Immobilization and enhanced catalytic activity of lipase on modified MWCNT for oily wastewater treatment

Abstract

In this article, we report results of experiments on covalent immobilization of Candidia rugosa lipase enzyme on modified multiwall carbon nanotubes (MW-CNTs) for oily wastewater treatment application. MWCNTs were produced using chemical vapor deposition (CVD) and surface-modified by nitric acid and organic cross-linkers. Successful attachment and high enzyme loading up to 30 wt % was confirmed via FTIR and TGA analysis. Enzymatic activity and loading, which are dependent on the oxidized MWCNT surfaces, cross-linker types and concentrations, resulted with high thermal and operational stability in the microenvironment conditions. This demonstrates the potential for improved resistance to the severe conditions in industrial applications. Furthermore, the CNTs-immobilized enzyme yielded a catalytic activity about 93 times higher than those immobilized on other reported support materials. Up to 98% biological activity retention was also achieved, marking a significant improvement over literature-reported activities (1-20%). Titrimetric analysis of hydrolyzed samples using MWCNT-Lipase (after 1 hr reaction time at 378C) resulted in an enzymatic activity increase of about five times over those from lyophilized lipase.

Biocatalyst of Nanocomposite using Functionalized Low-Cost Activated Carbon from Zea mays L. (maize) Husk Leaf with Lipase for Hydrolysis of Olive Oil

“…Under an optimum temperature of 50 °C, relative activity of CRL-FZHLAC was the highest at 66.13 µmol/min/g. The optimum temperature of CRL-FZHLAC is higher as compared to a previous work by Jamie et al [40].…”

“…Firstly, the range of the temperatures in the system was near the optimal working temperature of CRL-FZHLAC. Secondly, the increase in temperature literally increases the interfacial area for the enzymes and substrates to interact, contributed by the thermal effect coupled with adequate mixing of the system [40]. Conversely, the decline in relative activity at temperatures beyond the optimum point (50 °C) was mainly due to the gradual thermal deactivation (denaturation) of lipase in CRL-FZHLAC.…”

“…An increase in relative activity from pH 5.0 to pH 9.0 is attributable to the fact that disruptions on the ionization and deionization of basic or acidic groups in the active sites of the lipase are increased [40,44]. These alterations interfered with the correct binding of the biocatalysts with olive oil, in turn reducing the rates of the hydrolysis.…”

Technological Microbiology: Development and Applications

“…On the other hand, the direct use of microbial enzymes in the treatment of effluents, especially industrial effluents, has been encouraged because the enzymatic action is faster, dispensing with the conditions necessary for the fermentative process. Lipases, for example, are used in the treatment of wastewater containing mainly triglycerides ( Jamie et al, 2016 ). The presence of these enzymes in activated sludge and in other aerobic degradation processes is important for the continuous removal of the fat layers formed on the surface of aerated tanks to allow oxygen transport ( Hasan et al, 2006 ).…”

Immobilization of Chaetomium erraticum dextranase (CED) by adsorption on carboxylated multi walled carbon nanotubes (c-MWCNT)

“…There are not any report in the related literature about the immobilization of CED by using c-MWCNT. In some study with c-MWCNT, enzyme immobilization resulted in 5 times [45] and 12 times [48] increased activity. Therefore, the main goal of this study was to obtain sustainable higher immobilization yield and activity yield than previous results reported in the literature in the immobilization of CED on c-MWCNT by optimizing the conditions of adsorption.…”