Maurício Alves da Motta Sobrinho

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.

Preparação e utilização de uma argila esmectítica organofílica como adsorvente de fenol

The main goal of this research was the preparation and use of a organophilic smectitic clay able to promoting the adsorption of phenol. In this work was used a natural clay called Chocolate, from Campina Grande - PB (Brazil). The natural clay was treated with a solution of sodium carbonate. After this the sodium clay was treated with quaternary ammonium salt. The adsorptive study was conducted by different values of pH and temperature. The results showed a better performance in adsorptive at pH 7 and temperature 30 oC, with removal of more than 80% of phenol.

Dye removal from textile industrial effluents by adsorption on exfoliated graphite nanoplatelets: kinetic and equilibrium studies

The concept of physical adsorption was applied for the removal of direct and reactive blue textile dyes from industrial effluents. Commercial graphite nanoplatelets were used as substrate, and the quality of the material was characterized by atomic force and transmission electron microscopies. Dye/graphite nanoplatelets water solutions were prepared varying their pH and initial dye concentration. Exceptionally high values (beyond 100 mg/L) for adsorptive capacity of graphite nanoplatelets could be achieved without complicated chemical modifications, and equilibrium and kinetic experiments were performed. Our findings were compared with the state of the art, and compared with theoretical models. Agreement between them was satisfactory, and allowed us to propose novel considerations describing the interactions of the dyes and the graphene planar structure. The work highlights the important role of these interactions, which can govern the mobility of the dye molecules and the amount of layers that can be stacked on the graphite nanoplatelets surface.

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

The use of metal hydroxide sludge (in natura and calcined) for the adsorption of brilliant blue dye in aqueous solution.

ABSTRACT Industrial waste such as metal hydroxide sludge (in natura and calcined) from galvanic bath was evaluated as an adsorbent in the removal of brilliant blue synthetic dye (NB 180) in aqueous solution. The samples were characterised using X-ray fluorescence analysis (XRF), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), infrared spectroscopy (FT-IR), as well as the specific surface area (BET) and the point of zero charge (pHZCP). The effects of the conditions in relation to pH and adsorbent dosage were also investigated. For the conditions of 5 g.L−1 and pH of 4, the sludge in natura (LG-IN) reached equilibrium after 60 min, removing 78% of NB 180 dye, while the calcined sample at a temperature of 250°C (LG-250) removed 100% of dye in solution in 30 min. The effect of calcium salts and the leaching study showed that the presence of (Ca2+) ions in solution and metal oxides/hydroxides are the main factors responsible for the removal of colour. As for the study of kinetics and adsorption equilibrium, the experimental data were better adjusted to the pseudo-second order models and Freundlich model, respectively. The parameters of the kinetics, equilibrium and intraparticle diffusion models demonstrated a better performance of the sample LG-250 (qe = 4.09 mg.g−1), when compared to the sample LG-IN (qe = 2.76 mg.g−1). These results demonstrated that metal hydroxide sludge can be reused and applied in dye removal processes for the treatment of textile effluent. GRAPHICAL ABSTRACT

Comparative substitution of butane by hydrogen/oxygen mixture in a domestic room heating convector

The search for new energy sources has a fundamental importance concerning better quality of life for the mankind. Looking for a substitute for the existing pollutant fueled heating equipment, the Hydrogen Group of the Federal University of Paraiba (Brazil), has studied the application of hydrogen to this purpose. This work shows performance tests realized with a convective commercial heater exchanger, adapted to be fueled by hydrogen and applied for the environmental heating. The study also compared its gain and efficiency using butane. The results showed that the commercial heat exchanger adapted for hydrogen has a high gain and efficiency taking into account fuel consumption and that can be improved if the suggested alterations are implemented.