Intensification the Features of Interaction Between Components of Pollutants of Industrial Waste Waters with Modified Zeolites Based on the Results of Integrated Physical and Chemical Researches

The results of a study on the adsorption of oil products and heavy metal ions by modified zeolites from industrial wastewater are presented. As a modifier of zeolites of the Holinsky deposit, a sulfur polymer is proposed that is obtained from waste during the production of epichlorohydrin, the main components of which is 1,2,3-trichloropropane. The mechanisms of adsorption and the results of investigations by the methods of infra-red pectroscopy and energy differential X-ray spectroscopy of the initial samples of materials are described in detail. On the Irspectres new absorption bands are considered. These bands reflect the nature of fixation of modifier on the surface of sorbent. Also the results of original investigations of the thermodynamic laws of sorption extraction of Ni2+, Zn2+, Cu2+ from wastewater are presented. The limiting parameters of the adsorption process are described by the Langmuir equation. The graphical method the limiting value of adsorption, the adsorption equilibrium constant, the differential heat of adsorption, the adsorption rate constant, the activation energy, the Gibbs energy was founded. It is proved that the investigated processes obey the laws of physical adsorption and are spontaneous.

Separation of N–C5H12–C9H20 Paraffins Using Boehmite by Inverse Gas Chromatography

The separation of a mixture of C5–C9 n-paraffins was achieved by Inverse Gas Chromatography (IGC) by using boehmite; AlO(OH), in a packed column with short exposure times and temperatures; from 45 °C to 52 °C. The boehmite was characterized by XRD; ATG; SEM; IR spectroscopy and N2 adsorption. The material exhibited a low crystalline boehmite (AlOOH) structure and presented high hydration (pseudoboehmite). The reverse gas chromatography measurements showed that the elution temperatures of the C5–C9 n-paraffins were low compared with those obtained for other adsorbents. The differential heat of adsorption values ensures the satisfactory separation of the components in the C5–C9 mixture under suitable chromatographic conditions.

Removal of Brilliant Red from Aqueous Solutions by Adsorption on Fish Scales

Removal of brilliant red (C. I. Reactive Red 2) from aqueous solutions by adsorption on fish scales of Labeo rohita was investigated. Batch adsorption experiments were carried out under different experimental conditions such as contact time, initial concentration of dye solutions, temperature and pH of the solution. The optimum pH for the adsorption experiment was found to be 7.2. The equilibrium time for the adsorption of brilliant red (BR) on fish scales was estimated and found to be three hours. The amount of brilliant red adsorbed on fish scale surface decreased with increasing pH and temperature of the solution. The negative value of differential heat of adsorption suggests that the adsorption process is exothermic. Langmuir adsorption isotherm was found to fit the experimental data better than that of the Freundlich adsorption isotherm. Dhaka Univ. J. Sci. 61(1): 7-12, 2013 (January) DOI: http://dx.doi.org/10.3329/dujs.v61i1.15089

Modification of Fagus sylvatica (L.) with 1,3-dimethylol-4,5-dihydroxyethylene urea (DMDHEU): Part 1. Estimation of heat adsorption by the isosteric method (Hailwood-Horrobin model) and by solution calorimetry

The differential heat of adsorption (ΔH s ) of Fagus sylvatica wood modified with 0.8 M, 1.3 M, and 2.3 M solution of 1,3-dimethylol-4,5-dihydroxyethylene urea (DMDHEU) was determined at different equilibrium moisture contents (EMCs) by both the isosteric method, using the Hailwood-Horrobin model at 20, 30, and 40°C and by solution calorimetry. Both methods revealed that at 1% EMC, the 2.3-M modified wood releases approximately double the amount of energy as does unmodified wood. At EMC below approximately 5%, DMDHEU-modified wood appears to be more hygroscopic than unmodified wood, indicating that more OH groups are available for adsorption. The bulking effect of the cell wall and the increase of OH groups caused by the modification with DMDHEU are probably the reason for this observation. As expected, higher EMC led to a reduction of ΔH s .

Determination of Differential Enthalpy and Isotherm by Adsorption Calorimetry

An adsorption microcalorimeter for the simultaneous determination of the differential heat of adsorption and the adsorption isotherm for gas-solid systems are designed, built, and tested. For this purpose, a Calvet heat-conducting microcalorimeter is developed and is connected to a gas volumetric unit built in stainless steel to record adsorption isotherms. The microcalorimeter is electrically calibrated to establish its sensitivity and reproducibility, obtaining K=154.34±0.23 WV−1. The adsorption microcalorimeter is used to obtain adsorption isotherms and the corresponding differential heats for the adsorption of CO2 on a reference solid, such as a NaZSM-5 type zeolite. Results for the behavior of this system are compared with those obtained with commercial equipment and with other studies in the literature.

Experimental and Simulation Study of n-Heptane Adsorption on Rutile

The adsorption of n-heptane on microcrystalline rutile has been studied experimentally by thermodynamic techniques (adsorption isotherms and microcalorimetry) over a wide range of coverage at 303 K and complemented by Grand Canonical Monte Carlo simulations. The differential heat of adsorption exhibited three descending segments corresponding to the adsorption of n-heptane on three types of surfaces. The mean molar adsorption entropy of n-heptane in the monolayer was less than the entropy of the bulk liquid by ca. −23 J/(mol K), thus revealing a hindered state of motion for the n-heptane molecules on the surface of rutile. Simulations of the adsorption of n-heptane were performed on the three most abundant crystallographic faces of rutile. The adsorption isotherm obtained from the combination of the isotherm for each face weighted by the respective abundance was found to be in good agreement with experimental data. A structural characterization of n-heptane near the surface was also conducted which indicated that the substrate strongly perturbed the distribution of the n-heptane conformations relative to the situation found for the gaseous phase. Adsorbed molecules are predominantly orientated with their long axes, with the zig-zag planes of their backbones parallel to the surface and preferentially aligned along the five-fold cus Ti4+ ions of the faces. Fewer gauche conformations were observed for molecules near the surface than was characteristic of the bulk phase.

Adsorption of Carbon Dioxide on Mesoporous Silicas near the Critical Temperature

The adsorption of carbon dioxide on mesoporous silicas was studied near the critical temperature (Tc) of CO2, i.e. 304.2 K. The critical temperature in the mesopores at which the first-order phase transition (capillary condensation) was observed (Tcp) was estimated from the inverse slope of the adsorption isotherms and the behaviour of the adsorption isotherms per unit surface area. The values of Tcp for CO2 in mesopores whose radii, rp, were 3.02 and 2.14 nm were higher than those estimated using a slab model in which the adsorbing parts of layer were clearly separated from the non-adsorbing regions. The differential heat of adsorption decreased with increasing pore size of the mesoporous adsorbent. This result also suggested a deviation from the slab model.

Moisture adsorption thermodynamics of wood from fractal-geometry approach

The fractal-geometry approach was used to calculate the thermodynamic properties of moisture sorption by wood from the adsorption isotherms in this study. The results were compared with those from an isosteric approach and a calorimetric approach. The adsorption isotherms of Southern yellow pine (Pinus spp.) were measured at 4, 15, 30, and 40°C to provide source data for the calculation of both fractal-geometry and isosteric approaches. The results show that the fractal dimensions of the internal surfaces of wood vary between 2.4 and 2.5. The curves of the differential heat of adsorption −∆H against moisture content from the fractal-geometry approach are similar to those from calorimetric measurements in previous research. The −∆H values from the isosteric approach increased with moisture content within a moisture content range up to 3%. And, at moisture contents higher than 3%, the −∆H values from this method are much higher than those from the fractal-geometry approach and calorimetric approach. As a result, the fractal-geometry approach is applicable to calculate the differential thermodynamic properties of moisture sorption by wood in future research.