Impregnation synthesis of a novel macroporous silica-based TODGA polymeric composite and its application in the adsorption of rare earths in nitric acid solution containing diethylenetriaminepentaacetic acid

A macroporous silica-based N,N,N′,N′-tetraoctyl-3-oxapentane-1,5-diamide (TODGA) polymeric composite (TODGA/SiO₂-P) was synthesized. It was done through impregnation and immobilization of TODGA molecule into the pores of the SiO₂-P particles utilizing a vacuum sucking technique. The macroporous SiO₂-P particles were the silica-based organic/inorganic composite synthesized by immobilizing styrene-divinylbenzene copolymer inside SiO₂ through the complicated polymerization reaction. The adsorption of rare earth (RE(III)) elements onto TODGA/SiO₂-P was investigated in HNO₃ solution containing diethylenetriaminepentaacetic acid (DTPA), an acidic multi-dentate chelating agent. It was found that in the presence of 0.05 M DTPA, and H⁺ had significant effect on the TODGA/SiO₂-P adsorption due to the competition reactions of RE(III) with different species, H₄DTPA⁻ and H₂DTPA³⁻. With an increase in the concentration of from 0.115 M to 3.015 M, the adsorption of RE(III) onto TODGA/SiO₂-P increased noticeably. On the other hand, RE(III) showed strong adsorption at 0.1 M H⁺, weak adsorption at around pH 2, and no adsorption in excess of pH 2.3. In a 0.1 M H⁺-0.115 M -0.05 M DTPA solution, a change of the distribution coefficient of RE(III) onto TODGA/SiO₂-P with an increase in atomic number of RE(III) from La(III) to Lu(III) was investigated. The silica-based TODGA/SiO₂-P polymeric composite showed strong adsorption for heavy RE(III) over the light one. In a 0.01 M H⁺-1.0 M -0.05 M DTPA solution, the effect of the ratio of solid phase to liquid one on the relationship of the distribution coefficient of RE(III) with the change in atomic number of RE(III) was also studied. Based on the complicated disassociation equilibrium of DTPA, the influence of the concentrations of and H⁺ on the adsorption of TODGA/SiO₂-P for RE(III) was demonstrated. This makes the partitioning of RE(III) and MA(III) together from high level liquid waste (HLLW) by the polymeric composite TODGA/SiO₂-P promising.     

One-Step Preparation of Chitosan-Based Magnetic Adsorbent and Its Application to the Adsorption of Inorganic Arsenic in Water

Chitosan is a kind of biodegradable natural polysaccharide, and it is a very promising adsorber material for removing metal ions from aqueous solutions. In this study, chitosan-based magnetic adsorbent CMC@Fe₃O₄ was synthesized by a one-step method using carboxymethyl chitosan (CMC) and ferric salts under relatively mild conditions. The Fe₃O₄ microspheres were formed and the core–shell structure of CMC@Fe₃O₄ was synthesized in the meantime, which was well characterized via SEM/TEM, XRD, VSM, FT-IR, thermo gravimetric analysis (TGA), XPS, size distribution, and zeta potential. The effects of initial arsenic concentration, pH, temperature, contact time, and ionic strength on adsorption quantity of inorganic arsenic was studied through batch adsorption experiments. The magnetic adsorbent CMC@Fe₃O₄ displayed satisfactory adsorption performance for arsenic in water samples, up to 20.1 mg/g. The optimal conditions of the adsorption process were pH 3.0, 30−50 °C, and a reaction time of 15 min. The adsorption process can be well described by pseudo-second-order kinetic model, suggesting that chemisorption was main rate-controlling step. The Langmuir adsorption model provided much higher correlation coefficient than that of Freundlich adsorption model, indicating that the adsorption behavior is monolayer adsorption on the surface of the magnetic adsorbents. The above results have demonstrated that chitosan-based magnetic adsorbent CMC@Fe₃O₄ is suitable for the removal of inorganic arsenic in water.     

PAN基活性炭纤维的表面及其孔隙结构解析

通过氮吸附等温线、Ｘ射线光电子能谱以及扫描电子显微镜（ＳＥＭ）对聚丙烯腈（ＰＡＮ－Ｐｏｌｙａｃｒｙｌｏｎｉｔｒｉｌｅ）－基活性炭纤维（ＡＣＦ－Ａｃｔｉｖａｔｅｄ Ｃａｒｂｏｎ Ｆｉｂｅｒ）的表面和孔隙结构进行了分析，结果表明吸附测量可以提供有关碳质吸附剂的孔结构复杂性；通过ＸＰＳ对ＰＡＮ基ＡＣＦ的表面官能团的种类及含量进行了表征，由ＳＥＭ对ＰＡＮ基ＡＣＦ的表面以及断面的孔隙结构进行直拉观察，提供了     

Extraction of naringin from pomelo peels as dihydrochalcone's precursor

A new method for the separation of naringin from pomelo peels was investigated by using ultrasonic-assisted extraction and macroporous resin purification technology. The ultrasonic extraction efficiency was dependent on agent's concentration, ratio of sample and solvent and ultrasonic time. Several parameters of macroporous resin-purified process, including resin selection, initial concentration, concentration of eluted agent and pH, were optimized. The experimental results showed that the naringin content in the mature pomelo peels was 2.20% and purification rate of naringin was 77.26% under optimum conditions of purification. The structure of synthetic naringin dihydrochalcone was determined by a series of spectroscopic methods, such as UV, NMR and MS.     

大孔网状聚合物吸附剂在中药、天然药物分离纯化上的应用

随着科学技术的高速发展和中药现代化发展战略的提出,传统的水提醇沉淀等方法已远远满足不了工业生产需求。新的分离纯化方法中以大孔吸附树脂最受中药开发者青睐,它具有效果显著、工艺简单、再生方便、生产成本低等优点。本文就中药及天然药物中生物碱、黄酮、萜类、皂苷、内酯、蒽醌、醌类及有机酸类等活性成分的富集、分离、纯化等方面的应用研究进行了概述。     

导向性二维大孔金阵列的制备及光谱电化学应用

为研究多孔材料的光谱电化学应用,以模板-电沉积法制备了导向性的二维大孔金阵列,将其制成光透薄层电极,测定3,3'-二甲基联苯胺的E°'和n.采用原子力显微镜和扫描电子显微镜对其进行表征.测定了不同厚度的大孔金膜的吸收光谱.结果表明,在-0.8 V电沉积约300 s,得到大面积的厚度为292 nm的大孔金膜,透光率达20...     

天然气吸附储存的进展

天然气作为绿色替代能源,其吸附储存在移动应用方面至关重要,目前广泛关注的3种吸附储存技术存在着各自的优势和劣势。本文综述了多孔碳质吸附剂、金属有机框架吸附剂和吸附天然气水合物的研究进展,总结了天然气吸附性能的主要影响因素和改进途径,介绍了超临界吸附理论和分子模拟预测的相关工作,比较了3种技术的优劣及相关发展趋势。     

Differential Scanning Calorimetry Evaluates Relative Proportions and Strength of Acid-Sites in Catalytic Materials and Adsorbents Alumina and Amorphous Silica-Alumina

Abstract

Differential scanning calorimetry (DSC) is employed to evaluate the relative proportions and strength of acid-sites in gammaalumina and amorphous silica-alumina through presorption of tri-ethylamine (TEA) followed by its thermal desorption in the DSC equipment. From the data obtained, total acid-sites in silica-alumina is found to be 2.3 times as large as those present in gamma-alumina, and 5–5% of total acidity in alumina is of Bronsted type whereas in silica-alumina this type comprises 28.9%' The Bronsted acidity strength in alumina and silica-alumina is identical although greatly different in quantity. Lewis acidity in silica-alumina is significantly stronger than that in alumina.     

Preconcentration of Uranium in Seawater with Heterocyclic Azo Dyes Supported on Silica Gel

Abstract

The chelating adsorbents, heterocyclic azo dyes supported on silica gel, were prepared and their adsorption behaviors of metal ions were investigated. The 1-(2-pyridylazo)-2-naphthol(PAN)-SG and 2-(2-thiazolylazo)-p-cresol(TAC)-SG show greater affinity for UO₂(II) and ZrO(II), compared with the other metal ions like Cu, Cd, Fe and alkaline earths. Trace uranyl can be quantitatively retained on the column of the gels at neutral pH region and flow-rate 3–4 ml/min. The uranyl retained is easily eluted from the column bed with a mixture of acetone and nitric acid(9:1 v/v) and determined by spectrophotometry using Arsenazo-III. Matrix components in seawater do not interfere and the spiked recovery of uranyl in artificial seawater was found to be average 98.6 %, with the relative standard deviation of 1.08 %. Both gels were applied to the determination of uranium in seawater with satisfactory results.     

Process Optimization and Modeling of Phenol Adsorption onto Sludge-Based Activated Carbon Intercalated MgAlFe Ternary Layered Double Hydroxide Composite

A sewage sludge-based activated carbon (SBAC) intercalated MgAlFe ternary layered double hydroxide (SBAC-MgAlFe-LDH) composite was synthesized via the coprecipitation method. The adsorptive performance of the composite for phenol uptake from the aqueous phase was evaluated via the response surface methodology (RSM) modeling technique. The SBAC-MgAlFe-LDH phenol uptake capacity data were well-fitted to reduced RSM cubic model (R² = 0.995, R²-adjusted = 0.993, R²-predicted = 0.959 and p-values < 0.05). The optimum phenol adsorption onto the SBAC-MgAlFe-LDH was achieved at 35 °C, 125 mg/L phenol, and pH 6. Under the optimal phenol uptake conditions, pseudo-first-order and Avrami fractional-order models provided a better representation of the phenol uptake kinetic data, while the equilibrium data models’ fitting follows the order; Liu > Langmuir > Redlich–Peterson > Freundlich > Temkin. The phenol uptake mechanism was endothermic in nature and predominantly via a physisorption process (ΔG° = −5.33 to −5.77 kJ/mol) with the involvement of π–π interactions between the phenol molecules and the functionalities on the SBAC-LDH surface. The maximum uptake capacity (216.76 mg/g) of SBAC-MgAlFe-LDH was much higher than many other SBAC-based adsorbents. The improved uptake capacity of SBAC-LDH was attributed to the effective synergetic influence of SBAC-MgAlFe-LDH, which yielded abundant functionalized surface groups that favored higher aqueous phase uptake of phenol molecules. This study showcases the potential of SBAC-MgAlFe-LDH as an effective adsorbent material for remediation of phenolic wastewater