In this research, the influence of natural zeolites obtained from the volcanic ash of the Ubinas volcano has been studied as synergistic agents in a flame-retardant system (composed of ammonium polyphosphate, pentaerythritol, and polypropylene). Four zeolites were synthesized from volcanic ash, including those that had been calcined and those that had not. These were then placed in an alkaline solution at three synthesis temperatures. Zeolites were characterized through X-ray diffraction, specific surface area by nitrogen adsorption analysis (Brunauer–Emmett–Teller) and scanning electron microscopy. Polypropylene matrix composites were prepared with ammonium polyphosphate, pentaerythritol and zeolites at 1, 5 and 9%. Its thermal stability and fire resistance were evaluated by thermogravimetric analysis, limiting oxygen index, vertical burning test and cone calorimeter and its morphological structure by scanning electron microscopy. It was determined that the synthesis temperature and the use of calcined and without calcined volcanic ash have an influence on the characteristics of the zeolites and on its synergistic action.

The present work studies the mechanical behavior of rice husk as a reinforcement element in mixtures of polyolefins. The composites were made by polyolefin mixtures of 30% LDPE, 40% HDPE and 30% PP, rice husk and Polybond as a compatibilizer. Samples for the tensile test were prepared by injection and compressive methods. The results confirm that rice husk alongside the compatibilizer bring about positively in the strength of composites. In reference to the adherence of rice husk to the mixture of polyolefins, which was studied from the microstructure of composites, the addition of compatibilizer improves the adherence between the polyolefins and rice husk, and thereby the quality in the fracture surface. These composites are considered to be a good alternative for the recovery of plastic agricultural waste.

This current work has focused on the evaluation of the hexavalent chromium – Cr (VI) adsorption carried out by a biocomposite based on rice husk and chitosan. The chromium IV is an agro industrial contaminant residual while chitosan is a natural biopolymer with a great adsorption of heavy metals. Conditions for the biosorption such as concentrations of rice husk and Cr (VI) alongside the contact time, were identified in order to achieve the highest biosorpion of the heavy metal – Cr (VI). The morphology of rice husk, carried out in a Scanning Electron Microscopy (SEM), showed a porous surface which can allow the adherence of chitosan. Different concentrations of rice husk (10, 20, 30, 40, 50 ) were used for the synthesis of the biopolymer. Furthermore, the capacity of Cr (VI) adsorption of the biocomposite based on rice husk and chitosan was evaluated throughout the contact time, resulting in a 68.28 % of Cr (IV) removal at 120 minutes. Additionally, the results of the experimental design consistent with the adsorption kinetic designs are shown in this work.