Use of nanomaterials in the pretreatment of water samples for environmental analysis

The challenge of providing clean drinking water is of enormous relevance in today’s human civilization, being essential for human consumption, but also for agriculture, livestock and several industrial applications. In addition to remediation strategies, the accurate monitoring of pollutants in water sup-plies, which most of the times are present at low concentrations, is a critical challenge. The usual low concentration of target analytes, the presence of in-terferents and the incompatibility of the sample matrix with instrumental techniques and detectors are the main reasons that renders sample preparation a relevant part of environmental monitoring strategies. The discovery and ap-plication of new nanomaterials allowed improvements on the pretreatment of water samples, with benefits in terms of speed, reliability and sensitivity in analysis. In this chapter, the use of nanomaterials in solid-phase extraction (SPE) protocols for water samples pretreatment for environmental monitoring is addressed. The most used nanomaterials, including metallic nanoparticles, metal organic frameworks, molecularly imprinted polymers, carbon-based nanomaterials, silica-based nanoparticles and nanocomposites are described, and their applications and advantages overviewed. Main gaps are identified and new directions on the field are suggested.publishe

Estimation of limiting equivalent conductivity and ionic radius of tetraborate anion from conductivity measurements of concentrated tetraborate solutions

The conductivities of aqueous solutions of sodium sulphate and sodium tetraborate at different concentrations were measured. Using a novel method, these data were used to determine the limiting equivalent ionic conductivity and ionic radius of tetraborate ion. It was found that the limiting equivalent ionic conductivity of tetraborate ion is 34.58 ohm(-1) cm(2) and the ionic radius of tetraborate is 3.507 +/- 0.076 angstrom

Reprint of “Ion beam sputter coating in combination with sol-gel dip coating of Al alloy tube inner walls for corrosion and biological protection”

© 2019Aluminium alloy AlCuMg is an alloy with high mechanical strength and fracture toughness, but it suffers from poor corrosion resistance and friction behaviour. With a combined process of sol-gel deposition of zirconium oxide and a top coating of diamond-like carbon formed by ion beam sputtering with a movable conical sputter target inside the tube, the inner walls of AlMgCu tubes were homogeneously coated with a duplex coating with high resistance against corrosion in chloride solution. When Ag was added to the carbon sputter target, a DLC coating that contained Ag was obtained. Microbial tests showed that the coating is effective against pathogenic E. coli bacteria

p-tert-Butylcalix[8]arene loaded silica gel for preconcentration of uranium(VI) via solid phase extraction

This paper reports silica gel loaded with p-tert-butylcalix[8]arene as a new solid phase extractor for determination of trace level of uranium. Effective extraction conditions were optimized in column methods prior to determination by spectrophotometry using arsenazo(III). The results showed that U(VI) ions can be sorbed at pH 6 in a mini-column and quantitative recovery of U(VI) (> 95-98%) was achieved by stripping 0.4 mol L-1 HCl. The sorption capacity of the functionalized sorbent is 0.072 mmol uranium(VI) g(-1) modified silica gel. The relative standard deviation and detection limit were 1.2% (n = 10) for 1 mu g uranium(VI) mL(-1) solution and 0.038 mu g L-1, respectively. The method was employed to the preconcentration of U(VI) ions from spiked ground water samples

Ion beam sputter coating in combination with sol-gel dip coating of Al alloy tube inner walls for corrosion and biological protection

Aluminium alloy AlCuMg is an alloy with high mechanical strength and fracture toughness, but it suffers from poor corrosion resistance and friction behaviour. With a combined process of sol-gel deposition of zirconium oxide and a top coating of diamond-like carbon formed by ion beam sputtering with a movable conical sputter target inside the tube, the inner walls of AlMgCu tubes were homogeneously coated with a duplex coating with high resistance against corrosion in chloride solution. When Ag was added to the carbon sputter target, a DLC coating that contained Ag was obtained. Microbial tests showed that the coating is effective against pathogenic E. coli bacteria