Characterisation of products from fungally modified wollastonite and the simulation experiment of Pb2+ fixation.

Using cheap raw materials and simple biological modification methods to obtain modified materials to remediate heavy metals has potential application prospects. Here, Aspergillus niger was used to modify wollastonite and further explore its fixation capacity and mechanism. The results showed that the growth and metabolism of A. niger promoted the weathering of wollastonite and the synthesis of whewellite, forming a mineral composite through fungal modification (MCF) with excellent fixation properties of heavy metal Pb2+. The maximum adsorption capacity of MCF for Pb2+ (434.78 mg/g) is significantly greater than that of original wollastonite (11.86 mg/g) with a desired lower desorption rate. Additionally, its removal rate of Pb2+ is higher than 75% under varying acidic conditions (1 ≤ pH ≤ 5.5). The results of XRD, FTIR, BET specific surface area, and SEM-EDS showed that MCF has a special organic-inorganic composite structure, which imparts a larger contact area for ions, and efficient removal of Pb2+ through combined physico-chemical adsorption. Batch adsorption results also indicated that the adsorption process by MCF was mainly a spontaneous endothermic reaction in the monolayer. This study provides a new perspective for the bio-modification of wollastonite and its application in the remediation of heavy metal pollution.