Removal of Metals by Sorption with Metal Concentration Colour Sensitive Azotized Polyethylene Terephthalate Adsorbent

Abstract

Abstract This paper reports on the preparation and modification of azotized polyethylene terephthalate (PET) as a stable and colour sensitive absorbent for metals in aqueous media and its application in the removal of heavy metal ions from water. This study successfully functionalized PET to produce an azotized material which was confirmed by FTIR (Fourier transform infrared) analysis and its metal adsorption property confirmed by FAAS (flame atomic absorption spectroscopic) analysis. The modified material exhibited colour variations upon interaction with metal ions. The material was capable of indicating when exhausted, and was then applied for the removal of the metals from water. Sorption parameters were investigated and optimized at fixed temperature (25°C). The optimum pH for the adsorption of copper, lead and chromium was 6.0 except that of cadmium was that was adsorbed at a pH value of 5.5. The uptake of the metals studied was found to be very fast as about 90% was adsorbed within the first 10 min of contact time. The adsorption of lead and cadmium prescribed to first order kinetics thus monolayer adsorption implying a chemisorption process while the adsorption of copper and chromium was of second order kinetics of multilayer adsorption. This could also be due to copper and chromium being smaller species hence being more interactive than lead and cadmium. The adsorption capacities of copper, lead, cadmium and chromium were found to be 46.47, 33.65, 70.93 and 59.06 mg g− 1 respectively. The metal ions attached on the adsorbent were easily stripped of by the use of 1.0 M nitric acid, hence easily regeneratable. The results obtained confirmed that azotized PET has potential application as a colour sensitive sorbent for the removal of heavy metal pollutants from water.