title: Phosphinic acid functionalized carbon nanotubes for sensitive and selective sensing of chromium(VI).
abstract: Single-walled carbon nanotubes (SWCNTs) have been functionalized with a phosphinic acid derivative 'bis(2,4,4-trimethylpentyl) phosphinic acid' (PA/d). It has been achieved by treating the chlorinated SWCNTs with PA/d at 80°C. Successful functionalization and different nanomaterial properties have been investigated by UV-vis-NIR, FTIR, Raman spectroscopy, AFM and FE-SEM. PA/d conjugated SWCNTs (CNT-PA) are dispersible in some common organic solvents, e.g. CH2Cl2, DMF, CHCl3, and THF. The 'CNT-PA' complex was spin-casted on boron doped silicon wafer. Thus fabricated sensing electrode is demonstrated for sensitive and selective electrochemical sensing of chromium(VI) ions. A linear response is obtained over a wide range of Cr(VI) concentration (0.01-10 ppb). The sensor's sensitivity and the limit of detection are observed to be 35 ± 4 nA/ppb and 0.01 ppb, respectively. The practical utility of the proposed sensor is demonstrated by determining the Cr(VI) concentration in an industrial effluent sample and an underground water sample.
authors.affiliation: Central Scientific Instruments Organisation (CSIR-CSIO), Sector 30 C, Chandigarh 160030, India. Electronic address: dr.akashdeep@csio.res.in.
authors.forename: Akash
authors.initials: A
authors.lastname: Deep
authors.affiliation: Central Scientific Instruments Organisation (CSIR-CSIO), Sector 30 C, Chandigarh 160030, India.
authors.forename: Amit L
authors.initials: AL
authors.lastname: Sharma
authors.affiliation: Central Scientific Instruments Organisation (CSIR-CSIO), Sector 30 C, Chandigarh 160030, India.
authors.forename: Satish K
authors.initials: SK
authors.lastname: Tuteja
authors.affiliation: Central Scientific Instruments Organisation (CSIR-CSIO), Sector 30 C, Chandigarh 160030, India.
authors.forename: A K
authors.initials: AK
authors.lastname: Paul
mesh_terms: D002857:Chromium / Q000032:analysis* / Q000737:chemistry; D004563:Electrochemistry; D004566:Electrodes; D004595:Electroplating; D007220:Industrial Waste / Q000032:analysis; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010721:Phosphinic Acids / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry
chemical_list: D007220:Industrial Waste; D037742:Nanotubes, Carbon; D010721:Phosphinic Acids; D014874:Water Pollutants, Chemical; D002857:Chromium; C074702:chromium hexavalent ion
keywords: Amperometry; Carbon nanotubes; Cr(VI); Determination; Microsensor; Phosphinic acid modifier