Marilda Nascimento Carvalho

Evaluation of BTEX and phenol removal from aqueous solution by multi-solute adsorption onto smectite organoclay.

The removal process of BTEX and phenol was evaluated. The smectite organoclay for single-solute system reached removal was evaluated by adsorption on smectite organoclay adsorbent by kinetic and equilibrium efficiencies between 55 and 90% while was reached between 30 and 90% for multi-solute system at 297 K and pH 9. The Langmuir-Freundlich model was used to fit the experimental data with correlation coefficient between 0.98 and 0.99 providing kinetic and equilibrium parameter values. Phenol and ethylbenzene presented high maximum adsorbed amount, 8.28 and 6.67 mg/g, respectively, compared to the other compounds for single-solute. Toluene and p-xylene presented high values of adsorption constant which indicates a high adsorption affinity of compounds to organoclay surface and high binding energy of adsorption. Phenol presented low kinetic adsorption constant value indicating slow rate of adsorption.

Removal of Effluent from Petrochemical Wastewater by Adsorption Using Organoclay

Water contaminated with petroleum derivates is produced in large volumes in many stages of refining oil. This mixture should be treated to separate these derivates from water before it can return to the environment. However, treatment with conventional processes is very often not economically feasible, or do not have the appropriate efficiency with regard to separation, or produce large amounts of mud that also need treatment (Almeida Neto et al., 2006).

Applying Combined Langmuir-Freundlich Model to the Multi-Component Adsorption of BTEX and Phenol on Smectite Clay

Adsorption using clay is increasingly being applied in the secondary treatment of effluents contaminated with organic compounds discharged from oil industries. This study was aimed at applying a combined Langmuir–Freundlich model to describe the multi-component adsorption of organic compounds such as benzene, toluene, ethylbenzene, xylenes and phenol using smectite clay. The results of the study well fitted with the model developed. In addition, the model parameters suggest that maximum adsorption capacities (qm) can be achieved between 2.45 (toluene) and 22.40 mg g−1 (phenol). The equilibrium points for the compounds were achieved in approximately 20–30 minutes.

Anomalocardia brasiliana shellfish shells as a novel and ecofriendly adsorbent of Nylosan Brilliant Blue acid dye

Malacoculture waste (Anomalocardia brasiliana) shellfish shells (ABSS) were evaluated as adsorbents of Nylosan Brilliant Blue (NBB) acid dye. The ABSS were thermally activated at 1,000 °C for 10 h and then characterized by Fourier-transform infrared spectroscopy, analysis of specific surface area (BET), X-ray diffraction (XRD), and scanning electron microscopy. Point of zero charge (PZC) analysis of ABSS verified pHPZC 13.0. The study of kinetics showed that the pseudo-second-order model fit the experimental data best and the system reached equilibrium within 5 min. Adsorption isotherms followed the Langmuir-Freundlich isotherm and ABSS reached an outstanding maximum adsorption capacity of 405 mg·g-1 under the following optimum conditions: pH 12.4, 303 K, 450 rpm, 2.0 g of adsorbent, and 150 μm average particle size. These conditions were obtained after a previous statistical analysis of the variables. Enthalpy and Gibbs energy obtained in the thermodynamics experiments were -23.79 kJ·mol-1 and -4.07 kJ·mol-1, respectively. These parameters confirm that the process is exothermic, spontaneous, and indicative of the physical nature of the adsorption. The adsorption of NBB onto ABSS tended to be more favorable at a lower temperature. Low value of enthalpy suggested that weak binding forces, such as electrostatic interactions, govern the sorption mechanism. ABSS high availability in the environment, its low toxicity and high efficiency make it a promising ecofriendly adsorbent of textile dyes.

Treated residue from aluminium lamination as adsorbent of toxic reactive dyes – a kinetic, equilibrium and thermodynamic study

ABSTRACT The residue generated in the aluminium cold lamination (TTR) was submitted to a direct burning and then it was calcined at 500°C. BET, FTIR, SEM with EDX and TGA techniques were performed to characterize the adsorbent before and after the adsorption. BET analysis showed that TTR specific surface area was 55.37 m2 g−1 and there were no significant changes after the adsorptive process. Afterwards, the TTR was applied as adsorbent of the reactive Drimaren Blue (DB), Drimaren Red (DR) and Drimaren Gold (DG). Its employment consists in a sustainable alternative for the treatment of textile wastewater, once the TTR was used as low-cost adsorbent of textile dyes. Kinetic studies showed that the process reached the equilibrium state between 5 and 10 min. The pseudo-second-order model better fitted the adsorption kinetics, with kinetic rate constants 10.51, 34.71 and 31.51 mg min g−1 for DB, DR and DG respectively. The equilibrium experiments were performed to obtain the adsorption parameters for each dye; moreover, the maximum adsorption capacity was 6.27, 0.42 and 1.23 mg g−1 for DB, DR and DG, respectively. Thermodynamics studies allowed to obtain the values of enthalpy for DB, DR and DG, −7.90, 14.03 and −17.75 kJ mol−1, respectively. Furthermore, the negative values of Gibbs free energy confirmed the spontaneity of the adsorption. The results point to the physisorption characteristic of the process, in which the temperature negatively influenced the adsorption for the DB and DG; the opposite result was observed for the DR. GRAPHICAL ABSTRACT