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    Description

    In this study the capacity of sorbents prepared from juniper wood (JW) and bark (JB) to adsorb cadmium (Cd) from aqueous solutions at different pH values was compared. Adsorption behavior was characterized through adsorption kinetics, adsorption isotherms, and adsorption edge experiments. Results from kinetics and isotherm experiments showed that JB (76.3–91.6 lmol Cd g_1 substrate) had 3–4 times higher adsorption capacity for Cd than JW (24.8–28.3 lmol Cd g_1). In addition to higher capacity, JB exhibited a higher strength of adsorption (45.3 versus 9.1 L mmol_1) and faster uptake kinetics (0.0119 versus 0.0083 g lmol_1 min_1) compared to JW. For both these adsorbents, increasing Cd adsorption with increasing solution pH in the range of 2–6 suggests that surface carboxyl groups (RCOOH) might be involved in interaction with Cd. Diffuse reflectance infrared Fourier transform (DRIFT) spectra showed that the surface concentration of carboxyl groups was higher on JB compared to JW. The ratio of Ca released to Cd adsorbed was 1.04 and 0.78 for JB and JW, respectively, indicating that Ca–Cd ion-exchange was the primary mechanism involved. The higher Ca content in JB (15 times more) and the surface RCOOH concentration (2.5 times more) can be attributed to the observed differences in Cd adsorption behavior between the two lignocellulosic adsorbents.

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    Citation

    Shin, Eun Woo; Karthikeyan, K. G.; Tshabalala, Mandla A. 2007. Adsorption mechanism of cadmium on juniper bark and wood. Bioresource technology. Vol. 98 (2007): pages 588-594.

    Keywords

    Bark, wood, lignocellulosic sorbents, cadmium, calcium, adsorption, ion- exchange, chemical kinetics, lignocellulose, metal ions, absorption, fourier transform infrared spectroscopy, water quality management, juniper, utilization, water pollution, heavy metals, carboxyl groups, kinetics, lignocellulosic fibers

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https://www.fs.usda.gov/treesearch/pubs/27105