Invention And Application Of Adsorbent Materials Made From Corcobs

As a kind of high-yield productions on drylands, corncobs account for a large proportion of the food crops. With the development of interplanting technology and expanding of its application scope, corncobs output increased year by year.Nowadays, some of the corncobs are used for producting xylose, thereby producing furfural, xylitol and other substances. While, most of the corncobs are not fully utilized, it not only caused a waste of resources, but also puolluted the environment to some extent. Many irregular holes are distributed on inner and outer surfaces of corncobs densely, the chemical structure of corncobs contains carboxyl groups, amino groups, benzene rings and some other reactive chemical groups, so heavy metals, nitrite can be adsorbed effectively. In addition, through chemical modification can the adsorption ability be improved. Therefore, it has great theoretical and practical significance to invent and apply modified corncob adsorbent material.Most international experts have studied only a certain kind of modification methods for corncobs, various methods beening studied simultaneously is poor. In this research subject, we established a new modified method based on acidification and ammoniation, and invented a kind of efficient adsorbent materials made from corncobs, the adsorbent materials were applied in water and food. The following research results were obtained.1. In the comparative experiment of different adsorbent materials, the adsorption rate of corncobs, corn stalks, twigs, bagasses, peanut shells, silica gels, molecular sieves, ammonia stones, coconut shell activated carbons for nitrite in water are 52.00%, 35.50%, 19.00%, 34.00%, 28.50%, 28.50%, 14.50%, 20.50%, 3.50%, 6.50% respectively. The results show that corncobs have the best adsorption capacity, the adsorption rate of corncobs for nitrite is 71.41% after modified by 1.0mol / L phosphoric acid solution, 10.01% better than unmodified ones; modified twigs 33.72%, 14.91% better than unmodified ones; modified peanut shells 45.35%, 14.91% better than unmodified ones;modified bagasses 35.20%, 11.20% better than unmodified ones.2. In the experiment of innovative modified methods for corncobs, the adsorption rate of corncobs modified by phosphoric acid, nitric acid, citric acid are 88.1%, 42.8%, 41.7% respectively, phosphoric acid has the best modifying effect; Besides, ammoniation was applied in modification process for the first time, this is the optimal conditions for modification: Corncobs were soaked with 0.02mol/L aqueous solution of ammonia for 3 hours, then rinsed, and soaked with 0.60mol/L phosphoric acid solution for 3 hours.3. In the adsorption experiment of modified corncobs, the optimal adsorption experiment conditions is this: Temperature is 40℃, dosage of modified corncobs is 6.0g, the initial concentration of nitrite solution is 2.0ug / m L, p H is 6-7; Adsorption properties of modified corncobs were not influenced too much by interfering ions such as Al3+ and Cu2+. Results of FTIR spectroscopy and SEM showed that active groups such as-OH,-NH2 were introduced in corncobs through modification. Also the surface of corncobs became rough, loose and porous after modification, which were more conducive to the adsorption of nitrite.4. In the application experiment of modified corncobs, modified corncobs of 3.0-5.0mm were most suitable for the production of modified corncob filters. The optimal internal structure of modified corncob filter is 7-layer clapboard-like structure; The maximum water purification quantity of modified corncob filter is 34344 L, life cycle is 140 days. The removal rates of modified corncob filter for nitrite and Cr(VI) were 95.58% and 98.57% respectively through regeneration, 17.23% and 15.40% better than not being regenerated. In addition, modified corncobs were applied in the cleaning device to adsorb nitrite in food, it showed that the adsorption rate of corncobs for nitrite in pickles, overnight vegetables, long time cold food were 60.02%, 57.58%, 65.73% respectively.To sum up, the modified corncob filter have advantages of high water purification quantity, long life cycle, renewable, low production costs, etc. Also, modified corncobs have significant purifying effect for nitrite in food.