Absorption Property of Direct Fast Black on Acid-thermal Modified Sepiolite and Optimization of Absorption Conditions Using Box-Behnken Response Surface Methodology

摘要

The decolorization rate of direct fast black from aqueous solution onto acid-thermal modified sepiolitewas investigated such as initial dye concentration, initial pH and adsorbent dosage on adsorption process ofinfluential factors. At the same time, the three-factor and three-level Box-Behnken RSM was utilized for modelingand optimization the adsorption process. The decolorization rate was selected as one response value, while pH andadsorbent dosage as well as reaction time were considered as influential factors. The relationship betweendecolorization rate and these three influential factors was established, followed by obtaining the optimumoperating conditions for direct fast black on the acid-thermal modified sepiolite. The nature sepiolite was alteredto acid-thermal modified sepiolite, changes in the FTIR absorption bands of the sample were noted at (3435, 1617,and 1427) cm1. The zeolitic water disappeared upon acid-thermal modification. The pH had a more significanteffect than absorbent dosage and reaction time. The decolorization rate of direct fast black adsorbed increasedfrom 68.2%to 98.9%for acid-thermal modified sepiolite as the pH decreased from 10 to 2 at 12h. When theabsorbent dosage was 2.5g/l, 2.0g/l, 1.5g/l and 1.0g/l, the decolorization rate was 90.3%, 86.7%, 61.0%and29.8%, respectively. The interaction of absorbent dosage and reaction time, interaction pH and reaction time weresignificant factors. The optimum conditions were that the absorbent dosage was 1.99g/l, pH was 4.22 and reactiontime was 5.2h. Under this condition, the three dimensional fluorescence spectra of direct fast black after treatmentwas showed that the direct fast black be absorbed more completely by acid-thermal modified sepiolite.