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1

Heavy metal adsorption by dewatered iron-containing waste sludge

Yildiz S., Sevinç S.

Ecological Chemistry and Engineering. S

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2018

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Vol. 25, nr 3

431--456

EN

Drinking water treatment plants produce significant amounts of waste sludge. In this study, removal of Nickel ion by use of wastewater sludge was aimed. The adsorption capability of waste sludge was optimized with varying physical parameters such as pH, adsorbent dosage, adsorbate concentration, contact time, shaking speed and temperature. Initial concentration was set as 25 mg/dm3, absorbent dose was set as 0.3 g/cm3, and temperature was set as 25 °C. Compliance of balance data with Langmuir, Freundlich, Temkin and D-R isotherm models was investigated. The highest R 2 values were obtained with Freundlich isotherm (R 2 = 0.92-0.95). Adsorption kinetics was analysed using pseudo-first order, pseudo-second order, Weber and Morris intraparticle diffusion and Elovich kinetic models, and the system was found to be in a better compliance with pseudo-second order kinetic model. Iron sludge was used as sorbent, and accordingly total iron ion measurements were carried out to determine its possible effects on water. Additionally, SEM, EDX, FTIR spectroscopy, XRD spectrum and atomic force microscope (AFM) measurements were conducted to determine the interaction between the sorbent and metal ions, in addition to characterization of the sorbent. As indicated by research results, drinking water treatment sludge proved to be a potential adsorbent for removal of nickel(II) ions from the solution.

2

Artificial neural network approach for modeling of Ni(II) adsorption from aqueous solution by peanut shell

Yildiz S.

Ecological Chemistry and Engineering. S

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2018

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Vol. 25, nr 4

581--604

EN

In this study, ANN (artificial neural network) model was applied to estimate the Ni(II) removal efficiency of peanut shell based on batch adsorption tests. The effects of initial pH, metal concentrations, temperature, contact time and sorbent dosage were determined. Also, COD (chemical oxygen demand) was measured to evaluate the possible adverse effects of the sorbent during the tests performed with varying temperature, pH and sorbent dosage. COD was found as 96.21 mg/dm3 at pH 2 and 54.72 mg/dm3 at pH 7. Also, a significant increase in COD value was observed with increasing dosage of the used sorbent. COD was found as 12.48 mg/dm3 after use of 0.05 g sorbent and as 282.78 mg/dm3 after use of 1 g sorbent. During isotherm studies, the highest regression coefficient (R 2) value was obtained with Freundlich isotherm (R 2 = 0.97) for initial concentration and with Temkin isotherm for sorbent dosage. High pseudo-second order kinetic model regression constants were observed (R 2 = 0.95-0.99) during kinetic studies with varying pH values. In addition, Ni(II) ion adsorption on peanut shell was further defined with pseudo-second order kinetic model, since qe values in the second order kinetic equation were very close to the experimental values. The relation between the estimated results of the built ANN model and the experimental results were used to evaluate the success of ANN modeling. Consequently, experimental results of the study were found to be in good agreement with the estimated results of the model.

3

Adsorption kinetic, equilibrium and thermodynamic investigations of Zn(II) and Ni(II) ions removal by poly(azomethinethioamide) resin with pendent chlorobenzylidine ring

Kumar P. S., Ethiraj H., Venkat A., Deepika N., Nivedha S., Vidhyadevi T., Ravikumar L., Sivanesan S.

Polish Journal of Chemical Technology

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2015

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Vol. 17, nr 3

100--109

EN

This paper reports the application of poly(azomethinethioamide) (PATA) resin having the pendent chlorobenzylidine ring for the removal of heavy metal ions such as Zn(II) and Ni(II) ions from the aqueous solutions by adsorption technology. Kinetic, equilibrium and thermodynamic models for Zn(II) and Ni(II) ions adsorption were applied by considering the effect of contact time, initial metal ion concentration and temperature data, respectively. The adsorption influencing parameters for the maximum removal of metal ions were optimized. Adsorption kinetic results followed the pseudo-second order kinetic model based on the correlation coefficient (R2) values and closed approach of experimental and calculated equilibrium adsorption capacity values. The removal mechanism of metal ions by PATA was explained with the Boyd kinetic model, Weber and Morris intraparticle diffusion model and Shrinking Core Model (SCM). Adsorption equilibrium results followed the Freundlich model based on the R2 values and error functions. The maximum monolayer adsorption capacity of PATA for Zn(II) and Ni(II) ions removal were found to be 105.4 mg/g and 97.3 mg/g, respectively. Thermodynamic study showed the adsorption process was feasible, spontaneous, and exothermic in nature.

4

Zdolności adsorpcyjne modyfikowanych bentonitów wobec adsorbatów kationowych

Ziółkowska D., Szymańska D., Waszak K., Shyichuk A.

Inżynieria i Ochrona Środowiska

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2006

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T. 9, nr 4

457-466

PL

Przemysłowy bentonit sodowy poddano obróbce chemicznej za pomocą roztworów NaOH i H2SO4 oraz obróbce termicznej. Próbki bentonitu surowego oraz modyfikowanego badano pod kątem ich przydatności jako ekonomicznych adsorbentów stosowanych do usuwania barwników kationowych oraz jonów metali z roztworów wodnych. Wielkości powierzchni właściwych adsorbentów oszacowano na podstawie adsorpcji błękitu metylenowego. Stwierdzono, że tak określone powierzchnie właściwe bentonitów nie korelują z powierzchniami wyznaczonymi metodą BET. Izotermy adsorpcji błękitu metylenowego i jonów Ni(II) dla bentonitu surowego oraz próbek modyfikowanych wyznaczono metodą statyczną w temperaturze pokojowej. Surowy bentonit jest skutecznym adsorbentem dla błękitu metylenowego, osiągając pojemność adsorpcyjną 122 mg/g. Bentonit może być także stosowany do usuwania jonów Ni(II) z roztworów wodnych, gromadząc 21 mg Ni²+/g. Jego pojemność adsorpcyjna względem jonów Ni(II) zwiększa się o 14% na skutek przemywania roztworem NaOH.

EN

Industrial Na-bentonite was examined as an economic adsorbent employed for elimination of cationic dyes and metal ions from aqueous solutions. Four adsorbent samples were prepared: a non-modified bentonite, that washed with 1M H2SO4 solution, that washed with 1M NaOH solution as well as that heated at 750°C. The adsorption isotherms of methylene blue as well as Ni(II) ions were determined for all the bentonite samples. The batch experiment was carried out at the room temperature. Adsorbate concentrations were determined with the spectrophotometric method (λ = 666 nm) for methylene blue and AAS for Ni(II) ions. Experimental adsorption isotherms were described with the Langmuir and Freundlich equations. Bentonite was found as the effective adsorbent for both the dye and the Ni(II) ions comparing to other clay minerals - its adsorption capacity reaches values 122 and 21 mg/g, respectively. The methylene blue dye appeared to have a quite high affinity to bentonite (the isotherms are of the Langmuire shape) whereas Ni(II) ions have less affinity to bentonite (almost all the isotherms are of the Freundlich shape). Adsorption capacity of bentonite towards Ni(II) ions was improved by 14% as a result of washing with NaOH solution or by 20% as a result of calcination. It is worth to notice that basic modification of adsorbent is efficient at low concentrations of nickel in the solution. It was also observed that specific surface areas of bentonite samples depicted with BET method do not agree with those obtained with the aid of methylene blue adsorption.