Synthesis Of High Silicon Zeolites From Kaolin And Bentonite

In this paper problems of chemical and physical activation of local raw materials caoline and bentonite, and textural characteristics of high silicon zeolites and surface morphology were studied. The effect of the activation method of caoline and bentonite on the colloidal and sorption capacity was also studied. During the studies, the heat of wetting, adsorption linked water content and effective relative surface area were determined. Calculated distribution of pores by cycles (loops) of isothermal hysteresis r ≈ 8.5 nm. The volume of porosity of the sorbent when the capillaries were filled with water was determined as Vn= 0.135 cm3/g.

Bimodal behavior in fabric drying kinetics: An interpretation of modes

Thermo-physiological comfort is an essential property attributed to fabrics. Perceived comfort can be related to the delay in the user experiencing the ambient conditions and the manner in which the fabric manages liquid water. A multitude of material characteristics, ranging from the surface chemistry of the fibers, yarn packing and knit geometry, affect perceived comfort. Standard measures of thermal and evaporative resistance characterize the fabric response at steady state and do not provide insight into the thermal/vapor balance kinetics under dynamic conditions. While investigating an existing dynamic test, International Organization for Standardization 13029:2012, for relating fabric properties to comfort, we observed that the fabric drying kinetics exhibited bimodal behavior. Here, we describe the mechanism that leads to the observed bimodal drying kinetics. While the standard measures the time taken to reach steady state, we use the power profile of the modes to derive quantitative metrics to characterize fabric properties. The derived metrics are based on the observation that the heat of wetting is nearly a constant for a given relative humidity for a material, and that the heat of sorption per unit of absorbed water is identical for a wide range of fabrics. The derived metrics distinguish different fiber types and fabric geometries. The proposed metrics are easily calculated from experimental observations without requiring any modification to the standard test.

Modification of activated carbons for application in adsorption cooling systems

In this paper commercially available activated WD-extra carbon (Gryfskand) which is applied for water treatment was used. Activated carbon was modified by the following chemical agents: H2O2, HNO3 and HCl. Chemical modifications significantly affect the chemical, structural and surface properties of activated carbons. Hydrophobization with ethereal stearic acid was performed on the raw material and samples after chemical modification. Hydrophobic properties of the samples were specified. The relationship of the chemical modification agents with hydrophobization degree was indicated. The thermal effects of wetting by methanol was measured. The heat of wetting was calculated. The purpose of the work was to modify the WD carbon properties to obtain an adsorbent for cooling systems characterized by both good thermal capacity and moisture resistance. The modifying chemical substances applied accounted for an increase in the concentration of the acid functional groups. The hydrophobized and HCl-modified WD(HCl) carbon has the best hydrophobized properties. The results of studies describing such modifications allow to conclude that the use of hydrophobic materials may lead to the production of sorbents with new functions facilitating their storage and use.

Nanostructural Materials for Energy Storage Systems

The aim of this study was to assess of carbonaceous monoliths used for adsorption cooling systems. The carbonaceous monoliths prepared from coal precursors are obtained. The porous structure of monoliths was evaluated on the basis of nitrogen adsorption-desorption data. The investigated monoliths have significantly developed microporous structure. The large specific area of carbonaceous monoliths (about 2000 m2/g) and volume of micropores are observed. Methanol adsorption isotherms and heat of wetting using methanol was determined. Results show that monoliths materials are high adsorption capacity of methanol and heat of wetting, which can improve of heat exchange and efficiency in processes of refrigeration and air conditioning.