Microwave preparation and adsorption properties of EDTA‐modified cross‐linked chitosan

A novel chitosan‐based adsorbent (CCTE) was synthesized by the reaction between epichlorohydrin O‐cross‐linked chitosan and EDTA dianhydride under microwave irradiation (MW). The chemical structure of this new polymer was characterized by infrared spectra analysis, thermogravimetric analysis, and X‐ray diffraction analysis. The results were in agreement with the expectations. The static adsorption properties of the polymer for Pb²⁺, Cu²⁺, Cd²⁺, Ni²⁺, and Co²⁺ were investigated. Experimental results demonstrated that the CCTE had higher adsorption capacity for the same metal ion than the parent chitosan and cross‐linked chitosan. In particular, the adsorption capacities for Pb²⁺ and Cd²⁺ were 1.28 mmol/g and 1.29 mmol/g, respectively, in contrast to only 0.372 mmol/g for Pb²⁺ and 0.503 mmol/g for Cd²⁺ on chitosan. Kinetic experiments indicated that the adsorption of CCTE for the above metal ions achieved the equilibrium within 4 h. The desorption efficiencies of the metal ions on CCTE were over 93%. Therefore, CCTE is an effective adsorbent for the removal and recovery of heavy metal ions from industrial waste solutions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and adsorption properties of metal ions of crosslinked chitosan azacrown ethers

The novel azacrown ether chitosan derivatives (CCAE‐I, CCAE‐II) were prepared by reaction between crosslinked chitosan with epoxy‐activated azacrown ethers. Their structures were confirmed by elemental FTIR spectra analysis and X‐ray diffraction analysis. The adsorption and selectivity properties of the crosslinked chitosan azacrown ethers for Pb²⁺, Cu²⁺, Cr³⁺, Cd²⁺, and Hg²⁺ were also investigated. The experimental results showed that they have high adsorption capacity for Cu²⁺, Cd²⁺, and Hg²⁺. The adsorption capacity of CCAE‐II is higher than CCAE‐I for Cd²⁺ and Hg²⁺. The selectivity properties of CCAE are better than chitosan and crosslinked chitosan. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3053–3058, 1999     

Synthesis and adsorption properties of metal ions of novel azacrown ether crosslinked chitosan

Azacrown ether chitosan (CTSC) was synthesized by the reaction of chitosan with N‐allyl benzo 15‐crown‐5 crown ether. Azacrown ether crosslinked chitosan (CCTSC) was prepared by the crosslinked reaction of CTSC and epichlorodydrin. Their structures were confirmed by infrared spectral analysis and X‐ray diffraction analysis. The adsorption properties of CTSC and CCTSC for metal ions were also investigated. The experimental results showed that the two chitosan derivatives not only had a good capacity to adsorb Pd²⁺ and Ag⁺ but also was highly selective for Pd²⁺ and Ag⁺ in the coexistence system containing other metal ions. At 20°C ± 1°C and pH = 4, the adsorption capacity of CTSC and CCTSC for Pd²⁺ was 186.1 and 173.1 mg/g, respectively; and for Ag⁺ was 90.2 and 56.5 mg/g, respectively. The selectivity coefficients were K = 6.99, K = ∞, K = 35.38, K = ∞ for CTSC and K = 10.66, K = ∞, K = 85.45, K = ∞ for CCTSC. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2705–2709, 2006     

Synthesis and adsorption properties for metal ions of crosslinked chitosan acetate crown ethers

Two novel chitosan derivatives—crosslinked chitosan dibenzo‐16‐c‐5 acetate crown ether (CCTS‐1) and crosslinked chitosan 3,5‐di‐tert‐butyl dibenzo‐14‐c‐4 diacetate crown ether (CCTS‐2)—were synthesized by the reaction of crosslinked chitosan with dibenzo‐16‐c‐5 chloracetate crown ether and 3,5‐di‐tert‐butyl dibenzo‐14‐c‐4 dichloracetate crown ether with the intent of forming polymers that could be used in hazardous waste remediation as toxic metal‐binding agents in aqueous environments. Their structures were confirmed with elemental analysis, infrared spectral analysis, and X‐ray diffraction analysis. In the infrared spectra of CCTS‐1 and CCTS‐2, the characteristic peaks of aromatic backbone vibration appeared at 1595 cm⁻¹ and 1500 cm⁻¹; the intensity of the N H and O H stretching vibration in the region of 3150–3200 cm⁻¹ decreased greatly. The X‐ray diffraction analysis showed that the peak at 2θ = 20° decreased greatly in CCTS‐1 and CCTS‐2. The adsorption and selectivity properties of CCTS‐1 and CCTS‐2 for Pb²⁺, Cu²⁺, Cr³⁺, and Ni²⁺ were studied. Experimental results showed that the two crosslinked chitosan derivatives had not only good adsorption capacities for Pb²⁺, Cu²⁺, but also high selectivity for Pb²⁺, Cu²⁺ in the coexistence of Ni²⁺. For aqueous systems containing Pb²⁺, Ni²⁺, or Cu²⁺, Ni²⁺, CCTS‐1 only adsorbed Pb²⁺ or Cu²⁺. For aqueous systems containing Pb²⁺, Cr²⁺ and Ni²⁺, CCTS‐2 had high adsorption and selectivity properties for Pb²⁺. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2069–2074, 1999     

Study on the adsorption properties of novel crown ether crosslinked chitosan for metal ions

We first synthesized N‐benzylidene chitosan (CTB) by the reaction of benzaldehyde with chitosan (CTS). Chitosan‐dibenzo‐18‐crown‐6 crown ether bearing Schiff‐base group (CTBD) and chitosan‐dibenzo‐18‐crown‐6 crown ether (CTSD) were prepared by the reaction of 4,4′‐dibromodibenzo‐18‐crown‐6 crown ether with CTB and CTS, respectively. Their structures were confirmed by Fourier transform infrared spectral analysis and X‐ray powder diffraction analysis. These novel crown ether crosslinked CTSs have space net structures with embedded crown ethers and contain the double structures and properties of CTS and crown ethers. They have stronger complexation with and better selectivity for metal ions than corresponding crown ethers and CTS. Moreover, these novel CTS derivatives can be used to separate and preconcentrate heavy or precious metal ions in aqueous environments. From this practical viewpoint, we studied the adsorption and selectivity properties of CTB, CTBD, and CTSD for Ag⁺, Cu²⁺, Pb²⁺, and Ni²⁺. The experimental results showed that CTBD had better adsorption properties and higher selectivity for metal ions than CTSD. For aqueous systems containing Pb²⁺–Ni²⁺ and Pb²⁺–Cu²⁺, the selectivity coefficients of CTSD and CTBD were K/Ni²⁺ = 24.4 and K/Cu²⁺ = 41.4 and K/Ni²⁺ = 35.5 and K/Cu²⁺ = 55.3, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 29–34, 2002; DOI 10.1002/app.10180     

Microwave preparation and properties of O-crosslinked maleic acyl chitosan adsorbent for Pb2+ and Cu2+

A novel chitosan-based adsorbent (CCTM) was prepared by the reaction of epichlorohydrin O-crosslinked chitosan with maleic anhydride under microwave irradiation. The chemical structure of this polymer was characterized by infrared spectroscopy and X-ray diffraction analyses. The effects of various variables such as degree of substitution, adsorption time, initial metal ion concentration, solution pH, and temperature, on the adsorption of Pb²⁺ and Cu²⁺ by CCTM were investigated. The results demonstrate that the microwave irradiation can remarkably enhance the reaction. CCTM has higher adsorption capacity than chitosan. The maximum adsorption capacities for Pb²⁺ and Cu²⁺, with initial concentrations of 0.02 mol L⁻¹ at pH 5, are 246.3 and 132.5 mg g⁻¹, respectively. The adsorbent can be recycled. These results have important implications for the design of effective chitosan-based adsorbents in the removal of heavy metal ions from wastewaters. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Microwave irradiation-induced alterations in physicochemical properties and methane adsorption capability of coals: An experimental study using carbon molecular sieve

In order to comprehend the applicability of microwave irradiation for recovering coalbed methane, it is necessary to evaluate the microwave irradiation-induced alterations in coals with varying levels of metamorphism. In this work, the carbon molecular sieve combined with KMn O4oxidation was selected to fabricate carbon molecular sieve with diverse oxidation degrees, which can serve as model substances toward coals. Afterwards, the microwave irradiation dependences of pores, functional groups, and highpressure methane adsorption characteristics of model substances were studied. The results indicated that microwave irradiation causes rearrangement of oxygen-containing functional groups, which could block the micropores with a size of 0.40-0.60 nm in carbon molecular sieve; meanwhile, naphthalene and phenanthrene generated by macro-molecular structure pyrolysis due to microwave irradiation could block the micropores with a size of 0.70-0.90 nm. These alterations in micropore structure weaken the saturated methane adsorption capacity of oxidized carbon molecular sieve by 2.91%-23.28%, suggesting that microwave irradiation could promote methane desorption. Moreover, the increased mesopores found for oxidized carbon molecular sieve after microwave irradiation could benefit CH₄ diffusion. In summary, the oxidized carbon molecular sieve can act as model substances toward coals with different ranks. Additionally, microwave irradiation is a promising technology to enhance coalbed methane recovery.     

Preparation,characterization, and adsorption properties of chitosan microspheres crosslinked by formaldehyde for copper (II) from aqueous solution

The chitosan microspheres crosslinked by formaldehyde were prepared by spray drying method and used as an adsorbent for copper (II) from aqueous solution. A batch adsorption system was applied to study the adsorption of copper (II) from aqueous solution by chitosan microspheres. The maximum adsorption capacity of the chitosan microspheres for copper (II) was 144.928 mg/g at pH 6.0. Langmuir adsorption model was found to be applicable in interpreting the adsorption process. To elucidate the adsorption mechanism, the chitosan microspheres before and after copper (II) adsorption were further characterized by Fourier transform infrared spectra, zeta potential analysis, and scanning electron microscope. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

L-胱氨酸交联球形壳聚糖凝胶的制备与Cu2+吸附性能

以L-胱氨酸(L-CYS)作为交联剂,利用滴液成球法制备交联球形壳聚糖凝胶,用傅里叶红外光谱、¹³C NMR、扫描电镜对产物进行了表征,结果表明L-CYS与壳聚糖发生了酰胺化及酯化反应,并且制得的凝胶内部存在着疏松的网络状大孔。交联剂L-CYS中的二硫键有助于二价铜离子的吸附。以L-CYS交联得到的球形壳聚糖凝胶对Cu²⁺的吸附量达到了72.96 mg·g^-1,接近于未交联的球形壳聚糖凝胶的吸附量,而耐溶胀性优于未交联的壳聚糖凝胶。     

Studies of adsorption properties of crosslinked chitosan for vanadium(V), tungsten(VI)

In this article, the adsorption properties of crosslinked chitosan (CCTS) for V(V) and W(VI) were studied. Experimental results showed the adsorption rates of CCTS for V(V) and W(VI) were closely related to the acidity of solution. The adsorption rates were 97% for V(V) at pH 4.0 and 96% for W(VI) at pH 4.5. The adsorption balance times, adsorption capacities, and adsorption mechanism were explored. This research is of significance for removal of V(V) and W(VI) in industrial wastewater and their preconcentration in trace analysis. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1584–1588, 2004     

Microwave preparation of a titanium-substituted mesoporous molecular sieve

A titanium-containing redox material with disordered wormhole-like mesoporous structure was prepared using microwave heating. Substantially accelerated crystallization was achieved using microwave heating compared with the conventional oven heating. Development of the mesopore structure was confirmed by XRD, TEM, and N₂ physisorption. Incorporation of titanium into the mesopore structure was confirmed by UV-vis spectroscopy. A laser light particle size analyzer showed that smaller particle size and narrower particle size distribution were obtained with microwave heating than with oven-heated hydrothermal synthesis. These mesoporous titanosilicates were equally active as catalysts for liquid-phase oxidation of 2,6-di-tert-butylphenol with hydrogen peroxide as an oxidant. This revised version was published online in July 2006 with corrections to the Cover Date.     

Preparation and properties of chitosan/poly(vinyl alcohol) blend foams for copper adsorption

A new form of polymer blend, macroporous chitosan/poly(vinyl alcohol) (PVA) foams made by a starch expansion process, exhibits the functionalities of chitosan while avoiding its poor mechanical properties and chemical instabilities. The appropriate conditions for foaming are discussed using both insoluble and water‐soluble chitosan. The chitosan/PVA foams demonstrated interconnected and open‐cell structures with large pore size from tens to hundreds of micrometers and high porosities from 73.6 to 84.3%. Glutaraldehyde was employed to improve the retention of chitosan and copper adsorption of the chitosan/PVA foams. While it increased the retention of chitosan and the adsorption capacities, glutaraldehyde decreased the pore size and porosity. The macroporous structure of the chitosan/PVA foams indicates extensive application prospects in terms of the considerable adsorption of heavy metal ions. Copyright © 2006 Society of Chemical Industry     

Synthesis of novel low‐cost porous gangue microsphere/geopolymer composites and their adsorption properties for dyes

A novel porous coal gangue microsphere/geopolymer (CG/KGP) composite was firstly synthesized by adding gangue microspheres into geopolymer matrix. Effects of precalcined temperature of CG microspheres on the microstructure and specific surface area of the porous CG/KGP particles were systematically investigated. Adsorption properties of the CG/KGP composites were also reported. Results showed that the CG/KGP composites contained mainly amorphous phase and many functional groups were on the particle surface. The precalcined CG microspheres were dispersed homogenously and bonded well with the KGP matrix. The CG900/KGP samples showed better adsorption properties than the pure KGP. As for the dosage of 4 g/L (starting concentration, 100 mg/L), adsorption capacity achieved the highest value of 24.6 mg/g and the removal efficiency reached 98%. Adsorption of MB onto CG900/KGP particles followed the pseudo‐second‐order kinetic model. The novel porous CG/KGP composite has potential application in wastewater filtration and adsorption treatment.     

丙酮酸改性壳聚糖对金属离子的吸附性能研究

丙酮酸经Schiff碱反应对壳聚糖进行修饰 ,合成了高取代的水溶性丙酮酸缩壳聚糖 (PCTS) ,研究了PCTS、SCTS(水杨醛改性壳聚糖 )、CTS(壳聚糖 )对Cu(Ⅱ )、Zn(Ⅱ )、Co(Ⅱ )的静态吸附性能 ,并采用正交实验法考察了金属离子浓度、介质酸度、吸附量和吸附时间对吸附剂去除金属离子能力的影响。结果表明 ,PCTS的吸附性能优于SCTS与CTS ,对Cu(Ⅱ )、Zn(Ⅱ )、Co(Ⅱ )的吸附容量 (pH =7 0 )分别为 2 79 56、1 96 63、70 2 1mg/g ,金属离子浓度、介质酸度对吸附性能影响大 ,而吸附剂用量、吸附时间对吸附性能影响较小。     

Simultaneous adsorption of aniline and Cr(VI) ion by activated carbon/chitosan composite

Activated carbon/chitosan composite has been used as an adsorbent to remove aniline and Cr(VI) ions from aqueous solutions simultaneously. The effects of preparation conditions such as the ratio of activated carbon to chitosan, crosslinking reagents, crosslinking time, and adsorption conditions including adsorbent dosage, pH value of solution, and contact time on simultaneous adsorption of aniline and Cr(VI) ion were investigated. Experimental results showed that epichlorohydrin was the proper crosslinking reagent, and the ratio of activated carbon to chitosan was kept at 1. When the adsorbent dosage was 4.0 g/L, and the concentrations of aniline and Cr(VI) were lower than 50 and 100 mg/L, respectively, both aniline and Cr(VI) were simultaneously removed at natural pH with high removals (>95%). The presence of Cr(VI) enhanced the adsorption of aniline, while the presence of aniline almost had no influence on the adsorption of Cr(VI). The adsorption processes of both aniline and Cr(VI) followed the pseudo‐second‐order kinetics model, but the sorption of Cr(VI) was preferential to that of aniline by this composite. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39903.     

Enhanced adsorption of malachite green onto carbon nanotube/polyaniline composites

To enhance adsorption of organic dyes like malachite green (MG) onto polymeric absorbents, we prepared carbon nanotube (CNT) filled polyaniline (PANI) composites with large surface areas by simply using entangled CNTs as porous frameworks during PANI polymerization. Adsorption behavior of the CNT/PANI composites in MG solutions was experimentally investigated and theoretically analyzed. The CNT/PANI composites exhibit much higher equilibrium adsorption capacity of 13.95 mg g^?1 at an initial MG concentration of 16 mg L^?1, increasing by 15% than the neat PANI, which is mainly attributed to large surface areas and strong CNT‐PANI interactions of the composites. In addition, theoretical analyses indicate that the adsorption kinetics and the isothermal process of the composites can be well explained by using the Ho pseudosecond‐order model and the Langmuir model, respectively. In light of their high MG adsorption and easy operation, the CNT/PANI composites have great potential as high‐efficiency adsorbents for removal of dyes from wastewater. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Na型Y/β复合分子筛的合成及吸附脱氮研究

分别以铝酸钠、硅溶胶为铝源和硅源,采用两步水热晶化法合成Na型Y/β复合分子筛,采用XRD和TG-DTA等方法对其结构进行表征,并对其吸附脱氮性能进行研究,优化工艺条件。结果表明,Na型Y/β复合分子筛具有Y型沸石和β沸石的特征,复合分子筛在烘箱150 ℃晶化4天,焙烧温度控制在550 ℃焙烧4 h效果最佳。吸附温度40 ℃、吸附时间4 h和剂油质量比1∶20为最佳吸附工艺条件。     

Effect of molecular weight and degree of deacetylation of chitosan on urea adsorption properties of copper chitosan

Copper chitosan complexes prepared by different specifications of chitosan and copper sulfate were used as urea sorbents. Experimental results showed that the adsorption capacity for urea of copper chitosan increased with an increasing degree of deacetylation and decreasing molecular weight of chitosan. The urea adsorption capacity of copper chitosan was 120.0 mg/g, when 1.0 g of copper chitosan was admitted to 100 mL of a 1300 mg/mL (pH 6.0) urea solution, with chitosan degree of deacetylation of 84.3% and viscosity molecular weight of 6.5 × 10⁵, at 37°C for 8 h. No elution of the copper from the copper chitosan could be detected under the optimal conditions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1520–1523, 2003     

分子筛对CH_4/空气混合气的变压吸附分离研究

为提高煤层气变压吸附浓缩效果,以一种商品分子筛为对象,研究了该分子筛在小型四塔变压吸附装置上的CH4/空气混合气浓缩分离效果,分析了吸附时间、吸附压力以及原料气浓度对混合气浓缩效果的影响。结果表明,吸附时间过长或吸附压力过高,均不利于获得较好的产品气浓度及回收率。吸附时间180 s,吸附压力300 k Pa时,试验商品分子筛对CH4/N2的浓缩分离效果最佳。其中,10%浓度原料气提浓至30.56%,提高约20%,产品气中CH4回收率达到94.45%,对原料气的处理量达到67.77 m3/(t·h);35%浓度原料气提浓至76.33%,提高约40%,产品气中CH4回收率达到69.68%,对原料气的处理量达到68.99 m3/(t·h);65%原料气提浓至89.18%,提高约25%,产品气中CH4回收率达到87.22%,对原料气的处理量达到83.36 m3/(t·h)。     

分子筛吸附在石化领域的应用研究现状

综述了分子筛吸附在石化领域清洁燃料生产、石脑油分离和环保方面的应用进展和研究现状,并且指出随着研究的深入,分子筛吸附在石化领域的应用会更加广泛和成熟。