Transformation of hydroxylamine to nitrosated and nitrated products during advanced oxidation process.

Recently, hydroxylamine (HAm) was introduced to drive advanced oxidation processes (AOPs) for removing organic contaminants. However, we found that HAm-driven Cu(II)/peroxymonosulfate oxidation of phenol produced p-nitrosophenol, 2-nitrophenol and 4-nitrophenol. The total nitro(so) products accounted for approximately 25.

Sustainability analysis of implementing sludge reduction in overall sludge management process: Where do we stand?

Sustainable sludge management has significance due to the great potential of recovering energy and resources, potentially achieving carbon neutrality and energy positivity in the process. However, whether the sludge reduction strategy really benefits the aim of a sustainable sludge management process requires a holistic analysis. In this study, nine scenarios involving different sludge management strategies with or without sludge reduction methods were environmentally and economically assessed to clarify the necessity of adopting a sludge reduction or not.

Efficient degradation and deiodination of iopamidol by UV/sulfite process: Assessment of typical process parameters and transformation paths.

Iopamidol (IPM) is widely used in medical clinical examination and treatment and has immeasurable harm to the ecological environment. The combination of UV and sulfite (UV/sulfite) process was developed to degrade IPM in this study. In contrast to that almost no removal of IPM was observed under sulfite reduction alone, the UV/sulfite process could efficiently reductively degrade IPM with the observed rate constant (k) of 2.

Formation of nitrosated and nitrated aromatic products of concerns in the treatment of phenols by the combination of peroxymonosulfate and hydroxylamine.

Recently, the combination of peroxymonosulfate (PMS) and hydroxylamine (HA) has been proposed as a green and efficient sulfate radical ()-based advanced oxidation process (AOP) for eliminating organic contaminants. However, we found that toxic nitrosated and nitrated aromatic compounds were generated during the treatment of phenolic compounds by PMS/HA system, indicating the involvement of reactive nitrogen species (RNS) during the interaction of PMS with HA. Specifically, considerable production of p-nitrosophenol (p-NSP) and mononitrophenol were obtained when phenol was oxidized by PMS/HA system under various conditions.

A novel diagnostic method for distinguishing between Fe(IV) and OH by using atrazine as a probe: Clarifying the nature of reactive intermediates formed by nitrilotriacetic acid assisted Fenton-like reaction.

In this work, we found that the distribution of two specific atrazine (ATZ) oxidation products (desethyl-atrazine (DEA) and desisopropyl-atrazine (DIA)) was different in oxidation processes involving aqueous ferryl ion (Fe(IV)) species and OH. Specifically, the molar ratio of produced DEA to DIA (i.e.

Effects on photosynthetic and antioxidant systems of harmful cyanobacteria by nanocrystalline Zn-MOF-FA.

Metal-organic frameworks (MOFs) constitute new class of materials recently used by researchers in the field of controlling cyanobacteria. However, the use of MOFs in combination with allelochemicals for cyanobacteria inhibition had not been investigated before. The present study is aimed towards the investigation of the effect and mechanism of cyanobacteria inhibition by combining MOF with allelochemical (ferulic acid, FA) for the first time.

Unexpected degradation and deiodination of diatrizoate by the Cu(II)/S(IV) system under anaerobic conditions.

Transition metal catalyzed sulfite auto-oxidation is a promising technology used in water and wastewater treatment for the elimination of contaminants. In the literature, this process has been reported to be efficient only in the presence of oxygen. However, in this study, we unexpectedly found that the degradation of diatrizoate (DTZ) by a system based on the combination of copper ion and sulfite (Cu(II)/S(IV)) reached over 95% under anaerobic conditions, but was considerably retarded under aerobic conditions at pH 7.

Fe(II)-activated persulfate oxidation to degrade iopamidol in water: parameters optimization and degradation paths.

Iodinated contrast media (ICM), which was widely used in medical imaging and was difficult to remove by conventional wastewater treatment methods, attained much attention due to its potential environmental impacts. Herein, iopamidol (IPM), one typical compound of ICM, was found to be rapidly degraded by ferrous activated persulfate oxidation (Fe(II)/PS) as compared with PS or Fe(II) alone. With a persulfate concentration of 1 mmol L, n(Fe(II))/n(PS) of 1:10, and a pH of 3.

An overview of bromate formation in chemical oxidation processes: Occurrence, mechanism, influencing factors, risk assessment, and control strategies.

Chemical oxidation processes have been extensively utilized in disinfection and removal of emerging organic contaminants in recent decades. Some undesired byproducts, however, are produced in these processes. Of them, bromate has attracted the most intensive attention.

Risk assessment and inactivation of invertebrate-internalized bacteria in pilot-scale biological activated carbon filtration.

It is well documented that invertebrates can ingest and transport pathogenic bacteria, thus protecting the bacteria against disinfection in the laboratory. However, the risk assessment of and corresponding disinfection methods for natural invertebrate-internalized bacteria in biological activated carbon (BAC) filtration systems remain poorly understood. In this study, the risk of natural invertebrate-internalized bacteria was comprehensively assessed and methods to inactivate these bacteria were compared in a pilot-scale BAC filtration column study lasting one year.

Transformation of iodide by Fe(II) activated peroxydisulfate.

This work investigates the transformation of iodide (I) by Fe(II)-activated peroxydisulfate (PDS). The transformation of I into iodate (IO) is a two-step process, involving reactive iodine species, such as hypoiodous acid (HOI), as a key intermediate, and IO as the final product. In the first step, SO produced by Fe(II)-activated PDS is mainly responsible for the transformation of I into HOI.

Quantitatively assessing the role played by carbonate radicals in bromate formation by ozonation.

Bicarbonate scavenges OH to form CO that enhances the bromate formation by ozonation. However, the role of CO in the bromate formation during ozonation has never been quantitatively investigated. Herein, we establish a quantitative approach for evaluating the role played by CO based on the detection of CO-involved bromate and CO exposure.

Is Sulfate Radical Really Generated from Peroxydisulfate Activated by Iron(II) for Environmental Decontamination?

It is well documented that the traditional Fenton reagent (i.e., the combination of Fe(II) and HO) produces hydroxyl radical (OH) under acidic conditions, while at near-neutral pH the reactive intermediate converts to ferryl ion (Fe(IV)) that can oxidize sulfoxides to produce corresponding sulfones, markedly differing from their OH-induced products.

Does Soluble Mn(III) Oxidant Formed in Situ Account for Enhanced Transformation of Triclosan by Mn(VII) in the Presence of Ligands?

In previous studies, we interestingly found that several ligands (e.g., pyrophosphate, nitrilotriacetate, and humic acid) could significantly accelerate the oxidation rates of triclosan (TCS; the most widely used antimicrobial) by aqueous permanganate (Mn(VII)) especially at acid pH, which was ascribed to the contribution of ligand-stabilized Mn(III) (defined Mn(III)) formed in situ as a potent oxidant.

Transformation of Methylparaben by aqueous permanganate in the presence of iodide: Kinetics, modeling, and formation of iodinated aromatic products.

This work investigated impacts of iodide (I) on the transformation of the widely used phenolic preservative methylparaben (MeP) as well as 11 other phenolic compounds by potassium permanganate (KMnO). It was found that KMnO showed a low reactivity towards MeP in the absence of I with apparent second-order rate constants (k) ranging from 0.065 ± 0.

Effects of Dracontomelon duperreanum Leaf Litter on the Growth and Photosynthesis of Microcystis aeruginosa.

This study investigated the use of Dracontomelon duperreanum leaf litter extract (DDLLE) in inhibiting the growth and photosynthesis of the algae Microcystis aeruginosa. The goal of the study was to evaluate a potential solution for cyanobacterial bloom prevention. M.

Chlorination of bisphenol S: Kinetics, products, and effect of humic acid.

Bisphenol S (BPS), as a main alternative of bisphenol A for the production of industrial and consumer products, is now frequently detected in aquatic environments. In this work, it was found that free chlorine could effectively degrade BPS over a wide pH range from 5 to 10 with apparent second-order rate constants of 7.6-435.

Transformation of Iodide by Carbon Nanotube Activated Peroxydisulfate and Formation of Iodoorganic Compounds in the Presence of Natural Organic Matter.

In this study, we interestingly found that peroxydisulfate (PDS) could be activated by a commercial multiwalled carbon nanotube (CNT) material via a nonradical pathway. Iodide (I) was quickly and almost completely oxidized to hypoiodous acid (HOI) in the PDS/CNT system over the pH range of 5-9, but the further transformation to iodate (IO) was negligible. A kinetic model was proposed, which involved the formation of reactive PDS-CNT complexes, and then their decomposition into sulfate anion (SO) via inner electron transfer within the complexes or by competitively reacting with I.

A new insight into Fenton and Fenton-like processes for water treatment: Part II. Influence of organic compounds on Fe(III)/Fe(II) interconversion and the course of reactions.

The interconversion of Fe(III)/Fe(II) in Fenton (Fe(2+)/H2O2) and Fenton-like (Fe(3+)/H2O2) reactions has been studied to better understand their intrinsic mechanisms. The reactions were conducted at an initial pH of 3.0, with H2O2 in excess and iron in catalytic concentrations, and with nitrobenzene and atrazine as model organic compounds.

A new insight into Fenton and Fenton-like processes for water treatment.

In this study, two Fenton (Fe(2+)/H(2)O(2)) and Fenton-like (Fe(3+)/H(2)O(2)) reactions were compared to clarify their roles in phenol degradation under varying H(2)O(2) concentrations, iron dosages and pHs, as well as in the presence of radical scavenger. The results of this study showed that a Fenton-like reaction must proceed concurrently with a classic Fenton reaction, and the concurrent Fenton reaction played a major role in the degradation of pollutants. For the Fenton-like reaction, some oxidation intermediates of phenolic compounds may promote the conversion of Fe(III) to Fe(II) in addition to the uni-molecular decomposition of the Fe(III)-hydroperoxy complexes.

A new concept of desulfurization: the electrochemically driven and green conversion of SO2 to NaHSO4 in aqueous solution.

A new concept of desulfurization was developed by designing a series of electrochemical reactions to drive an SO2 absorption-and-conversion process in aqueous solution, hence the SO2 in gas was eventually converted to a valuable chemical of NaHSO4. A model experiment of chemically substantiating this concept includes two steps: (I) absorption of SO2 gas by aqueous solution and oxidation of the absorbed SO2 to SO4(2-) by air and (II) transformation of the SO4(2-) to NaHSO4. The experiment demonstrated that in Step I, the cathodic reduction of 02 from ambient air scavenged the H+ released due to the SO2 absorption and its further oxidation, which thereby were accelerated.

A novel electro-fenton process for water treatment: reaction-controlled pH adjustment and performance assessment.

A novel electro-Fenton (E-Fenton) process was developed, in which the desired pH for an effective E-Fenton reaction and for a neutral treated media could be obtained by utilizing the reaction-released H+ and OH- in stead of chemical addition. In the laboratory-scale process using three chambers, the substrate solution pH > 4.0 was designed to be adjusted in situ through three sequencing steps: (I) pH reduction, (II) pH keeping for the effective E-Fenton reaction, and (III) pH recovery to neutral while the E-Fenton reaction continued.

The influence of pH on the degradation of phenol and chlorophenols by potassium ferrate.

This paper presents information concerning the influence of solution pH on the aqueous reaction between potassium ferrate and phenol and three chlorinated phenols: 4-chlorophenol (CP), 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP). The redox potential and aqueous stability of the ferrate ion, and the reactivity of dissociating compounds, are known to be pH dependent. Laboratory tests have been undertaken over a wide range of pH (5.