Abstract
The disposal of solid waste is a serious problem worldwide that is made worse in developing countries due to inadequate planning and unsustainable solid waste management. In Mexico, only 2% of total urban solid waste is recycled. One non-recyclable material is poly (styrene-co-butadiene), which is commonly used in consumer products (like components of appliances and toys), in the automotive industry (in instrument panels) and in food services (e.g. hot and cold drinking cups and glasses). In this paper, a lab-scale strategy is proposed for recycling poly (styrene-co-butadiene) waste by sulfonation with fuming sulfuric acid. Tests of the sulfonation strategy were carried out at various reaction conditions. The results show that 75°C and 2.5 h are the operating conditions that maximize the sulfonation level expressed as number of acid sites. The modified resin is tested as a heterogeneous catalyst in the first step (known as esterification) of biodiesel production from a mixture containing tallow fat and canola oil with 59% of free fatty acids. The preliminary results show that esterification can reach 91% conversion in the presence of the sulfonated polymeric catalyst compared with 67% conversion when the reaction is performed without catalyst.
Highlights
The Guadalajara Metropolitan Zone (GMZ) is the second largest urban area in México
Poly waste was sulfonated with fuming sulfuric acid under varying times and temperatures
It was verified that the sulfonated polymer waste under these conditions was able to act as catalyst in the esterification of a synthetic mixture of tallow fat and canola oil with a high free fatty acids (FFAs) content
Summary
The Guadalajara Metropolitan Zone (GMZ) is the second largest urban area in México. More than 4 million inhabitants in the GMZ generate approximately 0.508 kgperson-1day-1 of household solid waste. The major components of the household solid waste are putrescible elements (53%), different types of paper (10%) and plastics (9%). From all of this waste, only 2.2% is separated for reuse/recycling, whereas the rest is deposited in municipal landfills. It is well known that the widespread use of fossil fuel reserves has increased the air pollution levels worldwide, affecting global climate These not recommended because the reaction between FFAs and the alkaline catalyst makes soap, thereby reducing biodiesel conversion and creating difficulties in separating and purifying the product (Marchetti et al 2007). Solid-acid catalysts have lower reaction rates, but they are often preferred over sulfuric acid because they are separated from the product, prevent corrosion (Silva and Rodrigues 2006) and can be reused (Vieira Grossi et al 2010)
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