The tailings from coal mine instead of waste became applicable as enzyme supports

Abstract

Some coal mines suffer from problem of having huge deposits of bentonite that they regard as undesirable, since bentonite can cause problem due to its swelling property. Instead of piling stacks of bentonite and regarding it as ecological problem the bentonite can be used as enzyme support by immobilization of enzymes as the challenging new application in the field of biotechnology. The enzyme catalysts in the industrial application present lower energy costs and are more environmentally friendly in comparison to traditional chemical processes. The advantages of enzymes are even more prominent when enzymes are applied in immobilized form. In this work the enzyme supports were prepared from bentonite from Coal mine "Bogovina", Serbia where bentonite, although valuable resource, is still considered to be tailings. Bentonite was modified by common methods: acid activation (AA), pillaring (P), and pillaring followed by acid activation (PAA) and tested as enzyme support. All the obtained materials were characterized by the X-ray powder diffraction and FTIR spectroscopy. The amylase, xylanase, and pullulanase were immobilized on different bentonite based supports by 24 h adsorption at 25 °C. The experimental results revealed that under the investigated conditions AA, P, and PAA, were the most suitable for amylase (106 IU/g), xylanase (74 IU/g), and pullulanase (45 IU/g) immobilization, respectively.