Presence of heavier molecules and toxic brominated compounds in pyrolysis products of printed circuit boards (PCB) make their use difficult. In the present work to overcome this problem PCBs were pyrolyzed in presence of catalysts such as ZSM-5 and Ca(OH)2 to study their effect on pyrolysis products. The comparison of non-catalytic pyrolysis of PCB was done with oil and gas compositions produced by both techniques. Pyrolysis experiments were done at a lab scale set-up. However, the increased concentrations of ZSM-5 were found to increase char and gases were found to be rich in CH4 and O2. The composition of oils was mainly composed of phenols, phenol derivatives and aromatic compounds, which increased with pyrolysis with ZSM-5 and Ca(OH)2. Ca(OH)2 was found effective in removing brominated compounds from oil and no halogens were observed in oil. Char produced during pyrolysis was mesoporous in nature and composed of some fractions of metals and glass fibers.

With advancing technology, printed circuit board (PCB), one of the most important components of ewaste, has become a source of pollution due to an ineffective waste management system. This problem can be solved by converting PCB waste into a valuable product which will emerge to maximize the renewable energy supplies. In this aspect, co-pyrolysis is advantageous in both simple and successful in producing high-quality pyrolysis oil. In this paper, cotton stalk (CS) as biomass was used and pyrolysis of PCB, CS, and a mixture of both in 1:1 have been carried out. CS has a good combustibility at 500°C which was chosen for the pyrolysis reaction in a fixed bed reactor for slow pyrolysis. The pyrolytic oil was analysed by GC–MS and FTIR. The results indicate that there is an increase in oil yield from 19.6% to 27.5% by weight and phenol and phenolic compounds in oil of co-pyrolysis from 60.94% to 76.82% compared to literature available. There is an increase in bromine solidification in char by 25% with a mixture of CS and PCB compared to CS and PCB individually which is much higher than literature data. To the best of the authors’ knowledge, co-pyrolysis of PCB:CS has been attempted first time and debromination of oil was found excellent in the present work.

Stevia rebaudiana Bertoni which has gained industrial and scientific interests is a suitable nutritional alternative to sucrose as a sweetener. Recently, there have been studies which show the extraction of this phytochemical substance from stevia leaves and purification methods by several alcohols and chromatographic methods. However, these methods are not cost-effective. Therefore, an attempt was made to extract and purify ST using inexpensive, scalable and simple techniques where different steps like extraction, electrocoagulation, ion exchange, activated charcoal, vacuum evaporation and butanol wash were used as purification steps. The present study established a new improved technology of extraction of ST from stevia leaves using water as a solvent followed by various purification steps. 496 mg of Stevioside extracted in the form of crystals was obtained from 100 g of leaves which is 10 times more than the reported yield of 54 mg from 100 g stevia leaves in literature. This methodology can be scaled up at the industry level for future large production to meet the huge demand for natural sweeteners.