal exhibited in ESR of alpha-cellulose and holocellulose might be bound with glucose in cellulose part of coir pith. In addition, xylose which is main in pentosan part of coir pith, indicated that it is involved in form complex with Cr(V) on coir pith. The adsorption kinetic of Cr(VI) from aqueous solution on coir pith was also investigated and described well with pseudo second order model. ESR and desorption experiments confirmed that Cr(VI), Cr(V) and Cr(III), exist in coir pith after Cr(VI) adsorption. The desorption data indicated that the percentage of Cr(VI), Cr(V) and Cr(III) in coir pith were 15.63%, 12.89% and 71.48%, respectively.     

Synthesis of ordered large-pore mesoporous carbon for Cr(VI) adsorption

Highly ordered mesoporous carbon with large accessible pores (OMC-P) was prepared by using laboratory-made poly(ethylene oxide)-b-polystyrene diblock copolymer as template via the evaporation-induced self-assembly method. The OMC-P was first used as adsorbent for removal of Cr(VI) ion from aqueous solution. Adsorption behavior was studied as a function of time, concentration of adsorbate, temperature, and pH. The kinetics of adsorption of Cr(VI) ion onto OMC-P is well fit to the pseudo-second order model. The Cr(VI) ion adsorption is favored at lower temperatures and at initial acid pH values in the equilibrium. The Freundlich and the Langmuir isotherm fit the equilibrium data satisfactorily. The influence of porosity on equilibrium adsorption capacity was investigated on three types of carbon materials, namely, OMC-P, ordered mesoporous carbon templated from amphiphilic triblock copolymer F127 (OMC-F) and commercial activated carbon (AC). The prepared OMC-P exhibits much higher adsorption performance than the other two carbons.     

羟基铁插层膨润土的制备及其对铀(VI)的吸附特性与机制

通过羟基铁对钠基膨润土插层改性制备了羟基铁插层膨润土（OH-Fe-Bent）,用于去除废水中的U（VI）。实验考察了pH值、U（VI）初始浓度、温度和吸附时间对OH-Fe-Bent吸附U（VI）效果的影响,并进行吸附动力学和热力学分析。采用FTIR、SEM、XRD等手段分析相关吸附机制。实验结果表明:OH-Fe-Bent吸附U（VI）的最佳pH为4,在温度为15℃,投加量为0.8 g/L,U（VI）初始浓度为10 mg/L时,OH-Fe-Bent对U（VI）的去除率达到99.55%,吸附平衡时间为90 min。Langmuir等温吸附模型和准二级动力学模型（相关系数的平方约为1）均可较好地拟合其吸附过程,理论饱和吸附量可达97.09 mg/g,OH-Fe-Bent对U（VI）是单分子层吸附。FTIR、SEM分析表明OH-Fe-Bent吸附U（VI）后自身结构没有改变,XRD分析表明羟基铁已经成功插入膨润土层间。      

Influence of cationic surfactant on adsorption of Cr(VI) onto activated carbon

The effect of a cationic surfactant on the adsorption of Cr(VI) on activated carbon was investigated using cetylpyridinium chloride (CPC). At a concentration below the critical micelle concentration (CMC) of CPC, the adsorption of CPC and Cr(VI) reached equilibrium within 60 min, while it took 180 min at the concentration above CMC. CPC decreased the adsorption rate of Cr(VI) and increased the adsorption amount of Cr(VI) onto activated carbon. To analyze adsorption phenomena of Cr(VI), adsorption kinetic and isotherm were used and fitted well with the pseudo-second order kinetic model and Langmuir adsorption model, respectively. CPC introduced a cationic functional group on the surface of activated carbon and provided an adsorption site for Cr(VI).     

Characteristics of cellulosic amine-crosslinked copolymer and its sorption properties for Cr(VI) from aqueous solutions

A new cellulosic amine-crosslinked copolymer was prepared after the amination reaction with cotton stalk peel (CSP). The physicochemical characteristics of amine-crosslinked cotton stalk peel (AC-CSP) and raw CSP were determined after the surface analysis (including specific surface area, micropore volume and SEM), zeta potential analysis and spectrum analysis (FTIR and Raman spectrum). The sorption properties of AC-CSP for Cr(VI) were evaluated in the static, column sorption and desorption tests. The surface characteristics indicated the absence of porous adsorption in the potential Cr(VI) sorption mechanism. Zeta potential and spectrum analysis of AC-CSP illustrated the involvement of amine groups in the Cr(VI) sorption process. The sorption capacity of AC-CSP for Cr(VI) was 129.0mg/g as comparison with 14.8 mg/g of raw CSP. Flow rate and influent Cr(VI) concentration were demonstrated as two influencial factors in the column sorption tests. NaCl was used as the eluent, and the desorption efficiencies during three successive cycles were 75.9%, 69.8% and 64.3%, respectively. In addition, the results of the static, column sorption and desorption tests illustrated the complicated interactions between Cr(VI) and AC-CSP including complexation and ion exchange mechanisms.     

Cr(VI) adsorption on functionalized amorphous and mesoporous silica from aqueous and non-aqueous media

A mesoporous silica (SBA-15) and amorphous silica (SG) have been chemically modified with 2-mercaptopyridine using the homogeneous route. This synthetic route involved the reaction of 2-mercaptopyridine with 3-chloropropyltriethoxysilane prior to immobilization on the support. The resulting material has been characterized by powder X-ray diffraction, nitrogen gas sorption, FT-IR and MAS NMR spectroscopy, thermogravimetry and elemental analysis. The solid was employed as a Cr(VI) adsorbent from aqueous and non-aqueous solutions at room temperature. The effect of several variables (stirring time, pH, metal concentration and solvent polarity) has been studied using the batch technique. The results indicate that under the optimum conditions, the maximum adsorption value for Cr(VI) was 1.83 ± 0.03 mmol/g for MP-SBA-15, whereas the adsorption capacity of the MP-SG was 0.86 ± 0.02 mmol/g. On the basis of these results, it can be concluded that it is possible to modify chemically SBA-15 and SG with 2-mercaptopyridine and to use the resulting modified silicas as effective adsorbents for Cr(VI).     

Polypyrrole decorated ZnTi hydrotalcite with enhanced adsorption and Cr(VI) photoreduction activity under visible-light

A conjugated polymer polypyrrole (PPy) was used to decorate the ZnTi hydrotalcite (ZnTi-LDH) for constructing an organic–inorganic PPy/ZnTi-LDH composite by a facile in-situ oxidation polymerization. It was found that the as-prepared composite displayed a superior photocatalytic performance and excellent stability under visible light irradiation, which Cr(VI) reduction efficiency (99.72% for 35 min) was around 53 and 12 times higher than those of the pristine ZnTi-LDH and pure PPy, respectively, and still maintained 95.10% even after 5th cycles. The dramatically enhanced photocatalytic performances were attributed to the beneficial combination of the ZnTi-LDH stratified structure and conductive PPy, which effectively facilitated charge transfer, restrained recombination, and increased visible-light absorption. Particularly, PPy as a remarkable conductive polymer, played a crucial role in the Cr(VI) reduction, which not only was a light acceptor to produce photo-generated charge carriers but also provided a good electron transport path to accelerate the separation and migration of electron-hole pairs to improve the photoreduction performances. Finally, possible photocatalytic reaction mechanism of the PPy/ZnTi-LDH was also proposed.     

基于生物质吸附效应的石膏基多功能化复合材料制备与性能

采用废弃核桃壳制备生物质多孔活性炭（PC）,利用真空吸附法将癸酸（CA）封装于PC的孔结构中,形成癸酸-多孔活性炭（CA-PC）。然后将CA-PC与硅藻土（Di）、石膏（Gy）进行复合制备CA-PC/Di-Gy多功能化复合材料,并对其热性能、湿性能以及吸附性能进行测试。采用BET、FTIR、SEM以及DSC等技术对CA-PC/Di-Gy多功能化复合材料进行表征,并分析其结构。结果表明:以废弃核桃壳制备的PC具有发达的孔隙结构,不仅能够包裹CA,而且可以吸附甲醛。CA-PC/Di-Gy多功能化复合材料具有良好的调温调湿性能与吸附率,即在32℃附近出现温度平台,在相对湿度40%~60%的平衡含湿量为0.0859~0.2310 g/g,经过4 h对甲醛气体的吸附率接近40%。     

真空浸渍制备膨胀石墨基C/C复合材料及其甲醛吸附性能

以蔗糖为炭源,磷酸为活化剂,采用真空浸渍法经炭化、活化制得膨胀石墨基C/C复合材料.采用SEM、氮气吸脱附法、TG和TEM等测试手段,研究了磷酸/蔗糖质量比(Xp)、蔗糖浓度对复合材料孔结构和比表面积的影响,利用FTIR和Boehm滴定法对复合材料表面的化学官能团进行表征,并考察了C/C复合材料对甲醛的吸附能力.结果表明:膨胀石墨基C/C复合材料含有大量的微孔、一定量的介孔和大孔,表面含有丰富的含氧官能团,有利于对甲醛极性分子的吸附.在Xp=1.0、蔗糖溶液浓度为30％(质量分数)时所制得的膨胀石墨基C/C复合材料比表面积最高,达到2112m2/g,孔容为1.08 mL/g,其对甲醛的吸附量为854mg/g,较同工艺制备的活性炭提高了26.9％.