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Novel lignocellulosic wastes for comparative adsorption of Cr(VI): equilibrium kinetics and thermodynamic studies

Haroon H., Gardazi S. M. H., Butt T. A., Pervez A., Mahmood Q., Bilal M.

Polish Journal of Chemical Technology

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2017

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Vol. 19, nr 2

6--15

EN

Cr(VI) adsorption was studied for abundantly available low-cost lignocellulosic adsorbents in Pakistan namely, tobacco stalks (TS), white cedar stem (WCS) and eucalyptus bark (EB). Several process variables like contact time, adsorbent dose, pH, metal concentration, particle size and temperature were optimized in batch mode. EB showed high Cr(VI) adsorption of 63.66% followed by WCS 62% and TS 57% at pH 2, which is higher than most of the reported literature. Langmuir isotherm (R2 = 0.999) was well fitted into the equilibrium Cr(VI) data of EB, suggesting homogeneous active sites and monolayer coverage of Cr(VI) onto the EB surface. Freundlich (R2 = 0.9982) isotherm was better fitted to the equilibrium data of TS and WCS, revealing the adsorption sites with heterogeneous energy distribution and multilayer Cr(VI) adsorption. Moreover, the Cr(VI) adsorption of studied adsorbents followed the pseudo-second order kinetic model. Thermodynamic properties were investigated in two temperature ranges, i.e., T1 (303–313 K) and T2 (313–323 K). TS and EB showed the exothermic at T1 and endothermic reactions at T2 with entropy controlled adsorption at the solid-liquid interface, and WCS exhibited an opposite thermal trend with decreasing disorderness at solid-liquid interface as temperature rises. Gibbs free energy (ΔG>0) confirmed the non-spontaneous adsorption process for all studied adsorbents.

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Boundary layer flow of magneto-micropolar nanofluid flow with Hall and ion-slip effects using variable thermal diffusivity

Bilal M., Hussain S., Sagheer M.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2017

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Vol. 65, nr 3

383--390

EN

In the present article, magneto-micropolar nanofluid flow with suction or injection in a porous medium over a stretching sheet for the heat and mass transfer is analyzed numerically. Both Hall and ion-slip effects are considered along with variable thermal diffusivity. The governing partial differential equations are transformed to ordinary differential equations using usual similarity transformations. These coupled non-linear differential equations are solved using the shooting method. Effects of prominent parameter on velocities, temperature and concentration are discussed graphically. Numerical values of skin-friction coefficient, local Nusselt number and local Sherwood number are also tabulated and discussed.

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Prediction and Correlation of Air Permeability and Light Transmission Properties of Woven Cotton Fabrics

Nazir A., Hussain T., Afzal A., Faheem S., Ibrahim W., Bilal M.

Autex Research Journal

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2017

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Vol. 17, no. 1

61--66

EN

The aim of this study was to develop statistical models for predicting the air permeability and light transmission properties of woven cotton fabrics and determine the level of correlation between the two parameters. Plain woven fabrics were developed with different warp and weft linear densities, ends per inch and picks per inch. After desizing, scouring, bleaching, drying and conditioning, the air permeability and light transmission properties of the fabric samples were determined. Regression analysis results showed statistically significant effect of the fabric ends, picks and warp linear density on both the fabric air permeability and light transmission. Correlation analysis was performed to analyze the relation between the fabric air permeability and light transmission. A linear equation was also formulated to find the fabric air permeability through transmission of light intensity. A fitted line plot between the air permeability and light transmission exhibited significant correlation with R-sq. value of 96.4%. The statistical models for the prediction of fabric air permeability and light transmittance were developed with an average prediction error of less than 7%.