Nicotinic Acid Molecularly Imprinted Composite Membrane And Its Properties,

Molecularly imprinted membranes (MIMs) provide a feasible and effective approach of specific target molecule separating from mixed solution with a similar structure substance which possessed of advantage of MIT and membrane separation. Compared with ordinary separation membrane, MIMs have high selectivity for specifical substance. Compared with traditional molecular imprinted polymer, MIMs' preparing process doesn't need smash and have high imprint bind cavity hold rate. The research of MIMs favored the development of ordinary membrane separation technology.In this study nicotinic acid molecularly imprinted composite membranes were developed using surface modified polymerization by UV irradiation in the presence of nicotinic acid as template, followed by a deposition of molecularly imprinted polymer layer on the surface of polyvinylidene fluoride microfiltration membranes.The main component of the experimental study:1.During the preparation press of nicotinic acid molecularly imprinted composite membranes, the proportioning of molecular template and functional monomer Acrylamide was 1:4, N,N'-Methylenebisacrylamide was cross linker, the polymerization reaction was initiated by UV irradiation for 12h, the molecular template in the polymer and unreacted functional monomer and cross linker were eluted by methanol and acetic acid (V:V=9:1).2.The presence of hydrogen bond between template and monomer was proved by ultra violet spectrophotometry, the surface morphology were analyzed by means of scanning electron microscope. Scanned picture indicated, the experiments covered successfully a deposition of molecularly imprinted polymer layer on the surface of polyvinylidene fluoride microfiltration membranes, the shape of cavity in membranes was regulated, and the distribution was uniform.3.The investigation of the membranes'thermal arrest and chemically stable function showed, the interception ratio of nicotinic acid molecularly imprinted composite membranes was influenced less when heat treatment was lower than 60℃. The pattern of membranes were remain unchangeable primarily after treating by means of acetous and alkaline solution, the water flux and interception ratio were decreased slightly.4.The Scatchard of balanced combination experiment of molecularly imprinted composite membranes revealed, there were equivalent binding sites in the imprinted composite membranes. The dissociation constant Kd=5.55×10-2 mmol·L-1, and the maximal apparent bonding constant Qmax=6.10μmol·g-1. And the combining quantity of nicotinic acid is 24.20μmol·g-1, it was 2.05 time of nicotinamide, then their partition ratio were similar in non-imprinted composite membranes. The experiment indicated, imprinted composite membranes revealed preferable bindir ability for nicotinic acid.5.The transit dose and speed which molecularly imprinted composite membranes for nicotinic acid were greater far and away than non-imprinted composite membranes. The permeation experiment proceeded for 7h, the permeation quantity of nicotinic acid was 0.465μmol·cm-2 which was 3.63 time of non-imprinted composite membranes.6.Nicotinic acid molecularly imprinted composite membranes were used to separate and concentrate Nicotinic acid of vitamin troche, the result displayed, the molecularly imprinted composite membranes exhibited better binding performances for nicotinic acid. Because the arrange of functional groups in cavity was disorganized, the combining capacity of non-imprinted composite membranes for nicotinic acid was lower than molecularly imprinted composite membranes.The selectivity and permeation which molecularly imprinted composite membranes to the mixed solution were investigated, with nicotinamide as a similar structure to nicotinic acid, the result showed, molecular template was transferred constantly from side to reverse side, then they were better condensed at the membranes's back. However, nicotinamide was worse concentrated, so it in favor of separation between nicotinic acid and nicotinamide, the permeation mechanism conformed to "Piletsky" model.