Biomass-Based Silica/Calcium Carbonate Nanocomposites for the Adsorptive Removal of Escherichia coli from Aqueous Suspensions

The present study deals with the adsorptive removal of Escherichia coli (E. coli) by making use of chitosan-silica/calcium carbonate (CS-SiO2/CaCO3) nanocomposites (NCs) where it was synthesized using the waste eggshells and rice husks occurred by natural sources. The bioadsorbent CS-SiO2/CaCO3 NCs were synthesized by incorporating eggshell-CaCO3 nanoparticles (NPs) and rice husk-SiO2 NPs in chitosan NPs solution. The adsorbents were characterized using HRTEM, BET, DLS, and TGA. The characterization of NCs revealed the formation of adsorbents in the range of 10-50 nm and some structural changes to the spectra of adsorbents before and after the adsorption of E. coli was revealed by the FTIR analysis. Moreover, the adsorption efficiency of E. coli over the adsorbents after 35 min of incubation was about 80% for CS-SiO2/CaCO3 NCs. Further, the kinetics of adsorption studies were observed to be well-fitted to the Langmuir isotherm model with an adsorption capacity of 3.18 x 10(1) (CFU E. coil per gram of CS-SiO2/CaCO3). From the analysis, the synthesized bioadsorbent demonstrated the potential for ameliorating the inherent risk of pathogens in water.

Automated summary

The present study synthesized chitosan-silica/calcium carbonate (CS-SiO2/CaCO3) nanocomposites using waste eggshells and rice husks as natural sources. The adsorbents were characterized and showed a particle size range of 10-50 nm. Structural changes before and after the adsorption of E. coli were observed. The adsorption efficiency of CS-SiO2/CaCO3 nanocomposites for E. coli was about 80% after 35 minutes of incubation. The kinetics of adsorption followed the Langmuir isotherm model, with an adsorption capacity of 3.18 x 10(1) (CFU E. coil per gram of CS-SiO2/CaCO3). The synthesized bioadsorbent demonstrated potential for reducing the risk of pathogens in water.