Liquefaction Of Bionmass Preparing Slow-controlled Release Fertilizer

Compared with the traditional fertilizer, slow-controlled release fertilizer can greatly improve the utilization rate of fertilizer, but the coating materials of coated fertilizer on the market are petroleum-based polymer, which is difficult to be degraded, further, the coatings can accumulate in the soil and destroy the environment in the long run. Therefore, it is one of the hotspots in the field to find a kind of coating material that is ease to be degraded and friendly to the environment. Biomass resource, especially crop straws and starches are applied to synthetize biopolyurethane materials, and which are eco-friendly and can improve the utilization ratio of the fertilizers to coat the fertilizers. In this paper, the wheat straws, corn straws and corn starch were liquefied, and the liquefaction production was used to synthetize on the surface of the urea, and then the degradatively slow-controlled release fertilizer was prepared. The release effects of various factors were studied by orthogonal test, further, the influence of some single factor was studied on the liquefaction and release effect, and the coating’s degradation was studied.The effect of dose of reagent, sulfuric acid, tungsten trioxide(WO3), tween-20 on the liquefaction, and the effect of dose of liquefaction, ethyenediamine, polyaryl polymethylene isocyanate(PAPI) on the release, those were studied by orthogonal test. The optimal formula of prepare coating urea was found by range analysis, and it was studied to improve the formula of liquefaction and coating urea. Based on the optimal formula, the technical formula of liquefaction and coating were studied, the variety of liquefaction matrals and the main reagent, the different ratio of liquefaction products and polyether glycol, and different kinds of MMT to the release were studied by the means of range analysis, FTIR, TG, SEM, etc. The release dates were the main indicators and the main results are as follows:1. The optimum formula was found by orthogonal test. The first part was liquefy process, polyethylene 400(PEG 400) : ethylene(EG) : glycerin(GL) = 130 : 0: 20(150g, 100 parts), WO3 : 98% H2SO4 =0.22,(4.5g, 3 parts) and tween-20 was 0.5g; the second part was coat process, ureas were 2.0kg(100 parts), PAPI : combined polyols(CP) = 1.9(139g, 7 parties, CP was combined with four parts of liquefaction and one part of polyether glycol), ethylenediamine was 2.2g in per 100 g CP. The coating was compact and even uniform, thin and smooth, the coating closely contacted with urea and its release date was 37 days.2. The ratio of PAPI and CP was the most important factor, and the second was reagent. Wo3, tween-20 and ethylenediamine were good to improve the release effect.3. Adding different kinds of MMT to preparing composite coating materials. The coating contain 0.5% 1.31 PS MMT was best in release effect and the thermal stability. Its release date was 49 days, which was prolonged 32%.4. The liquefaction was studied, the result showed that the more corn starch the higher liquefaction rate increased, the acid value of the liquefaction dramatically increased in the later period, the hydroxyl value increased at first and then decreased, so did the release days of relevant urea. The period was 43 days when he liquefy material was corn straw: corn starch= 3:1, the liquefaction rate was 87%, the hydroxyl value was 310 mg KOH/g, the acid value was 17 mg KOH/g. The liquefaction rate and the hydroxyl value decreased with the increase of liquefy material, the acid value increased, the release period was 53 days when the liquefy material was 20%.5. The liquefied production’s acid value increased with the molecular weight of the main reagent, on the contrary, the hydroxyl value decreased, and the liquefaction rate was unvaried. The fertilizer synthetize by the liquefaction liquefied in PEG400 could last for 53 days. TG and DTG analysis showed the final lost weight rate of the three coating were approximate, and the decompose rate of that coating’s soft segment was fastest.6. The release effect of the urea increased with the increase of polyether glycol. TG and DTG analysis showed that the more polyether glycol, the faster thermal decomposition of the coating, SEC analysis showed that the coating contained polyether glycol was more uniform, compact, thin and smooth than the blank.7. TG, SEM and FTIR demonstrated that the coatings were obviously degraded after buried in the soil for 6 months, the chemical structure and functional groups of the materials broken or changed. The coatings synthesized by the liquefied production that was got from wheat straw had a good degradability.