Guillermo Tiburcio Munive

LIGHTWEIGHT AND THERMAL BLOCKS FROM ZEOLITES AS AGGREGATED

The present research is focused on the design of mixtures containing zeolite (Z), as an alternative aggregate and their use in the production of blocks with lightweight and insulating properties that comply with the specific requirements of standards for its application in construction. To improve lightweight and insulating properties in blocks, first mixtures zeolitic sand/cement/lime (ZS/C/L) were prepared and their compression resistances were evaluated. After that, mixtures with the best compression resistances were choice to evaluate lightweight and insulating properties. Mixtures with the best properties (compression resistance, lightweight, and thermal conductivity) were use to make blocks by pressing in an industrial machine. Properties like compression resistance at 28 days after being cured, weight and thermal conductivity were evaluated in blocks and compared with those made out from traditional mixtures containing river sand (RS), C, and L. Results reveals that it is possible design alternative blocks with the following characteristics and properties: weight of 11 kg (15.4% lower than traditional block), thermal conductivity of 0.37 W/m°C (77.30% less than traditional bocks [1.63 W/m°C]), and compression resistance at 28 days of 74 kg/cm2 (above the resistance required [60 kg/cm2] in blocks).

Uso de Resina de Intercambio Aniónico para la Recuperación del Complejo Oro Tiosulfato desde Soluciones Acuosas

Resumen Se estudio la adsorcion de oro utilizando la resina AuRIX ® 100 en medio tiosulfato de amonio, evaluando algunas variables que afectan la cinetica del proceso tales como: temperatura, velocidad de agitacion, pH, concentracion de tiosulfato de amonio (NH 4 ) 2 S 2 O 3 y concentracion de oro. El estudio se llevo a cabo en un reactor batch y una columna de intercambio ionico. Las condiciones de operacion que presentaron mejores resultados de extraccion de oro a 25oC, fueron: pH=10.5, velocidad de agitacion=500 rpm, [Au]=1 mg/l, [(NH 4 ) 2 S 2 O 3 ]=0.04 M, 5 gramos de resina. Los resultados indican que al aumentar [(NH 4 ) 2 S 2 O 3 ] favorece la adsorcion en un 99% durante tres horas, siendo afectado notablemente por la presencia de amonio. Las condiciones con mejores resultados en la columna a 25oC fueron, pH= 10.5 y [Au] =1 mg/l. Palabras clave: adsorcion oro, tiosulfato, resina AuRIX ® 100, cinetica Use of Anion Exchange Resin for the Recovery of the Complex Gold Thiosulfate from Aqueous Solutions

Selective adsorption of gold and silver in bromine solutions by acetate cellulose composite membranes coated with polyaniline or polypyrrole

This paper presents the selective adsorption of bromine-metallic complexes of Au and Ag on composite membranes, as well as the desorption process and redoping of the conducting polymers. The polyaniline (PANI) and polypyrrole (PPy) membranes exhibited relevant adsorption properties. 72% for gold and 98% for silver with PANI, 50% for gold and 97% for silver with PPy, in bromine complexes. The adsorption capabilities of the composite membranes were attributed to the ion exchange between the dopant and the AuBr4− or AgBr2− complexes. Both materials fitted to a Langmuir isotherm. PANI-based membranes reached 31.4% of gold and 54.4% of silver desorption whereas PPy-based membranes reached 54% of gold and 28.8% of silver. Redoping studies suggested the potential reuse of the PANI-based membranes at least for six cycles of the adsorption/desorption process. The preparation of cellulose acetate membranes modified with poly (acrylic acid) and triphenyl phosphate and coated with the conducting polymers, PANI or PPy was in accordance to our previously reported method. The composite membranes were characterized by FT-IR, scanning electron microscopy, electrical conductivity measurements, I–V, mechanical tests, contact angle measurements, XRD and energy disperse spectroscopy. The novelty of the present work is the combination of electroconductive polymers, for the recovery of metals, and bromide as a leachate, less harmful than the traditionally used leachers.