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Schematic illustration of the enzymatic pretreatment of GTW using both batch and continuous flow reactors. [Display omitted] • Enzymatic pretreatment of grease trap waste for biodiesel production. • Optimization of batch and flow reactors using response surface methodology. • Comparison of ANOVA and ourselves developed statistical flow process automation. • Results show superiority of continuous flow reactors over their batch counterparts. In this study, we investigated enzymatic pre-treatment of grease trap waste (GTW) as an environmentally beneficial procedure for biodiesel production. Different enzymes, both commercial and newly designed industrial enzymes, were used to reduce the free fatty acids (FFA) level of GTW through an esterification reaction. The process conditions were optimized using response surface methodology with central composite design parameters. A set of 30 experiments, for both batch and continuous flow reactors, were designed to identify the optimal process conditions in which the highest conversion of FFA is achieved. Within the range of the selected operating conditions, the optimized values of reaction temperature, catalyst quantities, ethanol to oil molar ratio, and reaction time for the batch reactor, in which FFA level was reduced to 31.5 %, were found to be 70 °C, 4.5 wt%, 3:1, and 25 min respectively. A significant improvement in the reduction of FFA, of which FFA amount is only 9.9 %, was obtained in the flow reactor when using the commercial enzyme (T = 57 °C, catalyst loading 4.85 %, ethanol to oil ratio 2:1, t = 25 min). In addition to achieving higher conversion, the continuous-flow experiments saved time since the entire series of experiments were completed in<1.5 days, compared to the 6 days required for the equivalent batch processes. These results confirm the superiority of the continuous-flow reactors over their batch counterparts and open the door for future automation of the methods. [ABSTRACT FROM AUTHOR]

Over the years, numerous studies have explored the green synthesis of ethylene. Within this context, the focus of this perspective shifts toward plasma technology, which has demonstrated the capability to convert methane into ethylene. Plasma catalysis creates distinctive physical and chemical environments, particularly at normal temperature and pressure, distinguishing it from alternative methods. Nevertheless, the utilization of atmospheric pressure plasma is intricate, posing scientific challenges in the realms of physics and chemistry. In this viewpoint, various key performance aspects are evaluated, encompassing methane conversion efficiency, ethylene selectivity, and specific energy input. These scientific pros and cons are then assessed for their readiness for industrial-scale implementation. Initially, the potential for small-scale ethylene production is examined, leveraging existing robust process technologies to unlock fresh market and supply chain opportunities. Subsequently, the sustainability of plasma technology for green ethylene production is compared to conventional ethylene production and alternative green ethylene production methods, including biomass-based approaches. Contrary to perhaps optimistic expectations, current literature evidence does not uniformly favor the latter, indicating the potential for plasma-based green ethylene processes. Additionally, this paper underscores the importance of considering Environmental, Social, and Governance factors that influence business decisions. Finally, this review underscores plasma technology as a potentially promising approach for green ethylene synthesis from methane, offering unique advantages under normal conditions while simultaneously presenting scientific challenges. It assesses its viability for small-scale production and benchmarks its sustainability against conventional and alternative methods, emphasizing the importance of a sustainable future for the green petrochemical industry. • Potentials of plasma catalytic methane conversion are compared with other green methods. • Conversion efficiency, selectivity, and sustainability are reviewed in terms of specific energy input. • Small-scale plasma technology enables robust ethylene production and opens new market opportunities for green synthesis. • Green ethylene is analyzed in relation to green hydrogen and ammonia from different aspects. • Plasma-based green ethylene processes are more sustainable than conventional and biomass-based methods. [ABSTRACT FROM AUTHOR]