Biosorption of Cr(VI) on Japanese Cedar Bark

Mechanisms of the removal of hexavalent chromium by biomaterials or biomaterial-based activated carbons

“…It has been proved that, when Cr(VI) comes in contact with organic substances or reducing agents, especially in an acidic medium, the Cr(VI) is easily or spontaneously reduced to the Cr(III), because Cr(VI) has high redox potential value (above +1.3 V at standard condition) [4][5][6][7][8][9][10][11][12][13][14][15][16]. Therefore, it is very important to check the reduction of Cr(VI) by organic materials.…”

Removal of Cr(VI) from aqueous solutions by the culm of bamboo grass treated with concentrated sulfuric acid

“…The Langmuir constant Q 0 increased from 76.3 to 84.0 mg g -1 with rising temperature from 5 to 25°C, indicating that the process is endothermic. The sorption capacity compares favorably with those of the other lignocellulosic sorbents (Aoyama and Tsuda 2001;Aoyama 2003;Aoyama et al 2004). The increase in the sorption of Cr with rising temperature is explained by the thermodynamic parameters such as changes in Gibbs free energy (DG 0 ), enthalpy (DH 0 ), and entropy (DS 0 ), which are determined using the following Eqs.…”

Heavy metals removal in aqueous environments using bark as a biosorbent

“…Only in one research (Aoyama et al 2004), the inner and outer barks of Cryptomeria japonica were tested separately for heavy metal adsorption and concluded that adsorption capacity was higher in the outer bark (rhytidome) than in the inner bark (phloem): At the same experimental conditions, Cr(VI) uptake values of inner bark and outer bark were 23.0 and 28.4 mg/g, respectively. However, more studies are needed before making a generalization on the adsorption differences between the differentiated parts of bark.…”

“…Abundant, renewable and low-cost barks appear as excellent alternatives to ion-exchange resins and activated carbon for industrial applications. Other important advantages of barks are their adsorption capacity at low metal concentrations (below 100 ppm) (Vazquez et al 2002) and their reductive ability which is important in chromium (VI) removal (Fiol et al 2003;Aoyama et al 2004;Ş en et al 2012).…”