The equilibrium moisture content is an important parameter for several post harvesting operations for pistachio nuts, such as drying processes and storage. In this research the adsorption and DESORPTION equilibrium moisture content were determined for two major varieties of Iranian pistachios at 11 to 85 percent relative humidities and a constant temperature of 50°C. A significant hysteresis effect between the adsorption and DESORPTION processes was observed statistically. For predicting the adsorption and DESORPTION EMC, the Halsey model was found the most proper equation for adsorption processes for two varieties (Ohadi and Kalehghochi), whereas the Oswin and Smith models were most appropriate for Ohadi and Kalehghochi for DESORPTION processes, respectively, at constant a temperature of 50°C.

Physical adsorption is one of the powerful methods to analyze structure of porous materials especially for catalytic precursors. With emerging of physical adsorption devices, adsorbed gas amounts versus varied relative pressures data lead to obtain beneficial results like surface area, pore volume and pore size distribution based on various theories. Additionally by consideration of adsorption-DESORPTION isothermal curve, we can estimate shape of the porous. In this work, it has been tried to present briefly adsorption physical concepts, conventional methods of surface area measurement, pore volume and pore size distribution.

In this study, a nano-layer polydopamine (PDA) coated superparamagnetic maghemite nanoparticles (MNPs) was applied to investigate the asphaltene adsorption-DESORPTION behavior using a model solution. In this process, Fourier-transform infrared spectrum (FT-IR) spectroscopy of the polydopamine/MNP core/shell (MNP@PDA) before and after asphaltene adsorption was indicated the attachment of asphaltene molecules on the polymeric nano-adsorbent surface. The isotherms and kinetics of the asphaltene adsorption process on the MNP@PDA were studied. The good prediction of asphaltene adsorption by the modified Langmuir model indicated that adsorption occurs on an MNP@PDA surface by multilayer adsorption. Also, within the kinetic models, the double-exponential model can fit the experimental data well. The obtained results revealed that about 90% removal for asphaltene happened within 30 min which can be acceptable. The results of this study showed that natural polymers can be used for surface modification of nanoparticles and use it successfully for asphaltene adsorption from prepared asphaltene-toluene solution.

Studies have shown that magnesium-based compounds can be used as solid state hydrogen storage materials. In this investigation, the Al3Mg2 intermetallic compound was prepared by casting method. Then, produced powders of this compound were ball milled under hydrogen atmosphere at different times. Results of thermo-gravimetry and X-ray diffraction analyses showed that the highest amount of hydrogen storage was achieved after 2 h of ball milling under hydrogen atmosphere. The highest weight loss of about 2. 4% was achieved from mentioned sample. This weight loss occurred during three steps at temperatures of 150, 220 and 360 ° C. In the next step, Al3Mg2 powders were ball milled at different times under hydrogen atmosphere along with TiO2 (as catalyst). The results of thermo-gravimetry and X-ray diffraction tests showed that the highest amount of hydrogen storage in these sample was achieved after 2 hydrogenation and a weight loss of about 2. 6% by weight was obtained due to hydrogen DESORPTION, which is close to the theoretical value.

Humic substances are the most important organic fractions in soils and have affinity towards trace metals. In order to evaluate the effect of humic acid on zinc (Zn) sorption and DESORPTION by soil, a batch experiment was conducted with two soil samples which were different in clay and calcium carbonate contents. Three levels of humic acid (0, 200, 500 mg/L) and various Zn concentrations (0 to 450 mg/L) were applied at constant ionic strength (0.05 M NaCl). Adsorption data were fitted to Langmuir, Freundlich and Temkin equations. Freundlich equation fitted relatively better (R2= 0.86-0.98). Results showed that the application of humic acid increased both sorption and DESORPTION of Zn in the two sample soils. Increasing of humic acid concentration increased maximum adsorption of Langmuir (qmax) up to 8-21% and Freundlich sorption capacity (Kf) up to 73-95%. All sorption parameters including Langmuir binding energy (KL), Freundlich intensity factor (n) and coefficients of Temkin equation (A, KT) were increased by adding humic acid, so that the above mentioned sorption parameters of S1 (with low clay and calcium carbonate) were lower than those of S2 (with high clay and calcium carbonate). Application of humic acid (500 mg/L) increased DESORPTION of Zn (DTPA-Zn) from 511 to 711 mg/kg for S1 and 499 to 609 for S2.

Adsorption DESORPTION behaviors of widely applied atrazine soil were studied, employing a batch technique as a case study in Darehasaluie Kavar corn field in Fars Province in 2005. Samples were collected into 0 to 20 cm soil depth, where was cultivated under a crop rotation (corn-wheat) during the past 10 years. Sorption kinetics exhibited two phenomena: an immediate rapid sorption (1.31 µg/g soil after 12 hours) followed by a slow sorption process (1.37 µg/g soil after 24 hours). DESORPTION behavior of atrazine was similar to its adsorption, but at a very slower rate. Atrazine DESORPTION efficiencies were much less effective and incomplete even after a long equilibration time (only 9.16% after 96 hours). The adsorption-DESORPTION rate for most of the time was positively related to the amount of applied atrazine and the time required for equilibration (P<0.01). DESORPTION data exhibited hysteresis phenomena. Atrazine adsorption data described well according to Freundlich (r2=0.95), Langmuir (r2=0.82) and Temkin (r2=0.84) isotherms. However, the fit to Freundlich adsorption model in a non linear form (1/n <1) was closer than the others. DESORPTION isotherm could be well described by the Temkin (r2=0.96) and Freundlich (r2=0.92) isotherms, but the fit to Temkin model was closer than that of Freundlich.    

Birnessite is one of the most common manganese oxides in the clay-sized fraction (<2 mm) of soils and has high cation exchange capacity and larger surface area. Birnessite was previously studied for decomposition of selected antibiotics from water. In this study, the removal of tetracycline (TC) by birnessite from aqueous solution was investigated as a function of initial tetracycline concentration, solution pH, temperature, and equilibrium time. Changes in solid phase after TC adsorption and DESORPTION were characterized by X-ray photoelectron spectroscopy, X-ray diffraction (XRD), and Fourier transform infrared analyses. DESORPTION of exchangeable cations accompanying TC removal and partial DESORPTION of TC from birnessite by AlCl3 confirmed that cation exchange was responsible for TC removal at low initial concentrations. Both the external and internal surface areas were readily available for TC uptake by birnessite. The intercalated TC formed a horizontal monolayer configuration in the interlayer of birnessite as deduced from XRD analyses.

The sorption of metallic zinc from the pH-adjusted aqueous solution at varying initial concentrations onto a clay soil through batch equilibrium experiments has been studied. The pH of the initial concentrations ranging between 50 mg/L to 250 mg/L has been varied from 3 to 7. The sorption data fitted very well with both Langmuir and Freundlich isotherm models and Freundlich model gave higher correlation coefficients. The maximum sorption of metallic zinc occurred at pH=6. The pseudo-second order kinetics model was most agreeable with the experimental sorption data, whereas the pseudo-first order model was found to be insufficient. A nonionic surfactant was tested for its DESORPTION potential and was found to be fairly effective at 2% concentration with removal of more than 60% sorbed Zinc.