Research Seminar #6, Oct 10, 2012, 14h00-15h30h
1. Recycling agroindustrial by-products by composting technologies
Margarida J. Quina
CIEPQPF, DEQ-FCTUC, Reaction, Separation and Environmental Engineering Group (GERSE)
Composting may be defined as the biological decomposition and stabilization of organic subtracts, under aerobic and thermophilic conditions, to obtain a final product that can be beneficially applied to land as soil conditioner. There are many agroindustrial by-products that can be recycled by this technology, which can be used both at small (domestic) or industrial scales. This presentation will give an overview about the process technologies and future trends, as well as some results from a case study.
2. Tailoring of silica based aerogels for Space applications
Luísa R. Durães
CIEPQPF, DEQ-FCTUC, Computing, Statistics & Materials Group (CEM)
Tetra-alkoxysilane precursors (Si(OR)4) are widely used to obtain silica aerogels. These aerogels exhibit low density (~100–350 kg/m3), high porosity (>90%) and surface area, low thermal conductivity (~0.01–0.02 W/m K) and high transparency (>90%). These properties make them suitable for use as thermal or acoustic insulators, optical materials, filters, catalysts, among others. Despite these appealing properties, they are brittle, absorb moisture and still have a relatively high density, which might be a drawback for their performance in certain applications, namely in Space insulation applications. Using trialkoxysilanes (R’-Si(OR)3) as precursors in a two-step acid-base catalyzed sol–gel chemistry, the produced silica based aerogels can fulfill the targets for Space applications. In this work, the effect of changing of R’ and R groups (methyl, ethyl or vinyl) on the aerogels density, thermal conductivity, hydrophobicity and mechanical strength will be presented, considering the specifications for their use in Space.