Study On The Preparation Of Fulvic Acid By Brown Black Humic Acid Degradation

Humic acid is a macromolecular organic mixture with abundant functional groups.It is mainly found in coal and can be widely used in agriculture and industry.Humic acid can be divided into brown-black humic acid and fulvic acid,and the effect is exactly about 5% of the fulvic acid contained in coal.The lyophilic acid can be used as raw material for agricultural fertilizer.In this thesis,the brown humic acid was oxidatively degraded to obtain fulvic acid.The brown humic acid extracted from lignite was oxidized by hydrogen peroxide,hydrogen peroxide-ultrasonic enhancement and hydrogen peroxide-ultraviolet enhancement.The first part of the work is the extraction of raw material brown-black humic acid,mainly researching the extraction process of different methods of brown-black humic acid.The raw material is brown coal,and the brown-black humic acid in lignite is extracted by alkali-soluble acid precipitation method,and then the process conditions of alkali-soluble acid precipitation method are explored.The optimal extraction conditions were as follows: the solid-liquid ratio was 0.04,the temperature at the time of alkali dissolution reached 80°C,the solution used in the alkali dissolution was 1% sodium hydroxide,the reaction time was 60 min,and the reaction was filtered to obtain a humic acid solution.Acid precipitation to p H=1.5,centrifugal filtration to obtain brownish black humic acid precipitation,washing the precipitate 3 to 4times,drying as a degradation material.In the second part of the work,the oxidative degradation of brown humic acid was used to prepare fulvic acid.The preheating temperature of single factor variable was 55 ?,the ratio of raw material oxidant was 1:0.5,and the degradation time was 60 min.On the basis of single factor,the orthogonal test of three degradation methods was carried out.The results showed that the degradation yield of brown black humic acid obtained by hydrogen peroxide,hydrogen peroxide-ultrasonic enhancement and hydrogen peroxide-ultraviolet strengthening was 11.4%,13.8% and 15.3%,respectively.Finally,in order to determine whether the degradation product is fulvic acid,the degradation products were characterized by means of infrared spectroscopy and other characterization methods,and finally the degradation product was determined to be fulvic acid product.