Removal of mercury (II) via a novel series of cross-linked polydithiocarbamates

Abstract

A series of novel Polydithiocrabamates (DTCP) series were synthesized via Mannich-type polycondensation where Aniline and a series of diaminoalkanes were linked together with paraformaldehyde. The resultant polymer series were converted to dithiocarbamate (DTC) groups by reaction with carbon disulphide in the presence of potassium hydroxide. The size distribution, morphology, molecular structure, and properties of the DTCP series were analysed by FT-IR, 13C NMR, X-ray diffraction, FESEM, AFM, and TGA. A factorial design was created in order to study the effect of the alkyl chain length, pH, contact time and Hg (II) ions initial concentration on the performance of the DTCP towards the removal of Hg (II) ions from aqueous solution. After DTCP screening, further studies were performed on CS2-buta. The adsorption of Hg (II) ions on CS2-buta was spontaneous and endothermic, giving negative and positive values for ΔG and ΔH, respectively. The experimental data fitted the pseudo-second order kinetic model and Langmuir isotherm model (Qm = 0.11 mmol/g). CS2-buta demonstrated high selectivity for the removal of Hg (II) ions (99.87% removal) from wastewater samples. This suggests that CS2-buta demonstrates high potential towards removal of Hg (II) ions as well as other toxic heavy metals from wastewater.