abstract herbicides are the main sources of soil and water pollution in paddy fields. herbicides mobility to the surface and ground water is a major concern for human health and the environment. it is, therefore, necessary to investigate their fate and their interactions in natural ecosystems. to meet this purpose, field experiments were conducted to measure kinetic of thiobencarb dissipation i...

organic acids exuded by plant roots increase solubility of soil micronutrient complexes. this study was carried out to evaluate adsorption isotherms of 4 acidic and 4 calcareous soils at presence of organic acids (citric, malic and oxalic acids). iron sorption and desorption isotherms are defined in to two systems including; system 1; soil-water-metal, system 2; soil-water-organic acid-metal). ...

The contribution of variable grain sizes to uranium adsorption/desorption was studied using a sediment from the US DOE Hanford site. The sediment was wet sieved into four size fractions: coarse sand (1-2 mm), medium sand (0.2-1 mm), fine sand (0.053-0.2 mm), and clay/silt fraction (<0.053 mm). For each size fraction and their composite (sediment), batch and flow-cell experiments were performed ...

Silica aerogels are frequently employed as solid desiccants in enthalpy wheels for dehumidifying the supply stream in air-conditioning systems. These desiccant materials possess good moisture adsorption and desorption characteristics due to their porous structure. Analysis of adsorption and desorption isotherms is critical for performance characterization and is often performed to evaluate the ...

moisture sorption isotherms for pistachio powder were determined by gravimetric method according to cost 90 project at temperatures of 15, 25, 35, and 40oc . maximum hysteresis level in sorption isotherms curve was observed at the range of water activity 0.2-0.7 . on the other hand hysteresis was diminished between adsorption-desorption isotherm curves when temperature reached 40oc. some mathem...

Water adsorption isotherms are calculated by grand canonical Monte Carlo simulations for the SPC/E water model in carbon nanopores at 298K. The pores are of slit or cylindrical morphology. Carbon-slit pores are of widths 0.8, 1.0 and 1.6 nm. The simulated single-walled carbon nanotubes are of 1.4 and 2.7 nm diameter ((10:10) and (20:20) respectively). In all cases considered, the adsorption iso...

We have studied adsorption in regular, self-ordered alumina pores open at both ends or only at one end. The straight, non-connected pores have diameters ranging from 22 to 83 nm, with a relative dispersion below 1% in the pore size. Adsorption isotherms measured in open pores with a torsional microbalance show pronounced hysteresis loops characterized by nearly vertical and parallel adsorption ...

This investigation was undertaken to determine whether desorption hysteresis effects were dependent upon methods used in obtaining desorption data. Adsorption-desorption isotherms were obtained for two organophosphorus insecticides in aqueous suspensions of a clay, a sandy loam, and an organic soil. Desorption isotherms were obtained using both the consecutive desorption method and the dilution...

An understanding of sorptive processes is key to describing the fate of chlorpyrifos [O,O-diethyl-O-(3, 5, 6-trichloro-2-pyridyl) phosphorothioate] in aquatic environments. The objectives of this study were to evaluate isotherms for adsorption and desorption of chlorpyrifos on colloidal materials and to advance understanding of interaction mechanisms between chlorpyrifos and colloidal materials...