No abstract

A non-enzymatic direct electrochemical glycerol detection method at a commercial boron-doped diamond (BDD) electrode in 0.1 M NaOH supporting electrolyte was developed. All the used electrochemical techniques proved useful features for the oxidation and direct amperometric determination of glycerol at a BDD electrode in 0.1 M NaOH aqueous solution. It was found that the direct electrooxidation of glycerol on the BDD electrode requires both adsorbed glycerol and hydroxyls at the electrode surface. Also, the sp(2) carbon did not allow enhancement of the glycerol oxidation process. The electronalytical sensitivity for the determination of glycerol at the BDD electrode ranged from 0.040 to 0.226 μA mM(-1) as a function of the technique used. The highest electroanalytical sensitivity for the determination of glycerol at the BDD electrode was reached in batch system amperometric quantification under stirring conditions. Performed recovery studies indicated that it is possible to determine glycerol in real samples, and the proposed batch system analysis-based methodology can be a valuable tool for practical glycerol analysis.

In this paper, a new material based on zeolite has been investigated in an attempt to explore the possibility of using it as an efficient adsorbent of copper(II) from industrial wastewater. This composite material is composed of volcanic tuff (containing 83 % zeolite) and cellulose in a 4 to 1 ratio. The performances of the new adsorbent composite have been examined against those of a common adsorbent, the zeolitic volcanic tuff. The adsorption studies were carried out in a batch process at room temperature, and the effect of various parameters (i.e., initial concentration, contact time, adsorbent dosage and pH) was tested. The experimental data have been modeled with Langmuir, Freundlich and Temkin isotherms. The results correspond to Langmuir model showing a monolayer adsorption with a maximum adsorption capacity of 12.74 mg g -1 at 25°C. The copper adsorption onto zeolitic composite was well described by a pseudo-second order kinetic model. The experimental results indicate a superior adsorption of copper(II) onto the new adsorbent when compared against the common zeolite.