Adsorption of Alizarin and Fluorescein Dyes onto Palm Seeds Activated Carbon: Kinetic and Thermodynamic Studies

Activated carbon was prepared from date palm seed using one step procedure with 56.54% efficiency, 2.89% ash content, 781.40 m(2) g(-1) surface area, 711.2 mg g(-1) iodine number and the CHN analysis gave 69.25% C, 3.91% H and 1.56% N. The FTIR spectroscopy revealed O-H, C-H, C=C, C=C and C-O stretching; XRF revealed P, Ca, Si, S and K as major elements. The influences of agitation time, initial dye concentration, adsorbent dose and temperature were studied in batch experiments. A 57.78% Alizarin and 68.40% Fluorescein removal were attained within the first 15 min of agitation. Kinetic studies showed good correlation coefficient for pseudo-first and pseudo-second order kinetic models. The adsorption data fitted well into Langmuir isotherm than Freundlich isotherms with correlation coefficient (R) very close to unity and Langmuir maximum adsorption constant, q(m) > 1000. The Freundlich coefficients relating to overall adsorption capacity, K-f (mg g(-1)) is 197.65 and 396.28 and surface heterogeneity, n is 3.34 and 3.18 for Alizarin and Fluorescein respectively. The activation energy (E-a) of the adsorption process of alizarin and fluorescein on DPA were found to be -8.19 and +21.43 Kj mol(-1) respectively. The evaluation of the thermodynamic quantities showed that the adsorption process was spontaneous and endothermic.