Treatment of synthetic textile wastewater containing dye mixtures with microcosms

The aim was to assess the ability of microcosms (laboratory-scale shallow ponds) as a post polishing stage for the remediation of artificial textile wastewater comprising two commercial dyes (basic red 46 (BR46) and reactive blue 198 (RB198)) as a mixture. The objectives were to evaluate the impact of Lemna minor L. (common duckweed) on the water quality outflows; the elimination of dye mixtures, organic matter, and nutrients; and the impact of synthetic textile wastewater comprising dye mixtures on the L. minor plant growth. Three mixtures were prepared providing a total dye concentration of 10 mg/l. Findings showed that the planted simulated ponds possess a significant (p < 0.05) potential for improving the outflow characteristics and eliminate dyes, ammonium-nitrogen (NH4-N), and nitrate-nitrogen (NO3-N) in all mixtures compared with the corresponding unplanted ponds. The removal of mixed dyes in planted ponds was mainly due to phyto-transformation and adsorption of BR46 with complete aromatic amine mineralisation. For ponds containing 2 mg/l of RB198 and 8 mg/l of BR46, removals were around 53%, which was significantly higher than those for other mixtures: 5 mg/l of RB198 and 5 mg/l of BR46 and 8 mg/l of RB198 and 2 mg/l of BR46 achieved only 41 and 26% removals, respectively. Dye mixtures stopped the growth of L. minor, and the presence of artificial wastewater reduced their development

Designing an Efficient Multimode Environmental Sensor Based on Graphene–Silicon Heterojunction

By exploiting the adsorbent gaseous molecules induced changes in intrinsic properties of graphene/silicon (Gr/Si) Schottky junction, the authors report a sensitive, low-power consuming, multimode environmental sensor. By combining an array of Gr/Si Schottky diodes with a differential amplifier circuit, the authors are able to not only differentiate the temperature coefficient and humidity sensing, but also monitor the sun-light exposure time. Our device is particularly sensitive toward humidity in both forward and reverse biased, and works in resistive as well as capacitive mode. Sensitivity of our devices reached to 17%, 45%, 26%, and 32% per relative humidity (%RH) for reverse biased, forward biased, resistive, and capacitive modes, respectively. In the reverse mode, the power consumption is as low as 2 nW. Moreover, our sensor response is highly selective, with sensitivity lower than 1% for other gases present in atmosphere including H$_{2}$, O$_{2}$, N$_{2}$, and CO$_{2}$. High sensitivity, low-power consumption, multiple operation modes, and high selectivity promises application of our sensor for industrial and home safety, environmental monitoring such as indoor and outdoor air conditions, process monitoring, and others