Adsorptive detoxification of Cd2+ and Pb2+ from wastewater using MWCNTs functionalized with -di-(2-ethyl hexyl phosphoric acid) and bis-(2,4,4-trimethyl pentyl) phosphonic acid.

Abstract

Selective and rapid determination of procedure for Cd2+ and Pb2+ samples using MWCNT surfaces can be modified by loading ligands such as D2EHPA and Cyanex 272 which is described. The adsorbent was modified with D2EHPA and Cyanex 272. Effect of pH, amount of adsorbent, contact time for adsorption, and the optimum eluent for the quantitative recovery of Cd2+ and Pb2+ were investigated and the subsequent determination by FAAS. The adsorption was found to be mainly due to the chemical interactions between the metal ions and functional groups -COO- and -OH which were characterized by FT-IR. The adsorption of metal occurs at pH 4.5 with 500 mg of MWCNTs. The enrichment factor was 40 and 30. The detection limit was 0.03 and 0.05 μg L-1. The quantitative recovery of metal ion used 1 mol L-1 HNO3. The thermodynamic parameter of Langmuir and Freundlichadsorption isotherm revealed that the adsorption of free energy (ΔG) was spontaneous and the monolayer adsorption of Cd2+ and Pb2+ was mainly on the surfaces. The adsorbent performance of R2 in the range of 0.93-0.99 and also the identified adsorption efficiency of Cd2+ and Pb2+ are linear or non-linear curves respectively. The proposed method was applied to heavy metals from environmental samples.