2008, Vol.9, No.1

Carbon Letters 2023 KCI Impact Factor : 1.35 KCI-WoS Impact Factor : 4.82

pISSN : 1976-4251 / eISSN : 2233-4998
https://journal.kci.go.kr/carbon

The ability of cow dung ash without any pretreatment to remove color from textile dyes N Blue RGB, Green B and EOSINYWS from aqueous solution has been investigated in this work. Cow dung ash, an ecofriendly and low cost adsorbent wasprepared by burning cow dung cakes in the mufle furnace at 500˚C. The adsorption was achieved under diferent pH andadsorbate concentration. The data was fitted to simple polynomial and the isotherms similar to Langmuir and Freundlichisotherms.

Oxidized activated carbons were prepared by reacting steam-activated carbon developed from pecan shells with nitric acidof varying strength (15, 30, 45 and 60%). The textural properties and the chemistry of the surface of the non-oxidized and ofthe oxidized carbons were determined from nitrogen adsorption and base neutralization capacities. The uptake of Pb(I) andCd(II) from aqueous solution by these carbons was determined by kinetic and equilibrium experiments as well as by thecolumn method.Treatment with nitric acid brought about drastic decrease in surface area and remarkable increase in the pore size of thecarbon with these changes depending on the strength of nitric acid. Nitric acid increased the surface acidity by developingnew surface oxygen functional groups of acidic nature. HNO3-oxidized carbons exhibited high adsorption capacities for Pb(II)and Cd(II). The adsorption of these ions increased with the decrease of the surface pH of the carbon and with the increase ofthe solution pH from 2.5 to 6 and 7. The amount adsorbed from lead and cadmium was also related to the amount of surfaceacidity, the pH of the point of zero charge and on some metal ion parameters. Cadmium and lead uptake by the investigatedcarbons followed pseudo-second order model and the equilibrium sorption data fitted Langmuir adsorption model.

A carbon nanotube (CNT) of diameter ~ 20 nm has been synthesized by spray pyrolysis of turpentine oil using Ni/Fe catalyst. Pellet of CNTs has been used as a target to produce semiconducting carbon thin film of band gap 1.4 eV. Presence of oxygen pressure in the pulse laser deposition (PLD) chamber helped to control the sp3/sp2 ratio to achieve the desired band gap. Results are discussed with the help of Raman spectra, SEM TEM micrographs and optical measurements suggest that semiconducting carbon thin film deposited by PLD technique has retained its nanotubes structure except that its diameter has increased from 20 nm to 150 nm.