To recover high quality plastics from mixed plastic waste by selective extraction using simple, cheap and non-toxic solvents at moderately elevated pressure and temperature.
The study of neurological effects of drugs and environmental chemicals has led to discovery of molecular targets in the nervous tissue which are also present in non-neural more accessible sites in the body such as plasma or peripheral blood cells. In some instances, changes in the concentration and or characteristics of molecular components located in these peripheral tissues have been shown to precede clinical manifestations of chemical insult to the nervous system and may therefore represent ideal markers for identifying early neurotoxic events. The objective of the studies is to develop and validate peripheral indicators allowing the quantitative assessment of early, subclinical effects of human exposure to neurotoxic chemicals. Experiments have been performed on a series of biomarkers of potential clinical interest including myelin basic protein (MBP) polyamines, serotonin (5-HT) in platelets and lymphocyte neurotransmitter receptors. Primary or secondary damage to the myelin sheath of nerve fibres is a common feature of many neurological and neurotoxicological conditions in man. MBP is an important constituent of normal myelin, and is normally excluded from the cerebrospinal fluid in health subjects. However, free MBP is liberated during myelin damage, and it has been possible to detect it in cerebrospinal fluid following experimental lesions of the central nervous system in rats. An interesting finding is that myelin basic protein has an half life of about 2 hours to 3 hours in rats. This indicates that monitoring MBP will give a measure of the ongoing rate of myelin destruction, which may be particularly useful as a predictive measure in the clinical situation. The study of polyamines has suggested an involvement of these substances in the response of brain tissue to ischemic, mechanical or chemical mediated injuries. Research has been carried out to characterise the action exerted in the central nervous system and in platelets by neurotoxicants such as ecstasy (MDMA), fenfluramine, and related amphetamines which are known to reduce neuronal 5-HT content. Attention has also been devoted to clarify the profile of molecular interactions of neurotoxic chemicals which are of major concern as industrial or environmental pollutants.
Good results were obtained with hexane, pentane and CH2CL2.
Polyolefins such as HDPE and LDPE and also PVC have been extracted. Upon cooling of the extract the dissolved polymers precipitate and can be recovered as a colourless powder. Contaminations such as pigments, fillers and other particulate material remain in the extraction residue. By varying the solvent and the extraction conditions, different types of plastics have been selectively recovered.
The innovative aspect of the research is in the use of these solvents, which offers several advantages in comparison with solvents, usualy used for these purposes:
1. The recovery of the polymer requires not as much energy.
2. The recovery of the solvent is easier.
3. The solvents are cheap and not very toxic.
4. The energy-balance is suitable.
The recovered plastic has been shown to be of similar characteristics as the comparable virgin plastics.
Funding SchemeCSC - Cost-sharing contracts
LE1 9HN Leicester