Montmorillonite-Rifampicin Nanohybrid for pH-Responsive Release of the Tuberculostatic.

The present work describes the development of a hybrid and pH-responsive system for rifampicin using the clay mineral 'montmorillonite' as a nanocarrier. The influence of operational variables on the drug incorporation process was evaluated using 24 factorial designs. Under optimized conditions, the experiment allowed an incorporated drug dose equivalent to 98.60 ± 1.21 mg/g. Hybrid systems were characterized by different characterization techniques (FTIR, XRD, TGA, DSC, and SEM) to elucidate the mechanism of interaction between the compounds used. Through in vitro release studies, it was possible to verify the efficacy of the pH-dependent system obtained, with approximately 70% of the drug released after sixteen hours in simulated intestinal fluid. The adjustment of the experimental release data to the theoretical model of Higuchi and Korsmeyer-Peppas indicated that the release of rifampicin occurs in a prolonged form from montmorillonite. Elucidation of the interactions between the drug and this raw clay reinforces its viability as a novel carrier to develop an anti-TB/clay hybrid system with good physical and chemical stability.

Combined Treatment (Alkali + Thermal) of Calotropis procera Fiber for Removal of Petroleum Hydrocarbons in Cases of Oil Spill.

The objective of this study was to evaluate the Calotropis procera fiber treated with NaOH combined with heat treatment as sorbent material for removal of petroleum and derivatives in cases of oil spill. The effects of oil viscosity, fiber/oil contact time, and the type of sorption system (oil and oil/water) were evaluated by experimental planning. The fiber obtained was characterized by Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (SEM-FEG), thermogravimetric analysis (TG/DTG), contact angle, and wettability. The fiber treated by combining NaOH and heat treatment (CPNaOHT) exhibited a large structure with an internal diameter of 42.99 ± 3.98 µm, roughness, and hydrophobicity on the surface with a contact angle of 101 ± 2°. The sorption capacity of oil ranged from 190.32 g/g to 98.9 g/g. After five cycles of recycling, the fiber still maintains about 70% of its initial sorption capacity and presented low liquid desorption (0.25 g). In this way, it can be used as an efficient sorbent to clean up spills of oil and oil products.

Evaluation of Thermally Treated Calotropis Procera Fiber for the Removal of Crude Oil on the Water Surface.

Biosorbents have been highlighted as an alternative method for the removal of contaminants from spills or leaks of oil and its derivatives, since they are biodegradable, are highly available, low-cost, and have a good sorption capacity. This research investigated the sorption capacity of Calotropis procera fiber in natura (CP) and thermally treated (150 °C and 200 °C) for crude oil removal and recovery. The oil sorption tests were carried out in a dry and water (layer) static systems. The assays revealed that CP fiber has excellent hydrophobic-oil properties and good crude oil sorption capacity, about 75 times its own weight (76.32 g/g). The results of the treated fibers, CPT150 and CPT200, showed oil sorption capacities (in 24 h) higher than CP, between 94.31-103.37 g/g and 124.60-180.95 g/g, respectively. The results from sample CPT200 showed that it can be an excellent biosorbent for the removal of crude oil and other derivatives due to its high hydrophobicity, great reuse/resorption capacity, and ability to retain oil within the fiber lumens. Thus, it can be applied in the recovery, cleaning, and removal of petroleum products and its derivatives from spills and leaks in the future.

Development of a Zeolite A/LDH Composite for Simultaneous Cation and Anion Removal.

Wastewater from the oil industry is a major problem for aqueous environments due to its complexity and estimated volume of approximately 250 million barrels per day. The combination of these petroleum pollutants creates risks to human health, and their removal from the environment is considered a major problem in the world today. Thus, this work has the objective of studying the treatment of this type of effluent through the adsorption method using the following exchange materials: cationic, anionic, their combination by a sequential method, and a composite material. Zeolite A, a layered double hydroxide (LDH), and the new composite material formed by zeolite A and LDH structures were synthesized for this study. All were used for the simultaneous treatment of cations and anions in a complex sample such as water produced from petroleum production. The composite demonstrated an excellent ability to simultaneously remove cations and anions. The results obtained after the different treatment modes of the effluent using different materials varied from 85% to 100% for the removal of cations and from 56% to 99.7% for the removal of anions.

Chlorine determination via MgCl molecule in environmental samples using high resolution continuum source graphite furnace molecular absorption spectrometry.

This paper describes a method development for chlorine determination through the formation of MgCl molecule, applied for the first time for Cl quantification, by high resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS) in environmental samples. Pyrolysis and vaporization temperatures were optimized as well as the use of chemical modifier. Determinations were carried out at the wavelength of 377.010 and the compromise conditions of the graphite furnace temperature program were 500°C and 2500°C for pyrolysis and vaporization, respectively, using 10µg of chemical modifier Pd. The concentration of reactants for the generation of MgCl molecule was optimized through Box-Behnken experimental design, using MgCl2 solution as source of chlorine. The optimum values according to the surface response were 5gL-1 Mg, 25mgL-1 of chlorine and 2% vv-1 of HNO3, condition in which the amount of Mg is at least 200 times higher than that of chloride. This excess of the forming agent ensures the complete formation of MgCl molecular species, since Cl is the limiting reactant. Certified reference materials, BCR 182 and NIST 8414, and addition and recovery tests were used to evaluate the accuracy of the method and good results were achieved at a 95% confidence level. The method was applied to direct determination of Cl in five produced water samples from offshore oil wellbore, high complex matrix, whose conventional methods require tedious treatment before the analysis.

Electrochemical advanced oxidation processes as decentralized water treatment technologies to remediate domestic washing machine effluents.

Water scarcity is one of the major concerns worldwide. In order to secure this appreciated natural resource, management and development of water treatment technologies are mandatory. One feasible alternative is the consideration of water recycling/reuse at the household scale. Here, the treatment of actual washing machine effluent by electrochemical advanced oxidation processes was considered. Electrochemical oxidation and electro-Fenton technologies can be applied as decentralized small-scale water treatment devices. Therefore, efficient decolorization and total organic abatement have been followed. The results demonstrate the promising performance of solar photoelectro-Fenton process, where complete color and organic removal was attained after 240 min of treatment under optimum conditions by applying a current density of 66.6 mA cm-2. Thus, electrochemical technologies emerge as promising water-sustainable approaches.

Functional group influences on the reactive azo dye decolorization performance by electrochemical oxidation and electro-Fenton technologies.

Electrochemical water treatment technologies are highly promising to achieve complete decolorization of dyebath effluents, as demonstrated by several studies reported in the literature. However, these works are focused on the treatment of one model pollutant and generalize the performances of the processes which are not transposable since they depend on the pollutant treated. Thus, in the present study, we evaluate, for the first time, the influence of different functional groups that modify the dye structure on the electrochemical process decolorization performance. The textile azo dyes Reactive Orange 16, Reactive Violet 4, Reactive Red 228, and Reactive Black 5 have been selected because they present the same molecular basis structure with different functional groups. The results demonstrate that the functional groups that reduce the nucleophilicity of the pollutant hinder the electrophilic attack of electrogenerated hydroxyl radical. Thereby, the overall decolorization efficiency is consequently reduced as well as the decolorization rate. Moreover, the presence of an additional chromophore azo bond in the molecule enhances the recalcitrant character of the azo dyes as pollutants. The formation of a larger and more stable conjugated π system increases the activation energy required for the electrophyilic attack of •OH, affecting the performance of electrochemical technologies on effluent decolorization.

Solar photocatalytic application of NbO2OH as alternative photocatalyst for water treatment.

Water recycling and industrial effluents remediation are a hot topic of research to reduce the environmental impact of the human activity. Persistent organic pollutants are highly recalcitrant compounds with hazardous effects associated to their fate in water bodies. Several novel technologies have been developed during the last decades to deal with this novel contamination. However, the natural sources and idiosyncrasy of each country lead to the potential application of different technologies. In this context, we have focused on the development of phocotalytic treatment of solutions containing dyes using a novel photocatalytic material, the NbO2OH. The NbO2OH was synthesized and characterized with different techniques. Several assays demonstrated the solar photoactivity of this novel oxyhydroxide catalyst, achieving complete decolorizations after 10min of treatment under optimal conditions of 1.0gL-1 NbO2OH photocatalyst loading, 0.1M of H2O2 as electron scavenger, pH4.0 and methyl orange concentrations up to 15mgL-1. Also, the catalyst recuperation demonstrated the potential reuse of this photocatalyst without losing catalytic response after five cycles. This work is of significant importance because niobium is a natural resource, mainly extracted in Brazil and the annual global sunlight irradiation in the near-equatorial region of northeast Brazil is over the average solar irradiation of the planet. Thus, the solar photocatalytic treatment using NbO2OH in northeast Brazil appears as a highly potential environmental-friendly nanotechnology to mitigate the water pollution.

Scale-up of electrochemical oxidation system for treatment of produced water generated by Brazilian petrochemical industry.

Scale-up of anodic oxidation system is critical to the practical application of electrochemical treatment in bio-refractory organic wastewater treatment. In this study, the scale-up of electrochemical flow system was investigated by treating petrochemical wastewater using platinized titanium (Ti/Pt) and boron-doped diamond (BDD) anodes. It was demonstrated that flow cell was successfully scaled-up because when it was compared with batch mode (Rocha et al. 2012b), higher performances on organic matter removal were achieved. Under the suitable operating conditions and better anode material, the chemical oxygen demand (COD) of petrochemical wastewater was reduced from 2,746 to 200 mg L(-1) within 5 h with an energy consumption of only 56.2 kWh m(-3) in the scaled-up BDD anode system. These results demonstrate that anode flow system is very promising in practical bio-refractory organic wastewater treatment.