Lignin – from natural adsorbent to activated carbon: A review

Adsorption of metal ions on lignin

“…Demirbas [24] reported a maximum adsorption capacity of 8.2-9.0 mg/g for Pb(II) and 6.7-7.5 mg/g for Cd(II) on lignin from beech and poplar wood modified by alkaline glycerol delignification. From the above data and the review by Suhas et al [31] we find that there are significant differences in the metal sorption capacities of different types of lignin. Moreover, the related mechanisms of metal sorption by lignin are still subject to debate.…”

“…Similar to the adsorption kinetics, the maximum equilibrium adsorption capacity (q m ) was obtained for Pb(II) (0.432 mmol/g), which decreased to 0.360 mmol/g for Cu(II), 0.226 mmol/g for Cd(II), 0.172 mmol/g for Zn(II), and 0.102 mmol/g for Ni(II). The lignin in the present study showed higher adsorption capacities for the metal ions compared with the adsorption capacities of other lignin adsorbents published in the review paper [31] with the exception of the exceptionally high adsorption capacities reported by Srivastava et al and Mohan et al [16,20]. Tables 3 and 4.…”

“…Suhas et al [31] have reviewed the literature on lignin as a biosorbent. Srivastava et al [16] obtained remarkably high uptake of Pb(II) and Zn(II), up to 1587 and 73 mg/g for Pb(II) and Zn(II), respectively, by using lignin extracted from black liquor.…”

Lignin recovery from alkaline hydrolysis and glycerolysis of oil palm fiber

“…The first part was based on the hydrolysis or solubilisation of cellulose and hemicelluloses by chemical reagents leaving lignin as an insoluble material. Another part conducted are based on the dissolution or removal of lignin into the filtrate and can be recovered by subsequent treatment [6]. Some bases such as hydrogen peroxide, calcium hydroxide and sodium hydroxide can be used in alkaline extraction of lignin [5].…”

“…This treatment does not disturb the lignin aromatic structure significantly [7][8]. Alkaline hydrolysis requires lower temperature and pressure but the reaction time can be long compared to other methods [6]. Other lignin extracting method is through precipitation of black liquor by mineral acid.…”