Exploitation of Bentonite for Wastewater Treatment

Bentonite is a clay with interesting surface properties (affinity for water, adsorption capacity for electro-positive compounds….). The characteristics and clarifying properties of bentonite from various companies are the subject of numerous studies. The present work focuses on the study of the efficiency of bentonite and modified bentonite to purify aqueous solutions containing organic pollutants such as phenol. First, before starting the adsorption study, a physical–chemical characterization of the clay by FTIR, BET and XRD techniques was undertaken. The specific surface of the bentonite is calculated by BET. Then, the study of isotherms and kinetics of phenol adsorption on commercial BTC showed that this pollutant can be removed from liquid effluents with a significant percentage. Langmuir and Freundlich models were applied. Finally, the kinetic study performed by UV–Visible was reproduced by FTIR spectroscopy.

Prediction of Chlorophenols Adsorption on Activated Carbons By Representative Pores Method

The specification of a particular activated carbon adsorbents for removal of phenol and related derivatives, from dilute aqueous solutions, is still based on lengthy trial and error experimental tests. A predictive model of adsorption of these compounds would considerably reduce the carbon selection time and could also bring new information to support more efficient carbon synthesis. The use of molecular simulation and the methodology of representative pores, proved to be adequate for quantitative prediction of phenol adsorption. Here the methodology is being extended to chlorophenols, an important class of phenol-derived pollutants. A set of ortho and para-chlorophenol isotherms were simulated for different representative pores in order to predict carbon adsorption and determine the most significative pore size. At low concentrations (1x10-4 mol/L), the pores of 8.9 and 18.5 Å are the most effective. For concentrations above 3 x10-4 mol/L pores in the range of 27.9 Å must be present in the activated carbon. The adsorption isotherm difference between ortho and para-chlorophenol, identified experimentally, was reproduced in the simulation and its origin was investigated further. Finally, the adsorption isotherms of chlorophenols for other activated carbons were predicted with the help of the model.

Kinerja Aktivasi dan Impregnasi Fly Ash sebagai Adsorben Fenol

The purpose of this study was to determine the response and performance of fly ash as an adsorbent activated by HCl and impregnated with FeCl3 to absorb phenol. In this study, the fly ash activation process was carried out using 8 M HCl for 2 hours and impregnated with 2% FeCl3 for 2 hours. Activated and impregnated fly ash was analyzed using a Scanning Electron Microscope-Energy Dispersive Spectrophotometer (SEM-EDX). The results of the activated and impregnated fly ash surface using SEM-EDX showed that there were changes in morphology and functional groups. Then activated and impregnated fly ash was used to absorb phenol at a time variation of 60 minutes, 120 minutes, 180 minutes, 240 minutes and 300 minutes. At 180 minutes of contact time, the equilibrium point is obtained with an absorption efficiency of 90.5%. Second-order pseudo kinetics were used for phenol adsorption by Fe+ impregnated fly ash (R2 = 0.9916). The isotherm models used in the phenol adsorption process by fly ash impregnated with Fe+ are Langmuir Isotherm (R2 = 0.9927) and Freundlich Isotherm (R2 = 0.9984), which means that the adsorption process occurs in multi-layer and mono-layers.

Process Optimization and Modeling of Phenol Adsorption onto Sludge-Based Activated Carbon Intercalated MgAlFe Ternary Layered Double Hydroxide Composite

A sewage sludge-based activated carbon (SBAC) intercalated MgAlFe ternary layered double hydroxide (SBAC-MgAlFe-LDH) composite was synthesized via the coprecipitation method. The adsorptive performance of the composite for phenol uptake from the aqueous phase was evaluated via the response surface methodology (RSM) modeling technique. The SBAC-MgAlFe-LDH phenol uptake capacity data were well-fitted to reduced RSM cubic model (R2 = 0.995, R2-adjusted = 0.993, R2-predicted = 0.959 and p-values < 0.05). The optimum phenol adsorption onto the SBAC-MgAlFe-LDH was achieved at 35 °C, 125 mg/L phenol, and pH 6. Under the optimal phenol uptake conditions, pseudo-first-order and Avrami fractional-order models provided a better representation of the phenol uptake kinetic data, while the equilibrium data models’ fitting follows the order; Liu > Langmuir > Redlich–Peterson > Freundlich > Temkin. The phenol uptake mechanism was endothermic in nature and predominantly via a physisorption process (ΔG° = −5.33.56 to −5.77 kJ/mol) with the involvement of π–π interactions between the phenol molecules and the functionalities on the SBAC-LDH surface. The maximum uptake capacity (216.76 mg/g) of SBAC-MgAlFe-LDH was much higher than many other SBAC-based adsorbents. The improved uptake capacity of SBAC-LDH was attributed to the effective synergetic influence of SBAC-MgAlFe-LDH, which yielded abundant functionalized surface groups that favored higher aqueous phase uptake of phenol molecules. This study showcases the potential of SBAC-MgAlFe-LDH as an effective adsorbent material for remediation of phenolic wastewater.