Compounds based on iron mining tailing dams and activated carbon from macauba palm for removal of emerging contaminants and phosphate from aqueous systems.

In this work, an iron-rich residue, which is widely obtained as a by-product in the iron mining industry, and macauba endocarp, waste from the extraction of vegetable oil for the production of biofuels, were used in the preparation of different composites based on iron and carbon. The composites were obtained by manual grinding of the calcined iron residue and activated carbon prepared by the macauba endocarp followed by thermal treatment under nitrogen atmosphere. The effect of the thermal treatment was analyzed by Mössbauer spectroscopy and X-ray diffraction and showed that the increase in the treatment temperature promoted the formation of different reduced iron phases in the final composite, such as FeO, FeO, and Fe.

Influence of the surface modification of granular-activated carbon synthesized from macauba on heavy metal sorption.

Adsorption on activated carbon is a promising technique for the treatment of low-concentration heavy metal pollutants in water with high efficiency and simple operation. However, commercial-activated carbon is often associated with high costs. Therefore, much attention has been given to activated carbon derived from low-cost agricultural and residual biomass.

Emerging contaminants removal by granular activated carbon obtained from residual Macauba biomass.

The removal of emergent contaminants via adsorption on granular activated carbon, prepared from Macauba palm, has been studied, contributing to the recovery of the residual biomass, endocarp, obtained in the Macauba palm oil extraction process. The material was characterized by different techniques, such as Raman spectroscopy, thermal analysis, adsorption/desorption of N, zeta potential, and scanning electron microscopy. The N adsorption studies showed that the material presents wide micropores and narrow mesopores, and has a surface area of 907.

Polyurethane foams containing residues of petroleum industry catalysts as recoverable pH-sensitive sorbents for aqueous pesticides.

To investigate ways of mitigating the contamination of water with herbicides, which is a well-recognized global problem, we prepared natural resource-based polyurethane foams containing different amounts of petroleum industry catalyst residue (RC) and tested them as atrazine (ATZ, a common herbicide) sorbents in aqueous solutions. The above sorbents were characterized by infrared spectroscopy, electron microscopy, microtomography, thermogravimetric analysis, and X-ray diffraction. The adsorption/desorption of ATZ thereon was investigated as a function of foam composition, pH, initial ATZ concentration, and time.

Growth of carbon structures on chrysotile surface for organic contaminants removal from wastewater.

Amphiphilic magnetic composites were produced based on chrysotile mineral and carbon structures by chemical vapor deposition at different temperatures (600-900 °C) and cobalt as catalyst. The materials were characterized by elemental analysis, X-ray diffraction, vibrating sample magnetometry, adsorption and desorption of N2, Raman spectroscopy, scanning electronic microscopy, and thermal analysis showed an effective growth of carbon structures in all temperatures. It was observed that at 800 and 900 °C, a large amount of carbon structures are formed with fewer defects than at 600 and 700 °C, what contributes to their stability.

Synthesis and characterization of catalysts based on mesoporous silica partially hydrophobized for technological applications.

In this work, mesoporous silica mobil composition of matter no. 41 (MCM-41) was synthesized by the sol-gel method. Two different surface modifications were made to transform this material into a very active adsorbent and catalyst support: (i) impregnation of iron nanoparticles and (ii) hydrophobization via chemical vapor deposition (CVD) with ethanol.

Magnetic composites based on metallic nickel and molybdenum carbide: a potential material for pollutants removal.

New magnetic composites based on metallic nickel and molybdenum carbide, Ni/Mo(2)C, have been produced via catalytic chemical vapor deposition from ethanol. Scanning electron microscopy, thermal analysis, Raman spectroscopy and X-ray diffraction studies suggest that the CVD process occurs in a single step. This process involves the reduction of NiMo oxides at different temperatures (700, 800 and 900°C) with catalytic deposition of carbon from ethanol producing molybdenum carbide on Ni surface.

Controlled reduction of red mud waste to produce active systems for environmental applications: heterogeneous Fenton reaction and reduction of Cr(VI).

In this work, controlled reduction of red mud with H(2) was used to produce active systems for two different environmental applications, i.e. the heterogeneous Fenton reaction and the reduction of Cr(VI).

Potential application of highly reactive Fe(0)/Fe3O4 composites for the reduction of Cr(VI) environmental contaminants.

We describe the use of highly reactive Fe(0)/Fe3O4 composites for the reduction of Cr(VI) species in aqueous medium. The composites were prepared by simple mechanical alloying of metallic iron and magnetite in different proportions, i.e.

Investigation of reaction mechanisms by electrospray ionization mass spectrometry: characterization of intermediates in the degradation of phenol by a novel iron/magnetite/hydrogen peroxide heterogeneous oxidation system.

Electrospray ionization (ESI) mass spectrometry (MS) and tandem mass spectrometry (MS/MS) were used to monitor the oxidation of phenol by a novel heterogeneous Fenton system based on a Fe(0)/Fe(3)O(4) composite and H(2)O(2). On-line ESI-MS(/MS) shows that this heterogeneous system promotes prompt oxidation of phenol to hydroquinone, which is subsequently oxidized to quinone, other cyclic poly-hydroxylated intermediates and an acyclic carboxylic acid. A peroxide-type intermediate, probably formed via an electrophilic attack of HOO(.

Efficient use of Fe metal as an electron transfer agent in a heterogeneous Fenton system based on Fe0/Fe3O4 composites.

In this work a novel heterogeneous Fenton system based on Fe(0)/Fe3O4 composites is described. The composites with several Fe(0)/Fe3O4 ratios were prepared by two different methods, i.e.