Mercury(II) removal from aqueous solutions and wastewaters using a novel cation exchanger derived from coconut coir pith and its recovery.
A new adsorbent (PGCP-COOH) having carboxylate functional group at the chain end was synthesized by grafting poly(hydroxyethylmethacrylate) onto coconut coir pith, CP (a coir industry-based lignocellulosic residue), using potassium peroxydisulphate as an initiator and in the presence of N,N'-methylenebisacrylamide as a cross-linking agent. The adsorbent was characterized with the help of infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, and potentiometric titrations. The ability of PGCP-COOH to remove Hg(II) from aqueous solutions was assessed using batch adsorption technique under kinetic and equilibrium conditions. Adsorbent exhibits very high adsorption potential for Hg(II) and more than 99.0% removal was achieved in the pH range 5.5-8.0. Adsorption process was found to follow first-order-reversible kinetics. An increase of ionic strength of the medium caused a decrease in metal removal, indicating the occurrence of outer-sphere surface complex mechanism. The equilibrium data were fitted well by the Freundlich isotherm model (R(2)=0.99; chi(2)=1.81). The removal efficiency was tested using chlor-alkali industry wastewater. Adsorption isotherm experiments were also conducted for comparison using a commercial carboxylate-functionalized ion exchanger, Ceralite IRC-50. Regeneration experiments were tried for four cycles and results indicate a capacity loss of <9.0%.
Anirudhan
T S
TS
Department of Chemistry, University of Kerala, Kariavattom, Trivandrum, India. tsani@rediffmail.com <tsani@rediffmail.com>
Divya
L
L
Ramachandran
M
M
D000327:Adsorption; D002412:Cations; D016009:Chi-Square Distribution; D003059:Cocos / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry; D007700:Kinetics; D008031:Lignin / Q000031:analogs & derivatives* / Q000737:chemistry; D008628:Mercury / Q000737:chemistry / Q000302:isolation & purification*; D008855:Microscopy, Electron, Scanning; D015394:Molecular Structure; D011102:Polyhydroxyethyl Methacrylate / Q000031:analogs & derivatives / Q000737:chemistry; D012996:Solutions / Q000737:chemistry; D013055:Spectrophotometry, Infrared; D017186:Titrimetry; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*; D014961:X-Ray Diffraction
D002412:Cations; D003432:Cross-Linking Reagents; D012996:Solutions; D014874:Water Pollutants, Chemical; C507903:coir; D011102:Polyhydroxyethyl Methacrylate; C047731:hydroxyethyl methacrylate-ethyl methacrylate; D008031:Lignin; D008628:Mercury