Adsorption isotherms and kinetic characteristics of methane on block anthracite over a wide pressure range

It is important to quantitatively understand the methane adsorption and transport mechanism in coal for an evaluation of the reserves and for its production forecast. In this work, a block coal sample was chosen to perform the CH_4 adsorption experiments using the gravimetric method at temperatures of 293.60 K, 311.26 K, 332.98 K and 352.55 K and pressures up to 19 MPa. The excess adsorption capacity of CH_4 in dry block anthracite increased, followed by a sequence decrease with the increasing pressure. High temperature restrained the growth of the excess adsorption due to that the adsorption is an intrinsically physical and exothermic process. The excess adsorption peak decreased slowly with the increase of temperature and intersected at a pressure of more than 18 MPa; meanwhile, the pressure at the excess adsorption peak increased. The existing correlations were exanfined in terms of density rather than pressure. The DR＋k correlation, with an average relative deviation of 4-0.51%, fitted our data better than the others, with an average relative deviation of up to 2.29%. The transportation characteristics of CH_4 adsorption was also investigated in this study, including the adsorption rate and diffusion in block coal. The kinetic data could be described by a modified unipore model. The adsorption rates were found to exhibit dependence on pressure and temperature at low pressures, while the calculated diffusivities exhibited little temperature dependence. In addition, the kinetic characteristics were compared between CH_4 and CO_2 adsorption on the block coal. The excess adsorption ratios of CO_2 to CH_4 obtained from the DR＋k model decreased with the increasing pressure.

Chitosan and chemically modified chitosan beads for acid dyes sorption

The capabilities of chitosan and chitosan-EGDE （ethylene glycol diglycidyl ether） beads for removing Acid Red 37 （AR 37） and Acid Blue 25 （AB 25） from aqueous solution were examined. Chitosan beads were cross-linked with EGDE to enhance its chemical resistance and mechanical strength. Experiments were performed as a function ofpH, agitation period and concentration of AR 37 and AB 25. It was shown that the adsorption capacities of chitosan for both acid dyes were comparatively higher than those of chitosan- EGDE. This is mainly because cross-linking using EGDE reduces the major adsorption sites -NH3＋ on chitosan. Langmuir isotherm model showed the best conformity compared to Freundlich and BET. The kinetic experimental data agreed very well to the pseudo second-order kinetic model. The desorption study revealed that after three cycles of adsorption and desorption by NaOH and HCl, both adsorbents retained their promising adsorption abilities. FT-IR analysis proved that the adsorption of acid dyes onto chitosan-based adsorbents was a physical adsorption. Results also showed that chitosan and chitosan-EGDE beads were favourable adsorbers and could be employed as low-cost alternatives for the removal of acid dyes in wastewater treatment.

Effect of hemoperfusion cartridge on different internal environmental indicators

BACKGROUND:This study aimed to observe the effect of hemoperfusion(HP) cartridge on different internal environment indicators at different time points in patients with acute blood poisoning and to find alternative indicators for the detection of blood poisoning.METHODS:The levels of internal environment indicators(blood pH,P_vCO_2,P_vCO_2,blood lactate,potassium,free calcium,bicarbonate,and blood glucose) before and after HP treatment were recorded for patients with acute poisoning at time points of 30 minutes and 120 minutes.After calculating the difference value 5,the statistical software was used to analyze the statistical difference of the influence caused by HP cartridge at two time points.According to the formula,adsorption rate%=(a-v)/a×100,the adsorption rate of each indicator was calculated respectively.RESULTS:The difference of indicators at different time points in inlet and outlet such as blood glucose,free-calcium,and lactate was statistically significant(P<0.05),but the difference in indicators such as pH,P_vCO_2,P_vO_2,potassium,sodium,and bicarbonate was not statistically significant(P>0.05).CONCLUSION:During HP treatment,the indicators of blood glucose,free-calcium and lactate were significantly affected by HP cartridge,and the effect varies with time.

Effect of Delay Released Welan Gum on the Performance of Cement Mortar

Welan gum is widely applied in environmental admixtures due to its good thickening and rheological properties. With its powerful charge density in the molecular structure, the competitive adsorption between welan gum and other admixtures happened remarkably during the addition process. So controlling the releasing rate of welan gum will be able to improve the competitive adsorption, while having no disadvantages to its thickening and workability at the same time. The investigation of influences of the delay released welan gum（DRWG） on the fluidity and strength of cement mortar, bleeding rate and rheological properties of cement paste, adsorption amount and zeta potential of clinker single mineralogical phases, shows that there will be a better mortar workability and certain improvement in mortar strength with DRWG. For mortar with DRWG, the standing bleeding rate is 0, and there is less thixotropic, less adsorption, and a lower zeta potential value on the surface of clinker mineralogical phases.

Investigation of adsorption/desorption performance by aminopropyltriethoxysilane grafted onto different mesoporous silica for post-combustion CO_(2) capture

Mesoporous silicas with hexagonal structure(MCM-41 and SBA-15)and cubical interconnected pore structure(KIT-6)were synthesized and modified with aminopropyltriethoxysilane(APTES)for using as adsorbents in carbon-dioxide(CO_(2))-adsorption application.The CO_(2)-adsorption experiment was carried out at room temperature and atmospheric pressure using 15%CO_(2) with a flow rate of 20 mL/min and the desorption experiment was carried out at 100℃ under N_(2) balance with a flow rate of 20 mL/min.The adsorption capacity and adsorption rate of all modified mesoporous silicas were enhanced due to the presence of primary amine in the structure,which was able to form a fast chemical reaction with CO_(2).All adsorbents showed good adsorption performance stability after using over five adsorption/desorption cycles.Due to the effect of the adsorbents’porous structure on the adsorption/desorption process,an adsorbent with sufficient pore-size diameter and pore volume together with interconnected pore,KIT-6,represents a promising adsorbent that gave the optimum adsorption/desorption performance among others.It showed reasonable adsorption capacity with a high rate of adsorption.In addition,it could also be regenerated with 99.72% efficiency using 12.07 kJ/mmol CO_(2) of heat duty for regeneration.