물/초산 혼합물 분리를 위한 PVA/TA 분리막의 투과 증발 특성 연구

Abstract

Acetic acid is a one of the significant chemical reagent due to there diverse use in industiral area. It is manly used as the production of various synthetic fibers and other polymer materials, e.g., poly (ethylene terephthalate), cellulose acetate, and poly (vinyl acetate) and a solvent as a protic solvent, recrystallization of pruify oraganic compounds, and production of terephthalic acid (TPA), etc. The global demand for acetic acid has been estimated at around 6.5 million metric tons per year; of that amount, approximately 1.5 million tons per year is produced by recycling. Acetic acid is produced by both natural and synthetic method, such as bacterial fermentation and carbonylation of methanol, respectively. However, concentrations of acetic acid obtained from fermentation of biomass, forestry residue, and other by-products are very low, so approximately 75% of acetic acid production is dependent on synthetic manner. In the above processes, the concentration of obtained acetic acid is less than 5%. As per the water/acetic acid vapor-liquid equilibrium graph, at higher water concentrations, separating water and acetic acid becomes more difficult. Therefore, azeotropic distillation and extractive distillation processes are required to obtain acetic acid of a higher concentration and purity, owing to the comparable volatilities of water and acetic acid. However, these are energy-consuming and expensive processes. In order to increase the energy efficiency of separation processes, alternative methods, such as pervaporation, can be used for the separation of acetic acid from an aqueous mixture. Pervaporation has several advantages over the conventional distillation method, such as reduced energy demand and eco-friendliness. Pervaporation separation has been widely used in the dehydration of recovered solvents and separation of organic-organic mixtures. In this paper, the preparation of membrane by poly (vinyl alcohol) modified with a dicarboxylic acid (Tartaric acid) is reported. The resulting membrane was characterized by IR spectroscopy, swelling studies, differential scanning calorimetry (DSC), and contact angle testing, and was finally applied in the pervaporation. From the IR spectra of membranes it was observed that the crosslinking reaction became more intense with increase in tartaric acid concentration nevertheless there were no significant impact on the reduction hydroxyl groups due to reinforcement of hydroxyl group from the tartaric acid. And the results of both DSC and contact angle also supported this explanation. The membrane were applied for the pervaporation separation of water acetic mixture, it was observed that, the membrane give higher flux and lower separation factor with increase in water content in feed concentration. From pervaporation data it could concluded that membrane has a higher permeation rate and comparatively good selectivity.