Papers by Keyword: Potassium Release

Abstract: Owing to lack of soluble potassium resource in some countries, it will be the competitive alternative to obtain potassium from insoluble K-bearing minerals (e.g. K-feldspar, biotite) in order to satisfy the requirements of potassium fertilizers for the agricultural sustainable development. In this work, seven fungal species including Penicillium oxalicum, P. ochrochloron, P. simplicissimum, P. spinulosum, Aspergillus niger, A. fumigatus, and A. oryzae were investigated for potassium extraction from biotite (9.64% K₂O, weight fraction). Experiments were carried out in a shaker (30 °C, 180 rpm) with biotite directly dispersed in the leaching medium or enclosed in a dialysis bag. The concentrations of potassium, silicon and aluminum in the bioleaching solution were measured by Inductive Coupled Plasma (ICP), and K release amounts of biotite by seven fungal species were compared. It was found that all the strains had the abilities to enhance the dissolution of biotite, and P. oxalicum showed the highest K release amount among seven tested strains. Furthermore, the metabolites of fungi in the bioleaching process were analyzed by high performance liquid chromatography (HPLC), and the surface morphologies of biotite before and after bioleaching were characterized by Scanning Electron Microscope (SEM). The mechanism of microbial release of potassium from biotite by Penicillium and Aspergillus was discussed.

Abstract: The fly ash with a loose and porous structure has definite absorbent ability, which has a good effect on soil improvement. Illite belongs to clay minerals, it has absorbent ability and higher potassium, which can improve the soil fertility. In this study, poly(acrylic acid sodium-co-acrylamide)(PAANa-AM)/fly ash-illite superabsorbent composite was firstly prepared by solution polymerization. The structures were characterized using scanning electron microscope, X-ray diffraction, and infrared spectrum. The results showed that the fly ash and illite dispersed well in the composite. The K⁺ in illite was replaced by Na⁺ in acrylic acid sodium and thus the illite structure turned into paragonite during the process of preparing composite, however, the structure of fly ash was maintained in the composite. Moreover, the hydroxide radical in illite reacted with the carbonyl group in acrylic acid during polymerization. The best absorbent capacities of the composite in distilled water, tap water and normal saline were 1695, 445 and 106 g/g, respectively, which exceeded the requirements of The National 863 Program and Ministry of Agriculture of People’s Republic of China. The potassium release was measured using atomic absorption spectrometry and the results indicated that the composite can release 12.80% of the potassium ion in fly ash and illite. The superabsorbent material has low cost and favors improvement of soil and potassium-deficiency.