Preparation of urea-formaldehyde slow-release fertilizer with wastewater of hexamethylol melamine
Urea formaldehyde slow-release fertilizer was prepared from wastewater containing formaldehyde in the production of hexamethylene-melamine(HMM).The effects of U/F reaction molar ratio,temperature and pH on the preparation of the reaction were investigated.The results showed that the optimal conditions for preparing urea formaldehyde slow-release fertilizer from HMM wastewater were as follows:U/F =1.80,methylene reaction temperature 49.8℃,and hydroxymethylation reaction pH =7.7.Under optimal condi-tions,the formaldehyde conversion rate of HMM production wastewater can reach 99.1%,the urea nitrogen content of prepared urea formaldehyde slow-release fertilizer is 4.2%,the total nitrogen content is 36.7%,and the AI value is 45.3%,all of which meet the requirements of GB/T 34763-2017.
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