Study On Technology For Activation Of Humic Acid From Leonardite And Its Effect On Growth Of Vegetations

There are a larger quantity of humic acid in Leonardite( HAL). The HA is a kind of mixture consisting of condensed aromatic and carboxyl compounds, which formed through complex biochemical reactions or chemical oxidation( including efflorescence). It is soluble in aqueous solutions of caustic alkalis, like KOH and Na OH. There is a huge amount of HAL stored in China, together with a broad distribution. However, the low activity of HA has limited its applications in industry, agriculture and other fields. In our experiment, effect of different ranges of molecular weight of HA on germination of seeds of romaine lettuce and cabbage was tested, to reveal which molecular weight of HA is more work on promoting plant growth. Then, the optimal range of molecular weight of HA was selected as the technical parameter for the following experiments of HA activity. The results were listed below:Effect of HA on the growth of lettuce and Chinese Cabbage Seedlings1.Through a series of sprouting and sand cultivation experiments, the results was that HA with small molecular scale( molecular weight less than 10000) could promote the growth of lettuce and Chinese cabbage seedlings in low concentration( less than 100 mg/L),depressed the growth of seedlings under the high concentration( 500 mg/L)and It was the best under the middle concentration( 300 mg/L). Compared with water treatment(CK), the S2 treatment( 300 mg/L of HA with small molecular scale) increased the length of sprout, length of seedlings, and biomass of lettuce and Chinese cabbage in 66.02 % and 48.24 %, 59.74 % and73.28 %, and 171.54% and 43.67%, respectively. It was also found that S2 treatment mainly enlarged each single cells of roots so as to promote the whole growth of seedling roots.Effect of grinding with alkli under solid interface reaction on the activation of HAL2.1.Activitation technology was optimized through orthogonal test with KOH as the additive agent. The result showed that the best ratio was 1:10( alkli virsus Leonardite), with the grinding rate of 120 r/min and the duration of 90 min. Under such condition, resolution ratio in water of HA reached 27.1 % and proportion of organic carbon in small molecules 1.25 %.Effect of temperature on the activation of HAL2.2.After a series of experiments under the different temperatures, 100 ? was the toppest one. Ressolution ratio in water of HA was 32.28%, 51.52% and 26.26% % under 100 ?condition more than that of Compaired with the room temperatue, 55? and 145 ?,the organic carbon in small molecules was increased to 64.08%, 190.20% and 20.33%under100?, respectively.Effect of catalyst on the activation HAL3.Activation of HAL by use the both of TiO2 and FePc were investigated, under the condition of KOH as the activation agent. It was discovered that mixture of both the two catalysts performed better, especially when the ratio was Fe Pc:Ti O2=1:3. Compaired with CK, Fe Pc and Ti O2, Ti O2 plus Fe Pc increased the water-soluable of HA to 20.80%, 16.15 % and13.53%, respectively, the organic carbon in small molecules was increased to 117.57%,90.53% and 84.00% under 100?, respectively.