Adsorption kinetics of lysozyme on multi-walled carbon nanotubes and amino functionalized multi-walled carbon nanotubes from aqueous solution

In this work, adsorption capacity of egg whites lysozyme on multi-walled carbon nanotubes (MWCNTs) and amino group functionalized multi-walled carbon nanotubes (MWCNT-NH2) was examined. The different parameters affecting the adsorption process for protein were optimized such as initial protein concentration, contact time, initial pH levels, and temperature. Results revealed that optimum time for adsorption process onto the surface of both studied adsorbents was 12 min while the best pH values and temperature were found at 6 and 298 K, respectably. Different kinetic models were assessed such as the intra particle diffusion, the pseudo-first-order, and the pseudo-second-order models. Adsorption of lysozyme onto MWCNT and MWCNT-NH2 surfaces were found to be well fitted by the pseudo-second order kinetic model because of its high correlation coefficients (R-2) and the low chi-square statistic (X-2) values. (C) 2018 Elsevier B.V. All rights reserved.