Papers by Keyword: Adsorption Mechanism

Abstract: Stable TiO₂ aqueous dispersion with an averaged secondary particle size of about 10 nm was achieved by using commercially available dispersant Di-7N. The stability of the dispersion was measured by Zeta-potential test. And the results showed that the optimal mass fraction of Di-7N was 12 wt%. The adsorption mechanism examined by FTIR analysis indicates that the carboxylate groups in Di-7N is absorbed on the surface of nano-TiO₂ particles and the adsorbed structure is proposed to be bidentate chelating.

Abstract: The adsorption mechanisms of silicone rubber (SR)-stainless steel (SS) interfacial system and silicone rubber-HMX interfacial system were studied by molecular simulation method in the present paper. The molecular simulation results revealed that silicone rubber-stainless steel interface has obvious adsorption effect, while silicone rubber-HMX interface has certain adsorption effect. The systematic potential energy calculation results revealed that coulomb interaction and van de waals interaction might be the major microscopic adsorption mechanism for silicone rubber-stainless steel interfacial system and silicone rubber-HMX interfacial system.

Abstract: Oxidized alkaline loofah sponge (OAL) was given by treating alkaline loofah sponge (AL) with H₂O₂, four classic adsorption kinetics models which were Lagergren’s pseudo-first-order, Pseudo-second-order equation, the Elovich equation and Intraparticle diffusion were applied to study how the different oxidation degrees of loofah sponge impacted on the values of fitting goodness of the above models and to determine which kind of model was the best fit of the adsorption process and adsorption mechanism. The results showed that Pseudo-second-order equation’s fitting degree was proposed to be best and adsorption mechanism was chemical adsorption by ionic bonding, at the same time, as hydrogen bonds increased, water molecules formed a barrier to impede MB diffusing into the micro-structure.

Abstract: A novel magnetic adsorbent, magnetic EDTA/chitosan nanobeads was synthesized. The adsorption mechanisms of magnetic EDTA/chitosan nanobeads for removal of Cu (II) ions from aqueous solution were investigated in this paper. The interaction mechanisms of Cu²⁺ adsorption onto magnetic EDTA/chitosan nanobeads and active sites were interpreted by fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis. Uniting the analysis results of FTIR and XPS, the functional groups of participating in chelating were confirmed, and the results indicated that Cu²⁺ adsorption was mainly through interactions with electron donating atom N and O. This adsorption property was similar to N·O-type chelating agent and the adsorption mechanism was put forward. This work was very significant to control adsorption influence factor and improve adsorption capacity of magnetic EDTA-chitosan nanobeads, and then succeed to apply to magnetic adsorption fields.

Abstract: Due to the repeated cracking caused by the adsorption of cuttings on the surface of drilling bits and BHA during drilling operation, the rate of penetration (ROP) could reduce remarkably. The anti-balling additive for drilling fluids (ABA) could eliminate the adsorption effect of cuttings, and increase ROP significantly. In this paper, the mechanism of eliminating the adsorption effect of cuttings was investigated in details. The results indicate that ABA can form multilayer chemical and physical adsorption on the surface of drill bits and BHA in the form of oriented adsorption of organic phosphine, which is of great importance to the design of drilling fluid system and field operation to raise ROP.

Abstract: As the sign of social development, the vehicles and traffic flux have been increasing and have greatly influenced the ecological environment at the same time, especially on the cementitious based materials along roads as well as constructions. Heavy metal particle and ion absorption behavior and mechanism in cement materials were investigated and analyzed by means of ICP, SEM-EDS and XRD. The absorption mechanism was discussed and generalized.

Abstract: A type of cross-linking starch microspheres (CSMs) has been synthesized by reversed phase suspension method using soluble starch as raw material. Crosslinked starch microsphere has good adsorption performance to metal ions in water. The static adsorption behaviors of Co²⁺ on the cross-linked starch microspheresand were investigated. The CSMs and its adsorption product were comparatively characterized by Fourier Transform Infrared Spectroscopy (FTIR). The adsorption behaviour of CSMs in different temperatures is in agreement with the Freundlich isothermal equation and isothermal equation of Langmiur. The thermodynamic parameters of adsorption process indicate that entropy is the main adsorption driving force, and physical adsorption is main about the adsorption behaviors of CSMs on Co²⁺.These data are helpful for the adsorption separation of metal ions and the treatment of the wastewater containing Co²⁺. Keywords: cross-linked starch microspheres;cobalt ions;adsorption mechanism;thermodynamics adsorption

Abstract: In this paper, molecular dynamics method was used in researching the adsorption between single crystal aluminum and water, we built a molecular dynamics model of single crystal aluminum and water, researched the adsorption state of water on the surface of single crystal metal aluminum after nanofabrication, and gained the simulation value of the surface contact angle between aluminum and water. We also studied the impact of different orientations, different surface nanostructures, and different system temperatures on the surface contact angle. The simulation results show that: for single crystal aluminum of [10 crystal plane and water, when happen adsorption, the contact angle is approximately 61.5°, the same with the measured results; and for [11 single crystal aluminum, the contact angle is approximately 70.5 °, so different arrangement of crystal orientation has affect on surface contact angle, but does not change the hydrophilic nature. When the trench depth of the aluminum crystal surface increases, the surface contact angle is gradually increasing; and when the temperature rises, the surface contact angle increases to a certain extent.

Abstract: The modified carboxymethyl cellulose(CMC) was prepared and explored to adsorb uranium(Ⅵ) ions from aqueous solution in a batch system. The experimental results showed that on the condition of reaction temperature 70~80°C, CMC 30%-35% (w/w), CMC to AA (w/w) of 10:2.5 and reaction time 3.5-4 h, the modification effect was the best. High removal efficient of U(Ⅵ) was obtained 97.1% at temperature of 25°C, pH value of 5.0, dosage of modified CMC 0.1 g/L and contact time of 60 min. It was found that the adsorption process was best described by Freundlich model and pseudo-first-order kinetic model (R2=0.9618), indicating that the adsorption is mainly on the surface of the modified CMC. Thermodynamics parameters of negative value of ΔG0 and positive value of ΔH0 revealed the spontaneity and endothermic nature of the adsorption. The adsorption is primarily due to physical adsorption.

Abstract: Attapulgite from Xuyi in Jiangsu was characterized by X-ray spectrometer and FT-IR spectrophotometer, the coordination reaction degree of attapulgite/water interface and adsorption mechanism of humic acid(HA) on attapulgite was analyzed by Stumm-Schindle(SS) surface complexation model. The results showed that the main component of attapulgite is magnesia-alumina acid salt, the surface charge on attapulgite adapted from hydrolysates of Si-O and Al-O broken bond. After adsorption, zeta potential decreased firstly and then increased with ionic strength increasing, reduced with a pH value increasing. The zero point charge (pHzpc) of attapulgite was about 4~5, zeta potential and adsorption capacity reached the maximum values when pH= 4 and the minimum values when pH=12. The adsorption capacity increased with ionic strength rising. SS surface complexation model could well explain attapulgite / water interfacal coordination reaction, ionic strength can promote the interfacial coordination reaction and reduce electrostatic repulsion effects on adsorption, which has a definite theoretical and practical significance for guiding adsorption experiment and application of attapulgite in water-treatment technology.