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1

Multi-variant Sorption Optimization for the Uptake Of Pb(II) Ions by Jamun Seed Waste

Siyal A.N., Memon S.Q., Amanullah M., Pirzada T., Parveen S. S.

Polish Journal of Chemical Technology

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2013

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Vol. 15, nr 1

15-21

EN

In the present study, jamun seed waste has been explored for the removal of Pb(II) ions from aqueous solution. The multi-variant sorption optimization was achieved by the factorial design approach. 99.91% of Pb(II) ions was removed from aqueous solution. The results predicted by the model were in good agreement with the experimental results (the values of R2 and R2 adj. were found to be 99.89% and 99.95%, respectively). Langmuir and D-R isotherm studies were carried out to fi nd adsorbent's capacities (183.9 š 0.31 mg/g and 184.5 š 0.16 mg/g respectively), sorption free energy 13.17 š 0.16 and RL values in the range of 0.05-0.77, suggested the favorable chemical and/or ion exchange nature of the sorption process. The FT-IR study was carried out for unloaded and Pb(II) ions loaded jamun seed, indicated, Pb(II) ions associated with nitrogen and oxygen of jamun seed containing moieties during the adsorption process. The proposed method was successfully validated and applied for the treatment of Pb(II) ions contaminating drinking water.

2

Recycling of styrofoam waste: synthesis, characterization and application of novel phenyl thiosemicarbazone surface

Siyal A.N., Memon S.Q., Khuhawar M.Y.

Polish Journal of Chemical Technology

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2012

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Vol. 14, nr 4

11-18

EN

An attempt has been made to recycle Styrofoam waste to a novel functional polymer, Phenyl thiosemicarbazone surface (PTS). Polystyrene (PS) obtained from Styrofoam waste was acetylated and then condensed to PTS by reacting it with 4-Phenyl-3-thiosemicarbazide ligand and characterized by FT-IR spectroscopy and elemental analysis. Synthesized PTS was applied successfully for the treatment of lead contaminated water by batch extraction method. Sorption variables were optimized (pH 8, adsorbent dose 53mg, initial Pb(II) ion concentration 10mgl-1 and agitation time 90min) by factorial design approach. Lead uptake by PTS was found much sensitive to the pH of Pb(II) ion solution. The maximum removal (99.61%) of Pb(II) ions was achieved at optimum conditions. The Langmuir and D-R isotherm study suggested the monolayer, favorable (RL=0.0001-0.01) and chemisorption (E=20.41š0.12kJmol-1) nature of the adsorption process. The sorption capacity of PTS was found to be 45.25š0.69mgg-1. The FT-IR spectroscopy study showed the involvement of nitrogen and sulphur of thiosemicarbazone moiety of PTS for the uptake of Pb(II) ions by fi ve membered chelate formation.

3

Optimization and equilibrium studies of Pb(II) removal by Grewia Asiatica seed: a factorial design approach

Siyal A. N., Memon S. Q., Khaskheli M. I.

Polish Journal of Chemical Technology

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2012

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Vol. 14, nr 1

71-77

EN

This study aims to explore the efficiency of an agro waste material for the remediation of Pb(II) contaminated water. A factorial design approach is adopted to optimize removal efficiency and to study the interaction between effective variables. A face-centered Draper-Lin composite design predicted 100% removal efficiency at optimum variables; pH 8, initial concentration of Pb(II) ion 12mg/L, sorbent dose 200mg and agitation time 110 min. Regration coefficient (R2 = 99.9%) of a plot of the predicted versus the observed values and p value (>0.05) confirms the applicability of the predicted model. Langmuir and Dubinin-Radushkevich (D-R) isotherm models were applicable to sorption data with the Langmuir sorption capacity of 21.61š0.78 mg/g. The energy of sorption was found to be 13.62š0.32 kJ/mol expected for ion-exchange or chemisorption nature of sorption process. Characterization of Grewia seed suggested a possible contribution of carboxyl and hydroxyl groups in the process of biosorption. The present study shows that Grewia seeds can be used effectively for the remediation of Pb(II) contaminated water.

4

Novel Calix[4]arene network resin for Cr(VI) ions Remediation : A Response Surface Approach

Siyal A. N., Memon S. Q.

Polish Journal of Chemical Technology

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2012

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Vol. 14, nr 3

21-28

EN

Novel Calix[4]arene Netwok (NCN) resin has been synthesized using Amberlite XAD-2 as the starting material. Hydroxyl groups have been introduced onto the para position of alkylated phenyl ring of Amberlite XAD-2 followed by the condensation to NCN by reacting it with formaldehyde. The NCN resin has been used for the remediation of Cr(VI) contaminated water using factorial design approach. A face-centered Draper-Lin composite design predicted ~100% removal effi ciency at optimum variables (the initial concentration of Cr(VI) ion 10 mg/l sorbent dose 200 mg, agitation time 136 min and pH 2). The accuracy and the fi tting of the model were evaluated by ANOVA and R2 (0.9992) values. The 99.5% removal effi ciency has been achieved experimentally at the optimum values of the variables. The Langmuir and D-R isotherm models were applicable to the sorption data with the value of RL and the sorption free energy 0.0057-0.1 and 7.93 kJ/mol respectively, suggesting favorable and physical/ion-exchange nature of the sorption. The calculated sorption capacity was 176.1š2.4 mg/g. The recycling studies of NCN resin showed that the multiple use of resin is feasible. Effect of concomitants has also been studies and proposed method was applied successfully for removal (98.7%) of Cr (VI) from electroplating wastewater.

5

Bis(salicylaldehyde) orthophenylenediamine as complexing reagent in simultaneous determination of gold, chromium, iron, uranyl, and nickel using capillary zone electrophoresis

Soomro R, Memon S. Q., Ahmed M. J, Memon N, Mallah A

Acta Chromatographica

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2012

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Vol. 24, no. 4

543--558

EN

Bis(salicylaldehyde) orthophenylenediamine (BSOPD) is reported here as a complexing reagent for simultaneous determination of six metal ions, gold, chromium, iron(II)/(III), uranyl, and nickel, by capillary zone electrophoresis. The pre-derivatized complexes were injected onto 50 cm bare silica capillary (i.d. 75 µm) with background electrolyte 50 mM citrate:oxalate buffer in 1:1 at pH 4. All metal ions were separated within 15 min including coexisted ions at applied voltage of −15 kV at detection wavelength of 250 nm. Under the abovementioned conditions, limits of quantification and detection were found to be 0.5, 1.0, 1.0, 10.0, 1.0, and 10.0 µg mL-1; and 0.16, 0.33, 0.33, 3.33, 0.33, and 3.33 µg mL-1 for Au(III), Cr(VI), Fe(III), Fe(II), UO2(II), and Ni(II), respectively. Linear calibration graphs were obtained in the ranges of 0.5–100, 1–200, 10–100, 1–100, 1–100, and 10–200 µg mL-1 with the correlation coefficient values 0.9964, 0.9948, 0.9900, 0.9999, 0.9992, and 0.9918 for Au(III); and Cr(VI), Fe(III), Fe(II), UO2(II), and Ni(II), respectively. Applicability of the method has been evaluated by determining gold from wastewater samples of goldsmith factories and uranyl from ore samples. The developed method was also used for the determination of chromium in selected environmental waters (drinking and polluted). The data obtained with developed method were compared with those obtained from atomic absorption spectroscopy, and the results of the analysis were found to be in good agreement.

6

Micellar electrokinetic chromatographic separation and quantitative analysis of thorium, uranium, gold, and mercury from environmental ore samples

Mallah A, Memon S. Q., Khuhawar M.Y., Solangi A. R., Bhanger M. I.

Acta Chromatographica

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2011

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Vol. 23, no. 1

69--80

EN

A rapid and reliable analytical procedure has been developed for the separation and analysis of dioxouranium, thorium, gold, and mercury by micellar electrokinetic chromatography (MEKC) using bis(acetylacetone)ethylenediamine (H2AA2en) as complexing reagent. Under the optimized conditions (64 mM borate buffer containing 12.25 mM SDS and 13% acetonitrile, pH 8.0, 25 kV, 311 nm as detection wavelength) the ions were separated within 5.0 min. Linear dynamic ranges were 1–5, 8–42, 10–50, and 2–40 μg mL -1, respectively, for gold, mercury, thorium, and uranium and the respective detection limits were 0.66, 3.33, 1.6, and 3.3 μg mL -1. The applicability of method has been evaluated by application to uranium and thorium from ore samples.

7

Micellar electrokinetic chromatographic separation and analysis of thorium, uranium, gold, and mercury in environmental ore samples

Mallah A, Memon S. Q., Solangi A. R., Khuhawar M. Y., Bhanger M. I.

Acta Chromatographica

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2010

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Vol. 22, no. 3

405--417

EN

A fast and reliable analytical procedure has been developed for separation and analysis of dioxouranium, thorium, gold, and mercury by micellar electrokinetic chromatography (MEKC) using bis(acetylacetone)ethylenediamine (H 2 AA 2 en) as complexing reagent. Under the optimized conditions (64 mM borate buffer containing 12.25 mM SDS and 13% acetonitrile, pH 7.99; 25 kV; detection wavelength 311 nm), other ions present were separated within 5 min. Linear dynamic ranges 1–5, 8–42, 10–50, and 2–40 μg mL -1 and detection limits 0.66, 3.33, 1.6, and 3.3 μg mL -1, respectively, were achieved for gold, mercury, thorium, and uranium. The applicability of method was evaluated by analysis of uranium and thorium in ore samples.

8

Quantitative analysis of eight cephalosporin antibiotics in pharmaceutical products and urine by capillary zone electrophoresis

Solangi A. R., Memon S. Q., Khuhawar M. Y., Bhanger M. I.

Acta Chromatographica

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2007

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No. 19

81-96

EN

A simple and rapid capillary zone electrophoretic (CZE) method has been established for separation and quantification of a mixture of eight ce-phalosporins – cefadroxil (CFL), cefixime (CIX), cefuroxime sodium (CFR), ceftriaxone sodium (CTR), ceftizoxime (CFT), cefaclor (CFC), cefradine (CFD), and cefotoxime (CTA). Conditions affecting the separation were pH, buffer concentration, and applied potential. Separation was performed in less than 11 min with 50 mM sodium tetraborate buffer, pH 9.0, and an applied potential of 30 kV. Reproducible separation was achieved and calibration plots were linear over two to three orders of magnitude of analyte concentration. Limits of detection were in the range 0.5–5 µg mL–1. De-tection was by UV absorbance at 214 nm. When the method was assessed for analysis of cephalosporins in pharmaceutical preparations and in urine, relative standard deviations (RSD, n = 4) were in the range 0.3–1.9%.