The effect of HCl treatment on water vapor adsorption characteristics of clinoptilolite rich natural zeolite

In this study, water vapor adsorption properties of the clinoptilolite rich zeolite tuff, from Bigadic (Turkey), and its modified forms were examined. The modified forms were obtained by treating the tuff with HCl solutions (0.032, 0.16, 0.32, 1.6 or 5 M) at 25,40,75 and 100°C for 3 h. Infrared spectroscppy and water vapor adsorption were used for the characterization of the zeolites. Langmuir, BET and Dubinin-Raduschevich methods were applied in the analysis of water vapor adsorption data. Applications of Dubinin Raduschevich equation to the water adsorption data displayed that the super-micropore volume was not very sensitive to acid treatment. It was found out that the Langmuir surface area and ultra-micropore volume depend on the degree of the removal of aluminum from the structure

Cr(VI) sorption by using clinoptilolite and bacteria loaded clinoptilolite rich mineral

Batch sorption experiments were performed in order to understand the potential value of local clinoptilolite rich mineral and its bacteria loaded form in Cr(VI) sorption. The results indicated that Cr(VI) sorption capacities of the sorbents were increased after bacteria loading and the clinoptilolite rich mineral is a promising material in Cr(VI) sorption. Zeta potential and Fourier Transform IR (FTIR) analysis were performed to explain the possible mechanism involved in the Cr(VI) sorption. The results revealed that non-electrostatic forces played a significant role rather than the electrostatic forces. The existence of non-electrostatic forces was confirmed by the FTIR results. © 2011 Elsevier Inc. All rights reserved.Turkish Republic Prime Ministry State Planning Organization (DPT-1998 K122130

A review on adsorption heat pump: Problems and solutions

Adsorption heat pumps have considerably sparked attentions in recent years. The present paper covers the working principle of adsorption heat pumps, recent studies on advanced cycles, developments in adsorbent-adsorbate pairs and design of adsorbent beds. The adsorbent-adsorbate pair features for in order to be employed in the adsorption heat pumps are described. The adsorption heat pumps are compared with the vapor compression and absorption heat pumps. The problems and troubles of adsorption heat pumps are classified and researches to overcome the difficulties are discussed

Dynamic heat of adsorption of water vapour on zeolitic tuff and zeolite 4A by flow microcalorimetry

In this study a practical method for measurement of heat of adsorption of water vapour on adsorbents was developed to evaluate the feasibility of substitution of a zeolitic tuff with zeolite 4A in air drying and heat pumps. The change of heat of adsorption with inlet humidity of the air passing through the calorimeter was investigated. Samples were characterised by X-ray diffraction and thermal gravimetric analysis techniques. Specific heats of the zeolitic tuff and zeolite 4A were measured as 1.01 and 1.42 J/g K, respectively. Adsorption isotherms fitted to the Langmuir model with regression coefficient 0.93 and 0.94 with monolayer capacities, Xm 9.68% and 26.35% H 2O for the zeolitic tuff and zeolite 4A, respectively. The energy storage intensity was measured in the range 48-97 J/g and 464-201 J/g for the tuff and zeolite 4A, respectively. Heat of adsorption of zeolite decreased with surface coverage and it was in the range 1750-2835 and 1104-2640 J/g H 2O for the zeolitic tuff and zeolite 4A, respectively

Synthesis of zinc borate by inverse emulsion technique for lubrication

Lubricating oil additives based on boron compounds are promising materials for lubrication due to their tribological advantages such as antiwear efficiency, good film strength, and high temperature resistance. This article deals with the preparation of zinc borate particles that are well dispersed and colloidally stabilized in mineral oil. This method starts with preparing two inverse emulsions (water-in-oil) with sorbitan monostearate (Span 60) as a surfactant, light neutral oil as a continuous phase, and the aqueous solutions of borax decahydrate (Na2B4O7·10H 2O) and zinc nitrate (Zn(NO3)2·6H 2O) as the dispersed phases. The produced particles were zinc borate crystals having both rod-like and spherical morphologies, and the diameters of spherical particles were changing between 20 and 30 nm. FTIR spectra of the obtained particles showed the characteristic peaks of trihedral borate (B(3)-O) and tetrahedral borate (B(4)-O) groups as well as the specific peaks of the sorbitan monostearate. TG showed 30.42% and 22.08% mass loss at 600 °C for the samples prepared by inverse emulsion and precipitation techniques, respectively. The endothermic peak at 50 °C is observed due to the melting of sorbitan monostearate and the heat of melting is evaluated as -3.50 J/g. Tribological studies revealed that sorbitan monostearate not only outperformed as a dispersing agent of inorganic particles, but also it proved to be an anti-wear agent. Zinc borate produced by precipitation decreased the wear scar diameter from 1.402 to 0.639 mm and the friction coefficient from 0.099 to 0.064. The inverse emulsion was effective in decreasing wear scar diameter and the friction coefficient by lowering them to 0.596 and 0.089 mm, respectively.Scientific and Technical Research Council of Turkey (105M358

Effect of regeneration temperature on adsorption equilibria and mass diffusivity of zeolite 13x-water pair

The adsorption equilibrium and mass diffusivity of zeolite 13X-water pair for different adsorption and regeneration temperatures were determined by a homemade volumetric system. The isotherms of the zeolite 13X-water pair were obtained by collecting pressure versus time data and applying ideal gas law. The effective diffusivity of the pair was calculated by using long term analytical solution of mass diffusivity based on Fick's law. The experimental study showed that the adsorption capacity of zeolite 13X-water pair was 23% (kg/kg), 21% (kg/kg) and 19% (kg/kg) when the adsorption temperature was 35, 45 and 60 °C respectively for the desorption temperature of 90 °C. Furthermore, the adsorption capacity increased from 22% (kg/kg) to 24% (kg/kg) when the desorption temperature was increased from 90 °C to 150 °C. It was observed that the present adsorption equilibrium results were compatible with the reported results in the literature. The mass diffusivity of the pair was found in the range of 4 × 10-9-6 × 10-8 m2/s for the long time period when the initial adsorptive pressure was 2000 Pa. The effective mass diffusivity depends on concentration and it was decreased with increasing adsorbate concentration.Izmir Institute of Technology Scientific Research Projects Committee (2012-IYTE-13

Effect of temperature and time on zinc borate species formed from zinc oxide and boric acid in aqueous medium

The effect of temperature and time of heating of zinc oxide and boric acid in aqueous medium on product type, dehydration behavior, crystal morphology, and structure was investigated for the production of flame retardant and smoke suppressant zinc borate. Two different products dehydrated at 140 and 350°C were obtained and characterized by thermal gravimetric analysis, X-ray diffraction, energy dispersive spectroscopy, and Fourier transform infrared spectroscopy

A study of chemical and physical changes during biaxially oriented polypropylene film production

Polypropylene films obtained during the biaxial orientation process were characterized by energy dispersive X-ray analysis (EDX), scanning electron microscopy. X-ray diffraction, differential scanning calorimetry, infrared spectroscopy. Inorganic particles with Al, Si, Na, Mg, Ti, K,O elements were present in biaxially oriented films. Polypropylene had molecules with both isotactic configuration and it was crystallized only in isotactic α phase. The films drawn in one and two directions had unit cells with b axis parallel to surface of the films. The antioxidants present in the films were consumed during processing, preventing polypropylene oxidation in air at high processing temperatures. One surface of the films contained less polypropylene and had functional groups rich in oxygen such as C=O and COO

Antioxidative and antimicrobial screening of 19 commercial essential oils in Turkey

1st International Medicinal and Aromatic Plants Conference on Culinary Herbs, Antalya, Turkey, 30 April 2009Plant oils have been used for wide variety purposes for many years in Turkey. These essential oils have usage in many areas such as perfumery, cosmetic, food flavoring and folkloric medicine. In the study, 19 commercial essential oils were studied by means of antibacterial and antioxidant capacity. Antibacterial test was performed against S. aureus, S. epidermidis, K. pneumoniae and E. coli using standard disc diffusion method. Penicillin, gentamicin and vancomycin discs were also included. Inhibition zones (mm) were recorded to indicate antibacterial property. Penicillin (44 mm) and vancomycin (14 mm) could inhibit only S. aureus. Except essential oils of Juniperus nana (Ardiç), Ocimum basilicum (Feslegen), Urtica dioica (Isirgan), Foeniculum vulgare (Rezene) ressential oils indicated antimicrobial activity against some of the test microorganims. The most active essential oil was found as Thymus serpyllum (Kekik). It indicated highest inhibition zones for other microorganisms among others. Antioxidant capacities were measured using photochemiluminescence (PCL) method. The highest antioxidant activity was measured for Dianthus caryophyllus (Karanfil) as 547.781 103 ug trolox/mL of oil. It was followed by Thymus serpyllum (Kekik), Lilium candidum (Zambak) and Matricaria chamomilla (Papatya). Especially, Thymus serpyllum and Dianthus caryophyllus have significant antimicrobial and antioxidant capacity therefore it could be suggested for further investigations and applications