The removal of tannin from aqueous media by cationic surfactant-modified
bentonite clay
was studied in a batch system. The surfactant used
was hexadecyltrimethylammonium chloride. Adsor
bent characterizations
were investigated using X-ray diffraction, infrared spectroscopy, surface area analysis, and potentiometric titration. The effects of pH, contact time, initial solute concentration, adsor
bent dose, ionic strength, and temperature on the adsorption of tannin onto modified clay
were investigated. The adsor
bent exhibited higher tannin removal efficiency
JJGB8J-2&_mathId=mml14&_user=10&_cdi=6857&_rdoc=16&_handle=V-WA-A-W-CD-MsSAYWW-UUA-U-AACVDZWEWD-AACWBVBDWD-EYWCBECUE-CD-U&_acct=C000050221&_version=1&_userid=10&md5=33822ff0b7ea744ce07882dbe3f86ca8"" title=""Click to view the MathML source"">(>99.0 % ) from an initial concentration of 10.0 μmol/L at pH 3.0. Adsorption capacity decreased from 90.1 to 51.8 %
with an increase in temperature from 10 to 40 °C at an initial concentration of 25.0 μmol/L. The adsorption process
was found to follo
w pseudo-first-order kinetics. Film diffusion
was found to be the rate-limiting step. Tannin adsorption
was found to decrease
with increase in ionic strength. The tannin equilibrium adsorption data
were fitted to Langmuir and Freundlich isotherm models, the former being found to provide the best fit of the experimental data. The maximum monolayer adsorption capacity for tannin
was 69.80 μmol/g at 30 °C. Comparison of adsorption capacity of the modified clay
with reported adsor
bents in the literature
was also presented. Adsorbed tannin on modified clay can be recovered by treatment
with 0.1 M NaOH solution. Regeneration experiments
were tried for four cycles and results indicate a capacity loss of
w the MathML source""><10.0 % . From the results it can be concluded that the surfactant-modified clay could be a good adsor
bent for treating tannin-contaminated
waters.