Papers by Keyword: Adsorption

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Authors: Xian Hui Qiu
Abstract: Tannic acid, a natural polymer extracts from trees, was found to selectively depress galena while chalcopyrite was floated by xanthate. Micro-flotation studies, adsorption and Fourier transform infrared spectroscopy have been employed to investigate the mechanism. Micro-flotation studies shown that tannic acid can effectively depress galena while depress chalcopyrite weakly in the entire pH range. The adsorption results shown that the tannic acid adsorbed on chalcopyrite and galena surface influenced by the pH value, the higher the pH, the less of adsorption density. Tannic acid adsorb on galena through complexation with the lead ions, not with hydroxyl complex in the galena surface. Fourier transform infrared spectroscopy revealed that tannic acid interacted with lead ions by the hydroxyl groups on the phenol group. Tannic acid may be replace the hazardous inorganic depressants such as cyanide, dichromate and sulfur dioxide used in differential Cu-Pb sulfide separation.
Authors: Bao Jian Liu, Shi Wang Liu, Tie Bing Liu, Jian Wei Mao
Abstract: Levulinic acid (LA) is a new versatile platform chemical derived from renewable non-food biomass. A major challenge in the purification of LA from biomass hydrolysate is the separation of LA and formic acid. A novel granular activated carbon (GAC) adsorption and separation of LA and formic acid were investigated in this work. Adsorption equilibria elucidated that LA preferentially adsorbed onto GAC than formic acid. Mixed solution of LA and formic acid was fed into the GAC packed-bed at 30°C, then formic acid was washed out from the column in a pure form with 60°C water and finally LA was effectively eluted with 95% (v/v) ethanol at 60°C. LA can be completely separated from formic acid by this simple GAC adsorption process with good yield and high purity.
Authors: Wen Rui Zheng, Jing Li Xu
Abstract: The magnetite (Fe3O4) nanoparticles with immobilized metal affinity ligands were prepared for protein adsorption. First, magnetite nanoparticles were synthesized by hydrothermal method. Charged with Zn2+, the magnetic nanospheres were applied to adsorb bovine hemoglobin (BHb). The morphology and magnetic properties of magnetic nanospheres were investigated by TEM. These magnetic nanospheres modified with metal ligands can be used efficiently in protein affinity separation and purification.
Authors: Meng Wang, Fan Yong Yan, Dong Lei Cao, Xin Yu Song
Abstract: A novel supramolecular smart poly(N-isopropylacrylamide-co-tetra(5-hexenyloxy)-p- tert-butylcalix[4]arene) (P(NIPAAm-co-Calix)) hydrogel was synthesized by free radical polymerization of N-isopropylacrylamine(NIPAAm) and modified calix[4]arene. The swelling behaviours and ionic adsorption capacity were studied. It is found that the polymeric network of the P(NIPAAm-co-Calix) hydrogel is characterized by an open structure with more pores and higher swelling ratio compared to the PNIPAAm hydrogel. The adsorption abilities of heavy toxic metal ions (Ni2+, Cu2+, Pb2+, Cd2+) for P(NIPAAm-co-Calix) hydrogels and PNIPAAm hydrogel were different and depend on the temperature. This could provide a theoretical basis for the intelligent response mechanism to stimulate research of supramolecular hydrogel.
Authors: Zhi Yong Ji, Jun Sheng Yuan, Xiao Fu Guo, Jun Wang, Ling Li
Abstract: Based on preparing high purity powdered lithium ion-sieve precursor LiMn2O4, using lithium carbonate and manganese carbonate as raw materials, through roasting at high temperature of 800°C, laminar lithium ion-sieve precursor was prepared by commixing poly (vinyl chloride) (PVC) and powdered precursor in DMF (N, N-dimethylformamide) as solvent, and then powder and lithium ion-sieve flat sheet membrane was obtained through washing with HCl solution respectively. Their adsorption capacity and morphology was also characterized. The results show that both powdered lithium ion-sieve and laminar one have high adsorption capacity and selectivity for Li in solutions, and the effect of their retest is good. All these can provide a good foundation for the further study on lithium ion-sieve flat sheet membrane and lithium extraction from seawater.
Authors: O. Assowe, Olivier Politano, Vincent Vignal, Patrick Arnoux, B. Diawara
Abstract: The interaction of water molecules on a nickel surface was studied using ReaxFF (reactive force field) molecular dynamics. This approach was originally developed by van Duin et al. to study the hydrocarbon chemistry and the catalytic properties of organic compounds. To our knowledge, this method has not been used to study the corrosion processes of nickel exposed to water, which is what we set out to achieve in the present investigation. To do so, calculations were first performed using ReaxFF in order to reproduce certain well-known properties of pure nickel and nickel-water systems. This allowed us to study the adsorption of a single water molecule interacting with an optimized nickel surface. We also investigated the interaction of 405 molecules of water (ρ=0.99 on the (100), (110) and (111) surfaces of a single crystal of nickel at 300 K. The results show that a water bilayer is adsorbed on nickel surfaces: the first water layer is directly bonded to the surface, whereas the molecules in the first and second layers are held together by hydrogen bonds.
Authors: Han Xi Wang, Jian Ling Xu, Lian Xi Sheng, Xue Jun Liu
Abstract: Based on the improvements in the decontamination ability and decontamination range of constructed wetlands, this study of constructed wetland substrates was carried out using literature research and comparative meta-analysis. The results show that, for static adsorption, the absorption levels of nitrogen and phosphorus in a given constructed wetland are different. As for hydraulic load, the average removal rate of total nitrogen in wastewater is less than 50%. Compared with single substrates, a combination of substrates is typically superior in terms of the removal rate of sewage pollutants. Adsorption is the key in removing pollutants in constructed wetlands, and modification of the wetland materials is an effective way to improve the decontamination ability of the substrate material. At present, there are areas of potential improvement in the research on the development of new wetland materials for the study of pollutant characteristics, as well as a dearth of modification methods for single and reclaimable wetland substrates in constructed wetlands. These issues should be taken into account in the future studies on constructed wetland materials.
Authors: Sana Yaqub, Nurhayati Mellon, Azmi Mohamad Shariff
Abstract: The presence of carbon dioxide (CO2) in natural gas stream is a critical problem; besides causing corrosion it also reduces the energy contents and heating value of natural gas. Various separation techniques are available to separate CO2 from natural gas, such as metal organic framework (MOF), covalent organic framework (COF) and Covalent Organic Polymer (COP) adsorbents. The criteria of adsorbent selection that need to be fulfilled include high adsorption capacity, high selectivity of CO2 and hydrothermal stability at operating conditions. COPs are crystalline porous materials having high CO2 capacity and selectivity in the presence of water vapors. However, the research on COP material development is new and scarce information is available in literature. In this prospect, the paper highlights the different types of COPs, their basic constituents and the adsorption capacities.
Authors: Kai Li Zhang, Li Wei Xie, Li Hong Huang, Zong Qiang Zhu, Liang Liang Tan
Abstract: Compared with the treatment of heavy metal waste water by bamboo charcoal and modified bamboo charcoal. The mainly types and methods of modified bamboo charcoal adsorption of pollution water is introduced. some important factors that effecting the bamboo charcoal and modified bamboo charcoal adsorption of heavy metal pollution were described in detail, summarizes the desorption method of the specific adsorbent and adsorption mechanism.
Authors: Byeoung Ku Kim, Young Seak Lee, Seung Kon Ryu, Byung Joo Kim, Soo Jin Park
Abstract: In this work, to introduce polar functional groups on carbon surfaces, activated carbon fibers (ACFs) were treated by nitric acid in order to enhance the adsorption capacity of propylamine which was one of toxic gases in cigarette smoke. It was found that the polar functional groups were predominantly increased up to 2.0 M of nitric acid, resulting in the increase of total surface acidity. It was found that the adsorption amount of propylamine of the modified ACFs was increased around 17% after a nitric acid treatment. From the XPS results, it was observed that propylamine was reacted with strong or weak polar (acidic) groups, such as COOH, -COO or OH existed on the ACF surfaces.
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