Removal of mercury from water by carbonaceous sorbents derived from walnut shell

• Published in: Journal of hazardous materials Vol. 167; no. 1; pp. 230 - 236
• Main Authors: Zabihi, M., Ahmadpour, A., Asl, A. Haghighi
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15.08.2009; Elsevier
• Subjects: Adsorption; Applied sciences; Carbon - chemistry; Charcoal; Chemical engineering; Chlorides; Exact sciences and technology; Juglans; Kinetic; Kinetics; Mercury; Mercury - isolation & purification; Plant Structures; Pollution; Sorbent; Walnut shell; Water Pollutants - isolation & purification; Zinc Compounds; Adsorption; Kinetic; Sorbent; Walnut shell; Mercury; Second order; Adsorption isotherm; Metal ion; Activation; Density; Uptake; Powder; Heavy metal; Operating conditions; Sorption; Microporosity; Activated carbon; Preparation; pH; Kinetics; Aqueous solution; Surface area; Iodine
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2008.12.108

The adsorption ability of a powdered activated carbon (PAC) derived from walnut shell was investigated in an attempt to produce more economic and effective sorbent for the control of Hg(II) ion from industrial liquid streams. Carbonaceous sorbents derived from Iranian walnut shell (WS) were prepared by chemical activation method using ZnCl 2 as an activating reagent. To the best of our knowledge, this adsorbent was not used before for removing mercury from water. Adsorption of Hg(II) from aqueous solutions was carried out under different experimental conditions by varying treatment time, metal ion concentration, adsorbent amount, pH and solution temperature. It was determined that Hg(II) adsorption follows both Langmuir and Freundlich isotherms as well as pseudo-second-order kinetics. It was also shown that Hg(II) uptake decreases with increasing pH of the solution. The proper choice of preparation conditions resulted in a microporous activated carbon with 0.45 g/cm 3 density, 737 mg/g iodine number and 780 m 2/g BET surface area. The monolayer sorption capacity of this optimum adsorbent was obtained as 151.5 mg/g.