Synthesis of magnetically modified palygorskite composite for immobilization of Candida sp. 99–125 lipase via adsorption

Magnetically modified palygorskite composites were synthesized with γ-Fe2O3 dispersing on the external surface of clay mineral. The magnetic clay was characterized with Fourier transform infrared, X-ray diffrac- tion, transmission electron microscopy, and vibrating sample magnetometer. Candida sp. 99-125 lipase was immobilized on magnetic palygorskite composites by physical adsorption with enzyme loading of 41.5 mg· g^-1 support and enzyme activity of 2631.6 U· （g support）^-1. The immobilized lipase exhibit better thermal and broader pH stability and excellent reusabilitV compared with free lipase.

Efficiently Adsorbing CO Molecules Using Al_6Si Cluster

Based on the density functional theory with generalized gradient approximation, the stable geometrical structures of one or more CO molecules adsorbed on the Al6Si cluster are investigated and the corresponding adsorption energies are also calculated. It is found that the cluster Al6Si can adsorb six CO molecules. The thermal stability of the（CO）6@Al6Si complexes is examined using the atom centered density matrix propagation molecular dynamics calculations at 373 K. The results show that two isomers of Al6Si cluster can solidly adsorb six CO molecules, and the other isomer adsorbs four ones. Therefore, the Al6Si cluster is a promising candidate for eliminating CO effectively.

Enhanced carbon dioxide adsorption performance and kinetic study of K and Al co-doped Li4SiO4

Herein, we report the effects of doped K and Al on the carbon dioxide （CO2） adsorption performance of the Li4SiO4-based adsorbents. The CO2 adsorption capacity of 0.8 wt% K and 1.5 wt% AI doped Li4SiO4 is ～2.2 times and ～1.3 times higher than that of the pristine Li4SiO4 at 500 and 600℃, respectively. The kinetic study further indicated that the reaction rates of the lithium diffusion process is greatly improved by K and AI doping, and the lithium diffusion rate of 0.8 wt% K and 1.5 wt% AI doped Li4SiO4 is ～2 times higher than that of the pristine Li4SiO4 at 575-650 ℃. K and AI doping increases the adsorption capacity of Li4SiO4-based adsorbents, and widens its effective adsorption temperature range

Adsorption of Ca2+on single layer graphene oxide

Graphene oxide（GO） holds great promise for a broad array of applications in many fields,but also poses serious potential risks to human health and the environment.In this study,the adsorptive properties of GO toward Ca^（2＋） and Na＋were investigated using batch adsorption experiments,zeta potential measurements,and spectroscopic analysis.When pH increased from 4 to 9,Ca^（2＋）adsorption by GO and the zeta potential of GO increased significantly.Raman spectra suggest that Ca^（2＋）was strongly adsorbed on the GO via –COO Ca~＋ formation.On the other hand,Na＋was adsorbed into the electrical diffuse layer as an inert counterion to increase the diffuse layer zeta potential.While the GO suspension became unstable with increasing pH from 4 to 10 in the presence of Ca^（2＋）,it was more stable at higher pH in the NaC l solution.The findings of this research provide insights in the adsorption of Ca^（2＋）on GO and fundamental basis for prediction of its effect on the colloidal stability of GO in the environment.

Succinate-bonded pullulan: An efficient and reusable super-sorbent for cadmium-uptake from spiked high-hardness groundwater

Chemically modified pullulan was evaluated for its sorption efficiency and selectivity to remove cadmium（Cd） from spiked high-hardness groundwater（GW）. Pullulan esterified with succinic anhydride using dimethylaminopyridine showed a fairly high degree of substitution value as confirmed by1 H NMR spectroscopy. Pullulan succinate（Pull-Suc） was converted into the sodium salt（Pull-Suc-Na）. The effect of contact time（5–200 min） and p H（2–8） on Cd-uptake by the sorbent（Pull-Suc-Na） was investigated. The sorbent showed more than 90% Cd-removal in first 15 min from distilled water（DW） and GW solution,respectively. Comparison of Pull-Suc-Na with other polysaccharidal sorbents suggested its high efficiency（DW 476.2 mg/g and GW 454.5 mg/g） and selectivity for the removal of Cd by an ion exchange mechanism, which is further supported by the negative Gibbs free energy values calculated from Langmuir isotherms. A Langmuir isotherm kinetic model provided the best fit for the sorption of Cd using Pull-Suc-Na. The sorbent showed a negligible decrease in Cd-uptake over three regeneration cycles. The thermal stability testing of the sorbents indicated that Pull-Suc-Na（sorbent） is more stable than Pull-Suc.