n-n--ethylenediamine-disuccinic-acid and goethite

S,S-ethylenediamine-N,N-disuccinic acid (EDDS) enhanced reductive dissolution of α-FeOOH by Shewanella putrefaciens CN32 (CN32), resulting in formation of surface-bound Fe(II) species (Fe

Topics: Carbon Tetrachloride; Chelating Agents; Chloroform; Ethylenediamines; Halogenation; Iron; Iron Compounds; Kinetics; Minerals; Oxidation-Reduction; Shewanella putrefaciens; Succinates

The main disadvantage of using iron mineral in Fenton-like reactions is that the decomposition rate of organic contaminants is slower than in classic Fenton reaction using ferrous ions at acidic pH. In order to overcome these drawbacks of the Fenton process, chelating agents have been used in the investigation of Fenton heterogeneous reaction with some Fe-bearing minerals. In this work, the effect of new iron complexing agent, ethylenediamine-N,N'-disuccinic acid (EDDS), on heterogeneous Fenton and photo-Fenton system using goethite as an iron source was tested at circumneutral pH. Batch experiments including adsorption of EDDS and bisphenol A (BPA) on goethite, H(2)O(2) decomposition, dissolved iron measurement, and BPA degradation were conducted. The effects of pH, H(2)O(2) concentration, EDDS concentration, and goethite dose were studied, and the production of hydroxyl radical ((•)OH) was detected. The addition of EDDS inhibited the heterogeneous Fenton degradation of BPA but also the formation of (•)OH. The presence of EDDS decreases the reactivity of goethite toward H(2)O(2) because EDDS adsorbs strongly onto the goethite surface and alters catalytic sites. However, the addition of EDDS can improve the heterogeneous photo-Fenton degradation of BPA through the propagation into homogeneous reaction and formation of photochemically efficient Fe-EDDS complex. The overall effect of EDDS is dependent on the H(2)O(2) and EDDS concentrations and pH value. The high performance observed at pH 6.2 could be explained by the ability of O (2) (•-) to generate Fe(II) species from Fe(III) reduction. Low concentrations of H(2)O(2) (0.1 mM) and EDDS (0.1 mM) were required as optimal conditions for complete BPA removal. These findings regarding the capability of EDDS/goethite system to promote heterogeneous photo-Fenton oxidation have important practical implications for water treatment technologies.

Topics: Benzhydryl Compounds; Environmental Pollutants; Environmental Restoration and Remediation; Ethylenediamines; Hydrogen Peroxide; Iron; Iron Compounds; Kinetics; Minerals; Models, Chemical; Oxidation-Reduction; Phenols; Succinates

The efficiency of EDDS ([S,S]-ethylenediaminedisuccinate) in metal (phyto) extraction has been discussed in many recent papers. This study demonstrated that the presence of Fe- and Al-(hydr)oxides in soils influences the speciation of EDDS and thus can decrease the extraction of the targeted metallic contaminants (e.g., Pb, Cu, Zn). Above all, amorphous and poorly crystalline oxides (e.g., ferrihydrite) seem to significantly control dissolved Fe and Al concentrations in soils in the presence of metal-EDDS complexes and especially uncomplexed EDDS. Metals released from these minerals compete for the chelating agent and the extraction efficiency of the targeted metals is lowered. The formation of stable Cu-EDDS complexes, which are preferentially formed in soils with high Cu concentrations, results into a lower dissolution of ferrihydrite and goethite compared to free EDDS and Al-EDDS. Information about the contents of amorphous and poorly crystalline oxides in the treated soils would thus be beneficial for choosing efficient EDDS dosages.

Topics: Aluminum Hydroxide; Chelating Agents; Ethylenediamines; Ferric Compounds; Hydrogen-Ion Concentration; Iron Compounds; Minerals; Soil; Succinates; X-Ray Diffraction