Calcinated and acidified clay modified carbon graphite electrode was deployed in the simultaneous evaluation of traces of Pb2+ and Cd2+ in solution. After 5 minutes of accumulation in the circuit, the sensitivity of the electrode was evaluated in a solution of Na2SO4 (0.1 M) by square wave voltammetry on the one hand with Pb (II) and on the other hand with Cd (II). Several experimental conditions such as the composition of the carbon clay paste, the effect of preconcentration time, the sweeping speed, concentration effect, media pH, and interference ionic response to the electrochemical response of the working electrode were examined. It was observed that, after 5 minutes of preconcentration, detection limits of 0.15513 μmol·L−1 and 0.24227 μmol·L−1 were obtained for Pb2+ and Cd2+ in the electrolyte solution and 0.08438 μmol·L−1 and 0.46522 μmol·L−1, respectively, when tap water was used. The detection was effective by square wave voltammetry with a more intense current density with respect to lead.

The aim of this study was to produce an inexpensive and easy to implement electrochemical sensor. The synthesis of a composite from poly (vinyl alcohol) and natural clay enabled to obtain a material with interesting properties, in view of the results achieved from thermal analysis and transmission electron microscopy. The layer film of natural poly (vinyl alcohol) clays was used to modify the glassy carbon electrode of which electrochemical response was good in the presence of gallic acid in a phosphate buffer solution. The mechanism of electro-oxidation reaction was proposed, and the pH effect has been approached in order to confirm the reaction mechanism. The concentration linearly increased with the oxidation current peak, with a regression coefficient of 0.989 and a detection limit of 1.005 µM (S/N=3). The method thus proposed is satisfactory for the determination of gallic acid in a solution.

The recovery of plastic waste and agricultural residues has led us to develop composites based on polyethylene terephthalate (PET) filled with cocoa shell powder. These shells have been previously treated with the organosolv process to improve the fiber-matrix interaction. The objective of this work is to develop wall covering materials to replace tiles which require a lot of energy and from PET. The composites were made by the method of melt mixing followed by compression molding. The mechanical, physico-chemical properties and stability to environmental conditions were evaluated. The results showed that the incorporation of 20–30% of powder in the matrix made of PET gave rise to a composite material with good properties for application in construction, as a wall covering replacing the tile. The study showed that the optimum powder weight ratio for optimum composite properties was achieved at a powder weight ratio of 30%. The maximum tensile strength of 60.3 MPa, bending strength of 19.5 MPa, impact strength of 10.3 MPa and water absorption of 1.34% were obtained. Compared with ceramic tile, this water absorption test value is within the range and shows that this composite tile is suitable for use as a bathroom tile.

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The need to protect our environment by eliminating plastic waste as much as possible and by recycling waste from agricultural residue, has led us to formulate composites based on polyethylene terephthalate (PET) loaded with powder from the cocoa shell. The cocoa hulls were prior treated with organosolv process to improve the fiber-matrix interaction. This research is aimed at manufacturing composite wall tiles from recycled PET reinforced with cocoa hull powder (CCP). The composites were manufactured by the melt-mixing method followed by compression molding. The mechanical, physico-chemical properties and the stability to environmental conditions were evaluated. The results showed that the incorporation of cocoa powder at a content of 20-30% in the matrix consisting of PET gave rise to a composite material with good physico-mechanical and chemical properties suitable for use in several sectors. In the construction industry, in particular as wall covering as a replacement for tiles, these x from an economic point of view cost less and compared to clays which consumes enormous amount of energy for the elaboration of ceramics. The study showed that the optimum powder weight proportion for the optimal properties of the composite were achieved at 30% powder weight proportion. The maximum tensile strength of 60.3 MPa, flexural strength of 19.5 MPa, impact strength of 10.3 MPa and water absorption 1.34% were obtained. Water absorption of the tiles increased with the cocoa powder weight. Compare to the ceramic tile this value of water absorption test is in range and show that this composite tile is suitable for use as bathroom tile.