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الثلاثاء، 5 أغسطس، 2014

Novel Affinity Membranes for Wastewater Treatment

Author        : Hala El-Sayed Mohamed Abd El-Razek
Degree        : Ph.D. Chemical
Title: Novel Affinity Membranes for Wastewater Treatment

 Abstract
Affinity membranes have attracted the attention of membrane researchers especially in the field of wastewater treatment specifically in removing heavy metals by chelation from aqueous solutions. In the present work, several membranes made from either cellulose di-acetate (CA) or CA together with chitosan (CS) solutions, the CS prepared in our lab from shrimp shells or from readymade shrimp- or crab-shells. The variables investigated included mass ratio of CA to CS in the casting solution, initial concentration of Cu(II) ions, type of CS (shrimp- or crab-shells), type and ratio of solvents forming the casting solutions, type of stirring, stirring speed and membrane thickness. The membranes were fabricated by casting on a glass plate of a casting assembly using a doctor’s blade by the phase inversion technique. The permeation and adsorption capacity of each membrane were examined in a plexi-glass two compartment diffusion cell in which the membrane was placed between the two compartments to separate the copper ion solution from an equal volume of distilled water in the other compartment. The two compartments were each stirred either magnetically or mechanically. The results were presented as concentration-time curves and In (Col Ct) vs. time from which the overall mass transfer coefficient was computed in each case. It was found that the presence of CS obtained from shrimps acted as a better affinity membrane in high CA to CS ratios as well as high concentration of Cu(II) ions, and that crab CS has a poorer affinity to Cu(II) ions compared to that obtained from shrimps. It was also realized that the composition of the casting solution markedly affected the properties of the fabricated affinity membrane. In addition, scanning electron microscopic examination revealed the morphology of the membrane surfaces (upper, lower and cross section). It is worth mentioning that membrane thickness has a profound effect on both permeability and extent of chelation of the heavy metal examined. Later, batch experiments were conducted to study the kinetics of the adsorption.

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