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Adsorption of CO2, CH4, and N2was investigated using pulse concentration chromatography on polystyrene functionalized by covalently attached diethanolamine, dimethylamine, imidazole, and N-methyl piperazine. The adsorption equilibrium constants at different temperatures were estimated by fitting the experimental chromatograms into a non-linear equilibrium dispersive chromatography model using gPROMS. Axial dispersion was found to be the controlling mechanism for dispersion of the chromatograms. The heat of adsorption and corresponding equilibrium selectivities were determined from the adsorption equilibrium constants. The imidazole based adsorbent showed the highest affinity for CO2. [ABSTRACT FROM PUBLISHER]

A reactive sorption method has been devised for the purification of artemisinin from Artemisia annua extract using a polymeric adsorbent loaded with specific ligands. These ligands were designed by molecular simulation to selectively adsorb artemisinin. The specific interactions of artemisinin with different polymeric adsorbents in organic solvents of varying polarity were further quantified in terms of interaction energy, atomic charges, and vibrational spectral analysis. Solvation studies indicate use of methanol for adsorption while ethyl acetate for desorption of artemisinin. Batch equilibrium and dynamic adsorption-desorption studies were conducted to establish optimum parameters for the purification process. A weakly basic polymeric adsorbent with tertiary amino groups was chosen for artemisinic acid. After adsorption the final purity of artemisinin increases up to 90%. [ABSTRACT FROM PUBLISHER]

Organosulfur compounds were removed from commercial diesel by reactive adsorption on metal impregnated functionalized polymers at ambient temperature and pressure. The equilibrium adsorption capacities of Ag+ and Cu+ impregnated resins for dibenzothiophene (DBT) are 13 mg/gm and 9.6 mg/gm. Adsorption and desorption cycle studies in a column packed with Ag+ and Cu+ loaded BSR resin showed intraparticle resistance affecting uptake of the sulfur compounds. Only 40% of the adsorbed organo-sulfur compounds was recovered by solvent regeneration using toluene, but complete regeneration of the bed was possible by simultaneous microwave heating. Density functional theory (DFT) calculations show stronger interaction between organosulfur compounds and Cu(I) on the polymer resins. The interaction energy increases with the number of substituents around 'S' in the structure, giving stronger interaction of the metal ions with dialkyl-substituted dibenzothiophene than monosubstituted and unsubstituted thiophene. [ABSTRACT FROM AUTHOR]

Separation of nitrophenols (NP) has been studied by selective solubilization in organic solvents of different polarities. o‐NP dissolves very well in heptane and toluene while intermolecular hydrogen bonding among p‐NP molecules decreases its solubilization in these solvents. Thus partial separation of o‐/p‐nitrophenols is achieved by selective solubilization of o‐NP in heptane. The trace amounts of p‐NP from the o‐NP solutions are removed by its selective sorption on basic ion exchange resins. The sorption of nitrophenols, individually and in mixtures, is experimentally determined from their solutions in heptane, toluene, and methanol by using weakly basic Indion‐850 and Duolite A‐308 resins and strongly basic Indion‐810 resin. The equilibrium adsorption studies show very selective adsorption of p‐NP from heptane with a high loading capacity on Indion‐850. [ABSTRACT FROM AUTHOR]

Strong and weakly acidic ion exchange resins and polymeric adsorbents are used for recovery of 1,4‐dimethyl piperazine (DMP) from aqueous solutions. Sorption of the amine in undissociated form is the primary mechanism of uptake of DMP on the ion‐exchange resins. Equilibrium adsorption data for DMP on the resins, at various temperatures, are fitted in Langmuir adsorption isotherm. Kinetic studies show that intraparticle diffusional resistance controls the sorption of DMP into the resin matrix. A mathematical model based on intraparticle diffusion and external mass transfer is used for simulating breakthrough profiles and compared with the experimental results for a fixed bed of weakly acidic Indion‐652 resin. The DMP loaded bed of the resin was effectively regenerated with methanol. [ABSTRACT FROM AUTHOR]

Separation of o -/ p -aminoacetophenones ( o -/ p -AAPs) is investigated by a two-step process: selective solubilization in an organic solvent followed by reactive adsorption on functionalized polymers. Since, p -AAP and o -AAP show inter- and intra-molecular hydrogen bonding, respectively, the former is solubilized to a much lesser extent than the latter in an organic solvent. For example, o -AAP dissolves completely while p -AAP shows only 1.8% saturation solubility in toluene. Selective solubilization of o -AAP in toluene, therefore, gives pure p -AAP as residual solid in high yields. In the subsequent adsorption step, a strongly acidic ion exchange resin removes selectively the trace amounts of p -AAP from the toluene phase giving pure o -AAP. [ABSTRACT FROM AUTHOR]

Adsorption of penicillin acylase (PA) from a crude aqueous extract of Escherichia coli on chitosan beads and N-benzamide and N-phenylacetamide derivatives of chitosan was investigated. Penicillin acylase adsorbed specifically on the derivatized chitosan beads, with a strong interaction with the ligand groups. The interaction of the active site of PA with the affinity ligands was simulated by molecular modeling. The adsorbent was further used for immobilization of PA by using glutaraldehyde as the activating agent. The immobilized enzyme retained the same activity even after 20 weeks. [ABSTRACT FROM AUTHOR]

o-/p-Nitroanilines (o-/p-NAs), which are intermediates for pharmaceutical and dye industries, show widely different solubilization behavior in an organic solvent. For example, o-Nitroaniline (o-NA) dissolves well in toluene, but p-nitroaniline (p-NA) does not. The intermolecular hydrogen bonding among the molecules of p-NA resists its solubilization in poorly solvating solvents. A selective solubilization of o-NA from the mixture thus gives pure p-NA as a solid product and an o-NA rich solution in toluene with trace amounts of p-NA. These traces of p-NA could be removed by selective sorption on an acidic resin. The sorption of nitroanilines, individually and in mixture, therefore, was experimentally investigated from their solutions in toluene and methanol, by using a strongly acidic resin, Indion 190, with sulfonic acid groups. The molecular modeling studies confirmed the Lewis acid–base interactions between the resin's sulfonic acid group and p-NA's nitro group. The selective sorption is further aided by poor solvation of p-NA in the organic solvents. [ABSTRACT FROM AUTHOR]