Optimization of the reaction conditions for enzymatic removal of phenol from wastewater in the presence of polyethylene glycol

The effect of the additive, polyethylene glycol (PEG), on the horseradish peroxidase (HRP) catalysed removal of phenol from wastewater has been studied over the phenol concentration range of 1–10 mM (0.1–1.0 g/l). The optimum pH, HRP concentration, PEG concentration and the molar ratio of hydrogen peroxide and phenol have been investigated in the presence of PEG at room temperature in order to achieve the maximum phenol removal efficiency with the minimum cost. The effect of concentrations of HRP and PEG on reaction time was also investigated. Experimental results showed that the addition of PEG had significant protective effect on the activity of HRP. The amount of peroxidase required was reduced 40- and 75-fold less than that required without PEG for 1 and 10 mM phenol solutions, respectively. The higher the phenol concentration, the more effective was the addition of PEG. In the presence of PEG, the optimum pH is 8.0 and the optimum molar ratio of hydrogen peroxide and phenol is around 1.0. The minimum doses of HRP and PEG required for at least 95% removal were determined for several phenol concentrations and two empirical models are proposed to predict the minimum HRP and PEG doses required for 95% removal over the entire phenol concentration range of 1–10 mM. Under the optimum reaction conditions described above, the reaction times for at least 95% removal from 1 and 10 mM phenol solutions were 5 and 3 h, respectively. An increase in HRP concentration significantly reduced the reaction time; however, an increase in PEG concentration showed negligible influence.     

On diffusion of ideas in the academic world: the case of spatial econometrics

Spatial econometrics is a fast-growing field in the series of quantitative disciplines, auxiliaries of economics and related social sciences. Space, friction, interdependence, spatio-temporal components, externalities and many other aspects interact and should be treated adequately in this field. The publication of the Paelinck and Klaassen book in the late 1970s generated virtually the field spatial econometrics. This article studies the diffusion of spatial econometrics, through experienced history on the one hand, on the other through bibliometric methods. Although this field was an “Invisible College” up to 2006 (absence of any organization in form of association, conference, journal, etc.), the databases depict a fast diffusion in the past and strong prospects for the future.

---

     

室内空气中甲醛在ACF上的衍生反应动力学及其定量关系的研究

文章在对ACF的纳米空间结构及其载体功能特性以及ACF纳米结构上甲醛的衍生反应及其吸附/解吸原理,进行深入研究基础上,揭示了室内空气中甲醛在ACF上的吸附与解析动力学过程。根据Langmuir-Rideal定理,描述了甲醛与PFBHA-HCHO反应定量关系;推导出PFBHA-HCHO肟化合物浓度的反应速率与室内空气中甲醛浓度之间的一级反应线性回归方程,为定量检测室内空气中甲醛提供了理论依据。