Pd(II) ion adsorption onto emulsion gel beads in a fixed bed

We developed previously an emulsion gel adsorbent for improved metal adsorption. This study focuses on a continuous adsorption–desorption process of metal ions from a solution onto emulsion gel beads using the fixed-bed method. The monodisperse millimeter-sized emulsion gel beads, a polymeric hydrogel containing randomly distributed oil microdroplets of di-n-hexylsulfide as an extractant, were prepared using an automatic production method combining sedimentation polymerization and two-fluid atomization. The isotherms and the kinetics for Pd(II) adsorption were investigated. A continuous adsorption–desorption process was successfully demonstrated, and the breakthrough curve was successfully predicted by a mathematical analysis.     

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.     

Fixed bed column study for pesticide removal using silver nanoparticles-embedded polyurethane foam and glass beads

Abstract

This study reports the effectiveness of silver nanoparticles coated onto polyurethane foam (CPU), fused into polyurethane foam (FPU), and glass beads in a fixed bed column for removal of pesticide “Chlorpyrifos.” Silver nanoparticles coated on substrates were synthesized in laboratory using hibiscus leaf extract (SNP) and was compared with commercial silver nanoparticles (CNP). Characterization of silver nanoparticles and its interaction with the substrate were probed using XRD, TEM, and FTIR, respectively. Experiments were conducted by varying flow rate (20–40?mL/h) with a fixed bed height and pesticide concentration. The maximum removal of pesticide was obtained as 92% and 94% for CPU; 90% and 96% for FPU; 81% and 72% for glass beads with SNP and CNP, respectively, at 20?mL/h flow rate. A decrease in removal efficiency and breakpoint time was observed with an increase in flow rate of pesticide-laden water. The outcome of the study reveals that the polyurethane foam as substrate for silver nanoparticles is more effective for the removal of pesticide from the aqueous solution, which can be further developed into continuous portable modules at commercial scale.     

多孔壳聚糖微球的制备及其在污水处理中的应用

以液体石蜡为有机分散介质,戊二醛为交联剂,环己烷为致孔剂,制备了微米窄分布多孔壳聚糖微球,研究了多孔壳聚糖微球对污水中金属离子的吸附特性,测定了吸附动力学和吸附等温线。结果表明,多孔壳聚糖微球对污水中的金属离子具有很好的吸附特性,污水在pH值为2~5时吸附率接近100%。     

Experimental study and modelling of an azo colourant dynamic adsorption onto functional cross-linked chitosan/ceramic particles in a fixed bed column

The use of azo dyes in industrial activities generates a large volume of contaminated wastewater; these pollutants in water bodies affect aquatic biota and human health. A functional biocomposite sorbent material was synthesized using cross-linked chitosan with oxalic acid that forms a coating on alumina ceramic particles (AOCh). The removal of Reactive Red 195, a reactive azo dye, using a fixed-bed adsorption column filled with this material was tested. AOCh was physico-chemically characterized by Fourier transform infrared spectroscopy–total attenuated reflection (FTIR-ATR), scanning electron microscopy–energy dispersion spectrometry X-ray (SEM-EDS), X-ray diffraction (XDR), thermo-gravimetric analysis (TGA), and Z-potential. The dynamic adsorption performance was analyzed from experimental breakthrough curves obtained in fixed-bed columns by modifying different operating conditions (bed depth, volumetric flow rate, and dye inlet concentration). Equilibrium adsorption isotherms were determined under dynamic conditions and compared with batch results. The maximum adsorption capacity of the dynamic equilibrium isotherm obtained from the continuous assays was 331 mg/g; this value was the highest in comparison to other tested materials reported in the literature. Different dynamic adsorption models were applied to fit experimental data, including Thomas, Bohart–Admas, Yoon–Nelson, logistic general model, bed depth surface time (BDST), and modified dose response (Yan) models. A critical analysis of these equations was presented, showing the equivalences and the relationship among the coefficients. The Yan model achieved the highest level of agreement between the experimental and predicted values of the breakthrough curves. The use of this model enables scaling-up the industrial process for dye removal. The present work proposed a novel biosorbent material and contributes to the analysis of industrial dye removal under dynamic conditions.     

壳聚糖的功能化及其作为生物医用高分子材料的研究进展

简要综述了壳聚糖的功能化及其在生物医用高分子材料方面的应用。     

Preparation and adsorption properties of diethylenetriamine‐modified chitosan beads for acid dyes

This work has demonstrated that the novel chitosan derivative, synthesized by phase transition and grafting diethylenetriamine, has a great potential for the adsorption of acid dyes from aqueous solutions. Four acid dyes with different molecular sizes and structures were used to investigate the adsorption performance of diethylenetriamine‐modified chitosan beads (CTSN‐beads). Results indicated that the adsorption of dyes on CTSN‐beads was largely dependent on the pH value and controlled by the electrostatic attraction. In addition, the adsorption rate (AO10 > AO7 > AR18 > AG25) and adsorption capacities (AO7 > AR18 > AO10 > AG25) were directly related to the molecular size of the dye and the amount of the sulfonate groups on the dye molecules. The equilibrium and kinetic data fitted well with the Langmuir–Freundlich and pseudo‐second‐order model. Furthermore, thermodynamic parameters indicated that the adsorption processes occurred spontaneously and higher temperature made the adsorption easier. The reuse tests indicated that the CTSN‐beads can be recovered for multiple uses. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4090–4098, 2013     

流化床用树脂基球形活性炭及其VOCs吸附性能

以聚苯乙烯树脂为原料,采用水蒸气活化、氯化锌活化及水蒸气?氯化锌协同活化方法制备了3种流化床用树脂基球形活性炭,采用固定床反应器考察了活性炭对乙酸乙酯的动态吸附行为,对比了其传质区长度,并利用Yoon?Nelson模型对实验数据进行了拟合. 结果表明,3种活性炭的摩擦磨损指数均小于0.1%,耐磨性能出色,物理、化学协同活化活性炭比表面积高达1702.49 m2/g,对二甲苯的静态吸附容量达0.86 g/g.     

Capturing the effects of particle heterogeneity on adsorption in a fixed bed

To efficiently design new adsorption systems, industrial scale fixed beds are often scaled down to bench-top experiments and/or modeled using computational fluid dynamics (CFD). While there has been considerable work exploring adsorption of volatile organics onto activated carbon fixed beds in the literature, this article attempts to reckon with the high variability of adsorption capacities observed at small scales and improve small-scale experiments for industrial scale reactor design. This study integrates experimental results with CFD simulations, which can explicitly model system heterogeneities and their influence on adsorption by resolving local packing densities and flow paths. Activated carbon physical properties were determined through surface area analysis, proximate analysis, and toluene adsorption (measured via mass spectroscopy). Variability in the small-scale systems was not attributed to surface area or carbon content, as is often stated, but instead was due to local packing density variations and the heterogeneity of particle size distributions.     

Introduction of copper nanoparticles in chitosan matrix as strategy to enhance chromate adsorption

In this study, copper nanoparticles (CuNPs) were incorporated to chitosan (CHI) matrix as strategy to enhance the chromate adsorption by CHI membrane. The CuNPs were synthesized using NaBH₄ as the reducing agent. Dispersive X-ray Absorption Spectroscopy (DXAS) was used to monitor the in situ reduction of Cu(II). The influence of the presence of CuNPs on the hygroscopic behavior was also evaluated. DXAS technique showed that the adsorbed Cu(II) was reduced to Cu(I) (63%) and Cu(0) (37%) species, at the end of the reduction reaction (using NaBH₄, after ∼30 min). The hygroscopic behavior of the proposed sorbent was more influenced by CuNPs when the water vapor adsorption was conducted under synthetic air atmosphere. A decrease in the energy of interaction among the water molecules adsorbed on the monolayer was observed. The chromate adsorption study has shown a higher equilibrium concentration of adsorbed chromium species when the CHI membrane containing CuNPs was used as sorbent. The CuNPs offered a second active adsorption site, which was characterized by a higher coefficient of affinity (12 L mmol⁻¹, against 0.18 L mmol⁻¹ reported for CHI). The enhanced adsorption of chromium in the presence of CuNPs was associated to the redox reaction between the CuNPs and chromate anions.     

Competitive adsorption of Ag (I) and Cu (II) by tripolyphosphate crosslinked chitosan beads

Alkalization of chitosan before crosslinking was applied in this study to enhance the adsorption capacity of the modified chitosan. Competitive adsorption of Ag (I) and Cu (II) from bimetallic solutions was studied using the newly synthesized tripolyphosphate crosslinked alkalized chitosan beads. Results indicated that alkalization before crosslinking helps to protect amine group from crosslinking and hence increases the uptake capacity and selectively of the synthesized beads toward Ag (I). The maximum uptakes of Ag (I) and Cu (II) were 82.9 and 15.5 mg g^?1, respectively, at room temperature with an initial concentration of each metal being 2.0 mM and the sorbent dosage of 1.0 g L^?1. The uptake of Ag (I) and Cu (II) by the beads can be better described by Langmuir isotherm and pseudo‐second rate equation. Analyses from FTIR and XPS confirmed that free amine, hydroxyl, and groups are involved in metal binding with amine and hydroxyl groups more selective to Ag (I). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42717.     

Preparation and characterization of titanium oxide‐densified cellulose beads for expanded bed adsorption

Expanded bed adsorption (EBA) has been widely used in industrial downstream bioprocessing. Solid matrix is the principal pillar supporting the successful application of the EBA. A new type of TiO₂‐densified cellulose beads as matrix for EBA is exploited through the method of water‐in‐oil suspension thermal regeneration. The typical physical properties of beads are wet density 1.21 g/cm³, specific surface area 38.7 m²/mL, porosity 83.7%, and water content 69.5%. The results indicate that the custom‐assembled matrix can be derivated to function as an anion exchanger for EBA, by possessing a significant mechanical strength, stable hydrodynamics, and comparable protein breakthrough capacities with the commercial Streamline diethylaminoethyl (DEAE) adsorbent. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2848–2854, 2003     

水杨醛接枝壳聚糖的制备及其吸附性能

以壳聚糖和水杨醛为原料,采用超声波辐射技术制备了水杨醛接枝壳聚糖,并用红外光谱对产物的结构进行了表征,同时研究了接枝壳聚糖的吸附性能.结果表明:采用超声波辐射,大大提高了壳聚糖的接枝反应速度.所制得的水杨醛接枝壳聚糖对Cu2 、Cr6 的吸附容量和吸附速度要大于壳聚糖,在25℃下,其对Cu2 、Cr6 的吸附容量分别达到117.84 mg·g-1和58.14 mg·g-1,并且对Cu2 、Cr6 的吸附在1 h内即可达到饱和.     

香草醛接枝壳聚糖的制备及其吸附性能

以壳聚糖和香草醛为原料,乙醇为溶剂,采用超声波辐射技术制备了香草醛接枝壳聚糖,用红外光谱对产物的结构进行了表征,同时研究了接枝壳聚糖的吸附性能。结果表明:采用超声波辐射法,大大提高了壳聚糖的接枝反应速度,反应2 h时接枝率达到32.85%。香草醛接枝壳聚糖对Cr6+、Cu2+的吸附容量和吸附速度大于壳聚糖。在25℃下,它对Cu2+、Cr6+的吸附容量分别达到145.68 mg/g和56.75 mg/g,并且对Cu2+、Cr6+的吸附在2 h内即可达到饱和。     

新型改性壳聚糖的制备及其对2,4-二氯苯酚的吸附

采用水杨醛与壳聚糖反应生成Schiff’s碱,再用NaBH4还原,环氧氯丙烷交联制备壳聚糖衍生物,用FTIR对改性壳聚糖进行表征,并用于2,4-二氯苯酚的吸附研究。测试了改性产物的溶解性能,考察了吸附时间、溶液pH值、酚的浓度以及改性剂用量等因素对氯酚吸附的影响。结果表明,水杨醛改性环氧氯丙烷交联壳聚糖不溶于水、酸和碱;在pH=7、吸附时间为2 h时,对2,4-二氯酚的吸附量为128.2 mg/g。     

Novel chitosan/polyvinyl alcohol/talc composite for adsorption of heavy metals and dyes from aqueous solution

ABSTRACT

In this study, adsorption capability of chitosan/polyvinyl alcohol/talc composite (CPTC) in removal of Congo red, Methyl orange, Pb²⁺, and Cr⁶⁺ was evaluated. CPTC was characterized using Fourier transfer infrared spectroscopy, field emission scanning electron microscope, X-ray diffraction, thermogravimetric analysis, and weight loss test. Flocculation was the main phenomena in Congo red removal for 100 mg/L and in Methyl orange for <100 mg/L. The removal amounts of Pb²⁺ and Cr⁶⁺ were 96% and close to 100% up to 200 mg/L, and 88% and 92% at 400 mg/L, respectively. Langmuir model demonstrated better results in describing the heavy metals removal. Moreover, it was found that kinetics followed a pseudo-second-order equation.     

超大孔聚丙烯酰胺晶胶微球的制备及其生物相容性和吸附性能

利用反相悬浮结合溶剂结晶致孔法制备了具有超大孔隙、球形度良好的聚丙烯酰胺晶胶微球,晶胶微球平均粒径为234.1 mm,孔径约为10～50 mm。采用原位接枝法,将2-丙烯酰胺基-2-甲基-1-丙烷磺酸（AMPSA）接枝到晶胶微球孔隙表面上,得到了带有磺酸基团的阳离子交换晶胶微球。考察了晶胶微球的生物相容性和吸附蛋白质及重金属离子Cu²⁺的性能,结果表明：在大肠杆菌培养液中,添加晶胶微球,对大肠杆菌的生长影响不大。接枝了AMPSA的晶胶微球表现出更强的吸附Cu²⁺的能力,吸附容量达到1.14 mmol·g^-1。同时,接枝后的晶胶微球也具有一定吸附蛋白质的能力,溶菌酶的吸附容量达到54.5 mg·g^-1。因此,该大孔晶胶可望在微生物固定化、生物分离和重金属离子吸附中会发挥更大的作用。     

碳化物衍生碳及其在吸附领域中的应用研究进展

碳化物衍生碳（CDC）是近年来开发的一种具有纳米结构的新型多孔碳材料。该材料是将碳化物前体通过物理（如热分解等）或化学（如卤化等）过程,由表及里逐层刻蚀掉非碳原子得到的,可以实现原子水平上的调控。本文介绍了CDC的制备工艺、性质（孔和形貌）及其在吸附领域中的应用。结果表明,可以通过控制刻蚀温度、碳化物前体、后处理等合成条件实现CDC比表面积大范围可调、孔径及孔径分布等微观结构精确可控,得到从无定形碳到高度有序的石墨、碳纳米管或石墨烯等多种结构。最后指出了解制备过程-结构-性质之间的关系有利于精确调控CDC以满足特定应用的要求。