Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Polish Journal of Chemistry

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Separation of Organic Species from Wastewater Using a Polyol Supported Liquid Membrane

Ashraf W., Bukhari A.

Polish Journal of Chemistry

2007

Vol. 81, nr 9

1621-1628

This paper examines the application of supported liquid membrane for the removal of organic compounds in the aqueous waste effluents. Polypropylene glycol was employed as carrier mounted on PTFE supports. It has been demonstrated that polyols act as efficient carrier for selective removal of organic compounds having an acidic -OH group. Mass transfer coefficient in creased when the number of carbon atoms in creased from 4 to 6. A correlation between pKa, pH and flux of permeating species has been demonstrated. Aromatic compounds showed higher transportrates as compared to similar aliphatic compounds. Effect of temperature on the transportrates has been studied. It has been shown that a mock waste solution can be transported up to >90% under the conditions studied.

Studies on Transport of Pb(II) Ions Using Different Crown Ethers

Ashraf W., Fazal A.

Polish Journal of Chemistry

2006

Vol. 80, nr 6

881-887

Membrane based separation processes represent a sophisticated way to limit industrial wastes in the natural environment. Crown ethers have been recognized as very effective class of compounds to achieve selective separation of heavy metal ions from aqueous solutions. Lead (Pb) is a well known toxic metal and is heavily used in industry. Therefore, finding ways to selectively remove Pb(II) from aqueous solutions is important. In the present paper, different crown ethers of varying cavity size, subsituent groups, donor atoms, and ring number are compared for their ability to transport Pb2+ through a supported liquid membrane. All experiments were carried out in a laboratory scale membrane reactor with crown ether solution immobilized on a polypropylene porous sheet interposed between feed and strip solutions. It was observed that when O atoms of the same sized macrocycle are replaced with N or S atoms, percentage recovery of Pb(II) increases significantly. By substituting a benzene ring on the same sized macrocycle, the percentage of Pb(II) transport increased from 78 to 86%. The cavity size of the crown ether seems to affect the rate of transport. After different trials, it was found that transport is maximal where the ionic radius of Pb(II) matches maximum with the cavity diameter of the macrocycle. These interactions of crown ethers with Pb(II) are explained on the basis of metal-ligand coordination chemistry.