Preparation of Immobilized Enzymes on Pulp Fiber with the Layer-by-layer Self-assembly Technique and its Application in Whitewater Treatment

Rina Wu, Dongqin Zhou, Gaosheng Wang

Abstract


Anionic pectic substances in whitewater are harmful to the papermaking process and product quality. To diminish their negative effect, immobilized pectinase was prepared to treat pectic compounds in whitewater. Pectinase was immobilized on pulp fiber via a layer-by-layer assembly technique using polyethyleneimine. The activity of the immobilized enzyme varied nearly linearly, from 2876 U/g to 4838 U/g, until the number of layers reached four. The properties of the bound enzymes and their free counterparts were investigated. After being fixed on the pulp fiber, the optimum pH of the enzymes shifted from 4.4 to 4.0 and the optimum temperature increased by 5 °C to 50 °C. It was shown that the Vm value was slightly reduced for the immobilized enzymes, while the Km value noticeably decreased. Furthermore, the immobilized enzyme was tested in papermaking whitewater treatment. The four-layer immobilized enzymes lowered the whitewater cationic demand by 18% and 30% at pH values of 7 and 4, respectively. The immobilized pectinase could potentially be employed to treat wastewater in the papermaking industry.

Keywords


Immobilized; Fiber; Layer-by-layer; Papermaking; Whitewater; Polyethyleneimine

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