Extraction Of Fulvic Acid Isolated From Leonardite And Paper-making Black Liquor And The Effects On Maize Growth

Fulvic acid(FA)is a part of humic acid which has small molecular weight and dissolved with acid and alkali solution.Due to containing a variety of active functional groups,the FA has been widely used as a plant growth regulator.At present,the FA is mainly derived from mineral resources,such as leonardite and lignite,but the content of FA in the mineral material is low and it is a non-renewable resource.In addition,the structural properties of the FA isolated from different materials were quite different.In recent years,there is a similar FA substance exist in black liquor produced in paper-making.Whether this matter has similar structure and the same biological activity with FA is unclear.Based on the above problems,the objectives of study are,investigating the differences in the molecular structure and the effect on the promotion of maize seed germination and root growth through using the FA extracted from leonardite and paper-making black liquor.This study has an important guidance in promoting efficiently use of paper-making black liquor,reducing environmental pollution brought by it,and may provide a certain technical support and the theoretical basis for the future study of the chemical structure of similar FA substance extracted from paper-making black liquor and its stimulation on crop growth.The main results are as follows:1.The method of IHSS was used to extract fulvic acid from leonardite and paper-making black liquor.The differences of molecular strctures between them were tested by elemental analysis,infrared spectroscopy,nuclear magnetic resonance spectroscopy and hydrogen spectroscopy.It is found that both have similar elements and functional groups.The result of elemental analysis shows that the fulvic acid from paper-making black liquor has a higher content of oxygen and nitrogen functional groups.From infrared spectroscopy it can be observed that both have similar fulvic acis functional groups,but the functional groups in fulvic acid which isolated from paper-making black liquor was more complex.The spectroscopy of 13 C NMR and 1H can be concluded that the molecular structure of both is basically same,but it is more complex and more types in fulvic acid extracted from paper-making black liquor,which contains more aromatic structure.2.Maize seed germination test results show that fulvic acids material can promote water absorption of seed,thus inducing seed germination.With the concentration of FA increased,the promotion effect is enhanced.Fulvic acid extracted from leonardite achieves the best efficiency in 80 mg / L while fulvic acid extracted from paper-making black liquor achieves the best in120 mg / L.In addition,when the concentration of the FA reached 200 mg / L both inhibit seed germination.3.The sand culture results show that the fulvic acids could promote the growth of maize seedling and root.With the increasing of the fulvic acids concentration,the effect is enhanced.Fulvic acid extracted from leonardite achieves maximum efficiency in 80 mg / L while fulvic acid extracted from paper-making black liquor achieves the best in 120 mg / L.Moreover,when the concentration of the FA reached 200 mg / L both of the FA inhibit growth and development of maize.