Single, binary and multi-component adsorption of copper and cadmium from aqueous solutions on Kraft lignin—a biosorbent

• Published in: Journal of colloid and interface science 2006-05, Vol.297 (2), p.489-504
• Main Authors: Mohan, Dinesh, Pittman, Charles U., Steele, Philip H.
• Format: Article
• Language: English
• Subjects: Adsorption; Black liquor; Cadmium; Cadmium - isolation & purification; Chemistry; Copper; Copper - isolation & purification; Diffusion; Exact sciences and technology; General and physical chemistry; Kinetics; Lignin; Metal ions removal; Multi-component adsorption; Solutions; Surface physical chemistry; Thermodynamics; Water Pollutants, Chemical - isolation & purification; Water Purification - methods
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2005.11.023

A new biosorbent for removing toxic metal ions from water/industrial wastewater has been investigated using by-product lignin from paper production. Lignin was extracted from black liquor waste, characterized and utilized for the removal of copper and cadmium from aqueous solutions in single, binary and multi-component systems. Adsorption studies were conducted at different temperatures, lignin particle sizes, pHs and solid to liquid ratios. All the studies were conducted by a batch method to determine equilibrium and kinetic parameters. The Langmuir and Freundlich isotherm models were applied. The Langmuir model fits best the equilibrium isotherm data. The maximum lignin adsorption capacities at 25 °C were 87.05 mg/g (1.37 mmol/g) and 137.14 mg/g (1.22 mmol/g) for Cu(II) and Cd(II), respectively. Adsorption of Cu 2+ (68.63 mg/g at 10 °C and 94.68 mg/g at 40 °C) and Cd 2+ (59.58 mg/g at 10 °C and 175.36 mg/g at 40 °C) increased with an increase in temperature. Copper and cadmium adsorption followed pseudo-second order rate kinetics. From kinetic studies, various rate and thermodynamic parameters such as effective diffusion coefficients, activation energy, and activation entropy were evaluated. Adsorption occurs through a particle diffusion mechanism at temperatures 10 and 25 °C while at 40 °C it occurs through a film diffusion mechanism. The sorption capacity of black liquor lignin is higher than many other adsorbents/carbons/biosorbents utilized for the removal of Cu(II) and Cd(II) from water/wastewater in single and multi-component systems. Kraft lignin derived from Eucalyptus black Liquor can be used as a metal ion adsorbent for treating water/wastewater contaminated with Cu(II) and/or Cd(II) in both single and multicomponent systems. The use of Kraft lignins as a value added adsorbent (over its fuel value), while simultaneously reducing the quantity of this waste, should be now considered. The sorption capacity of this biosorbent is higher than adsorbents/carbons/biosorbents now utilized for the removal of Cu(II) and Cd(II) from water/wastewater