Pankaj Tewari - Academia.edu (original) (raw)

Papers by Pankaj Tewari

Journal of Polymer Science Part A: Polymer Chemistry, 2007

Skip to Main Content. ...

The Analyst, 2000

Thiosalicylic acid (TSA)-modified Amberlite XAD-2 (AXAD-2) was synthesized by coupling TSA with t... more Thiosalicylic acid (TSA)-modified Amberlite XAD-2 (AXAD-2) was synthesized by coupling TSA with the support matrix AXAD-2 through an azo spacer. The resulting chelating resin was characterized by elemental analyses, thermogravimetric analysis (TGA) and infrared spectra. The newly designed resin quantitatively sorbs Cd II , Co II , Cu II , Fe III , Ni II and Zn II at pH 3.5-7.0 when the flow rate is maintained between 2 and 4 ml min 21 . The HCl or HNO 3 (2 mol l 21 ) instantaneously elutes all the metal ions. The sorption capacity is 197.5, 106.9, 214.0, 66.2, 309.9 and 47.4 mmol g 21 of the resin for cadmium, cobalt, copper, iron, nickel and zinc, respectively, whereas their preconcentration factor is between 180-400. The breakthrough volume of HCl or HNO 3 for elution of these metal ions was found to be 4-8 ml. The limit of detection (LOD) for Cd II , Co II , Cu II , Fe III , Ni II and Zn II was 0.48, 0.20, 4.05, 0.98, 1.28 and 3.94 mg l 21 , respectively, and the limit of quantification (LOQ) was found to be 0.51, 0.29, 4.49, 1.43, 1.58 and 4.46 mg l 21 , respectively. The loading half time, t 1/2 , for the cations was found to be less than 2.0 min, except for nickel for which the value was 13.1 min. The determination of each of these six cations is possible in the presence of other five, if their concentration is up to 4 times. All six metals were determined in river water (RSD ≈ 0.7-7.7%) and tap water samples (RSD ≈ 0.3-5.7%). The estimation of Co was made in the samples of multivitamin tablets (RSD < 2.3%). The results agree with those quoted by manufacturers.

Fresenius' journal of analytical chemistry, 2000

A new chelating resin, Xylenol Orange coated Amberlite XAD-7, was prepared and used for preconcen... more A new chelating resin, Xylenol Orange coated Amberlite XAD-7, was prepared and used for preconcentration of Cd(II), Co(II), Cu(II), Fe(III), Ni(II) and Zn(II) prior to their determination by flame atomic absorption spectrophotometry. The optimum pH values for quantitative sorption of Cd(II), Co(II), Cu(II), Fe(III), Ni(II) and Zn(II) are 4.5-5.0, 4.5, 4.0-5.0, 4.0, 5.0 and 5.0-7.0, respectively, and their desorptions by 2 mol L -1 HCl are instantaneous. The sorption capacity of the resin has been found to be 2.0, 2.6, 1.6, 1.6, 2.6 and 1.8 mg g -1 of resin for Cd, Co, Cu, Fe, Ni and Zn, respectively. The tolerance limits of electrolytes, NaCl, NaF, NaI, NaNO 3 , Na 2 SO 4 and of cations, Mg 2+ and Ca 2+ in the sorption of the six metal ions are reported. The preconcentration factor was between 50 and 200. The t 1/2 values for sorption are found to be 5.3, 2.9, 3.2, 3.3, 2.5 and 2.6 min for the six metals, respectively. The recoveries are between 96.0 and 100.0% for the different metals at preconcentration limits between 10 to 40 ng mL -1 . The preconcentration method has been applied to determine the six metal ions in river water samples after destroying the organic matter (if present in very large amount) with concentrated nitric acid (RSD ≤ 8%, except for Cd for which it is upto 12.6%) and cobalt content of vitamin tablets with RSD of ~ 3.0%.

The Analyst, 1999

Chromotropic acid has been covalently linked with the benzene ring of Amberlite XAD-2, through an... more Chromotropic acid has been covalently linked with the benzene ring of Amberlite XAD-2, through an 2NNN2 group, to design a new polymer matrix. Elemental analyses, thermogravimetric analyses and infrared spectra were used to characterize the resulting functionalized Amberlite ...

Journal of Polymer Science Part A: Polymer Chemistry, 2007

Skip to Main Content. ...

The Analyst, 2000

Thiosalicylic acid (TSA)-modified Amberlite XAD-2 (AXAD-2) was synthesized by coupling TSA with t... more Thiosalicylic acid (TSA)-modified Amberlite XAD-2 (AXAD-2) was synthesized by coupling TSA with the support matrix AXAD-2 through an azo spacer. The resulting chelating resin was characterized by elemental analyses, thermogravimetric analysis (TGA) and infrared spectra. The newly designed resin quantitatively sorbs Cd II , Co II , Cu II , Fe III , Ni II and Zn II at pH 3.5-7.0 when the flow rate is maintained between 2 and 4 ml min 21 . The HCl or HNO 3 (2 mol l 21 ) instantaneously elutes all the metal ions. The sorption capacity is 197.5, 106.9, 214.0, 66.2, 309.9 and 47.4 mmol g 21 of the resin for cadmium, cobalt, copper, iron, nickel and zinc, respectively, whereas their preconcentration factor is between 180-400. The breakthrough volume of HCl or HNO 3 for elution of these metal ions was found to be 4-8 ml. The limit of detection (LOD) for Cd II , Co II , Cu II , Fe III , Ni II and Zn II was 0.48, 0.20, 4.05, 0.98, 1.28 and 3.94 mg l 21 , respectively, and the limit of quantification (LOQ) was found to be 0.51, 0.29, 4.49, 1.43, 1.58 and 4.46 mg l 21 , respectively. The loading half time, t 1/2 , for the cations was found to be less than 2.0 min, except for nickel for which the value was 13.1 min. The determination of each of these six cations is possible in the presence of other five, if their concentration is up to 4 times. All six metals were determined in river water (RSD ≈ 0.7-7.7%) and tap water samples (RSD ≈ 0.3-5.7%). The estimation of Co was made in the samples of multivitamin tablets (RSD < 2.3%). The results agree with those quoted by manufacturers.

Fresenius' journal of analytical chemistry, 2000

A new chelating resin, Xylenol Orange coated Amberlite XAD-7, was prepared and used for preconcen... more A new chelating resin, Xylenol Orange coated Amberlite XAD-7, was prepared and used for preconcentration of Cd(II), Co(II), Cu(II), Fe(III), Ni(II) and Zn(II) prior to their determination by flame atomic absorption spectrophotometry. The optimum pH values for quantitative sorption of Cd(II), Co(II), Cu(II), Fe(III), Ni(II) and Zn(II) are 4.5-5.0, 4.5, 4.0-5.0, 4.0, 5.0 and 5.0-7.0, respectively, and their desorptions by 2 mol L -1 HCl are instantaneous. The sorption capacity of the resin has been found to be 2.0, 2.6, 1.6, 1.6, 2.6 and 1.8 mg g -1 of resin for Cd, Co, Cu, Fe, Ni and Zn, respectively. The tolerance limits of electrolytes, NaCl, NaF, NaI, NaNO 3 , Na 2 SO 4 and of cations, Mg 2+ and Ca 2+ in the sorption of the six metal ions are reported. The preconcentration factor was between 50 and 200. The t 1/2 values for sorption are found to be 5.3, 2.9, 3.2, 3.3, 2.5 and 2.6 min for the six metals, respectively. The recoveries are between 96.0 and 100.0% for the different metals at preconcentration limits between 10 to 40 ng mL -1 . The preconcentration method has been applied to determine the six metal ions in river water samples after destroying the organic matter (if present in very large amount) with concentrated nitric acid (RSD ≤ 8%, except for Cd for which it is upto 12.6%) and cobalt content of vitamin tablets with RSD of ~ 3.0%.

The Analyst, 1999

Chromotropic acid has been covalently linked with the benzene ring of Amberlite XAD-2, through an... more Chromotropic acid has been covalently linked with the benzene ring of Amberlite XAD-2, through an 2NNN2 group, to design a new polymer matrix. Elemental analyses, thermogravimetric analyses and infrared spectra were used to characterize the resulting functionalized Amberlite ...