In this work the production of synthesis gas from a mixture of methane (CH4) and carbon dioxide (CO2) by thermal plasma was studied. The best relation found for the gas mixture [CO2]/[CH4] was 1.3. Under the excess of CH4 in the gas mixture soot was formed and also benzene, indene and naphthalene were identified. The disulfides compounds in the gas mixture were degraded causing no interference in the synthesis gas production, suggesting no needs of pretreatment step for sulfurorganic compounds removal in the process

Decomposition of carbon tetrachloride in a DC thermal plasma reactor was investigated in argon atmosphere. The operational parameters such as plasma torch power and argon flow rate versus CCl4 conversion were examined. The CCl4 net degradation was determined by GC-FID, the chlorine produced was quantified by iodometric titration, the solid carbon was characterised by Raman spectroscopy and by BET analysis. The solid carbon collected inside de plasma reactor was submitted to solid/liquid extraction and the desorbed species were identified by GC-MS.

The contamination level of silicon oil used as insulation liquid in high-voltage transformers by ascarel (PCBs) is above those permitted by the Brazilian law. Thus new techniques able to detect ascarel, with low operational costs, are very attractive. The present work proposes an analysis of the contamination levels of silicon oil using the following techniques: naphthalene anion radical reaction for ascarel dechlorination; and potentiometry with an ion-selective electrode for chloride ion determination. The data obtained with the proposed methodology agree well with those from the official methodology, (method IEC 61619).

Anodic electrodissolution procedure in a flow injection system for determination of constituents in alloys is discussed. This approach implement sample preparation procedure by using a chamber and a DC power supply with constant direct current. Solid sample was attached to chamber as anode. In this review a general overview of these procedure is presented. The procedure presented a good performance characterized by a high sample throughput determinations, good accuracy and relative standard deviation.

An on-line electrodissolution procedure implemented in a flow injection system for determination of copper, zinc and lead in brasses alloys by ICP-AES is described. Sample dissolution procedure was carried out by using a PTFE chamber and a DC power supply with constant current. Solid sample was attached to chamber as anode and a gold tubing coupled in the chamber was used as cathode. An electrolytic solution flowing through the gold tubing closed the electric circuit with sample, in order to provide condition for electric dissolution when the DC power supply was switched on. The best results were achieved by using a 1.5 mol l-1 nitric acid solution as electrolyte and a 2.5 A current intensity. The procedure presented a good performance characterized by a relative standard deviation better than < 5% (n=5) and a sample throughput of 180 determinations per hour for Cu, Zn and Pb. Results were in agreement with those obtained by conventional acid dissolution (99% confidence level).

A new automated system for acid-base flow titrations is proposed. In the operation mode, several sample to titrant volumetric ratios are injected in an air segmented plug. Five three way solenoid valves and three acrilic junctions, assembled in a hidrodynamic injection system, were accountable for the monosegmented reagents plug formation. A turbulent flow reactor was used for a perfect mix of reagents in the plug. The detector system employed a glass combined electrode fitted in an acrilic holder. Titrations of hydrochloric, nitric and acetic acids, in several concentrations, were performed with standard sodium hidroxide, for evaluation of the efficiency of the system. The relative standard deviation of the determinations was about ±0,5% and each titration was carried out in 3-4 minutes. A Quick BASIC 4.5® program was developed for the titrator control.

A on-line thermostatization system that use simples materials, for flow injection and continuous flow analysis is described. The proposed system showed good performance between 10 to 40ºC.

A simple flow cell for potentiometric detection is described. It was assembled by making use of two perspex pieces fixed together by means of four screws, and allow the connection of plane membrane conventional electrodes to flow system. Details about its construction are presented. The device performance was evaluated by making use of a cyanide ion-selective electrode. The relative standard deviation was about 0.5% with a detection limit of 8.0 x 10-6 mol CN- dm-3. Under experimental conditions, the linear range was 10-5 to10-2 mol dm-3.

This paper describes the construction and performance of homemade electrodes for voltammetric purpose using cheap materials, like pipette tips and asbestos fiber. A good cost-to-benefit relation makes this devices specially designed for student use, expecting to improve the broadcasting of electroanalytical methods in Brazilian schools.