Extraction of chlorophyll from pandan leaves using ethanol and mass transfer study

Green pigments are used in many industrial branches including food, drinks, soap and cosmetics. Chlorophyll can substitute synthetic dyes which may affect health. Chlorophyll can be extracted from pandan leaves; the pandan crop grows in many tropical areas. The effects of temperature, 30–70°C and agitation speed, 100–400 rpm on chlorophyll extraction from pandan leaves, using ethanol and the evaluation of mass transfer coefficient, using dimensionless analysis were investigated. The optimal conditions of extraction was obtained at 60°C and 300 rpm; the chlorophyll concentration was 107.1 mg L-1. The volumetric mass transfer coefficient increased with the temperature and agitation speed. Determination of volumetric mass transfer coefficient and dimensionless correlations are useful for further process development or industrial applications

Highly Stable Copper Nanowire-Based Transparent Conducting Electrode Utilizing Polyimide as a Protective Layer

We report the significant improvement of the stability of a copper nanowire (Cu NW)-based transparent conducting electrode (TCE). Our study confirms that in contrast to the common use of poly(vinyl pyrrolidone) (PVP) as a surface passivation agent, PVP facilitates the surface oxidation of CuNWs, which, in turn, severely affects the stability and performance of TCEs. To mitigate this issue, polyimide (CPI) is used as a protective layer for the fabrication of the Cu NW TCEs in the absence of PVP, which shows exceptional stability. The conductivity (resistivity) measurement confirms the stability of TCEs over a period of 90 days without any major degradation, while the conductivity of the reference TCE degrades completely after ∼15 days. In addition, we also demonstrate the device application of our Cu NW TCEs by fabricating a thin-film transistor (TFT) and an organic solar cell showing good operational stability. This study provides an insight into the role of PVP in the poor stability of Cu NWs and offers an alternative for the fabrication of Cu NW-based TCEs with improved stability