Papers by Keyword: Adsorbent

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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: Ming Hua Liu, Piao Piao Huang, Jian Yun Ou
Abstract: The spherical chitosan adsorbent was prepared by graft copolymerization of acrylic acid onto the cross-linked spherical chitosan beads, and then was adopted to adsorb the L-histidine. The adsorption conditions, i.e., solution pH, adsorption time, initial concentration and adsorption temperature were optimized. The spherical chitosan adsorbent showed excellent equilibrium adsorption capacity of 78.3 mg/g for the L-histidine when the solution pH value was 7.5, adsorption time was 180 min, initial concentration was 1500 mg/L and the adsorption temperature was 25 °C. Moreover, the inorganic salt of NaCl also showed great effect on the equilibrium adsorption capacity exceeding 0.8 mol/L. The static adsorption processes followed the Langmuir adsorption isothermal equation and Freundlich adsorption isothermal equation. Furthermore, L-histidine could be desorbed with 1.5 mol/L of ammonia solution, and the regeneration capacity of the spherical chitosan adsorbent was excellent.
Authors: Li Li Yu, Lin Yao
Abstract: The crosslinked starch microspheres(CSM) were synthesized from soluble starch by inverse suspension polymerization with N,N′-methylenebisacrylamide as cross-linking agent. Experiments showed that adsorption isotherms of CSM for Cd(II) and Pb(II) could be described by Freundlich model, while that for Cu(II), Cr(III) fits well with Langmuir equation. The equilibrium capacity of Cu(II), Cr(III), Cd(II) and Pb(II) on the CSM were 1.10, 0.87, 0.35 and 0.31 mmol•g-1 respectively at 25°C, when adsorption process was undertaken with initial concentration from 0.7 to 11.5 mmol•L-1, and adsorption kinetics were examined according to the adsorption isotherm. Furthermore, the impact bring by other ions to CSM adsorption of Cu(II) were investigated in details.
Authors: Bin Li, Hong Bin Wang, Yan Yuan
Abstract: The adsorption kinetics and influencing factors deduction showed that adsorption process accorded with a second-order kinetic equation according to academic hypothesis. The result was validated by the phosphate adsorption onto Veria-Based adsorbent. The factor (m/V) b had the close relation with the adsorption speed and the adsorbent dosage, intensity exponent b=0.44 (0b1) in this test condition. All the results show that phosphate adsorption on the adsorbent surface was mono-layer chemisorptions and that the hypothesis of kinetic inference was reasonable.
Authors: Yin An Ming, Ying Ru Wang, Zheng Liu, Fu Rong Zhou
Abstract: In this paper, the mechanism that lithium-modified rectorite (Rec-Li) and raw rectorite adsorbed methylene blue dye in wastewater was investigated, and the adsorption properties of the two adsorbents were also compared. The results showed that the static saturated adsorption capacity of raw rectorite was 77.75mg/g, however, the capacity of lithium-modified rectorite was up to 189.62mg/g, the adsorption efficiency was increased by 144%. Therefore, the adsorption capacity of Rec-Li to methylene blue was much higher than raw rectorite. The Rec-Li and raw rectorite were characterized respectively by means of fourier transform infrared spectrophotometer (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) and colloid index measurement. The analysis indicated that, after modification by lithium, the colloid index was changed from 12mL/3g to 198mL/3g and the interlayer spacing was changed from 0.01~0.1μm to 1~1.5μm. With the increasing of the colloid index, the dispersion effect of adsorbent in wastewater and the contact area between adsorbent and pollutants were improved. And the increase of interlayer spacing was conducive to pollutants entering the hole and so that the adsorption capacity of Rec-Li was increased significantly.
Authors: Shan Ping Li, Jiang Jie Cui
Abstract: We studied the effects of surface modification of bentonite with chitosan on its ability to adsorb Congo Red (CR) dye. The adsorption behavior of CR from aqueous solution onto raw (RB) and chitosan-modified (CMB) bentonite samples was investigated as a function of parameters such as initial CR concentration, contact time, pH and temperature. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to confirm the surface modification. Compared with RB, the adsorption capacity of CMB for CR was greatly enhanced. Kinetic studies indicated that the adsorption of CR on both RB and CMB followed the pseudo-second-order kinetic model. From the thermodynamic parameters, the adsorption of CR on RB and CMB is spontaneous and endothermic. The results indicate that chitosan-modified bentonite provides an important advantage for CR dye adsorption over raw bentonite.
Authors: Guo Xian Yu, Ji Bing Li, Xiao Long Zhou, Cheng Lie Li, Li Fang Chen, Jin An Wang
Abstract: Transition metal-modified carbon-based adsorbents were prepared by impregnating activated carbon with solutions of copper, cobalt or nickel chloride or nitrate. The mixtures were dried and then calcined under nitrogen stream. The surface metal species were analyzed by XRD technique and the surface oxygen-containing groups were characterized by FTIR. Their adsorption capacities for dibenzothiophene (DBT) were measured by using DBT-containing n-octane solution as model oil. Experimental results show that the metal species on the carbon surface could be controlled by the calcination process under nitrogen atmosphere. Both the transition metal precursors and kinds of metal species on the carbon surface have significant effects on DBT adsorption capacity.
Authors: Zhong Hua Huang, Yan Zou, Fang Yuan, Wei Jing Li, Xue Pu
Abstract: A new low cost adsorbent crosslinked chitosan resin has been used to remove dyes from wastewater. The crosslinked chitosan resin was prepared using inverse suspension polymerization with methanal and epichlorhydrin (ECH) using pre-crosslinking and crosslinking techniques. As comparison, the adsoption ability of chitosan and activated carbon was also investigated.
Authors: Jong Oh Kim, Jin Woo Lee
Abstract: This study focused on the adsorption characteristics of hazardous heavy metals using reactive inorganic agents in synthetic wastewater. Basic properties of five reactive agents were analyzed by zeta potential, particle size, XRF and SEM. Zeta potential of five adsorbents was 45, 7, 14, -2 and 45 mV, respectively. Average particle size was in the range of 1.4 to 9㎛. By XRF analysis, main components were Na, Al, Si, S and Fe in reactive agents and no great differences in Mg, K, Ca and Ti components. As, Zn, Ni, Cu, Cr, Cd and Pb were used as target heavy metals. Adsorption capacity of Pb and Cu was in the order: TN 315Ny-T3>TN820L>TN315NY.
Authors: Fang Yan Chen, Wei Ye, Yu Bin Tang
Abstract: A novel organic-inorganic composite sodium polyacrylate-humic acid-rectorite was prepared by polymerization reaction of acrylic acid, humic acid and rectorite in aqueous solution and used as adsorbent for removal of heavy metals Pb(II), Cd(II), Cu(II) and Zn(II) ions from aqueous solution. The effects of contact time, pH, temperature and adsorbent dosage on adsorption capability were investigated. Adsorption kinetics, adsorption isotherm and desorption of adsorbed heavy metal ions were also researched. The results indicated that the adsorption reaction of heavy metals was rapid and reached equilibrium in 30 min. Adsorption capacities of heavy metals increased with increasing initial pH, temperature and adsorbent dosage. Adsorption reaction is endothermic. The optimum pH for all the four ions adsorption was observed at 5.5-6.5. The removal rate of Pb(II), Cd(II), Cu(II) ions with initial concentration of 50mg/L are more than 98%, and Zn(II) ions removal is about 90%. The suitability of adsorption kinetics for heavy metals to a pseudo-second-order kinetics model suggested that the adsorption rate may be governed by chemiadsorption involving ions exchange or sharing between adsorbent and metal ions. The adsorption equilibrium data was well interpreted by Langmuir and Freundlich isotherm model. The adsorption behaved as monomolecular layer. The maximum monolayer adsorption capacity was 1666.7, 666.7, 303.0 and 454.6 mg∙g-1 for Pb(II), Cd(II), Cu(II) and Zn(II) ions, respectively, at 25°C. Adsorbed metal ions were desorbed effectively by 0.1M HCl solution. Desorption rate was about 95.2, 92.4, 98.7 and 94.3% for Pb(II), Cd(II), Cu(II) and Zn(II) ions, respectively. Adsorbent can be reused for three cycles without any significant loss in adsorption performance.
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