Beatriz Miguel

Bio: Beatriz Miguel is an academic researcher from University of Cartagena. The author has contributed to research in topics: Freundlich equation & Adsorption. The author has an hindex of 1, co-authored 2 publications receiving 1 citations.

Kinetic Study of the Ultrasound Effect on Acid Brown 83 Dye Degradation by Hydrogen Peroxide Oxidation Processes

Abstract: The effect of ultrasound on the degradation of the dye Acid Brown 83 by seven different degradation methods (blank test using only ultrasound, hydrogen peroxide in a neutral medium, hydrogen peroxide in a sulfuric acid medium and hydrogen peroxide in a sulfuric acid medium in the presence of Fe(II), both without and with ultrasonic irradiation) is studied in this paper. The effectiveness of these methods is compared by analyzing the degradation percentages of the dye and its initial degradation rate. The application of ultrasound leads to a significant increase in the efficiency of any of the degradation method studied. Kinetic study of Acid Brown 83 degradation by the above-mentioned methods is carried out by using four kinetic models (first order, second order, Behnajady and pseudo-first order). The pseudo-first order model is the one that best fits the experimental data in all the used degradation methods. Although when the degradation is performed in the presence of Fe(II), the Behnajady model presents correlation coefficients slightly higher than those of the pseudo-first order, the maximum experimental conversions obtained fit much better in all cases to the pseudo first order model.

Activated Olive Stones as a Low-Cost and Environmentally Friendly Adsorbent for Removing Cephalosporin C from Aqueous Solutions

Abstract: In this paper, we describe the removal of cephalosporin C (CPC) from aqueous solutions by adsorption onto activated olive stones (AOS) in a stirred tank. For comparative purposes, several experiments of adsorption onto commercial granular activated carbon were carried out. A quantum study of the different species of cephalosporin C that, depending on the pH, exist in aqueous solution pointed to a favorable mass transfer process during adsorption. Activated olive stones were characterized by SEM, EDX and IR techniques and their pHzc was determined. A 10-3 M HCl cephalosporin C solution has been selected for the adsorption experiments because at the pH of that solution both electrostatic and hydrogen bond interactions are expected to be established between the adsorbate and the adsorbent. The adsorption process is best described by the Freundlich isotherm model and the pseudo-second-order kinetic model, while the adsorption mechanism is mainly controlled by film diffusion. Under the conditions studied, the adsorption process is of a physical nature, endothermic and spontaneous. Comparison of the adsorption results obtained in this paper with those of other authors shows that the efficiency of AOS is 20% of that of activated carbon but 65% higher than that of the XAD-2 adsorbent. Considering its low price, abundance, easy accessibility and eco-compatibility, the use of activated olive stones as adsorbents for the removal of emerging pollutants from aqueous solutions represents an interesting possibility from both the economic and the environmental points of view.

Super-Adsorbent Hydrogels for Removal of Methylene Blue from Aqueous Solution: Dye Adsorption Isotherms, Kinetics, and Thermodynamic Properties

Abstract: Removal of dyes through adsorption from wastewater has gained substantial interest in recent years, especially in development of hydrogel based adsorbents, owing to their easy use and economical nature. The aim of the present study was to design a super-adsorbent hydrogel based on sodium styrenesulfonate (NaSS) monomer for removal of dyes like methylene blue (MB). NaSS displays both an aromatic ring and strongly ionic group in its monomer structure that can enhance adsorption capacity. Poly(sodium styrenesulfonate-co-dimethylacrylamide) hydrogels were prepared by solution free radical polymerization using gelatin methacryloyl (GelMA) as crosslinker, creating a highly porous, three-dimensionally crosslinked polymer network contributing to higher swelling ratios of up to 27,500%. These super-adsorbent hydrogels exhibited high adsorption capacity of 1270 mg/g for MB adsorption with above 98% removal efficiency. This is the first report for such a high adsorption capacity for dye absorbance for NaSS-based hydrogels. Additionally, the adsorption kinetics using a pseudo-first-order and the Freundlich adsorption isotherm models for multilayer, heterogeneous adsorption processes has been reported. The adsorbents’ reusability was confirmed through 4 repeated cycles of desorption-adsorption. The results discussed herein illustrate that NaSS based chemistries can be used as an efficient option for removal of organic dyes from contaminated wastewater.

Kinetic Study of Fenton-Like Degradation of Methylene Blue in Aqueous Solution Using Calcium Peroxide

Abstract: The textile industry is one of the fastest-growing industries that significantly contribute to the economic growth in Malaysia. Dyeing wastewater is one of the more difficult to control in industrial wastewater. Methylene blue is a widely used dye in the textile industry, which cannot be discharged directly into the natural environment without treatment. The present study involves the degradation of methylene blue by a Fenton-like system using calcium peroxide (CaO2, CP). The process of degradation was recorded spectrophotometrically. The field emission scanning electron microscope (FESEM) and energy dispersive X-ray (EDX) were measured for testing the purchased commercial calcium peroxide. The effect of pH, the initial dosage of CaO2, and temperatures were studied with kinetics modeling, respectively. The results indicated that 97.07% removal of methylene blue took place at the optimum condition (pH=3.0, initial CaO2, dosage=3.0 g, 65°C, 150 rpm, contact time=60 minutes). Over four models (zero-order, first-order, second-order, Behnajady, Modirshahla, and Ghanbary (BMG) model) applied in this study, the BMG model with the R2=0.9935 was in accordance with the experimental data.

Synthesis and Characterization of Ca-ALG/MgO/Ag Nanocomposite Beads for Catalytic Degradation of Direct Red Dye

Abstract: Increased water pollution due to the tremendous increase of dye-containing effluent is still a serious problem which, in turn, adversely affects aquatic life and, consequently, the balance of our ecosystem. The aim of this research was to investigate whether Ca-ALG/MgO/Ag nanocomposite beads successfully prepared from calcium alginate hydrogels with MgO (Ca-ALG/MgO) doped with Ag nanoparticles (Ag NPs) caused effective degradation of Direct Red 83 dye. The formation of nanocomposite beads was confirmed by X-ray diffraction (XRD), Transmission Electron Microscope (TEM), Dynamic Light Scattering (DLS), and Energy Dispersive X-ray Analysis (EDX). The results from the EDX analysis proved that both MgO and Ag nanoparticles within the alginate beads network were present. This study also examines the effects of various operating parameters, such as the reducing agent, time of reaction, the concentration of the dye solution, and the catalyst dosage, which were examined and studied carefully to find the optimum degradation conditions. The kinetics and isothermal study revealed that the degradation process using Ca-ALG/MgO/Ag nanocomposite beads as a catalyst in the presence of sodium borohydride (NaBH4) as a reducing agent was the best fit for the pseudo-first-order model and the Temkin isotherm model. The results indicated that the optimum dosage of Ca-ALG/MgO/Ag was 0.3 g for a dye concentration of 50 mg/L, and equilibrium of the degradation process was attained at 340 min. Accordingly, it could be stated that the catalyst, Ca-ALG/MgO/Ag nanocomposite beads, is considered efficient for the degradation of Direct Red 83 dye. The degradation efficiency reached 95% approximately. Furthermore, after four runs of reuse, Ca-ALG/MgO/Ag nanocomposite beads exhibited excellent performance and long-term stability.