Abstract
M.Tech. (Chemistry)
This work explores the synthesis, characterisation and application of carbon nanoparticles derived from glucose (GCNPs) and functionalised with ethylene diamine (EDA), towards the removal of Cd(II) and Pb(II) in water samples. Glucose is a simple sugar that is readily available in nature, since it is organic, it can be easily converted to carbon through dehydration. GCNPs were successfully modified to form EDA-GCNPs and characterised by electron microscopy (TEM and SEM), CHNS elemental analysis, Brunauer–Emmett–Teller (BET), X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) analysis.Modification of GCNPs with EDA was confirmed from an increase in C-H stretch. Disappearance of carboxyl in the GCNPs and appearance of an amide linkage in the infrared spectra. Based on the particle size results obtained from TEM studies, it was also confirmed that indeed carbon nanoparticles were formed (as the particle sizes were in the nanorange). The adsorption behavior of the two materials for Cd(II) and Pb(II) was investigated by batch adsorption and the effect of several conditions such as contact time, pH, initial metal concentration and competing ions on cadmium and lead uptake were investigated. The adsorption results show that both adsorbents could effectively remove Cd2+ and Pb2+, with lead adsorption being more favoured as compared to that of cadmium. Equilibrium results best fitted the Langmuir model, and the maximum adsorption capacities for Pb(II) were found to be 15.15 and 28.99 mg g-1 for GCNPs and EDA-GCNPs, respectively, whilst Cd(II) adsorption resulted in lower sorption capacities (GCNPs = 10.31 mg g-1 and EDA-GCNPs=18.71 mg g-1). The adsorption processes were found to favour chemisorption, given that the pseudo-second-order kinetic model and Langmuir isotherms best fitted the adsorption results, implying that the functional groups present on the adsorbent surfaces are behind the uptake of these metal ions. The adsorbents showed applicability in real water samples and multi-elemental systems, with competing ions not affecting adsorption processes, moreover, regeneration studies show that both adsorbents are fully recyclable, indicating possible industrial applicability.