Synthesis of novel polyaniline/MgO composite for enhanced adsorption of reactive dye

In this investigation, the porous structure of polyaniline/MgO (PANI/MgO) composites has been successfully synthesized by in‐situ oxidative polymerization method. The as‐prepared materials were characterized by Ultraviolet–visible absorption spectroscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy. The obtained composites, for the first time, are used as an adsorbent for the removal of the sulfonated anionic dye reactive orange 16 (RO) from aqueous solution. The equilibrium adsorption isotherms of RO on the PANI/MgO composites were analyzed by Langmuir and Freundlich models, suggesting that the Langmuir model provides the better correlation of the experimental data and maximum adsorption capacity was found to be 558.4 mg g^?1. In addition, adsorption kinetics was followed by both pseudo‐first‐order and pseudo‐second‐order, but the latter model matches the results much better than the former one. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40210.     

阳离子聚合物/膨润土纳米复合吸附材料的性能及对红色染料的脱色

利用阳离子聚合物-聚环氧氯丙烷二甲胺为插层剂,采用 “有机高聚物溶液直接插层复合法”制备了一系列阳离子聚合物聚环氧氯丙烷二甲胺/膨润土纳米复合吸附材料,经特性分析表明,经聚环氧氯丙烷二甲胺插层复合后的膨润土比表面积显著增加,表面电性由负值变为正值,颗粒的聚集程度增加,有较好的吸附和沉降性能.在此基础上,研究了还原大红R、分散大红S-R、活性艳红K-2BP等红色染料在复合膨润土上的吸附行为.结果表明,聚环氧氯丙烷二甲胺/膨润土对三种染料的吸附脱色能力明显大于钠基膨润土,平衡吸附量q_e与平衡浓度C_e之间的关系均符合Langmuir和Freundlich等温吸附模型,吸附动力学行为遵循Langmuir方程所述规律.     

Chitosan intercalated montmorillonite: Preparation, characterization and cationic dye adsorption

Chitosan intercalated montmorillonite (Chi-MMT) was prepared by dispersing sodium montmorillonite (Na⁺-MMT) into chitosan solution at 60 °C for 24 h. The Chi-MMT was characterized by XRD, XRF and FT-IR. The intercalation was accomplished via the ion-exchange of Na⁺ ions with –NH₃⁺ of chitosan, resulting in the expansion of d₀₀₁ from 1.42 nm of Na⁺-MMT to 2.21 nm of Chi-MMT. The chitosan content in the Chi-MMT measured by TGA was about 17 mass%. The adsorption capacity of Chi-MMT was investigated in comparison with the starting Na⁺-MMT and chitosan using three different cationic dyes, i.e. basic blue 9 (BB9), basic blue 66 (BB66) and basic yellow 1 (BY1). The Chi-MMT showed the highest adsorption capacity in the range of 46–49 mg/g when the initial dye concentration was 500 mg/L, being equivalent to 92–99 wt.% of dye removal. The adsorption capacities of Chi-MMT for all basic dyes increased with an increase of initial dye concentration. An increase of adsorption capability of Chi-MMT was attributed to the existence of intercalate-chitosan. It could enlarge the pore structure of Chi-MMT, facilitating the penetration of macromolecular dyes, and also electrostatically interact with the applied dyes. These results indicated the competency of Chi-MMT adsorbent for basic dye adsorption.     

Preparation and Characterization of Insensitive HMX/Graphene Oxide Composites

To improve the safety of HMX, a two‐dimensional (2D) graphene oxide (GO) was introduced to HMX by the solvent nonsolvent method. The morphology, composition, thermal decomposition characteristic were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), thermogravimetry (TG) and differential scanning calorimetry (DSC). Compared to the previous reports, GO sheets exhibited better desensitizing effect than [60]Fullerene and CNTs. When 2.0 wt‐% GO sheets were added, the impact sensitivity of raw HMX decreased from 100 to 10 %, and the friction sensitivity reduced from 100 to 32 %. The DSC results proved that GO sheets were compatible with HMX. In addition, by determining the thermal decomposition kinetic parameters of the samples, it was found that the activation energy (E_a) of HMX with 2.0 wt‐% GO increased by 23.5 kJ mol⁻¹, suggesting that GO sheets could improve the thermal stability of HMX.     

Use of superswelling acrylamide/maleic acid hydrogels for monovalent cationic dye adsorption

Acrylamide/maleic acid (AAm/MA) superswelling hydrogels prepared by irradiation with γ radiation were used in experiments on swelling, diffusion, and adsorption of some water‐soluble monovalent cationic dyes such as basic red 5 (BR‐5), basic violet 3 (BV‐3), and brilliant cresyl blue (BCB). The AAm/MA hydrogel containing 60 mg MA and irradiated at 5.20 kGy was used for swelling and diffusion studies in water and aqueous solutions of the monovalent cationic dyes. For this superswelling hydrogel the swelling studies indicated that swelling increased in the following order: BR‐5 > water > BV‐3 ≥ BCB. The diffusion of water and the dyes within the hydrogels was found to have a non‐Fickian character. The uptake of the cationic dyes to the AAm/MA superswelling hydrogels was studied by the batch adsorption technique at 25°C. The uptake of dyes within the hydrogel increased in the following order: BR‐5 > BV‐3 > BCB. In the experiments of the adsorption equilibrium, S‐type adsorption in Giles' classification system was found. The binding ratio of the hydrogel/dye systems was gradually increased with the increase of the MA content in the AAm/MA hydrogel and the irradiation dose. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1809–1815, 2001     

有机改性水滑石对染料废水的吸附处理研究

采用十六烷基三甲基溴化铵改性制得有机改性水滑石,并用XRD和红外光谱进行表征。考察了有机改性水滑石对染料废水的吸附能力及相关影响因素。结果表明,水滑石改性后对染料吸附能力提高,染料去除率随改性水滑石投加量的增加而提高,随染料初始浓度的增大而降低,温度太高不利于染料的吸附,p H对染料废水的处理效果影响不大。改性水滑石对染料的吸附可用Langmuir等温吸附方程拟合,二级吸附模型能很好地描述改性水滑石对染料的吸附行为。表征结果表明十六烷基三甲基溴化铵进入到水滑石层间,但水滑石结构并没有发生大的变化。     

Chitosan hydrogels for targeted dye and protein adsorption

There is an urgent requirement to devise and develop highly‐effective materials for the purification of industrial wastewater. Colored effluents are particularly problematic due to their toxicity in plants, aquatic organisms, and animals, dictating that polymeric adsorbents are highly sought for their capture. Chitosan hydrogels are a cost‐effective substrate for the adsorption of dye molecules as they contain a biopolymeric gelator that can form hydrogels with a polymer content as low as 3% by mass. Such materials are also highly suited for use within a biomedical context as carrier vehicles for the encapsulation and delivery of protein macromolecules, due to their hydrophilic nature. We disclose the capability chitosan‐based hydrogels to noncovalently adsorb both reactive and disperse dye molecules, and a model anionic protein from aqueous solution. The materials generated offer both a platform for dye removal from industrial wastewater, and for the encapsulation and pH‐mediated release of protein macromolecules. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44846.     

用活性炭吸附强化超滤过程脱除废水中染料的研究(英文)

In this study, orange G dye was efficiently removed from aqueous solution by ultrafiltration (UF) mem-brane separation enhanced with activated carbon adsorption. The powdered activated carbon (PAC) was deposited onto the UF membrane surface, forming an intact filter cake. The enhanced UF process simultaneously exploited the high water permeation flux of porous membrane and the high adsorption ability of PAC toward dye molecules. The influencing factors on the dye removal were investigated. The results indicated that with sufficient PAC incor-poration, the formation of intact PAC filtration cake led to nearly complete rejection for dye solution under opti-mized dye concentration and operation pressure, without large sacrificing the permeation flux of the filtration process. Typically, the dye rejection ratio increased from 43.6% for single UF without adsorption to nearly 100% for the en-hanced UF process, achieving long time continuous treatment with water permeation flux of 47 L·m 2·h 1. The pre-sent study demonstrated that adsorption enhanced UF may be a feasible method for the dye wastewater treatment.     

Radiation synthesis of graphene oxide/composite hydrogels and their ability for potential dye adsorption from wastewater

A high yield of graphene oxide (GO) was chemically synthesized from graphite powder utilizing adjusted Hummer's method. The contents of acidic functional groups in GO were determined using potentiometric titration. Composite hydrogels dependent on graphene oxide/poly(2-acrylamido-2-methylpropanesulfonic acid)/polyvinyl alcohol (GO/PAMPS/PVA) were synthesized utilizing a ⁶⁰Co gamma irradiation source at different doses. The synthesized graphene oxide and composite hydrogels were portrayed via X-ray diffraction, thermogravimetric analysis, and Fourier transform infrared analysis. The morphology of composite hydrogels was characterized by scanning electron microscope. The gel % and swelling % for the prepared hydrogel demonstrated that the swelling % of hydrogel increased with raising AMPS content. Whereas the increment of GO and increasing the irradiation dose lead to a reduction in the swelling %. The influences of pH, GO percentage, initial dye concentration, the adsorbent dosage, contact time, and temperature on the adsorption of basic blue 3 dye were evaluated and the adsorption capacity was 194.6 mg/g at optimum conditions; pH = 6, GO/PAMPS/PVA composite hydrogels with 5 wt% of GO, initial dye concentration = 200 mg/L, adsorbent dose = 0.1 g, solution volume = 50 mL after 360 min at room temperature (25°C). The adsorption of dye onto the GO/PAMPS/PVA composite hydrogels follows Pseudo-second-order adsorption kinetics, fits the Freundlich adsorption isotherm model.     

Adsorption performance of mesoporous silicas towards a cationic dye. Influence of mesostructure on adsorption capacity

The dye adsorption performance of four mesoporous silicas with different structure and textural properties, MCM-41, MCM-48, SBA-15 and mesocellular silica foam (MCF), was studied and compared by using toluidine blue O (TBO) as dye model in aqueous solution. These materials were characterized by X-ray diffraction (XRD), small-angle X-ray scattering, nitrogen adsorption-desorption analyses, and transmission electron microscopy (TEM). The effect of some parameters such as adsorbent dosage, contact time, temperature, and pH on the TBO removal in aqueous solution was studied. Results showed that adsorption capacity raised when adsorbent dosage, contact time and pH solution were increased while an increase in temperature decreased the adsorption of TBO. Langmuir, Freundlich and Temkin isotherm models were employed to elucidate the adsorption mechanism while the adsorption rate data were analyzed according to the pseudo-first and second-order kinetic models. Results showed that adsorption of TBO onto MCM-48, SBA-15, and MCF fitted well the Freundlich isotherm model while the kinetic studies showed that adsorption process could be better described by the pseudo-second-order model for all mesoporous silicas. Finally, some solvents were evaluated to carried out dye desorption from the TBO-loaded mesoporous silicas founding that acetic acid was the most efficient.     

Preparation of Carbonized Kapok Fiber/Reduced Graphene Oxide Aerogel for Oil-Water Separation

A carbonized composite aerogel was fabricated based on kapok fibers (KFs) and graphene oxide (GO) through hydrothermal and carbonizing reactions. The as-prepared carbonized kapok fiber/reduced graphene oxide (CKF/RGO) aerogel exhibited special features including light weight, fire resistance, stable structure, hydrophobicity, and oleophilicity. The wettability of the KF/GO aerogel was transformed to hydrophobicity after carbonization, which provided the CKF/RGO aerogel with a distinct ability for oil-water separation. The CKF/RGO aerogel was able to adsorb oil liquids up to 110 times of its own weight. The sorption capacity of the CKF/RGO aerogel was still higher than 90 % of the initial sorption capacity after eleven sorption-combustion cycles of n-hexane solvent.     

Graphene oxide/poly(vinyl alcohol) hydrogels with good tensile properties and reusable adsorption properties

Graphene oxide (GO)/poly(vinyl alcohol) (PVA) hydrogel (PGOH), which possesses good tensile and reusable absorption properties, has been prepared by the freezing–thawing method. The presence of GO visibly decreases the swelling ratio of PGOH and significantly enhances the tensile properties of PGOH due to the formation of hydrogen bonds between the GO and PVA. The maximum tensile strength and the equilibrium adsorption capacity of methylene blue (MB) of PGOH with 0.5?wt-% GO (PGOH-0.5) is found to be 15, being 4.1 times higher than that of pure PVA hydrogel. The spontaneous adsorption obeys the intraparticle diffusion kinetic model. In addition, PGOH-0.5 exhibits a promising cycling absorption performance. The 1st and 5th cycle of dye removal for PGOH-0.5 reached to 92 and 70%, respectively. Such enhancement in adsorption can be attributed to π–π stacking and strong electrostatic attraction between GO and MB.     

聚苯乙烯/氧化石墨烯复合建材的制备与保温性能研究

通过聚苯乙烯(PS)与氧化石墨烯(GO)共混,制备聚苯乙烯/氧化石墨烯(PS/GO)保温建筑材料,并对PS/GO阻燃性能以及保温性能进行研究。结果表明:GO含量为6%时,4号样品的综合性能最好。4号样品的LOI值为33.4%,阻燃等级达到V-1,热释放速率峰值(pHRR)为525.76 kW/m²,总产烟量(TSP)为629.37 m²。此外,4号样品具有较低的导热系数0.034 2 W/(m·K),并且吸水率以及水蒸气透过系数均满足标准值,说明其可以有效应用于建筑保温材料。     

氮化铝/氧化石墨烯对环氧树脂胶黏剂导热性能的影响

使用硅烷偶联剂KH-560对氮化铝进行了表面改性,并以其为导热填料,环氧树脂为基体,制备了氮化铝/环氧树脂导热胶黏剂。采用FTIR、SEM、TG、热常数分析仪对导热胶黏剂进行了表征。结果表明:改性后硅烷偶联剂分子成功接枝在氮化铝表面。改性后,氮化铝与环氧树脂的界面粘结力增强,热稳定性和导热性均得到明显改善。当氮化铝质量为导热胶黏剂质量的70%时,改性氮化铝/环氧树脂热胶黏剂的导热系数为2.24W/(m·K),而未改性氮化铝/环氧树脂的导热系数仅为1.73W/(m·K)。为进一步提高其导热性能,制备了改性氮化铝/氧化石墨烯/环氧树脂导热胶黏剂,当改性氮化铝和氧化石墨烯的质量分数分别为50%和3%时,导热胶黏剂导热系数为3.05 W/(m·K)。     

GO/AT复合材料的制备及其吸附性能分析

采用溶液共混法制备氧化石墨烯(GO)/凹凸棒石(AT)复合材料,探讨GO含量对复合材料吸附性能的影响,并对复合材料的组成和微观结构进行了表征和分析。结果表明,当GO/AT的质量比为3/4时,复合材料对盐酸四环素的吸附效果最佳,吸附率达到93.06%。进一步探讨了吸附时间、盐酸四环素初始浓度和溶液pH条件对复合材料吸附性能的变化,分析了复合材料吸附盐酸四环素的过程;GO/AT复合材料对盐酸四环素的吸附过程符合准二级动力学方程,其表观吸附活化能为37.19 kJ/mol,此吸附过程以静电吸附为主;对盐酸四环素的吸附行为符合Langmuir等温式,在研究的温度范围,吸附焓变(ΔHO)为7.77 kJ/mol,吸附自由能变(ΔGO)<0,吸附熵变(ΔSO)为57.62 J/(mol·K),表明该吸附是吸热、自发、熵增过程。     

Highly Efficient Method for Preparing Homogeneous and Stable Colloids Containing Graphene Oxide

Phase transfer method has been developed for preparing homogeneous and stable graphene oxide colloids. Graphene oxide nanosheets (GONs) were successfully transferred from water to n-octane after modification by oleylamine. Corrugation and scrolling exist dominantly in the modified GONs. GONs were single layered with the maximum solubility in n-octane up to 3.82 mg mL^-1. Oleylamine molecules chemically attach onto the GONs. Compared with traditional strategies, the phase transfer method has the features of simplicity and high efficiency.     

Electrospun cellulose acetate/P(DMDAAC-AM) nanofibrous membranes for dye adsorption

In recent years, organic nanofibrous membranes have received more attention because of their excellent performance in wastewater treatment. In this study, the soluble poly(dimethyldiallylammonium chloride-acrylamide) (P(DMDAAC-AM)) was first synthesized by aqueous copolymerization. Afterward, cellulose acetate (CA)/P(DMDAAC-AM) composite nanofibrous membranes were electrospun and utilized to remove acid black 172 from simulated wastewater. When the proportion of P(DMDAAC-AM) to CA was 20, 30, and 40 wt %, the equilibrium adsorption capacities were 116, 159, and 192 mg g⁻¹, respectively. The adsorption capacity of CA/P(DMDAAC-AM) composite nanofibrous membrane showed a well linear relationship with the average fiber diameter. When the average fiber diameter was 185 nm, the adsorption capacity of 231 mg g⁻¹ was achieved. The adsorption kinetics of CA/P(DMDAAC-AM) membranes with various fiber diameters was all consistent with the pseudo-second-order model. The rate-limiting step was primarily controlled by chemisorption. The adsorption isothermal data fitted well with the Langmuir isotherm model. The prepared CA/P(DMDAAC-AM) nanofibrous membrane was effective to remove the acid black 172 in the environmental interested pH range of 4.0–10.0. As an effective dye adsorbent, CA/P(DMDAAC-AM) nanofibrous membrane shows wide application prospect with its excellent adsorption performance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48565.     

聚丙烯酸/氧化石墨烯复合水凝胶制备及对亚甲基蓝吸附

以丙烯酸(AA)为原料,二丙烯酸酯(Pul DA)分散的氧化石墨烯(GO)纳米胶粒(GO-Pul DA)为增强剂,N,N'-亚甲基双丙烯酰胺(BIS)为交联剂,通过自由基共聚合制备了一系列结构均一的聚丙烯酸/氧化石墨烯复合水凝胶(PAA/GO-Pul DA)。考察了BIS质量浓度、GO质量浓度以及溶液pH值对复合水凝胶力学性能、吸水性和亚甲基蓝(MB)吸附量的影响。结果表明,当GO质量浓度从0.1 g/L增加至1.0 g/L时,复合水凝胶拉伸强度从5.0 k Pa增加至10.4 k Pa,断裂伸长率高于100%,当GO的质量浓度为0.3 g/L时,复合水凝胶的断裂伸长率最高为151%;复合水凝胶表现出pH敏感的高吸湿性,pH从3.0增加至6.8时,平衡溶胀比(SRe)变化可达386 g/g,pH=6.8时最大SRe高达490 g/g。当溶液pH值从3.0增加至11.0时,PAA/GO-Pul D对MB的平衡吸附量(qe)可增加1 400~1 500 mg/g,pH=11.0时最大的qe高达1 789 mg/g。复合水凝胶对MB的吸附行为符合准一级动力学模型。5次吸附-解吸附循环后,相对于首次吸附,PAA/GO-Pul D对MB的吸附能力仍保持高达60%,解吸附效率高于90%。     

氧化石墨烯/钒钛酸复合材料的制备及湿敏性能研究

通过Hummers法制备氧化石墨后进行超声分散,得到分散均匀的氧化石墨烯(GO)分散液,物理复合滴涂制备氧化石墨烯/钒钛酸薄膜并对其感湿性能进行了研究,并通过交流与直流方法对其感湿机理进行了深入探究。结果表明:氧化石墨烯/钒钛酸复合膜的湿敏性能优于氧化石墨烯和钒钛酸单层膜,该湿敏薄膜的湿滞为8.3%RH,灵敏度变化2个数量级,响应时间为8 s,还原时间为10 s,曲线线性度良好。材料在低湿阶段主要表现为电子导电,中高湿阶段为电子导电和离子导电同时存在,高湿阶段主要表现为离子导电。     

In Situ Synthesis of Reduced Graphene Oxide and Gold Nanocomposites for Nanoelectronics and Biosensing

In this study, an in situ chemical synthesis approach has been developed to prepare graphene–Au nanocomposites from chemically reduced graphene oxide (rGO) in aqueous media. UV–Vis absorption, atomic force microscopy, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy were used to demonstrate the successful attachment of Au nanoparticles to graphene sheets. Configured as field-effect transistors (FETs), the as-synthesized single-layered rGO-Au nanocomposites exhibit higher hole mobility and conductance when compared to the rGO sheets, promising its applications in nanoelectronics. Furthermore, we demonstrate that the rGO-Au FETs are able to label-freely detect DNA hybridization with high sensitivity, indicating its potentials in nanoelectronic biosensing.