ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Relationship between acidification factors and methylene blue uptake by Ca-bentonite: optimisation and kinetic study

Amin Salem and Mohsen Saghapour

Centre of Excellence for Colour Science and Technology, 55 Vafamanesh Street, Sayad Shirazi North Highway, 1668814811 Tehran, Iran

E-mail: a_salem@iust.ac.ir

Abstract: This investigation studied the uptake of methylene blue from wastewater by normal and treated bentonites to evaluate the effects of acidification factors on removal efficiency. Hydrochloric, sulphuric and nitric acids were blended in accordance with the response surface methodology to prepare acidic agents. The normal clay was then mixed with the prepared solutions after drying in a laboratory oven. The set-up provided controllable conditions for producing nano-porous powders for which the residence time and temperature were changed. The removal efficiency of the treated powders was assessed by defining an adsorption ratio and determining the optimal composition for acidic agent. Based on the statistical theory and experimental data, nitric acid is a suitable agent for manufacturing porous material to remove methylene blue from wastewater. In addition, the Brunauer-Emmett-Teller method, X-ray diffraction and Fourier transform infrared spectroscopy techniques were applied to identify the structural changes. The experimental data obtained from the batch tests were analysed by a new kinetic model which predicted the data variation with higher regression coefficients and lower relative errors. The proposed procedure can be an important tool in optimising the acidification conditions for manufacturing a nano-porous powder with maximal removal efficiency.

Keywords: bentonite – nano-porous active solid – response surface methodology – adsorption – methylene blue uptake – kinetics

Full paper is available at www.springerlink.com.

DOI: 10.1515/chempap-2015-0195

Chemical Papers 70 (2) 153–163 (2016)