Publications

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    ABSTRACT: The potential of Cr(VI) reduction by Escherichia coli in the presence of soluble Fe(III) was investigated to explore the chemo-biologically mediated reduction process under anaerobic condition. The reduction efficiency of Cr(VI) reached 95% within 24 h. The influences of experimental parameters, including initial pH, temperature, Fe(III) dosage, carbon source, and chelating agent, were also investigated. The highest efficiency of reduction was observed when pH was 5.8 and temperature was 32°C. Amendments of culture medium with Fe(III) and citric-3Na enhanced Cr(VI) reduction, while the addition of EDTA-2Na inhibited the process. Analysis showed that soluble Fe(III) enhanced the reduction process by shuttling electrons from bio-reduced Fe(II) to Cr(VI) in a coupled biotic-abiotic cycle and hence, Cr(VI) was reduced to Cr(III) followed by deposition to sludge.
    Desalination and water treatment 07/2014; 52. · 0.85 Impact Factor
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    ABSTRACT: Elevated arsenic concentrations have been detected in drinking water sources worldwide and it threatens to over 200 million people in both developing and developed countries. Adsorption is a conventional process for arsenic removal from contaminated water. Several classes of adsorbing materials have been tested so far. However, far less attention was paid towards granular-based adsorption and granulation processes. The present work is the first attempt to consider both the granular adsorbent and the granulation process. A particular emphasis was given to cost-efficient adsorbent for small scale arsenic removal. Some of the features of granular adsorbents are summarized in tables and graphs; address necessary outlines for readers to easily overview the adsorbents' characteristics and design sustainable adsorption system. Earlier, cost of arsenic removals from granular adsorbents were not widely affirmed, but in this review few of them are incorporated for comparisons in future studies. Thus, one gram of arsenic removal from water using novel and iron oxide-coated sand adsorbents is approximately ranged US$2.3–5.1 and US$3.3–4.2, respectively. Moreover, methods employed for regeneration of exhausted granular adsorbents are discussed. Field scale arsenic remediation measures and the performance evaluations are additionally reported to identify the feasibility of these approaches for scaling up, awareness raising and promotion.
    CLEAN - Soil Air Water 05/2014; · 2.05 Impact Factor
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  • Shams Ali Baig
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    ABSTRACT: Nanosized titanium nitride (nTiN) doped palladium/nickel (Pd/Ni) foam electrodes were successfully prepared via electroless deposition method. The electrodes were evaluated by different techniques including field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and linear sweep voltammetry (LSV). FE-SEM images demonstrated that two different morphologies existed in the Pd layer after nTiN doping. The nTiN doped Pd/Ni foam electrodes were found to be highly effective for electrochemical reductive dechlorination of 2,4-dichlorophenoxyacetic acid (2,4-D) with excellent activity and stability, as revealed by batch experiments. Under the conditions of nTiN doping content of 2 mg, Pd loading of 0.44 mg cm −2 , the energetic electrode achieved nearly 100% removal of 2,4-D (0.226 mmol L −1 ) within 2 h at a current density of 1.667 mA cm −2 . However, the removal efficiency reached only 57.13% when a normal Pd/Ni foam electrode with identical Pd loading and current density was utilized. A successive 2,4-D reductive dechlorination process was observed. o-Chlorophenoxyacetic acid (o-CPA), p-chlorophenoxyacetic acid (p-CPA) and phenoxyacetic acid (PA) were detected and identified as transformation products. Regression analysis proved that the pseudo-first order kinetic model was not suitable to describe the dechlorination process on nTiN doped Pd/Ni foam electrodes due to the appearance of a plateau in the beginning of the curve. Moreover, an adsorption theory for Pd chemisorption of active hydrogen atom was proposed to better explain the phenomenon. An adsorption equilibrium of hydrogen existed in the Pd lattice between hydrogen in Pd solid solution and hydrogen in metal hydride, which would influence the effective utilization of active hydrogen atom [H] for dechlorination treatment. An indirect reduction mechanism of the 2,4-D dechlorination on the as-prepared electrodes was also elucidated.
    Applied Catalysis B: Environmental 04/2014; 158-159:38-47. · 5.63 Impact Factor
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    ABSTRACT: In the present study, coupled reduction–sorption of Cr(VI) using three iron containing minerals (magnetite, hematite, and pyrrhotite) in aqueous solutions was investigated as a function of solution pH, contact time, and particle size. Detailed characterizations were performed using Brunauer–Emmett–Teller (BET), environmental scanning electron microscopy, and X-ray diffraction (XRD) techniques. Results demonstrated that over 99% of Cr(VI) removal was achieved just after 1 min of the reaction using pyrrhotite with particle size (100–200 mesh). In comparison, removal efficiency of hematite and magnetite against Cr(VI) was below 40% after 2 h of the reaction. Acidic aqueous medium proved effective for Cr(VI) removal and nearly 100% Cr(VI) removal was achieved at pH 3 using pyrrhotite (30–40 mesh), while the surface efficacy of hematite and magnetite has also improved in acidic solution. In terms of removal efficiency, the three minerals followed the order: pyrrhotite > magnetite > hematite. However, no significant difference in the BET specific surface area was recorded among these minerals, but the mineralogical compositions played an important role for removing Cr(VI) in aqueous solutions. Analysis of XRD pattern revealed that iron contents produce Fe3FeSiO4(OH)5 and FeCr2O4 after the reaction with soluble Cr(VI) and precipitated. This study suggested that high ferrous ions-based minerals can effectively remove Cr(VI) from contaminated water environments.
    CLEAN - Soil Air Water 02/2014; · 2.05 Impact Factor
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    ABSTRACT: The adsorptive removal of As(V) from aqueous solutions using iron-coated honeycomb briquette cinder (Fe-HBC) is presented. Low cost mechanical granulation process was integrated with surface amendment technology to prepare iron-oxide modified granular adsorbent for clean water production. Detailed characterizations were performed using FTIR, XRD, EDS and SEM techniques. Operating parameters including initial As(V) concentration, pH, contact time, adsorbent dose, iron leaching and the effects of competing ions on As(V) removal were evaluated. Results demonstrated that high amount of arsenate (961.5 μg g−1) was adsorbed at pH 7.5 in 14 h contact time. Langmuir, Freundlich and Temkin isotherm models were used to analyze the adsorption data, whereas Langmuir model was found to best represent the data with a correlation co-efficient (R2 = 0.999). Thus, As(V) sorption on Fe-HBC surface suggested monolayer adsorption and indicated surface homogeneity. Moreover, the dimensionless parameter (RL) value calculated to be about 0.118 that reiterated the process is favorable and spontaneous. The influences of competing ions on As(V) removal decreased in the following order: PO43->HCO3->F->Cl-. The profound inhibition effects of PO43- revealed a high affinity toward iron(oxy) hydroxide. Life-cycle assessment confirmed that spent HBC is non-hazardous and can be used as a promising sorbent for arsenic removal.
    Arabian Journal of Chemistry 01/2014; 7(1):27–36. · 2.27 Impact Factor
  • Chemical Engineering Journal. 01/2014; 257:1–9.
  • Applied Catalysis B: Environmental. 01/2014; s 158–159:38–47.
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    ABSTRACT: The presence of elevated concentration of arsenic in water sources is considered to be health hazard globally. Calcination process is known to change the surface efficacy of the adsorbent. In current study, five adsorbent composites: uncalcined and calcined Fe3O4-HBC prepared at different temperatures (400°C and 1000°C) and environment (air and nitrogen) were investigated for the adsorptive removal of As(V) and As(III) from aqueous solutions determining the influence of solution's pH, contact time, temperature, arsenic concentration and phosphate anions. Characterizations from FTIR, XRD, HT-XRD, BET and SEM analyses revealed that the Fe3O4-HBC composite at higher calcination temperature under nitrogen formed a new product (fayalite, Fe2SiO4) via phase transformation. In aqueous medium, ligand exchange between arsenic and the effective sorbent site ( = FeOOH) was established from the release of hydroxyl group. Langmuir model suggested data of the five adsorbent composites follow the order: Fe3O4-HBC-1000°C(N2)>Fe3O4-HBC (uncalcined)>Fe3O4-HBC-400°C(N2)>Fe3O4-HBC-400°C(air)>Fe3O4-HBC-1000°C(air) and the maximum As(V) and As(III) adsorption capacities were found to be about 3.35 mg g-1 and 3.07 mg g-1, respectively. The adsorption of As(V) and As(III) remained stable in a wider pH range (4-10) using Fe3O4-HBC-1000°C(N2). Additionally, adsorption data fitted well in pseudo-second-order (R2>0.99) rather than pseudo-first-order kinetics model. The adsorption of As(V) and As(III) onto adsorbent composites increase with increase in temperatures indicating that it is an endothermic process. Phosphate concentration (0.0l mM or higher) strongly inhibited As(V) and As(III) removal through the mechanism of competitive adsorption. This study suggests that the selective calcination process could be useful to improve the adsorbent efficiency for enhanced arsenic removal from contaminated water.
    PLoS ONE 01/2014; 9(6):e100704. · 3.73 Impact Factor
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    ABSTRACT: Flue gas desulfurization system used for SO2 removal has co-beneficial removal of Hg, which has resulted in Hg-laden gypsums. With growing beneficial reuse applications of the FGD gypsum, it has been recognized as a potential source of Hg pollution. In this paper, the fate and mobility of Hg were investigated. The Hg content in four samples varied widely and it showed a significant correlation between Hg and sulfite contents in gypsum. In leachate, Hg concentration varied during the leaching process. The Hg extraction rate generally increased with decreasing pH value, which suggested that the environmental risk of FGD gypsum increased during the multipurpose utilization processes, resulted from severe acid rain. The released Hg from FGD gypsum used in this study exhibited biphasic kinetics. Hg in FGD gypsum samples not only appeared in the leachate but also re-emitted into the air. The Hg reduction kinetics followed the pseudo-first-order kinetic model well. Our results provide the theoretical understanding for the co-removal of highly soluble oxidized Hg in WFGD systems and also in the recycling of the FGD gypsum.
    Fuel Processing Technology 01/2014; 118:28–33. · 2.82 Impact Factor
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    Shams Ali Baig
    Ecological Engineering 09/2013; 60:345-353. · 2.96 Impact Factor
  • Shams Ali Baig
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    ABSTRACT: Cr(VI) is a toxic pollutant and its reduction to relatively less toxic Cr(III) can solve this problem to a greater extent. In the present study, coupled reduction–sorption of Cr(VI) in aqueous solutions using limonite was investigated as a function of pH, limonite dose and particle size. Results demonstrated that the smaller limonite particle size and low pH aqueous medium favored high Cr(VI) removal. Significant Cr(VI) removal (> 55 ± 1%) was achieved with 100–200 mesh, whereas only 25 ± 0.7% and 10 ± 0.5% removals were attained using 30–40 mesh and 20–30 mesh, respectively, after 2 h reaction. Acid pH proved beneficial and the complete Cr(VI) removal was observed at pH < 4.0 compared to that of 10 ± 0.5% at pH 9.0. Moreover, above 53 ± 2.5% of Cr(VI) removal rates were maintained in the first three batch experiment runs and then drastically decreased to below 5 ± 0.3% in experiment Run-7. The Brunauer–Emmett–Teller (BET) surface area and sorption capacity of limonite were 35.22 m2 g− 1 and 10.03 mg g− 1, respectively. The reaction mechanism demonstrated that under acidic aqueous medium, the dissolved Fe(II) and S(II) on limonite surface reacted with Cr(VI) and formed Cr3S4 and Cr5Si3 precipitates. But the resultant precipitates on limonite surface hindered further Cr(VI) removal and passivated, affirmed in XRD and ESEM analyses. This study suggested that limonite can be used for the effective removal of Cr(VI) from contaminated water environments.
    Hydrometallurgy 06/2013; 138:33-39. · 2.17 Impact Factor
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    Desalination and water treatment 05/2013; 51(16-18):3454-3462. · 0.85 Impact Factor
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    ABSTRACT: The water quality and cyanobacterial variation of rivers surrounding southern Taihu Lake, China were purposively monitored from 2008 to 2010. Trophic level index (TLI) was used to evaluate the trophic levels of southern Taihu Lake. Results showed a considerable decline in the monitored data compared with 2007, and the data showed downward trends year after year. The TLI decreased from 55.6 to 51.3, which implied that southern Taihu Lake was mildly eutrophic. The water quality and cyanobacterial variation indicated a positive response to the adopted control measures in the southern Taihu Lake basin, but the intra- and inter-annual variability was still quite varied. High concentrations of nitrogen and phosphorus typically lead to algae outbreaks, however, the cyanobacteria growth may result in a decline of the concentration of nitrogen and phosphorus. Temperature and other weather conditions are also important factors for algae outbreaks; the risk of blue-green algal blooms still persists.
    Water Environment Research 05/2013; 85(5):397-403. · 1.13 Impact Factor
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    ABSTRACT: The suppressed ion chromatography (IC) and molybdenum blue methods were used to comparatively evaluate phosphorus (P) concentrations. Most of the P was more resistant to hydrolysis in ion chromatography as compared to the molybdenum blue method. However, P analysis by IC is more liable to be interfered than the molybdenum blue method because of the presence of high bivalent and trivalent metal ions. Polyvalent metal ions interfere with organic P hydrolysis or the release of P from colloids during P investigation, which leads to a difference of ortho-phosphate concentrations determined by IC and molybdenum blue methods. During the environmental samples analysis, the ortho-phosphate obtained by the IC method was usually less than that obtained by the molybdenum blue method.
    Communications in Soil Science and Plant Analysis 01/2013; 44(17). · 0.42 Impact Factor
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    ABSTRACT: Palladium/Iron (Pd/Fe) nanoparticles were prepared by using ultrasound strengthened liquid phase reductive method to enhance dispersion and avoid agglomeration. The dechlorination of 2,4-dichlorophenol (2,4-DCP) by Pd/Fe nanoparticles was investigated to understand its feasibility for an in situ remediation of contaminated groundwater. Results showed that 2,4-DCP was first adsorbed by Pd/Fe nanoparticles, then quickly reduced to o-chlorophenol (o-CP), p-chlorophenol (p-CP), and finally to phenol (P). The induction of ultrasound during the preparation of Pd/Fe nanoparticles further enhanced the removal efficiency of 2,4-DCP, as a result, the phenol production rates increased from 65% (in the absence of ultrasonic irradiation) to 91% (in the presence of ultrasonic irradiation) within 2h. Our data suggested that the dechlorination rate was dependent on various factors including Pd loading percentage over Fe(0), Pd/Fe nanoparticles availability, temperature, mechanical stirring speed, and initial pH values. Up to 99.2% of 2,4-DCP was removed after 300min reaction with these conditions: Pd loading percentage over Fe(0) 0.3wt.%, initial 2,4-DCP concentration 20mgL(-1), Pd/Fe dosage 3gL(-1), initial pH value 3.0, and reaction temperature 25°C. The degradation of 2,4-DCP followed pseudo-first-order kinetics reaction and the apparent pseudo-first-order kinetics constant was 0.0468min(-1).
    Ultrasonics Sonochemistry 12/2012; · 3.52 Impact Factor
  • Jiang Xu, Jie Tang, Shams Ali Baig, Xiaoshu Lv, Xinhua Xu
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    ABSTRACT: The Pd/FeFe(3)O(4) nanocomposites showed higher dechlorination efficiency of 2,4-dichlorophenol (2,4-DCP) rather than bare Pd/Fe nanoparticles in the batch dechlorination experiments. nFe(3)O(4) provided a convenient way to recycle the nanocomposites with an external magnetic field and significantly enhanced 2,4-DCP dechlorination. 2.0gL(-1)nFe(3)O(4) was the optimal dosage in the presence of 3gL(-1) Pd/Fe nanoparticles in our system, removing 76.4% 2,4-DCP within 5h in the aqueous environment. This was much higher than bare Pd/Fe nanoparticles (35.8%), 1.0gL(-1)nFe(3)O(4) (58.0%) and 2.5gL(-1)nFe(3)O(4) (66.3%) employed under the same conditions. However, excessive nFe(3)O(4) (3.0gL(-1)) partially overlapped on Pd/Fe nanoparticles to obstruct their contact with 2,4-DCP, and then 2,4-DCP removal efficiency was dropped to 7.4%. Efficiencies of dechlorination and phenol formations were increased significantly when the amount of Pd increased, whereas the highest 2,4-DCP removal efficiency was observed 98.2% at 0.20wt% Pd loading. Moreover, SO(4)(2-) would also inhibit the dechlorination while Cu(2+), Ni(2+) and Fe(2+) enhanced the dechlorination of 2,4-DCP by Pd/FeFe(3)O(4) nanocomposites. The nanocomposites showed stable catalytic activity, fairly good mechanic stability, and promising to recycle during the process.
    Journal of hazardous materials 11/2012; · 4.14 Impact Factor
  • Zhen Zhang, Sai Hu, Shams Ali Baig, Jie Tang, Xinhua Xu
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    ABSTRACT: Ni/Fe bimetallic nanoparticles were synthesized for treatment of Aroclor 1242, in order to evaluate their applicability for in situ remediation of groundwater and soil contaminated by polychlorinated biphenyls (PCBs). Our experimental results indicate that the total PCB concentration changed during the reduction of 3,5-dichlorobiphenyl (PCB 14), and biphenyl was produced as the final product. Initially, the concentration of 3-chlorobiphenyl (PCB 2) was increased in the prophase reaction and then slowly decreased, suggesting that Aroclor 1242 was first adsorbed by Ni/Fe nanoparticles, and then, the higher chlorinated congeners were converted gradually to the lower chlorinated congeners, and finally to biphenyl. The dechlorination efficiency of Aroclor 1242 reached approximately 80% at 25°C in just 5h, then 95.6% and 95.8% in 10h and 24h, respectively. The study revealed that high Ni/Fe nanoparticle dosage and high Ni content in Ni/Fe nanoparticles favor the catalytic dechlorination reaction. Moreover, a comparison of different types of catalysts on the dechlorination of Aroclor 1242 indicated that Ni/Mg and Mg powders showed a greater reactivity than Ni/Fe and Fe nanoparticles, respectively.
    Journal of Colloid and Interface Science 07/2012; 385(1):160-5. · 3.17 Impact Factor
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    Journal of Applied Sciences in Environmental Sanitation. 07/2012; 7(1):49-54.
  • Shams Ali A Baig, Xinhua Xu, Rashid Khan
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    ABSTRACT: In mid-July 2010 flash flooding in Pakistan destroyed the basic water, environmental sanitation and livelihood infrastructures in 82 districts. Two months later, the local press of Swat (northern Pakistan) reported that several residents of Marghazar town became ill and were hospitalized after drinking contaminated water. A non-governmental organization (Oxfam GB) team took action to determine the causes of this incident and analyzed the community drinking water supply. Standard methods were used to analyze six physio-chemical and four microbiological water quality parameters at five selected sampling locations in the water supply system. The samples from sites numbers (SN)02, 03, 04 and 05 were found to be microbiologically unfit for drinking due to the presence of Escherichia coli , Shigella , Salmonella and Staphylococcus aureus (range 18-96 ± 14 cfu/100 mL). However, the pH, conductivity, total dissolved solid, total hardness as calcium carbonate and nitrate as NO<sub>3</sub>-2 of all the samples were within WHO permissible limits. Higher turbidities were recorded at SN04 and 05 of 6 ± 0.23 and 9 ± 1.23, respectively. Quantitative results revealed the presence of pathogenic organisms and water quality risk factors due to the damaged water and environmental sanitation infrastructure. Continued water quality monitoring, the application of household based disinfectants, and healthy domestic hygiene practices are highly recommended in similar circumstances.
    Rural and remote health 07/2012; 12(3):2196. · 0.98 Impact Factor

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