In this paper, application of sawdust prepared from Narra wood (SD) modified with cationic surfactant of cetyltrimethylammonium
bromide (SD/CTAB) was used for removal of two typical acid dyes commercially named as Acid Green 25 (AG25) and Acid Red 14
(AR14) from aqueous solutions. The effects of experimental variables, such as pH, initial dye concentration, adsorbent dose, contact time
and temperature were investigated in order to find out the optimized conditions for removal of selected test dyes. Langmuir and Freundlich
Isotherms were used to analyse the experimental adsorption data. Pseudo- first and second order models suggested by Lagergren, Ho &
McKay were used for kinetic study. The van 't Hoff equation employed for obtaining of thermodynamic parameters. It was found that upon
simple treatment of sawdust with a cationic surfactant, the adsorption capacity of sawdust for uptake of anionic dyes is improved
considerably. The monolayer maximum adsorption capacity of SD/CTAB toward AG25 and AR14 dyes calculated using Langmuir
isotherm model was 17.5 and 18.9 mg g−1
at 298 K, respectively. Based on kinetics and thermodynamic studies, it was found that
adsorption process using SD/CTAB follows pseudo second-order rate equation and the adsorption investigated system is spontaneous and
endothermic in nature. Exhausted adsorbent can also be regenerated for reuse with high performance. It was found that via simple treatment
of agricultural wastes such as wood sawdust with cationic surfactants it is possible to improve the sorption capacity of sawdust for removal
of anionic dyes from aqueous wastes considerably.
Key words: Removal, acidic dyes, modified sawdust, cationic surfactant, isotherm, kinetic, thermodynamic
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