• Application of graphene-based materials for detection of nitrate and nitrite in water—a review

      Li, Daoliang; Wang, Tan; Li, Zhen; Xu, Xianbao; Wang, Cong; Duan, Yanqing; China Agricultural University; University of Bedfordshire (MDPI AG, 2019-12-20)
      Nitrite and nitrate are widely found in various water environments but the potential toxicity of nitrite and nitrate poses a great threat to human health. Recently, many methods have been developed to detect nitrate and nitrite in water. One of them is to use graphene-based materials. Graphene is a two-dimensional carbon nano-material with sp2 hybrid orbital, which has a large surface area and excellent conductivity and electron transfer ability. It is widely used for modifying electrodes for electrochemical sensors. Graphene based electrochemical sensors have the advantages of being low cost, effective and efficient for nitrite and nitrate detection. This paper reviews the application of graphene-based nanomaterials for electrochemical detection of nitrate and nitrite in water. The properties and advantages of the electrodes were modified by graphene, graphene oxide and reduced graphene oxide nanocomposite in the development of nitrite sensors are discussed in detail. Based on the review, the paper summarizes the working conditions and performance of different sensors, including working potential, pH, detection range, detection limit, sensitivity, reproducibility, repeatability and long-term stability. Furthermore, the challenges and suggestions for future research on the application of graphene-based nanocomposite electrochemical sensors for nitrite detection are also highlighted.
    • Impacts of industrial heterogeneity and technical innovation on the relationship between environmental performance and financial performance

      Li, Ruiqian; Ramanathan, Ramakrishnan; Harbin University of Commerce; University of Bedfordshire (MDPI AG, 2018-05-21)
      In this paper, we investigate the relationship between environmental performance (EP) and financial performance (FP) from the perspective of technical innovation in Chinese industrial sectors. We also consider industrial heterogeneity and take temporal variations of the link into account. We collect the required data from different Chinese statistical yearbooks from 2004 to 2015. We use an aggregated index of environmental pollutants as a proxy for EP and return on assets as a proxy for FP, and we employ research and development expenditure to capture technical innovation. The empirical results indicate that industrial heterogeneity exists and the EP–FP link varies in different industrial groups. There is no evidence that the EP–FP link becomes more positive and more significant over time. Furthermore, the mediation effect of technical innovation and environmental pressures can jointly affect the link. Finally, technical innovation partially mediates the EP–FP link but only in Chinese light-polluting sectors not in heavy-polluting sectors. The mediating role of technical innovation has a great impact on shaping the EP–FP link. When technical innovation partially mediates the focal link, apart from the indirect link, the direct EP–FP link is likely to be positive. If not, the direct EP–FP link is likely to be negative.