3.4 Effect of initial concentration of citric acid in feed phase
The effect of initial citric acid concentration range between 0 and 0,025M in feed phase on the transport flux is presented in Fig. 4. % transport increases with increasing citric acid concentrations from 0 to 0,01M and tends to stabilize for higher concentrations of citric acid 0.015 M and after 4 days of transport time, the occurrence of a milky layer was observed on the membrane surface. This observation was likely one of the reasons of the flux limit. However, other reasons could be related to the kinetics of the citric acid uptake, which could have reached its maximum value, or to a complex of different stoichiometries formed at a highest citric acid concentration less soluble…show more content… 5. Effect of carrier contents on the transport of citric acid.
Transport conditions: Feed phase: citric acid 10-2 M, pH 2. Stripping phase: deionized water, pH=6.8. Membrane: 12.60 cm2 of surface area, Calixresorcinarene (0- 0.25 g/g mixture of polymers), 1.5 2-NPOE/g mixture of polymer. Values obtained after 5 days of experimentation.
3.6 Effect of plasticizer content
Plasticizer plays a vital role in the transport of target as well as for membrane softness and flexibility in the PIMs. The influence of the plasticizer 2-NPOE content in the PIM on the removal of citric acid was investigated by preparing PIMs at fixed quantity of calixresorcinarene RC8 (0.15 g/g mixture of polymers ) and plasticizer in varying amounts (0 to 2.5g/g mixture of polymers). PIM generated with the different amount of plasticizer were transparent with uniform thickness. More-over, PIM with the carrier RC8 but without plasticizer resulting a basal transport of citric acid, further variation in the amount of NPOE gives higher transport efficiency up to 1,5 g of NPOE which might be due to the favorable plasticizer plasticization effect, beyond which a decrease in transport was been which was attributed to intermolecular interaction between target and plasticizer molecule resulting in lower mass