Nano iron-oxide coated ball-milled K-feldspar had high adhesion capacity for Bacillus subtilis

Abstract

This study describes a high-energy ball milling followed by nanoscale iron (Fe)-oxide coating technology to produce an activated potassium (K)-feldspar with strong adsorption capacity of K-solubilizing bacterial cells (Bacillus subtilis). The results demonstrated that ball milling treatment significantly reduced the particle size of the K-feldspar while increasing available K content, specific surface area (SSA) and total pore volume. Both Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) verified amorphization of the K-feldspar due to considerable damage appeared to the mineral structure. However, the generation of microaggregates restricted above changes in properties of K-feldspar by ball milling. Nanoscale Fe-oxide coating treatment formed numerous Fe oxides (length of ∼100 nm) on the surface of the optimal ball milled mineral, and greatly increased the SSA and total pore volume. According to the results of the microbial adsorption, Fe-coated K-feldspar minerals with the lowest available nutrient content and highest zeta potential had the greatest capacity to adsorb B. subtilis cells. This implies that we can use this new carrier material for bio-potassium fertilizer, which may be able to efficiently supply soil K by carrying significant quantities of K-solubilizing bacteria.