Oxygen Activation

There is a global need for new environmentally clean, industrial technologies, or so-called green chemistries (Allen et al., 2002 Lancaster, 2002 Tundo et al., 2000). Much attention has been focused on the goal to develop and refine a green oxidation system capable of degrading key priority organic pollutants (or xenobiotics). Many of these species that are persistent and bioaccumulative include dioxins, furans, chlorinated phenols, and many pesticides once released into the environment, they...

Nanosized ZVI nZVI

Zhang et al. (1998) at Lehigh University investigated the application of nanosized (1-100 nm) ZVI particles for the removal of organic contaminants and found that not only is the reactivity higher due to an elevated surface area (average of 33.5 m2 g for the nanosized particles compared with 0.9 m2 g for the commonly used microscaled particles) but the reaction rate is also significantly higher (by up to 100 times) on a surface area normalized basis. In one such system, 1.7 kg of nZVI particles...

Characteristics of Pesticides and Their Environmental Effects

The recalcitrance of a pesticide is largely determined by its chemical structure. Some herbicides (such as 2,4-D) are susceptible to environmental degradation, while others (including most chlorinated insecticides such as endosulfan, hep-tachlor, and dieldrin) are considerably more resistant. Solubility will affect not only transport but also pesticide degradation since degradation is believed to occur mainly in the solution phase. The characteristics and structures of pesticides investigated...

Pesticides Treatment and Management Practices

Pesticides play a critical role in worldwide agriculture, but uncontrolled releases are a major environmental concern. Remediation of soil and water contaminated with pesticides range from conventional treatment techniques (e.g. incineration, thermal desorption, soil flushing washing, bioremediation, land-farming, phytore-mediation, photochemical processes, and direct oxidative processes) to innovative remediation technologies such as ultrasound-promoted remediation and other advanced oxidation...

Degradation Byproducts by Combined ZVI and H2O2

Since similar molinate degradation behavior was observed with both ZVI and coupled ZVI H2O2, extraction experiments were conducted to examine whether there was any difference in the by-products generated for both processes. Figure 4.23. The effect of peroxide at constant ZVI molinate 100 ppb degradation in the presence of Fe0 and H2O2 pH0 6.4 0.3 . Figure 4.23. The effect of peroxide at constant ZVI molinate 100 ppb degradation in the presence of Fe0 and H2O2 pH0 6.4 0.3 . 800000 700000 600000...

Form of Reactive Oxygen Intermediate Species

Over the past two decades, much effort has been put forth to elucidate the reaction mechanism and intermediate reactive oxygen species present during the transformation of dioxygen by iron complexes in both abiotic and biotic systems. The reaction between FeIIEDTA and hydrogen peroxide has long been used as a model system to understand the mechanisms of more complicated iron systems Neese and Solomon, 1998 Sharma et al., 2004 Walling, 1975 . Several FeIIIEDTA-peroxide intermediate species have...

Synthesis of Nanoscale ZVI Particles

Nanoscale ZVI nZVI particles were prepared freshly each day by adding 0.16 M NaBH4 98 , Aldrich aqueous solution dropwise to a 0.1 M FeCl3 6H2O 98 , Aldrich aqueous solution at ambient temperature as described by Wang and Zhang 1997 . The synthesis of nZVI was performed under atmospheric conditions. The preparation of solutions involved the following steps sodium borohydride NaBH4, 0.6053 g solids were dissolved in 100 mL of 0.1 M NaOH solution 0.16 M NaBH4 in 0.1 M NaOH solution , and 2.7030 g...