In the current study, carpobrotus edulis were used to prepare three adsorbent surfaces; (dry adsorbent material, DAM), (hot activated carbon, HAC), and (acid activated carbon, AAC), and applied for safranin dye removal as a function of pH, contact time, adsorbent dose, initial dye concentration, and temperature. The ideal pH for DAM, HAC, and AAC efficient adsorption were 7-11, 7-9, and 5-11, respectively, employing an adsorbent dosage of 0.10 g and contact time of 30, 40, and 90 min, respectively. Furthermore, the adsorption processes were better explained by the pseudo-second-order-Kinetic model. It was also noticed that the safranin adsorption process demonstrated a favorable agreement with Freundlich isotherm for the three adsorbents with maximum calculated adsorption capacities of 47.49, 44.18, and 46.72 mg/g for DAM, HAC, and AAC, respectively. The results of the thermodynamic study revealed the exothermic nature of dye adsorption onto DAM and AAC and the endothermic nature onto HAC. Finally, results demonstrated that the studied surfaces are efficient adsorbents and could likely be utilized for dyes adsorption.

In the current study, carpobrotus edulis were used to prepare three adsorbent surfaces; (dry adsorbent material, DAM), (hot activated carbon, HAC), and (acid activated carbon, AAC), and applied for safranin dye removal as a function of pH, contact time, adsorbent dose, initial dye concentration, and temperature. The ideal pH for DAM, HAC, and AAC efficient adsorption were 7-11, 7-9, and 5-11, respectively, employing an adsorbent dosage of 0.10 g and contact time of 30, 40, and 90 min, respectively. Furthermore, the adsorption processes were better explained by the pseudo-second-order-Kinetic model. It was also noticed that the safranin adsorption process demonstrated a favorable agreement with Freundlich isotherm for the three adsorbents with maximum calculated adsorption capacities of 47.49, 44.18, and 46.72 mg/g for DAM, HAC, and AAC, respectively. The results of the thermodynamic study revealed the exothermic nature of dye adsorption onto DAM and AAC and the endothermic nature onto HAC. Finally, results demonstrated that the studied surfaces are efficient adsorbents and could likely be utilized for dyes adsorption.

Background: Adenosine deaminase (ADA) is an enzyme indispensable to the purine metabolic pathway. ADA is present in virtually all mammalian cells and has a central role maintaining competence.Aberrations in the expression and function of ADA have been implicated in several disease states such as severe combined immunodeficiency (SCID), acquired immunodeficiency syndrome (AIDS), anemia, various lymphomas, and leukemia. The ADA activity can be found at variable amounts in all cell types in nervous system. Both gene therapy and enzyme replacement therapy have been used to treat victims of this rare disease. Bovine ADA has been extracted from different sources such as intestinal, spleen, brain that have different molecular weight and iso-enzyme with different stability and Kinetic activity. In this study, we compared the thermodynamic and Kinetic parameter of two different bovine ADA's that obtained from intestinal and spleen.Materials and Methods: Kinetic and thermodynamic studies have been made on the effect of inosine on the activity of intestinal and spleen adenosine deaminase (ADA) in 50mM sodium phosphate buffer pH 7.5 at 27° C, using DV spectrophotometer and isothermal titration microcalorimetry (ITC). Results: A competitive inhibition was observed for inosine as a product of enzymatic reaction. A graphical fitting method was used for determination of binding constant and enthalpy of inhibitor binding by using isothermal titration microcalorimetry. The dissociation binding constants were equal to 140 µM and 152µM for intestinal and spleen ADA respectively by microcalorimetry method, which were good agreement with values of 143 µM and 149 M for inhibition constants obtained from spectroscopy method for intestinal and spleen ADA, respectively. Kinetics parameters of intestinal ADA (1<car 19.36 109S.1 and kcat/Km (50.92107 M-1S-1) were more than two time higher than spleen ADA (kcat 7.47109 s-1 and kcat/Km=22.36107M-1s-1). The comparative thermodynamic stability of intestinal ([DTAB] 1/2= 3.75 mM and ΔGº(H2o)=17.9 kJ/mol) and spleen ADA ([DTAB] 1/2 = 3.25 mM and ΔGº(H2o)= 16.8 kJ/mol) were obtained by interaction of these enzymes with dodecyl trimethyl ammonium bromide (DTAB) as a good denaturant. The results indicated that intestinal ADA is more stable compare to spleen ADA.Conclusion: Kinetic and thermodynamic comparison of adenosine deaminase from different sources (spleen, intestine) show that intestinal ADA is more active in Kinetics and more stable in thermodynamics.

The present work focused on the adsorption of Pb(II) from aqueous solutions by amino-functionalized nano titania in a batch system. Surface modification was based on immobilization of o-phosphoethanolamine on the surface. The effects of pH, adsorbent dose, contact time, initial metal concentration, and temperature on the adsorption process were examined. The maximum adsorption of Pb(II) was observed to occur at pH 6. 0. Kinetic data showed that the adsorption process achieved equilibrium within 90 min and experimental data were fitted well by the pseudo-second-order model. According to the equilibrium data, Pb(II) adsorption was well described by the Langmuir isotherm model. According to the evaluated thermodynamic parameters at different temperatures, the adsorption was a spontaneous (Δ 𝐺 <0) and endothermic (Δ 𝐻 >0) process. The presence of Mg and Ca ions as interfering cations up to 150 mg/g caused no considerable lowering effect on the Pb(II) adsorption. In addition, the regeneration of the adsorbent was performed using HNO3 (0. 1 mol/L). The obtained studies showed that amino-functionalized nano titania was successfully used as an efficient adsorbent for removal of the Pb(II) from aqueous solutions.

AlMCM-41 was applied for adsorption of methylene blue (MB) and auramine (AU) in single and binary component systems. In the single component systems, AlMCM-41 represents higher adsorption capacity for MB than AU with the maximal adsorption capacity of 2.07´10-4 and 1.15×10-4 mol/g at 25oC for MB and AU, respectively. In the binary component system, MB and AU exhibit competitive adsorption onto the adsorbent. In single and binary component systems, Kinetic and adsorption isotherm studies demonstrate that the data are following pseudo-second-order Kinetic model and Langmuir isotherm. Also, in both cases, Kinetic data is fairly described by two-step diffusion model. Effect of solution pH on the adsorption of MB and AU in single and binary component systems was studied and the results were described by electrostatic interactions.

In this study, absorption of sulfates on activated aluminum industry waste (red mud) has been investigated in a batch system by OFAT method. The properties of the absorbents were analyzed using scanning electron microscope (SEM), BET surface area, X-ray diffraction (XRD), XRF. The process of sulfate absorption was done in a volume of 200 mL and a mixer speed of 150 rpm. The optimum adsorption conditions were derived for in an equilibrium time of 90 minutes, the initial concentration of 100 ppm, pH=4, the temperature of 65 ◦, C and 1. 5 g/L dose of the absorbent. The efficiency of sulfate removal was 73. 1 percent at the optimum conditions. thermodynamic analysis of absorption showed that the absorption process at all analyzed temperatures had occurred spontaneously. Sulfate adsorption Kinetics on composite surfaces followed a pseudo second order equation and absorption isotherm had a high conformity with Langmuir, Dobinin-Radoshkovich and Temkin isotherms respectively and the maximum absorption capacity of it according to Langmuir isotherm is 13. 07 mg of sulfate per gram of the absorbent.