Abstract
In this study, citric acid was utilized to modify the surface of cellulose and the citric acid-modified cellulose (CAMC) was then used to remove Pb2+ from aquatic solutions. The surface characteristics of CAMC were determined by Fourier-transform infrared spectroscopy and zeta potential analyses. The exact effects of CAMC dosage, pH, and temperature on the adsorption of Pb2+ by CAMC were determined. After 180 min of reaction, the adsorption percentages of Pb2+ at 0.5, 1.5, and 2.5 g/L CAMC were 66, 87, and 94%, respectively. The Pb2+ removal efficiency of CAMC increased with CAMC dosage, pH, and temperature. Experimental results reveal that the pseudo-second-order model best represents the adsorption kinetics. The Freundlich model fits the experimental isotherms better than does the Langmuir model. ΔH° and ΔS° were 43.34 kJ/mol and 224.4 J/mol K, respectively. The value of ΔH° suggested that the Pb2+ was adsorbed onto CAMC via physisorption.
Acknowledgment
The authors would like to thank the National Science Council of the Republic of China, Taiwan, for financially supporting this research under Contract No. NSC 101-2221-E-151-038-MY3.