Fe(III) promoted LAS (linear alkylbenzenesulfonate) removal from waters

The mechanisms of the interactions between Fe(III) aquacomplexes and surfactants were investigated; three alkylbenzenzsulfonates, two surfactants (octylbenzenesulfonate (OBS) and dodecylbenzenesulfonate (DBS)), and a shorter derivative (ethylbenzenesulfonate (EBS)) were studied. The results with OBS show evidence for three different ways in which Fe(III) interferes with the surfactant: the widely described flocculation process, complexation of Fe(OH)2+ (aquacomplexes) by the surfactant, and a redox reaction. The formation of a weak complex is maximum for a ratio of three between the monomeric aquacomplex [FeOH(H2O)5]2+ and OBS. In the presence of oxygen, an intramolecular redox reaction occurs inside the complex. The interaction between commercial DBS and Fe(III) was also investigated. Immediate precipitation occurred, mainly involving derivatives of higher molecular weights that are contained in the DBS samples. The constituents with the shortest alkyl chain were not affected by the presence of Fe(III) as it was also observed with EBS.     

Photolysis of 2-(2-furyl)benzimidazole (Fuberidazole)

The photooxidatior. of 2-(4-thiazolyl)-1H-benzimidazole (Thia=bendazole (1) in methanol in presence and absence of a photo=sensitizer (methylene blue), is investigated. Dimethyl oxalate, thiazole-4-(N-carbomethoxy)-carboxamide (6), methyl benzimida=zole-2-carboxylate (7), benzimidazole-2-carboxamide (8), and benzimidazole (9), were the main products of the photolysis. Some reaction mechanisms are discussed.     

Biomagnification of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) studied in pike (Esox lucius), perch (Perca fluviatilis) and roach (Rutilus rutilus) from the Baltic Sea

Pike, perch and roach from rural waters of the Baltic Sea were investigated for possible biomagnification of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). For this we used data on delta15N, weight and sex of the fish. We were able to separate body size effects from trophic position effects on biomagnification. Both these parameters lead to biomagnification of PCBs and PBDEs. All investigated PCBs (tri- to deca-CBs) biomagnify and the biomagnification potential is positively correlated with hydrophobicity up to log Kow 8.18. Tri- to hepta-BDEs also biomagnify but showed a maximum biomagnification for the penta-BDEs (log Kow 6.46-6.97). The biomagnification of hexa- to hepta-PBDEs was negatively correlated with degree of bromination, likely due to large molecular size or high molecular weight (644-959 Da). Octa-, nona- and deca-BDEs did not biomagnify but were found in two (octa-BDE) and three (nona- and deca-BDEs) of the species, respectively. Increased size of pike is correlated with increased lipid weight based PCB and PBDE concentrations in males but not in females and mean PCB and PBDE concentrations in males are generally higher than in females. For the least hydrophobic PCBs, no sex difference is observed, probably as a consequence of faster clearance of these substances over the gills, making the spawning clearance of PCBs and PBDEs of lesser relative importance.     

Simultaneous conversion of CHClF(2) and CH(3)Br to CH(2)CF(2)

Gas phase reaction of CHClF(2) with CH(3)Br in an alumina tube reactor at 773-1123 K as a function of various input ratios of CH(3)Br to CHClF(2) is presented. The major products detected include C(2)F(4), CH(2)CF(2), and CH(4). Minor products include CH(3)Cl, CHF(3), C(2)H(4), C(2)H(2), CH(2)CF-CF(3), and C(2)H(3)F. The reaction produces a high yield of CH(2)CF(2) (53% based on CHClF(2) feed) at 1123 K and an input molar ratio of CH(3)Br to CHClF(2) of 1.8, suggesting that the reaction potentially can be developed as a process to convert two ozone depleting substances (CHClF(2) and CH(3)Br) to a highly valuable chemical, CH(2)CF(2). The reaction of CHClF(2) with CH(3)Cl and CH(3)I was also investigated under similar reaction conditions, to assist in understanding the reaction chemistry involved in the reaction of CHClF(2) with CH(3)Br.     

Metabolic fate of dichloromethyl-O,O-diphenyl phosphonate (I) and dichloromethyl-O,O-Di-(p-nitrophenyl) phosphonate (II) in/on rice plants.

Metabolic fate of two dichloromethyl diaryl phosphonates (32P labelled) in/on rice plants was investigated. The test compounds were found to be less persistent on the surface of rice leaves with half lives 7.4 and 6.7 days respectively. Main degradation product from both the phosphonates were dichloromethyl phosphonic acid with trace of dichloromethyl-O-aryl phosphonate as a transitory intermediate product.     

Degradation and photodegradation of tetraacetylethylenediamine (TAED) in the presence of iron (III) in aqueous solution

The dark degradation of tetraacetylethylenediamine (TAED) was investigated. It is a slow process which is favored in acidic medium. There is a hydrolysis of an imide group with the scission of the C---N bond giving rise to the triacetyl derivative (TAED'). When allowed to stand for longer times a second acetyl group is eliminated with the formation of the symetric diacetyl derivative (DAED). The degradation of TAED photoinduced by iron (III) was also investigated. It appears a faster degradation which does not lead to the same products. The process only involves ^•OH radicals formed upon photolysis of aquocomplex of iron (III). They preferentially abstract a hydrogen from the methylene group. The degradation is then assisted by oxygen and leads to the formation of carbonylated oxidation products.     

Sonolysis of alkylphenols in aqueous solution with Fe(II) and Fe(III)

The sonolytic degradation of alkylphenols (APs), such as butylphenol, pentylphenol, octylphenol, and nonylphenol (NP), in water was investigated at a sound frequency of 200 kHz with an acoustic intensity of 6 W cm(-2) under argon, oxygen, and air atmospheres. The sonolytic degradation rate of the APs under the conditions of the present study depended upon their alkyl chain length. The decrease in the degradation rate by the radical scavenging effect was in the range of about 48-82% for APs in the presence of 3 mM 2-methyl-2-propanol. The free radicals play a significant role in the sonolytic degradation process of the APs. In the presence of Fe(II) and Fe(III), the pseudo-first-order rate constants for the sonolytic degradation of 30 microM NP as a function of the concentration of Fe(II) and Fe(III) were estimated under argon and oxygen. The maximum rate constants were observed at 50 microM Fe(II) (0.139 +/- 0.008 min(-1)) and 100 microM Fe(III) (0.103 +/- 0.001 min(-1)) under oxygen. The total organic carbon concentration (TOC) was investigated under same conditions. TOC decreased in the range of about 50-70% during the sonication in the presence of Fe(II) and Fe(III) under argon and oxygen. The sonochemical effects by the addition of Fe(II) and Fe(III) as catalyst during the sonication under the proper atmosphere result in a remarkable enhancement of degradation and mineralization.     

As(V) and Sb(V) co-adsorption onto ferrihydrite: synergistic effect of Sb(V) on As(V) under competitive conditions

Competitive adsorption of As(V) and Sb(V) at environmentally relevant concentrations onto ferrihydrite was investigated. Batch experiments and XPS analyses confirmed that in a binary system, the presence of Sb(V) exhibited a slight synergistic effect on As(V) adsorption. XPS analyses showed that As(V) and Sb(V) adsorption led to obvious diminishment of Fe–O–Fe and Fe–O–H bonds respectively. At pH of 9, a more significant decrease of Fe–O–Fe was observed in the binary system than that in a single system, indicating that As(V) displayed an even stronger interaction with lattice oxygen atoms under competitive conditions. Basically, ionic strength demonstrated a negligible or positive influence on As(V) and Sb(V) adsorption in binary system. Study of adsorption sequence also indicated that the presence of Sb(V) showed a promotion effect on As(V) adsorption at neutral pHs. Considering that co-contamination of As and Sb in waters has been of great concern throughout the world, our findings contributed to a better understanding of their distribution, mobility, and fate in environment.

     

Abiotic reduction of antimony(V) by green rust (Fe(4)(II)Fe(2)(III)(OH)(12)SO(4).3H(2)O)

Green rust (Fe(4)(II)Fe(2)(III)(OH)(12)SO(4).3H(2)O) is an intermediate phase in the formation of iron (oxyhydr)oxides such as goethite, lepidocrocite, and magnetite. It is widely considered that green rust occurs in many soil and sediment systems. Green rust has been shown to reduce sorbed Se(VI), Cr(VI), and U(VI). In addition, it is also reported that green rust does not reduce As(V) to As(III). In this study, we have investigated for the first time the interaction between Sb(V) and green rust using XAFS and HPLC-ICP-MS. Most of the added Sb(V) was adsorbed on green rust, and Sb(III), a reduced form, was observed in both solid and liquid phases. Thus, it was shown that green rust has high affinity for Sb(V), and that Sb(V) was reduced to more toxic Sb(III) by green rust despite the high stability of the Sb(V) species even under reducing condition as reported in previous studies. Therefore, green rust can be one of the most important reducing agents for Sb(V), which can influence the Sb mobility in suboxic environments where green rust is formed.     

Pyrite-assisted degradation of trichloroethene (TCE)

Chemical kinetics of trichloroethene (TCE) degradation by pyrite was investigated at different experimental conditions. The TCE was transformed into C2H2, 1,1-dichloroethene (DCE) and C2H4 by a slow process (240 h required to convert TCE by 80%). Thereafter, the degradation rate showed a monotonous increase with the pH. A simple kinetic model was proposed to quantify the TCE degradation by pyrite.     

Removing and recovering gas-phase elemental mercury by Cu(x)Co(3-x)O(4) (0.75< or = x < or =2.25) in the presence of sulphur compounds

The Hg(0) oxidation ability and reusability of Cu(x)Co(3-x)O(4) were investigated in an attempt to improve SO(2) anti-poisoning ability of metal oxide and produce more economic and effective sorbents for the control of Hg(0) emission from combustion processes. The influence of copper content on Cu(x)Co(3-x)O(4)'s (0.75< or = x < or =2.25) oxidation ability of Hg(0) in the presence of SO(2) was investigated. According to the X-ray diffraction, Brunauer-Emmett-Teller (BET) and mass balance analysis on mercury, we found that Cu(1.5)Co(1.5)O(4) showed the highest S(BET) and best Hg(0) oxidation ability. With continuous increase of x from 0.75 to 2.25, Cu(x)Co(3-x)O(4)'s SO(2) anti-poisoning ability increased. The analysis results of the X-ray photoelectron spectroscopy manifested that the adsorptive mercury species on spent Cu(1.5)Co(1.5)O(4) was HgO. The spent Cu(1.5)Co(1.5)O(4) could be regenerated by thermal decomposition at 673K and regenerated Cu(1.5)Co(1.5)O(4) showed higher Hg(0) oxidation ability due to Hg-doping. Regenerated enrichment Hg(0) was collected using activated carbon at an ambient temperature to eliminate the secondary pollution.     

Influence of pH,EDTA/Fe(II) ratio,and microbial culture on Fe(II)-mediated autotrophic denitrification

Environmental Science and Pollution Research - Fe(II)-mediated autotrophic denitrification with four different microbial cultures under different pH and EDTA/Fe(II) conditions was investigated in...     

Micellar-enhanced ultrafiltration (MEUF) with mixed surfactants for removing Cu(II) ions

A nonionic surfactant, polyoxyethylene Octyl phenyl ether (Triton-X), is added to a micellar-enhanced ultrafiltration process to lower the critical micellar concentration (CMC) of an anionic surfactant, sodium dodecyl sulfate (SDS). The effects of adding Triton-X on the copper removal efficiency, the permeate SDS concentration, the copper binding capacity of SDS micelles, and membrane fouling are investigated. Our results show that the addition of Triton-X at concentrations greater than its CMC can reduce the SDS dosage required for effective Cu removal, and at the same time, minimize the permeate SDS concentration. Although, no adverse effect on the copper binding capacity of SDS micelle is observed by the addition of Triton-X, the membrane fouling is worsen. Cleaning the membrane with DI water allowed restoring the membrane flux, indicating that the fouling caused by Triton-X was reversible.     

Relationship between chromium(VI) resistance and extracellular polymeric substances (EPS) concentration by some cyanobacterial isolates

BACKGROUND, AIM, AND SCOPE: Chromium(VI) resistance and its association with extracellular polymeric substance (EPS) concentration in cyanobacteria was investigated. Increased EPS concentration was associated with Cr(VI) resistance. The most resistant isolate, Chroococcus sp. H(4), secreted the most EPS (427 mg/L). MATERIALS AND METHODS: EPS concentration of the two most resistant isolates (Chroococcus sp. H(4) and Synechocystis sp. S(63)) was investigated following exposure to 15 and 35 ppm Cr(VI). The composition of EPS produced by Chroococcus sp. H(4) following exposure to 10 ppm Cr(VI) was analyzed using high-performance liquid chromatography. Control EPS was composed of glucose (99%) and galactronic acid (1%); in the presence of 10 ppm Cr(VI), EPS composition changed to glucose (9%), xylose (75%), rhamnose (14%), and galacturonic acid (2%). RESULTS AND DISCUSSION: Results indicated that (1) exposure to elevated concentrations of Cr(VI) affected the composition of EPS produced by Chroococcus sp. H(4), and (2) there was a correlation between Cr(VI) resistance and EPS concentration in some cyanobacteria.     

Photochemistry of pesticides, 61). Comparative photochemical studies on methyl 2-benzimidazolecarbamate (Carbendazim) and methyl (1-n-butylcarbamoyl)-2-benzimidazolecarbamate (Benlate) in aqueous hydrochloric acid

The singlet oxygen photolysis of methyl 2-benzimidazolecarbamate (Carbendazim, 1) in aqueous hydrochloric acid has been investigated. 2-Guanidinobenzimidazole 7, benzimidazole 9, 2,4′- (13) and 2,5′-bibenzimidazole 14, were isolated from the reaction products and identified. A comparative study on the singlet oxygen photolysis of Benlate 2 both in MeOH and aqueous hydrochloric acid, was also undertaken.     

Impact of pyrolysis temperature and activation on oily sludge-derived char for Pb(II) and Cd(II) removal from aqueous solution

Environmental Science and Pollution Research - This study investigated the Pb(II) and Cd(II) sorption from aqueous solution by oily sludge-derived char (OSDC) prepared at different pyrolysis...     

Fe(III)-solar light induced degradation of diethyl phthalate (DEP) in aqueous solutions

The degradation of diethyl phthalate (DEP) photoinduced by Fe(III) in aqueous solutions has been investigated under solar irradiation in the compound parabolic collector reactor at Plataforma Solar de Almeria. Hydroxyl radicals *OH, responsible of the degradation, are formed via an intramolecular photoredox process in the excited state of Fe(III) aquacomplexes. The primary step of the reaction is mainly due to the attack of *OH radicals on the aromatic ring. For prolonged irradiations DEP and its photoproducts are completely mineralized due to the regeneration of the absorbing species and the continuous formation of *OH radicals that confers a catalytic aspect to the process. Consequently, the degradation photoinduced by Fe(III) could be an efficient method of DEP removal from water.     

Roles of ATP-dependent N-acylhomoserine lactones (AHLs) and extracellular polymeric substances (EPSs) in aerobic granulation

Aerobic granules which form through a cell-to-cell self-immobilization process have been intensively studied and developed for wastewater biotreatment. However, the microbiological origin of this phenomenon is still largely unknown. This study investigated the possible role of metabolic energy in the development of aerobic granules. Results showed that aerobic granulation was positively related to ATP-dependent N-acylhomoserine lactones (AHLs) and extracellular polymeric substances (EPSs) production. Inhibited ATP synthesis by a chemical uncoupler, 3,3′,4′,5-tetrachlorosalicylanilide, led to significant reduction of AHLs and EPSs production, which in turn prevented aerobic granulation. This study for the first time demonstrated the involvement of ATP-dependent AHLs in aerobic granulation.     

Metabolic fate of dichloromethyl‐0,0‐diphenyl phosphonate (I) and dichloromethyl‐0,0‐di‐(p‐nitrophenyl) phosphonate (II) in/on rice plants∗

Abstract

Metabolic fate of two dichloromethyl diaryl phosphonates (³²P labelled) in/on rice plants was investigated. The test compounds were found to be less persistent on the surface of rice leaves with half lives 7.4 and 6.7 days respectively. Main degradation product from both the phosphonates were dichloromethyl phosphonic acid with trace of dichloromethyl‐O‐aryl phosphonate as a transitory intermediate product.     

Equilibrium partitioning of (14)C-benzo(a)pyrene and (14)C-benazolin between fractionated phases from an arable topsoil

Equilibrium partitioning of hydrophobic (14)C-benzo(a)pyrene and hydrophilic (14)C-benazolin between fractionated phases from an arable topsoil of Merzenhausen (Germany) was investigated. Topsoil samples were collected from lysimeters which were incubated with different residual crops. A physical soil fractionation based on sedimentation and centrifugation steps was performed after water extraction. Four soil phases were obtained designated sediment (SED) phase (>20 microm), microaggregate (MA) phase (2 microm-20 microm), colloid (COL) phase (<2 microm) and electrolyte (EL) phase. The distribution of (14)C-benzo(a)pyrene, (14)C-benazolin and organic carbon between the soil phases was established. Enrichment factors for the two chemicals and organic carbon are higher in the COL and MA phases than in the SED phase. The distribution constant K(d) of chemicals for Merzenhausen topsoil was calculated according to two-phase or three-phase partitioning models. The three-phase partitioning model presumes the contribution of the organic carbon for the binding of chemicals. A log K(oc) of 5.55 can be calculated in the case of (14)C-benzo(a)pyrene, which is typical of the hydrophobic association with the soil organic carbon. In the case of (14)C-benazolin, much higher K(d) and K(oc) values were calculated than found with parent molecules after short-time experiments. Long-term aging processes must be considered. Specific effects on the chemical distribution due to the different crop residues were not detected.