Innovative aspects of environmental chemistry and technology regarding air,water, and soil pollution

Environmental Science and Pollution Research -     

Solvent-free biodiesel epoxidation

Biodiesel emerged again recently as an alternative for fossil fuels. Besides energy, biodiesel can be used as raw material to synthesize high value products such as epoxides. Indeed, epoxides are versatile intermediates in organic synthesis for numerous reactions due to the high reactivity of the oxirane ring. Actually common epoxidation by peracids in organic solvent can last several hours according to the double bonds number. The solvent confers selectivity to the reaction, preventing di-hydroxylation. Alternatively solvent-free reactions can be done in shorter times, but hydroxylation is less controlled. Here, we set up the synthesis of epoxides from methyl and ethyl esters of waste cooking oil, without solvent or metal catalyst. We tested molar ratio of hydrogen peroxide and formic acid, double bond number, reaction time, and temperature. Results show that the highest epoxide yields and selectivity, with high conversion of the double bonds, were obtained for temperature reactions between 50 and 65 °C, reaction times from 2 to 3 h, and molar ratio of 20/2/1. For those conditions, the double bonds conversion is equal or near 100 %, with epoxide yield and selectivity between 85 and 93 %. Organic solvent suppression, besides being environmentally friendly, also saves reaction time and subsequent purification steps.     

Beyond identity crisis: The challenge of recontextualizing ecosystem delimitation

In a series of papers, three important system ecologists, Bernard C. Patten, Sven E. Jorgensen and Milan Straškraba attempt to revise the old ecosystem field and construct a new systems ecology. Inevitably, their attempt is faced with some of the same problems that led the field to decline. The indefiniteness of ecosystem boundaries is one of them, maybe the most important. Systems’ ecology failure to define ecosystem boundaries was considered a significant obstacle for the conceptualization of the ecosystem as a valid organizing unit of nature and resulted in a disciplinary identity crisis. To surmount this crisis, the authors introduce into the field innovative ideas which have their origin in the so-called postmodern network theories. These ideas reinforce the concept of environment and allow for a relative conception of space, which might have beneficial effects in delimiting ecosystems. However, the problem-solving potential of these ideas is not activated because the authors remain stitched to the Odumian mode of ecosystem thinking and avoid recontextualizing the old building blocks.