varieties of st. john’s wort (hypericum perforatum l.) native to iran possess the largest percentage of hypercin in their leaves and flowers. isotherm curves show the relationship between the relative humidity and moisture content of the plant at a constant temperature. it is essential to understand the isotherms curves for successful storage and drying of the plant. this study used adsorption ...

Water extractable arabinoxylan (WEAX) aerogels were prepared by extracting the solvent from the alcogels (WEAX hydrogels with an alcohol as the solvent) with carbon dioxide under supercritical conditions. WEAX aerogels were characterized using scanning electron microscopy and adsorption and desorption nitrogen isotherms. The micrographs indicate a heterogeneous porous network structure in WEAX ...

gaz-angubin is a sweet exudate naturally produced by an insect from the gavan-e-gaz-angubin plant. adsorption and desorption isotherms for a gaz-angubin sample were determined at 15° and 25°c over a range of relative humidity from 0 to 90% using a dynamic vapor sorption system. at different levels of relative humidity, changes in sample mass were continuously measured versus time and described ...

The sorption hysteresis effect, i.e. different wood equilibrium moisture contents (EMCs) in desorption and adsorption for the same relative humidity, is well known. However, quantitative sorption isotherms, in the form of tables or analytical correlations, are almost always given as the average of the desorption and adsorption curves. Consequently most drying simulation models use these average...

this study was carried out to obtain quantitative relationships between zn in equilibrium solution and that retained by 20 calcareous soils. soils were brought into equilibrium with varying solution concentrations of zn, and the amounts removed from solution were used to check the fit to six adsorption isotherms, namely, freundlich, langmuir, temkin, gunary, two surface langmuir and adjusted fr...

Two SiO2 and three Al2O3 adsorbents with varying degrees of mesoporosity (pore diameter 2-50 nm) were reacted with 2,4-dichlorophenoxyacetic acid (2,4-D) at pH 6 to investigate the effects of intraparticle mesopores on adsorption/desorption. Anionic 2,4-D did not adsorb onto either SiO2 solid, presumably because of electrostatic repulsion, but it did adsorb onto positively charged Al2O3 adsorbe...

The aim of this work is to evaluate the adsorption performances of activated carbon derived from sewage sludge (ACSS) for gaseous formaldehyde removal compared with three commercial activated carbons (CACs) using self-designing adsorption and distillation system. Formaldehyde desorption of the activated carbons for regeneration was also studied using thermogravimetric (TG) analysis. The porous ...

1 CHILEAN JOURNAL OF AGRICULTURAL RESEARCH 76(1) JANUARY-MARCH 2016 3 ULY-SEPTEMBER The present study was conducted in order to investigate the adsorption and desorption behavior of tetramethylthiuram disulfide (thiram) using the batch equilibration technique in two soil namely: Ultisols and Inceptisols. The adsorptiondesorption isotherms were expressed by the Freundlich equation. The adsorptio...

sampling and desorption testing of fresh coal samples obtained from companies conducting exploration throughout the province. In addition methane adsorption isotherm tests arc: performed on some samples. During the summer of 1992 a project was undertaken to test coal seams intersected in the ongoing Manalta Coal Limited drilling program in the Telkwa coalfield. On-sitc activities consisted of t...

This paper presents a modular approach to motion control using a microconlroller-based stepper motor driver. As an application of the driver, an inexpensive and portable one-dimensional robot was built to automate an existing experimental setup for measurement of adsorption isotherms using the McBain-Bakr technique. Automatic recording of position versus time yields data for the sludy of adsorp...