Study On Oxidation Of Enzymatic Hydrolysis Residues Of Corn Stalk And Preparation Of Chelated Micro-fertilizers From The Oxidation Product

With the rapid development of economic globalization, the contradiction of the demand forenergy and the growing contradictions about the conventional energy supply become moreserious. So, more and more countries in the world concern about the clean, environmentalfriendly and renewable characteristics of the cellulosic bio-ethanol. However, the remainingproduct after its production has not been a good application and development so far, they onlyare burned mostly.Chelated micro-fertilizers were developed by potassium permanganate(KMnO₄) and hydrogenperoxide (H₂O₂) oxidizing residues from enzymatic hydrolysis of cornstalk and then chelatingwith Iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn) ions in this study. The main resultswere listed as follows:1). Hydrogen peroxide (H₂O₂) as oxidant, the percentage of residue dissolution and oxidationproducts chelation increased with the higher dosages of oxidants, pH value and temperature,and had no change with farther prolongation of the reaction time after1h. Carboxyl andphenolic hydroxyl group increased when the dosage of hydrogen peroxide added and decreasedwith rise in pH value. The lignin dissolved more than cellulose with the added dosage ofhydrogen peroxide and higher pH value. According to the results, The oxidizing conditions areoptimized, that is, the dosages of oxidants20%, oxidation temperature70℃, time60min andpH value11. Under optimum conditions, the dissolved rate of residues is32.5%, and thepercentage of chelation with iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn) ions is5.0%,4.5%,3.9%,4.0%, respectively. Through the orthogonal experiments analysis, pH valueis the key factor influence on the oxidation and chelation rate, the dosages of H₂O₂is thesecondary factor, and the temperature is the last one.2). Potassium permanganate (KMnO₄) as oxidant, the percentage of residue dissolution andoxidation products chelation increased with higher dosages of oxidants, and lower pH value, thepercentage ascend first and decreased later with the increase of temperature, maximalpercentage was at70℃. And both percentages reached maximum when the reaction time was90min. Carboxyl and phenolic hydroxyl group increased when the dosage of potassiumpermanganate added, and increased then decreased with rise in temperature, the maximum is at70℃. Dissolvability of the lignin and cellulose was not concerned with added dosage ofpotassium permanganate and higher temperature. According to the results, the optimum oxidizing condition is:10%(oxidant dosages),70℃(oxidation temperature),90min(oxidationtime),2(pH value). Under the condition, the dissolved rate of residues is22.5%, and thepercentage of chelation with iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn) ions is6.8%,5.9%,5.1%,4.5%, respectively. Through the orthogonal experiments analysis,temperature is the key factor influence on the oxidation and chelation rate, the dosages ofKMnO₄is the secondary factor, and the pH value is the last one.3). Through comparison of two oxidant, both oxidation products were good at chelatingreaction, and the percentage of chelation in potassium permanganate oxidation products washigher than in hydrogen peroxide oxidation products, especially with iron (Fe) and zinc (Zn),reproved by more than30%and50%respectively. The phenolic hydroxyl group of hydrogenperoxide oxidation products increased obviously, but carboxyl group had smaller change. Andthe opposite is true in potassium permanganate oxidation products. The lignin dissolved easilywith hydrogen peroxide as oxidant, and lignin and glycan dissolved at the same speed whenpotassium permanganate was oxidant. The percentage of chelation with iron (Fe) was higherboth in two kind of oxidation products. The percentage of chelation with zinc (Zn) was higherin potassium permanganate oxidation products. The rest of percentage of chelation has noobvious difference.