Bacterial degradation kinetics of poly(Ɛ-caprolactone) (PCL) film by Aquabacterium sp. CY2-9 isolated from plastic-contaminated landfill.

Despite the identification of numerous bioplastic-degrading bacteria, the inconsistent rate of bioplastic degradation under differing cultivation conditions limits the intercomparison of results on biodegradation kinetics. In this study, we isolated a poly (Ɛ-caprolactone) (PCL)-degrading bacterium from a plastic-contaminated landfill and determined the principle-based biodegradation kinetics in a confined model system of varying cultivation conditions. Bacterial degradation of PCL films synthesized by different polymer number average molecular weights (M) and concentrations (% w/v) was investigated using both solid and liquid media at various temperatures.

Elimination efficiency of synthetic musks during the treatment of drinking water with ozonation and UV-based advanced oxidation processes.

This study investigated the reaction kinetics and elimination efficiency of eleven synthetic musks during ozonation and UV-based, advanced oxidation processes. The synthetic musks containing olefin moieties with electron-donating alkyl substituents such as octahydro tetramethyl naphthalenyl ethanone (OTNE) and ambrettolide (AMBT) showed high reactivity toward ozone (k ≥ 3.7 × 10 M s) and free available chlorine (FAC) (k = 9.

Nitriles as main products from the oxidation of primary amines by ferrate(VI): Kinetics, mechanisms and toxicological implications for nitrogenous disinfection byproduct control.

Ferrate (Fe(VI)), a promising water treatment oxidant, can be used for micropollutant abatement or disinfection byproduct mitigation. However, knowledge gaps remain concerning the interaction between Fe(VI) and dissolved organic matter structures, notably primary amines. This study investigated degradation kinetics and products of several aliphatic primary amines by Fe(VI).

Kinetics of the reaction between hydrogen peroxide and aqueous iodine: Implications for technical and natural aquatic systems.

Oxidative treatment of iodide-containing waters can lead to a formation of potentially toxic iodinated disinfection byproducts (I-DBPs). Iodide (I) is easily oxidized to HOI by various oxidation processes and its reaction with dissolved organic matter (DOM) can produce I-DBPs. Hydrogen peroxide (HO) plays a key role in minimizing the formation of I-DBPs by reduction of HOI during HO-based advanced oxidation processes or water treatment based on peracetic acid or ferrate(VI).

Elimination efficiency of organic UV filters during ozonation and UV/HO treatment of drinking water and wastewater effluent.

The efficiency of elimination of organic UV filters by ozonation and UV/HO processes was assessed and predicted in simulated treatments of sewage-impaired drinking water and wastewater effluent in bench-scale experiments. Second-order rate constants (k) for the reactions of the eight UV filters with ozone and OH were determined by quantum chemical calculations and competition kinetics methods, respectively. The UV filters containing phenolic (ethylhexyl-salicylate, homosalate, and benzophenone-3) and olefinic moieties (4-methylbenzylidene-camphor, benzyl-cinnamate, and 2-ethylhexyl-4-methoxycinnamate) showed high ozone reactivity (k ≥ 8 × 10 Ms at pH 7), while those without such electron-rich moieties (isoamyl-benzoate and benzophenone) were ozone-refractory.

Reactions of Ferrate(VI) with Iodide and Hypoiodous Acid: Kinetics, Pathways, and Implications for the Fate of Iodine during Water Treatment.

Oxidative treatment of iodide-containing waters can form toxic iodinated disinfection byproducts (I-DBPs). To better understand the fate of iodine, kinetics, products, and stoichiometries for the reactions of ferrate(VI) with iodide (I) and hypoiodous acid (HOI) were determined. Ferrate(VI) showed considerable reactivities to both I and HOI with higher reactivities at lower pH.

Transformation of microcystin-LR and olefinic compounds by ferrate(VI): Oxidative cleavage of olefinic double bonds as the primary reaction pathway.

The presence of toxic microcystins in algal-impacted surface waters is a concern for drinking water quality management. In this study, the potential of ferrate(VI) to eliminate microcystins during drinking water treatment was assessed by investigating reaction kinetics, reaction sites, transformation products, and toxicity changes for the oxidation of microcystin-LR (MC-LR) as a representative microsystin. The investigations also included several substructural model compounds of MC-LR, such as cinnamic acid and sorbic acid, to elucidate the major transformation products and pathways of MC-LR and olefinic compounds.

Transformation of methylparaben during water chlorination: Effects of bromide and dissolved organic matter on reaction kinetics and transformation pathways.

The reaction kinetics, products, and pathways of methylparaben (MeP) during water chlorination with and without bromide (Br) were investigated to better understand the fate of parabens in chlorinated waters. During the chlorination of MeP-spiked waters without Br, MeP was transformed into mono-Cl-MeP and di-Cl-MeP with apparent second-order rate constants (k) of 64Ms and 243Ms at pH7, respectively, while further chlorination of di-Cl-MeP was relatively slower (k=1.3Ms at pH7).

N-nitrosodimethylamine (NDMA) formation during ozonation of N,N-dimethylhydrazine compounds: Reaction kinetics, mechanisms, and implications for NDMA formation control.

Compounds with N,N-dimethylhydrazine moieties ((CH)N-N-) form N-nitrosodimethylamine (NDMA) during ozonation, but the relevant reaction chemistry is hitherto poorly understood. This study investigated the reaction kinetics and mechanisms of NDMA formation during ozonation of unsymmetrical dimethylhydrazine (UDMH) and daminozide (DMZ) as structural model N,N-dimethylhydrazine compounds. The reaction of ozone with these NDMA precursor compounds was fast, and k at pH 7 was 2 × 10 M s for UDMH and 5 × 10 M s for DMZ.

Transformation of ranitidine during water chlorination and ozonation: Moiety-specific reaction kinetics and elimination efficiency of NDMA formation potential.

Ranitidine can produce high yields of N-nitrosodimethylamine (NDMA) upon chloramination and its presence in water resources is a concern for water utilities using chloramine disinfection. This study assessed the efficiency of water chlorination and ozonation in transforming ranitidine and eliminating its NDMA formation potential (NDMA-FP) by determining moiety-specific reaction kinetics, stoichiometric factors, and elimination levels in real water matrices. Despite the fact that chlorine reacts rapidly with the acetamidine and thioether moieties of ranitidine (k>10(8)M(-1)s(-1) at pH 7), the NDMA-FP decreases significantly only when chlorine reacts with the less reactive tertiary amine (k=3×10(3)M(-1)s(-1) at pH 7) or furan moiety (k=81M(-1)s(-1) at pH 7).