Andrew J. Saterlay

Sono-cathodic stripping voltammetry of manganese at a polished boron-doped diamond electrode: application to the determination of manganese in instant tea

Ultrasonically assisted cathodic stripping voltammetry at a boron-doped diamond electrode was developed for the detection of manganese. Differential-pulse voltammetry was used to give the analytical signal from a cathodic strip of electrodeposited MnO2; linearity was observed from 10(-11) M to at least 3 x 10(-7) M, with 10(-11) M being the detection limit for a 2 min deposition. The procedure involves both ultrasonic-anodic deposition of MnO2 and ultrasonic-cathodic stripping. This novel analytical tool is robust, reproducible, mercury free, oxygen insensitive and highly specific towards manganese. The differential-pulse sono-cathodic stripping voltammetric technique was used to determine successfully the manganese content of two instant tea samples, giving excellent agreement with independent AAS analyses.

Sono‐Cathodic Stripping Voltammetry of Lead at a Polished Boron‐Doped Diamond Electrode: Application to the Determination of Lead in River Sediment

Ultrasonically-assisted cathodic stripping voltammetry at a boron-doped diamond electrode, has been developed for the detection of lead. At concentrations above 3 µM, linear sweep voltammetry was used to give the analytical signal from a cathodic strip of electrodeposited PbO2; linearity was observed from 3–100 µM, with 3 µM being the lower detection limit. Square-wave voltammetry was then employed for the cathodic stripping step, to lower the detection limits of the technique while retaining linearity to the order of 10–8 M. The procedure involves ultrasonic electrode cleaning, cathodic preconditioning and sono-anodic deposition of PbO2. This novel analytical tool is mercury-free, oxygen insensitive and highly specific towards lead, yet still offers scope for further elemental diversity, particularly for the detection of copper and iron. The square-wave sono-cathodic stripping voltammetry technique was combined with an ultrasonically assisted acid digestion protocol to successfully determine the lead content of a contaminated sample of river sediment, offering significant time saving over the currently used analytical procedure.

Towards greener disposal of waste cathode ray tubes via ultrasonically enhanced lead leaching

The disposal of waste cathode ray tubes (CRT) from old televisions and discarded computer monitors is rapidly becoming an issue of growing environmental concern due to the leaching of lead and other toxins by groundwater from landfill sites. Imminent legislation in both the EU and the USA is likely to demand much stricter control on the disposal of such hazardous electronic equipment, with a drive towards lead removal prior to landfill and/or recycling. This paper describes the use of power ultrasound to facilitate the removal of lead from the heavily-leaded CRT glass via an accelerated leaching protocol, with the aim of producing a lead-free product for greener disposal or more ideally for glass recycling purposes. The paper also describes the use of cathodic stripping voltammetry at a boron-doped diamond sensor, as a quick, easy and cost-effective technique for monitoring the rate of lead released from the CRT glass into a mildly acidic leachate.

An Ultrasonically Facilitated Boron-Doped Diamond Voltammetric Sensor for Analysis of the Priority Pollutant 4-Chlorophenol

Electroanalysis of the ‘priority pollutant’, 4-chlorophenol, is largely unreported in the scientific literature, due mainly to the electrode passivation observed from oxidative by-products. Work is presented which details the combination of high-intensity ultrasound with a mechanically and chemically robust boron-doped diamond electrode allowing successful development of an aqueous 4-chlorophenol voltammetric sensor. The surface regeneration abilities of power ultrasound, through cavitational erosion of electrodeposited 4-chlorophenol by-products, facilitates a reproducible, insonated limiting-current oxidative signal in dilute acid conditions, with increased mass-transport offering enhanced sensitivity. A lower limit of detection of 1 μM and a linear range of 1–300 μM are reported; the technique being analytically useful over a concentration range where aquatic 4-chlorophenol pollution is known to occur. The use of power ultrasound during the electrooxidation of 4-chlorophenol at boron-doped diamond has also been shown to be advantageous in the electrochemical degradation of the substance, potentially offering further waste-water clean-up applications of this dual technology.

Sonoelectrochemical investigation of silver analysis at a highly boron-doped diamond electrode.

A study into the sonoelectroanalysis of silver at a highly boron-doped diamond electrode is presented, exploring the benefits of the introduction of power ultrasound and new electrode materials into classical electrochemical techniques. Both cathodic and anodic stripping voltammetry have been investigated in terms of their analytical suitability towards silver detection. Cathodic stripping voltammetry, via electrodeposited silver oxide, was affected by the unusual chemistry of the highly oxidising Ag(2+) species and the characterisation of this system is discussed in detail. Anodic stripping, via deposition of metallic silver on the bare boron-doped diamond electrode surface under ultrasound, coupled with square-wave voltammetry, was successfully employed in the development of a sensitive technique for the analysis of trace silver ions. A detection limit for Ag(+) of 10(-9) M for a 300-s deposition, with a linear range of at least two orders of magnitude, and the beneficial effects of controlling the speciation of Ag(+) via complexation with chloride ions are reported.

Lead Dioxide Deposition and Electrocatalysis at Highly Boron-Doped Diamond Electrodes in the Presence of Ultrasound

Boron-doped diamond (BDD) is u versatile and novel electrode material which, due to its mechanical and chemical robustness, wide potential window, low background interference, und ease of chemical modification, is becoming an interesting alternative to conventional electrodes for a wide range of electrochemical applications. It is shown in this study that BDD is a good substrate for the ultrasound-enhanced electrodeposition of lead dioxide, producing strongly adhered electrically conducting deposits. Power ultrasound is used to enhance both the efficiency of the PbO 2 deposition procedure and the rate of the electrocatalytic ethylene glycol oxidation process at the PbO 2 -modified BDO electrode. The presence of high levels of aqueous organic material is shown to interfere with the lead dioxide deposition process. Under optimized insonation conditions the PbO 2 deposit, quantified by using cathodic stripping voltammetry, is shown to be mechanically stable. When used in conjunction with power ultrasound to perform the electrocatalytic oxidation of ethylene glycol two distinct types of oxidation processes at PbO 2 , chemically rate limited and electrochemically rate limited, are observed.