Adsorption of Cd (II) by a novel living and non-living Cupriavidus necator GX_5: optimization, equilibrium and kinetic studies

Abstract

Biosorbents have been extensively studied for heavy metal adsorption due to their advantages of low cost and high efficiency. In the study, the living and non-living biomass of Cupriavidus necator GX_5 previously isolated were evaluated for their adsorption capacity and/or removal efficiency for Cd (II) through batch experiments, SEM and FT-IR investigations. The maximum removal efficiency rates for the live and dead biomass were 60.51% and 78.53%, respectively, at an optimum pH of 6, a dosage of 1 g/L and an initial Cd (II) concentration of 5 mg/L. The pseudo-second-order kinetic model was more suitable for fitting the experimental data, indicating that the rate-limiting step might be chemisorption. The Freundlich isotherm model fit better than the Langmuir isotherm model, implying that the adsorption process of both biosorbents was heterogeneous. FT-IR observation reflected that various functional groups were involved in Cd (II) adsorption: –OH, –NH, C=O, C–O and C–C groups for the living biomass and –OH, –NH, C–H, C = O, C–N and N–H groups for the dead biomass. Our results imply that non-living biosorbents have a higher capacity and stronger strength for absorbing Cd (II) than living biomass. Therefore, we suggest that dead GX_5 is a promising adsorbent and can be used in Cd (II)-contaminated environments.

Model-Assisted Optimization of Cobalt Biosorption on Macroalgae Padina pavonica for Wastewater Treatment

“…According to Li et al [30], during the adsorption process, the number of active sites is limited, and the existence of metal ion competition reduces the metal uptake until the According to the data depicted in Figure 4A, when the concentration of Co(II) ion increases from 20 to 100 mg/L, the efficiency removal of Co significantly decreases from 88.15% to 73.96% (p < 0.05). A higher cobalt removal percentage was observed at low Co(II) concentrations due to the many freely available sites on the surface of algal biomass [26].…”

“…According to Li et al [30], during the adsorption process, the number of active sites is limited, and the existence of metal ion competition reduces the metal uptake until the equilibrium time is reached. Accordingly, Bai and Venkateswarlu [31] pointed out that metal ions form a single-molecule-thick layer on the biosorbent surface, and the sorption process slows down over time.…”