Biodiesel is produced by the transesterification of oil triglycerides with methanol or ethanol, in the presence of a homogeneous or heterogeneous catalyst. This study aims to report the results of the transesterification of sunflower oil with methanol to produce biodiesel using CaO nanoparticles supported on NaX zeolite as catalyst. The effect of the CaO nanoparticles concentration on the NaX zeolite surface was studied in the range of 5−25 wt %. The transesterification reaction was carried out at reflux temperature of methanol, atmospheric pressure, a reaction time of 6 h, and with a 6:1 molar ratio of methanol to sunflower oil. Catalyst characterization was carried out by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. It was concluded that methyl esters content is highly influenced by basicity and that the best catalyst was the one holding 16 wt % CaO nanoparticles. The produced biodiesel was 93.5% methyl esters and was found to fulfill the specifications of Europ...

Preparation and Characterization of CaO Nanoparticles/NaX Zeolite Catalysts for the Transesterification of Sunflower Oil

A review on chemical coagulation/flocculation technologies for removal of colour from textile wastewaters.

A critical review on textile wastewater treatments: Possible approaches.

The hydrothermal synthesis of zeolites: precursors, intermediates and reaction mechanism

In the last few decades, pharmaceuticals, credited with saving millions of lives, have emerged as a new class of environmental contaminant. These compounds can have both chronic and acute harmful effects on natural flora and fauna. The presence of pharmaceutical contaminants in ground waters, surface waters (lakes, rivers, and streams), sea water, wastewater treatment plants (influents and effluents), soils, and sludges has been well doccumented. A range of methods including oxidation, photolysis, UV-degradation, nanofiltration, reverse osmosis, and adsorption has been used for their remediation from aqueous systems. Many methods have been commercially limited by toxic sludge generation, incomplete removal, high capital and operating costs, and the need for skilled operating and maintenance personnel. Adsorption technologies are a low-cost alternative, easily used in developing countries where there is a dearth of advanced technologies, skilled personnel, and available capital, and adsorption appears to be the most broadly feasible pharmaceutical removal method. Adsorption remediation methods are easily integrated with wastewater treatment plants (WWTPs). Herein, we have reviewed the literature (1990-2018) illustrating the rising environmental pharmaceutical contamination concerns as well as remediation efforts emphasizing adsorption.

Pharmaceuticals of Emerging Concern in Aquatic Systems: Chemistry, Occurrence, Effects, and Removal Methods.

We hypothesized that the six-monthly application of silver diamine fluoride (SDF) can arrest the development of caries in the deciduous dentition of six-year-old schoolchildren and prevent caries in their first permanent molars. A prospective controlled clinical trial was conducted on the efficacy of a 38% SDF solution for caries reduction. Four hundred and twenty-five six-year-old children were divided into two groups: One group received SDF solution in primary canines and molars and first permanent molars every 6 mos for 36 mos. The second group served as controls. The 36-month follow-up was completed by 373 children. The mean number of new decayed surfaces appearing in primary teeth during the study was 0.29 in the SDF group vs. 1.43 in controls. The mean of new decayed surfaces in first permanent molars was 0.37 in the SDF group vs. 1.06 in controls. The SDF solution was found to be effective for caries reduction in primary teeth and first permanent molars in schoolchildren.

Efficacy of Silver Diamine Fluoride for Caries Reduction in Primary Teeth and First Permanent Molars of Schoolchildren: 36-month Clinical Trial

Adsorption of anionic and cationic dyes on activated carbon from aqueous solutions: equilibrium and kinetics.

Competitive adsorption studies of caffeine and diclofenac aqueous solutions by activated carbon

Comparative adsorption performance of ibuprofen and tetracycline from aqueous solution by carbonaceous materials.

Multiwalled carbon nanotubes (CNTs) were functionalized with HNO3, HNO3/H2SO4, and HNO3/Na2CO3. The preparation of metal supported on mesoporous carbon nanotube catalyst is described. The catalysts were synthesized by impregnation of carbon nanotubes with different metallic precursors (H2PtCl6·6H2O, RuCl3·H2O, and CuCl2·2H2O) followed by reduction. The structures of the CNT modified with HNO3, HNO3/H2SO4, and HNO3/Na2CO3 and CNT-supported metal catalysts have been characterized by means of Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and nitrogen adsorption/desorption isotherms (BET), and their activity was tested in continuous catalytic wet air oxidation of aniline. For the catalysts prepared with metal precursors, activities were found in the order of Pt/N-CNT > Cu/N-CNT > Ru/N-CNT. The structure of carbon nanotubes supported metal catalyst is responsible for the activity, and the absence of micropores ...

Araceli Rodríguez

Papers

Efficacy of Silver Diamine Fluoride for Caries Reduction in Primary Teeth and First Permanent Molars of Schoolchildren: 36-month Clinical Trial

Adsorption of anionic and cationic dyes on activated carbon from aqueous solutions: equilibrium and kinetics.

Competitive adsorption studies of caffeine and diclofenac aqueous solutions by activated carbon

Comparative adsorption performance of ibuprofen and tetracycline from aqueous solution by carbonaceous materials.

Multiwalled Carbon Nanotubes for Liquid-Phase Oxidation. Functionalization, Characterization, and Catalytic Activity