Maria Paraschiv

Optimization of biodiesel production from animal fat residue in wastewater using response surface methodology

Animal fat residues (AFR) from waste water were used as feedstock to produce biodiesel by a two-step acid-catalyzed process. Treatment of the AFRs with 5.4% (w/w) of 17 M H2SO4 at a methanol/AFR ratio of 13:1 (50%w/w) at 60 °C converted more than 95% of the triglycerides into fatty acid methyl esters (FAMEs) with an acid value (AV) of 1.3 mgKOH/gbiodiesel. Response surface methodology indicated that a lower AV cannot be reached using a one-step acid catalyzed process. Thus a two-step acid catalyzed process was employed using 3.6% catalyst and 30% methanol for 5 h for the first step and 1.8% catalyst and 10% methanol for 1 h in the second step, resulting in a yield higher than 98% and an AV of 0.3 mgKOH/gbiodiesel. The product thus conforms to the European norm EN14214 concerning biodiesel.

Combination of pyrolysis and hydroliquefaction of CCB-treated wood for energy recovery: optimization and products characterization.

In this paper, pyrolysis and hydroliquefaction processes were successively used to convert CCB-treated wood into bio-oil with respect to environment. Pyrolysis temperature has been optimized to produce maximum yield of charcoal with a high metal content (Cu, Cr, and B). The results obtained indicate that the pyrolysis at 300 °C and 30 min are the optimal conditions giving high yield of charcoal about 45% which contains up to 94% of Cu, 100% of Cr and 88% of B. After pyrolysis process, the charcoal has been converted into bio-oil using hydroliquefaction process. The optimization approach for the yield of bio-oil using a complete factorial design with three parameters: charcoal/solvent, temperature and hydrogen pressure was discussed. It is observed that the temperature is the most significant parameter and the optimum yield of bio-oil is around 82%. The metal analysis shows that the metals present in the bio-oil is very negligible.

Energy and monomer recovery from polymer wastes

In this paper the products obtained through thermochemical processing of several polymer-based wastes are characterised. The influence of chemical composition of raw materials on the characteristics of obtained products has been investigated by using fixed bed reactor. The aim of this work is to identify the best use of products recovered after pyrolysis of plastic wastes collected from chemical and biochemical laboratories. This work is developed in a laboratory bench installation design to perform O2-free processing at atmospheric pressure. The process parameters such as pyrolysis temperature and adapted heating rate have been determined through the transposition of thermal and kinetic information provided by thermogravimetric analysis (TGA). Gas-chromatography techniques have been used to identify the chemical composition of gases (GC/TCD) and liquids (GC/FID-MS). It was established that polymer wastes can led to a valuable liquid products, with encouraging energetic properties that allow their blending with fuels currently used without altering the performances of burning devices.

Study on hydrogen and hydrogen-carriers production during rubbery wastes cracking

There is much interest in producing hydrogen from various materials, including rubbery wastes to help in the fulfilment of the predicted hydrogen economy of the future. In this paper thermal and catalyzed cracking processes have been investigated for their suitability in producing gaseous compounds during thermochemical decomposition of polymer-based materials. Hydrogen and hydrogen-carriers production through rubbery wastes cracking was carried out into a laboratory bench scale installation using a fixed bed reaction system. Experiments were conducted at 500 °C with a catalyst/waste ratio of 1/30. Catalysts influences on rubber decomposition were characterized using a variety of methods, including thermogravimetric analysis (TGA). The results indicated that the gas yield varied from 17 to 31 wt.% with addition of different catalysts. The potential of H2 production was significantly increased from 14 to 32 wt.% by using MgO-based catalytic bed. Moreover, it was found that the higher heating value (HHV) of gases varied from 10 to 44 MJ/Nm3, and the use of catalysts led to an increasing HHV especially in the first stage of cracking (250-350°C). This work highlights the evolution of hydrogen and hydrogen-carriers during thermal and catalyzed cracking, too.

Waste tyres pyrolysis: Managing the environmental hazards of scrap tyres

Thinking on environmental hazards, images of chemicals in waters, or air pollution coming out of industrial furnaces are most often seen. There are some hazards that are overlooked and one of them is scrap tires. Without a good management, scrap tires treatment can threaten not only our environment, but the public health as well. For instant, run-off from scrap tire fires can contaminate groundwater and surface water, and scrap tire sites are an ideal habitat for the breeding of insects carrying disease. In this paper we present an experimental approach on understanding and managing the environmental hazards of co-products resulted during energy recovery processes applied on scrap tyres. As tyre combustion faces serious problems related to harmful emissions, pyrolysis appears as a process that allows the management of toxic compounds. The experimental data were used to highlight the influence of textile and metal tyre compounds and provided worthy and substantive information on the issues to conduct and manage the thermochemical process in order to maximize the interest product yield. Thus, for the reactions occurs during pyrolysis and combustion of tyres organic matters the main intensive degradation thermal ranges have been established. The work was carried out by coupling thermogravimetric analysis (TGA) of tyre samples with bench scale reactor in order to identify the relationships between thermochemical behaviour and products distribution. TGA results afford the study of the kinetics parameters while the laboratory facilities allow the comprehension of tyres behaviours in real conditions. The processing temperature was limited at 700°C and the measures focused on the mass balance determination and gaseous products analysis. It was found that the three obtained products have a good energetic potential: the solid (20-32 MJ/kg), the liquid (41-43 MJ/kg) and the gas (32-36 MJ/m3). Nevertheless, the liquid need to be upgrading in order to be used as Diesel-like fuel and gases should be treated to remove sulphur compounds. With this purpose some catalysts, known for their ability to increase gaseous fraction have been studied in TGA and an important shift of degradation peaks was identified and discussed.