Optimization of the Pentachlorophenol Adsorption by Organo-Clays Based on Response Surface Methodology

Soufiane El Mahmoudi; Abdellah Elmchaouri; Assya El Kaimech; Antonio Gil

doi:10.3390/ma15207169

Optimization of the Pentachlorophenol Adsorption by Organo-Clays Based on Response Surface Methodology

Materials (Basel). 2022 Oct 14;15(20):7169. doi: 10.3390/ma15207169.

Authors

Soufiane El Mahmoudi^{1

2}, Abdellah Elmchaouri², Assya El Kaimech², Antonio Gil¹

Affiliations

¹ INAMAT^2, Departamento de Ciencias, Universidad Pública de Navarra, Campus de Arrosadía, 31006 Pamplona, Spain.
² Laboratory of Physical Chemistry & Bioorganic Chemistry, Faculty of Science and Techniques Mohammedia, University Hassan II of Casablanca, Mohammedia 20650, Morocco.

Abstract

The aim of this study is to optimize the adsorption of pentachlorophenol (PCP) using an organo-clay under the response surface methodology. The adsorbent was selected from a montmorillonite exchanged by various cations, such as Fe³⁺, Al³⁺, Zn²⁺, Mg²⁺, Na⁺, and modified by bromide cetyltrimethylammonium (CTAB) as surfactant. The obtained organo-montmorillonite was characterized using several techniques, such as Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and nitrogen adsorption, performed at -196 °C. The results showed an increase in basal space from 1.65 to 1.88 nm and a decrease in the specific surface and pore volume, with an increase in pore diameter, including the presence of characteristic bands of -CH₂- and -CH₃- groups at 2926 and 2854 cm^-1 in the FTIR spectrum after the modification. The optimization of PCP removal by clay adsorbents is achieved using the response surface methodology (RSM) with a four-factor central composite model, including pH of solution, mass of adsorbent, contact time, and initial concentration. The results proved the validity of the regression model, wherein the adsorption capacity reaches its maximum value of 38 mg/g at a lower adsorbent mass of 20 mg, pH of 6, contact time (t_c) of 5 h, and initial concentration of 8 mg/L.

Keywords: adsorption; montmorillonite; organo-clay; pentachlorophenol; response surface methodology.

Grants and funding

S.E.M. thanks the Universidad Pública de Navarra for a doctoral grant. A.G. also thanks Banco Santander for funding through the Research Intensification Program.