Modelling the dependence of the internal diffusion coefficient and hydrodynamic resistance on the structures and shapes of polymer membrane pores

Swimming pool water was treated using an ultrafiltration process using ceramic and polymer membranes for comparison. It was determined that the efficiency of the process depended on the type of membrane used. The polymer membrane decreased the absorbance and concentration of combined chlorine in the pool water to a greater extent than the ceramic membrane. In the case of a ceramic membrane, the concentration of combined chlorine in the permeate exceeded the limit values. During the ultrafiltration process, the permeate flux decreased, causing the blockage of membrane pores. The extent of this phenomenon was similar for both tested membranes. In the case of the ceramic membrane, flushing it with water could significantly restore its initial performance. For both tested membranes, a high regeneration efficiency was observed during chemical treatment with an alkaline solution. SEM photos of the polymer membrane showed low resistance of this polymer to the chlorine present in the swimming pool water.

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Mass transfer coefficient and effective internal diffusion coefficient for coke solution loss reaction with non-equimolar diffusion

Fuel ◽

10.1016/j.fuel.2020.118225 ◽

2020 ◽

Vol 278 ◽

pp. 118225

Author(s):

Junchen Huang ◽

Rui Guo ◽

Lin Tao ◽

Qi Wang ◽

Zhongsuo Liu ◽

...

Keyword(s):

Mass Transfer ◽

Diffusion Coefficient ◽

Transfer Coefficient ◽

Mass Transfer Coefficient ◽

Internal Diffusion ◽

Solution Loss Reaction

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Permeability of P and K-nutrient through polystyrene membrane from aqueous solutions of urea + KH2PO4

Polish Journal of Chemical Technology ◽

10.2478/pjct-2018-0063 ◽

2018 ◽

Vol 20 (4) ◽

pp. 113-122

Author(s):

Xiaonan Deng ◽

Kun Liu ◽

Xiaozhao Han ◽

Xianguo Hu ◽

Shufeng Zheng

Keyword(s):

Diffusion Coefficient ◽

Release Kinetics ◽

Ussing Chamber ◽

Solute Concentration ◽

Polymer Membrane ◽

Compound Fertilizer ◽

Low Concentrations ◽

Coated Urea ◽

High Concentrations ◽

Kinetics Of

Abstract With the polymer-coated fertilizer as background, the permeability of P- and K-nutrient through a representative polymer membrane-polystyrene membrane were investigated by measuring their permeability in the solutions of KH2PO4-water and urea-KH2PO4-water at nominal temperature of 298 K using the Ussing chamber method. To analyze and interpret the variation of permeability with solute concentration, the solubility of permeate in polymer membrane were determined experimentally and the permeate diffusion coefficient were assessed by the measurements of density and apparent molar volume of the aqueous fertilizer solutions. An interesting “increase-decrease” trend for the permeability of both phosphorous (P)-nutrient, and potassium (K)-nutrient fertilizer with permeate concentration was observed, in which the increases in permeability at low concentrations of permeate could be attributed to the increase in solubility of KH2PO4 in polymer while the decreases in permeability at high concentrations was due to the decrease in diffusion coefficient of permeate in polymer membrane. Finally, the release kinetics of these nutrients from a PS-coated urea-KH2PO4 compound fertilizer granule was predicted using the Shaviv’s model along with the permeability data of P- and K-nutrient generated.

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