The effect of the molecular structure of a cationic azo dye on the photoinduced intercalation of phenol in a montmorillonite

The effect of the molecular structure of a cationic azo dye on the photoinduced intercalation of phenol into the azo dye-montmorillonites was reported. Two types of cationic azo dyes were used; one has (2-hydroxyethyl)dimethylammonium group (AZ(OH)⁺), and the other has trimethylammonium group (AZ(CH₃)⁺). Phenol was intercalated into both cation exchanged azo dye-montmorillonites (Kunipia F) by mechanical mixing without solvent. By the UV irradiation, the basal spacings increased further, and subsequent visible light irradiation led to decrease the basal spacings, indicating the intercalation and the deintercalation of phenol by the UV and visible light, respectively. The amounts of the phenol intercalated both chemically and photochemically varied depending on the azobenzene cations, showing the interactions between the cationic head group and phenol.     

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.     

Polyurethane–attapulgite porous material: Preparation,characterization, and application for dye adsorption

A series of polyurethane–attapulgite porous (HATT/PU) materials were prepared from polyether polyol (NJ‐330), toluene diisocyanate (TDI), acid activated attapulgite (HATT), sodium bicarbonate as foaming agent, dibutylbis (lauroyloxy) tin (DBLT) as catalyst and silicon oil as stabilizer by foaming technique. The materials were characterized by FTIR, XRD and SEM. The polyurethane–attapulgite porous material as adsorbent was applied to malachite green (MG) dye wastewater treatment. Effects of attapulgite content, time, temperature, pH, and adsorbent dosage have been studied. The experimental results show that the maximum adsorption efficiency occurred at an attapulgite content of 6.0%, a time of 2.5 h, a temperature of 35°C, a pH >5 and a HATT/PU dosage of 40 mg/mL. Equilibrium isotherms for the adsorption of the dye have been measured experimentally. Results were analyzed by the Freundlich and Langmuir equation and the characteristics parameters for each adsorption isotherm were determined: Gibb's free energy (ΔG°), change in enthalpy (ΔH°) and change in entropy (ΔS°) have been calculated. The results indicated that the adsorption process was spontaneously an endothermic reaction and kinetically proceeded according to the pseudo‐second‐order model. The experimental results suggest that the prepared polyurethane–attapulgite porous materials have potential application for the wastewater treatment containing MG dye. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

阳离子淀粉染料吸附材料的制备及表征

以玉米淀粉为原料,以3-氯-2-羟丙基三甲基氯化铵（CHPTMAC）为阳离子醚化剂,以NaOH为催化剂,制备了天然高分子多糖基染料吸附剂阳离子淀粉（CS）,用于对活性染料的吸附。对醚化反应机理进行了系统研究,并考察了反应条件对CS取代度（DS）及反应效率（RE）的影响。采用RAM、XRD、SEM对产物进行表征。吸附实验表明,当DS为0.12,染料溶液pH为8时,CS对活性红195、活性金黄K-2RA的吸附量分别为21.0和20.4 mg·g^-1,去除率可达84.1%和81.6%,好于无机吸附材料活性炭。还进行了CS染料吸附材料的再生实验,4次再生后仍有较高的吸附量,表明CS染料吸附材料具有较强的可再生性能,可循环使用。该天然基染料吸附剂CS有望成为无机吸附剂及合成树脂吸附剂的理想替代品,用于工业染料废水的处理中。     

Graphene Oxide/ Polyacrylic acid-based double network skeleton for enhanced cationic dye adsorption

ABSTRACT

A three-dimensional (3D) porous graphene oxide/polyacrylic acid (GO/PAA) aerogel with double network skeleton was assembled by in situ solution polymerization method toward removing multi-cationic dyes from wastewater, such as methylene blue (MB), crystal violet (CV), methyl orange (MO), and rhodamine B (RhB), in which the adsorption capacities for CV and MB were 851.31 and 771.14 mg g^?1, respectively. This composite showed outstanding adsorption capacity due to the structure of 3D double network skeleton, large specific surface area, and remarkable carboxyl group content.     

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.     

The removal of cationic dyes from aqueous solutions by adsorption onto pistachio hull waste

The efficacy of pistachio hull powder (PHP) prepared from agricultural waste was investigated in this study as a novel adsorbent for the elimination of dye molecules from contaminated streams. Removal of methylene blue (MB) as a cationic model dye by PHP from aqueous solution was studied under different experimental conditions. The selected parameters were solution pH (2–10), PHP dosage (0.5–3 g/L), MB concentrations (100–400 mg/L), contact time (1–70), and solution temperature (20–50 °C). The experimental results indicated that the maximum MB removal could be attained at a solution pH of 8. The dosage of PHP was also found to be an important variable influencing the MB removal percentage. The removal efficiency of MB improved from 94.6 to 99.7% at 70 min contact time when the MB concentration was decreased from 300 to 100 mg/L at a pH and PHP dosage of 8 and 1.5 g/L, respectively. The kinetic analysis showed that the pseudo-second-order model had the best fit to the experimental data. The Langmuir equation provided the best fit for the experimental data of the equilibrium adsorption of MB onto PHP at different temperatures. In addition, the maximum adsorption capacity increased from 389 to 602 mg/g when the temperature was increased from 20 to 50 °C. The thermodynamic evaluation of MB adsorption on PHP revealed that the adsorption phenomenon under the selected conditions was a spontaneous physical process. Accordingly, pistachio hull waste was shown to be a very efficient and low-cost adsorbent, and a promising alternative for eliminating dyes from industrial wastewaters.     

Studies on equilibrium swelling,dye adsorption,and dynamic shear rheology of polymer systems based on chitosan-poly(vinyl alcohol) and montmorillonite

Chitosan-poly(vinyl alcohol)/clay membranes were prepared by physical blending. These hybrid systems were characterized through infrared spectroscopy, microscopy, swelling, and oscillatory rheology. Adsorption of a commercial reactive dye by these membranes was further studied. Results showed that more stable blend membranes were formed due to the strong interaction in the polymers. These membranes showed substantial percent swelling in water and shrinking in saline solution. Adsorption analysis showed the ability of the blends to fix organic dyes, and to be used in liquid waste processing. In dynamic rheology, it was observed that all measured viscoelastic properties were influenced by polymer composition and clay content. For all samples, results show a typical behavior of an entangled system in the case of low concentrated macromolecular viscoelastic fluids. The dynamic moduli exhibited higher values for blends, compared with values of the pure polymers, which is an indication of good stability and tendency of gel formation.     

Preparation and full characterization of cationic latex of styrene-butyl acrylate

Cationic latexes based on styrene and butyl acrylate using cetyl trimethyl ammonium bromide (CTAB) as surfactant were carried out using both batch and semicontinuous emulsion polymerization. Monomer conversion, particle size and its distribution, ζ potential, latex surface tension were determined as function of CTAB levels. Evolutions of these properties were followed, and the results from batch compared to those from semicontinuous process. It was revealed that polymerization rate in batch process was enhanced with CTAB, and the polymerization rate was controlled by addition rate of the preemulsion in semicontinuous process. Molecular adsorption area of CTAB on latex particle surface was calculated, which showed clearly that ζ potential and surface tension in the latex were directly related with surfactant adsorption on the particle surface. The molecular surface adsorption area of CTAB on latex particle could be used to explain the evolution of latex properties such as ζ potential and latex surface tension.     

Hexagonal strontium ferrite: cationic dye adsorption and antibacterial activity

ABSTRACT

Hexagonal strontium ferrite (SrFe₁₂O₁₉) powder was synthesized using sonochemical method and characterized. SrFe₁₂O₁₉ was used to adsorb malachite green (MG), a cationic dye, at various physical parameters and investigated against antibacterial activity. The experimental data for the isotherm kinetics followed the Langmuir isotherm model. The synthesized SrFe₁₂O₁₉ powder demonstrates an excellent removal ability with a maximum adsorption capacity (q_max) of 227.27 mg/g for MG. From the antibacterial activity, the material is active against both Gram-negative and -positive bacterial strains, Escherichia coli and Micrococcus luteus, respectively.     

Surface modification of pyrolyzed carbon fibres by cyclic voltammetry and their characterization with XPS and dye adsorption

Commercial carbon fibres were pyrolyzed up to 1000 °C and were then electrochemically treated by cyclic voltammetry in aqueous electrolyte solutions of H₂SO₄, in two potential sweep ranges: a narrow region, N, and a wide region, W, avoiding and including water decomposition, respectively. The anodic and cathodic peaks were correlated with oxide formation and their partial reduction, respectively. The nature of oxygen containing groups on the fibre surfaces was determined by XPS. Wide scan spectra and high energy resolution spectra were recorded through the C 1s, O 1s, N 1s and S 2p photoelectron regions. The ability of the fibres to adsorb methylene blue and alizarin yellow dyes from their aqueous solutions indicates the presence of electron acceptor or donor groups on the fibres, respectively. The carbon fibres were classified into two categories. The first includes electrochemically untreated and treated in the N region, and the second those treated in the W region. The high oxygen concentration and effective dye adsorption on the carbon fibres in the second category indicates that their surfaces were effectively modified. The adsorption of dyes on carbon fibres constitutes a complementary method to XPS for an indirect estimation of oxygen and other groups present on the carbon fibre surfaces.     

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.     

吸附法处理染料废水的工艺及其机理研究进展

介绍了近年来国内外对含染料废水处理工艺研究的最新进展,重点报道了以活性炭、树脂、矿物、废弃物和一些新材料为吸附剂吸附处理染料废水的最新研究成果,同时对上述方法处理染料工业废水的机理进行了探讨．并展望了吸附法处理染料废水技术的发展前景。     

介孔分子筛集砷材料的制备与表征

通过浸渍法在介孔分子筛上负载亲砷活性组分,制备了介孔分子筛集砷材料。用XRD、SEM、N2吸附和脱附进行了表征,并针对液态烃常温脱砷体系,对该材料的吸附集砷性能进行了进一步的测定。研究结果表明介孔分子筛集砷材料具有比常规脱砷剂更为优良的集砷性能。     

微波法制备有机蒙脱土及其结构表征

采用钠基蒙脱土、十六烷基三甲基溴化胺为原料,通过微波辐射制备了有机蒙脱土,并用红外光谱分析(IR)、热重分析(TGA)和X-射线衍射分析(XRD)对其结构进行了表征。     

Preparation and characterization of phosphonium montmorillonite with enhanced thermal stability

Quaternary phosphonium cations (hexadecyl tributyphosphonium; tetradecyl tributylphosphonium; tetraphenylphosphonium; methyl triphenylphosphonium; ethyl triphenylphosphonium and propyl triphenylphosphonium) were intercalated into montmorillonite (MMT) rich bentonite of Indian origin, by ion exchange reaction. The phosphonium MMT were characterized by Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction analysis (PXRD), particle size distribution (PSD) and thermogravimetric analysis (TGA). The phosphonium cations significantly influenced the particle size distribution. With longer alkyl chain finer particles were formed. The tetrabutylphosphonium and tetraphenylphosphonium MMT showed enhanced thermal stability (300–400 °C) and may be potentially useful materials for melt processing of polymer/layered silicates nanocomposites.     

Preparation and rheological characterization of intercalated polystyrene/organophilic montmorillonite nanocomposite

Polystyrene (PS)/organophilic montmorillonite (OMMT) clay nanocomposites were prepared by a solvent casting method using chloroform as a cosolvent. Intercalation of the OMMT in the PS matrix was achieved as revealed by X‐ray diffraction. The IR spectra of the products indicated that the OMMT is homogeneously dispersed in the PS matrix. A thermogravimetric analysis (TGA) showed that the onset temperature increases linearly with the clay content. The glass‐transition temperature of the PS, examined using differential scanning calorimetry, had a trend similar to that from the TGA. The rheological properties of the PS/OMMT nanocomposites were also investigated via a rotational rheometer with a parallel plate geometry, and they exhibited sharper shear thinning and increased storage and loss modulus with clay content. Furthermore, the shear viscosity obtained from the steady shear experiment was well correlated with the complex viscosity obtained from the oscillatory experiment via the Cox and Merz relation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2106–2112, 2003     

NaHCO处理胶乳生产污泥制备吸附剂对阳离子染料的吸附

以胶乳生产厂脱水污泥为原料、1.40mol/L的NaHCO₃作膨胀剂,60℃浸渍并超声处理30min,污泥烘干后再经高温炭化制备吸附剂,将其用于吸附阳离子兰X-GRRL染料溶液,考察炭化温度、炭化时间、吸附剂粒径、吸附剂投加量、吸附时间及溶液pH对吸附效果的影响,并对其吸附动力学和吸附等温线类型进行了探讨。结果表明：污泥在炭化温度700℃、炭化时间120min的条件下,制备的吸附剂（粒径<0.75mm）的比表面积为118.95m²/g,孔隙结构较为发达,对染料溶液吸附效果最佳;在振荡频率150r/min、吸附温度为25℃±0.10℃、初始染料质量浓度为250mg/L、吸附剂投加量为1.20g/L、溶液pH为5.47、吸附时间为300min时,溶液脱色率可达98.30%,染料吸附量为204.80mg/g;其吸附动力学可用准二级动力学方程进行描述;符合Langmuir型吸附等温线,属于单分子层吸附;吸附剂浸出液及吸附处理后的染料溶液的COD值分别为4.00mg/L和20.00mg/L,不会对水体造成二次污染。     

Preparation of a porous,magnetic, quaternary chitosan salt by preadsorption and desorption for azo dye adsorption from water

A porous magnetic quaternary chitosan salt (pre‐CS/EPTAC/Fe₃O₄) was successfully prepared via a kind of novel method of preadsorption and desorption. The physicochemical properties of pre‐CS/EPTAC/Fe₃O₄ were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and vibrating sample magnetometry. The adsorption of pre‐CS/EPTAC/Fe₃O₄ for methyl orange (MO) showed much higher dye uptakes compared with Npre‐CS/EPTAC/Fe₃O₄ without the preadsorption and desorption of MO, and the maximum adsorption capability for MO was 486.1 mg/g. Adsorption isotherms and adsorption kinetics were well fitted by the Freundlich isotherm model and the pseudo‐second order model, respectively. Thermodynamic parameters, such as the standard free energy change, enthalpy change, and entropy change, were also calculated; this indicated that the adsorption was spontaneous and exothermic. The introduction of MO preadsorption and desorption into the process of preparation improved not only the adsorption of MO but also the adsorption of acid red 1 and orange G. Furthermore, pre‐CS/EPTAC/Fe₃O₄ particles could be easily regenerated and remained almost constant (98.5%) for six cycles of adsorption and desorption. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43448     

双子阳离子表面活性剂改性蒙脱土的制备与表征

合成了新型双子阳离子表面活性剂Gemini-16,并用其对钠基蒙脱土进行改性。红外光谱(FTIR)、热重(TGA)分析表明,Gemini-16已插层到蒙脱土片层间。X射线衍射(XRD)表明,改性后蒙脱土层间距从1.47 nm增加到3.48 nm。分散性实验表明,经Gemini-16改性的蒙脱土在液体石蜡中表现出很好的相容性和分散性,改性效果优于目前常用的CTAB处理效果,更有利于聚合物单体进入蒙脱土层间形成聚合物/蒙脱土纳米复合材料。