Kinetic, isotherm and mechanism investigations of the removal of phenols from water by raw and calcined clays

Abstract

In this work, the phenols removal of phenol from water by raw clay (RCG) and calcined one at 1000 °C (CCG) of Goulmima city (Morocco) was investigated. The kinetics and isotherms experiments were also studied at pH = 4. The results indicated that the phenol adsorption reached equilibrium within 3 h, and the removal of phenol was enhanced at the same temperature by CCG (2.932 mg/g) adsorbent, compared to RCG (1.640 mg/g) due to the removal of organic matter by heat treatment, and an increase in adsorption temperature, indicating the endothermic process. The adsorbents were characterized by means of X-ray fluorescence, FTIR, XRD, B.E.T, and TGA/DTA analysis and showed that the clay consists essentially of silica and alumina. The experimental data were examined by using linear and nonlinear forms of the kinetics and the isotherms models. Based on the errors of the calculated values of R 2 (Coefficient of determination), χ 2 (Chi-square) and standard deviation (Δq (%)), it was found that the nonlinear forms of second-order kinetic model and Freundlich and Redlich-Peterson (R–P) isotherm models are best fit the experimental data for both adsorbents. However, the enthalpy ΔH° is less than 20 kJ/mol and the free energy ΔG° has a negative value, which shows that the adsorption is done physically and spontaneously on heterogeneous sites. The interest of this study is the use of FTIR and XRD to determine the effect of calcination on the phenol adsorption mechanism. However, the analysis of both adsorbents, before and after adsorption of phenol, shows that the adsorption mechanism of phenol is provided by the hydrogen bonding of the water molecules.

Study of the permeability of tubular mineral membranes: application to wastewater treatment

“…We notice some traces of organic matter at 1798 cm −1 and at 1633 cm −1 which are attributed to the vibration of the C–H and/or C–O bond, which explains the presence of organic matter in the studied clay [ 41 ]. We also noted vibrations of the carbonate group (CO 3 2- ) at 1435 cm −1 and 874 cm −1 , this result is confirmed by X-ray diffraction analysis [ 42 ]. The 465 and 1029 cm −1 bands attributed to the Si–O–Mg and Si–O–Si stretching vibrations of the clay mineral silicate [ 25 , 42 , 43 ].…”

“…We also noted vibrations of the carbonate group (CO 3 2- ) at 1435 cm −1 and 874 cm −1 , this result is confirmed by X-ray diffraction analysis [ 42 ]. The 465 and 1029 cm −1 bands attributed to the Si–O–Mg and Si–O–Si stretching vibrations of the clay mineral silicate [ 25 , 42 , 43 ].…”

Amine Modification of Silica Aerogels/Xerogels for Removal of Relevant Environmental Pollutants

“…It is clear that the addition of amine groups improves the q e when compared with pure MTMS-based material. The obtained values are higher than those reported for granular activated carbon (1.48 mg/g) [60], porous hydroxyapatite (8.2 mg/g) [61], calcinated clay (2.9 mg/g) [62] and MTMS xerogels (4.9 mg/g) [63], and are similar to q e values achieved by MTMS aerogels (21.1 mg/g) [63] and modified activated carbon (20 mg/g) [64]. However, the developed materials showed lower adsorption capacities if compared with, for example, graphene aerogels–mesoporous silica frameworks, that have much higher surface area (1000.80 m 2 /g) [65].…”

Rod-Shaped Carbon Aerogel-Assisted CdS Nanocomposite for the Removal of Methylene Blue Dye and Colorless Phenol

“…The result showed a BET surface of 27.67 m 2 /g, Barrett, Joyner, and Halenda (BJH) collective surface area of 30.95 m 2 /g, with BJH adsorption and desorption median pore diameter of 34.15 and 29.01 nm, respectively. The adsorption-desorption isotherm for CdS CA 8% displays typical Type IV properties and an H 2 -type hysteresis loop conferring to IUPAC classification, which is typical of mesoporous solids [40]. The presence of CA at a concentration of 8% in the CdS is revealed by the immediate increase in adsorption at relatively high pressure.…”

“…The adsorptiondesorption isotherm for CdS CA 8% displays typical Type IV properties and an H2-type hysteresis loop conferring to IUPAC classification, which is typical of mesoporous solids. [40] The presence of CA at a concentration of 8% in the CdS is revealed by the immediate increase in adsorption at relatively high pressure.…”