Mineralization Of Organic Contaminants Research Articles

Recycling of waste power lithium-ion batteries to prepare nickel/cobalt/manganese-containing catalysts with inter-valence cobalt/manganese synergistic effect for peroxymonosulfate activation

Developing a high-efficiency peroxymonosulfate (PMS) activator is of great significance for the elimination and mineralization of organic contaminants. Herein, a catalyst (LiNi0.5Co0.2Mn0.3O2, NCM) was constructed using the cathode scrap of spent lithium-ion battery (LIB) for activation of PMS to remove Rhodamine B (RhB). The excellent catalytic capacity of NCM-650 was observed, as RhB was completely removed after 25 min. The NCM-650/PMS process could function effectively over a broad pH scope with favorable reusability and adaptability. The non-radical channels (singlet oxygen and mediated charge transfer) played a dominant role in the removal of RhB. Several reactive radical species (sulfate radicals, hydroxyl radicals and superoxide radicals) also facilitated the degradation of RhB, where the Co2+ and Mn4+ on the surface served as active sites to activate PMS. The synergistic effect of inter-valence cobalt and manganese in the catalyst was the predominant medium during the whole reaction process. According to the intermediates identified by High performance liquid chromatograph-mass spectrometry (HPLC-MS) and the analysis of density function theory (DFT) calculations, N-de-ethylation, chromophore cleavage, ring opening, and mineralization were regarded as the primary decomposition pathways. This research provided a novel perspective on the potential application of waste LIBs for the effective activation of PMS.

Hybrid Advanced Oxidation Processes Involving Ultrasound: An Overview.

Sonochemical oxidation of organic pollutants in an aqueous environment is considered to be a green process. This mode of degradation of organic pollutants in an aqueous environment is considered to render reputable outcomes in terms of minimal chemical utilization and no need of extreme physical conditions. Indiscriminate discharge of toxic organic pollutants in an aqueous environment by anthropogenic activities has posed major health implications for both human and aquatic lives. Hence, numerous research endeavours are in progress to improve the efficiency of degradation and mineralization of organic contaminants. Being an extensively used advanced oxidation process, ultrasonic irradiation can be utilized for complete mineralization of persistent organic pollutants by coupling/integrating it with homogeneous and heterogeneous photocatalytic processes. In this regard, scientists have reported on sonophotocatalysis as an effective strategy towards the degradation of many toxic environmental pollutants. The combined effect of sonolysis and photocatalysis has been proved to enhance the production of high reactive-free radicals in aqueous medium which aid in the complete mineralization of organic pollutants. In this manuscript, we provide an overview on the ultrasound-based hybrid technologies for the degradation of organic pollutants in an aqueous environment.

Carbon nanomaterials differentially impact mineralization kinetics of phenanthrene and indigenous microbial communities in a natural soil

Previous reports on how carbon nanomaterials (CNMs) affect the biodegradation and mineralization of organic contaminants are mainly limited to pure culture studies, but little is known about the mineralization process by more complex and environmentally-relevant microbial communities. This study investigated the impact of fullerenes C60 and two multi-walled carbon nanotubes (outer diameter < 8 nm: M8; >50 nm: M50) at 300 and 3000 mg/kg on the mineralization kinetics of 14C-phenanthrene (18.5 mg/kg) by indigenous microorganisms in a natural soil for 120 days. Phenanthrene mineralization kinetics fitted well with the logistic growth equation regardless of the CNMs present (R2 = 0.965–0.985). The maximum mineralization rates and the total mineralization fraction were positively correlated with the initial phenanthrene bioavailability, assessed via β-HPCD extraction. Phenanthrene exposure induced significant responses of the catabolic gene biomarker nidA, fungi and bacteria communities by 275, 30, and 5 times, respectively, indicating a non-neglectable role of the fungal communities in phenanthrene mineralization. CNMs exerted a sorption- and level-dependent suppression (7.4–47.2%) on the total phenanthrene mineralization fractions at 120 d. Carbon nanotubes (300, 3000 mg/kg) caused significant adverse effects on the biomass of bacterial (47.8–60.7%), fungal (31.4–71.6%) and nidA-carrying degraders (25.7–59.9%) in the absence or presence of phenanthrene, which contributed to the inhibition of the total mineralization fractions at 120 d. Bacterial community structure was not significantly impacted by CNMs alone or co-exposure of CNM-phenanthrene. However, the fungal community showed a significant shift upon exposure to carbon nanotubes, especially M8, with the relative abundance of potential PAH degraders repressed (8.5–40.3%) at both levels of M8 tested. This corroborates the higher sensitivity of fungal communities. The findings from this study are important to inform how the released CNMs affect soil microbial communities that play a key role in the fate and remediation of organic contaminants in soil.

Protocatechuic Acid Promoted Alachlor Degradation in Fe(III)/H2O2 Fenton System

In this study, we demonstrate that protocatechuic acid (PCA) can significantly promote the alachlor degradation in the Fe(III)/H2O2 Fenton oxidation system. It was found that the addition of protocatechuic acid could increase the alachlor degradation rate by 10 000 times in this Fenton oxidation system at pH = 3.6. This dramatic enhancement of alachlor degradation was attributed to the complexing and reduction abilities of protocatechuic ligand, which could form stable complexes with ferric ions to prevent their precipitation and also accelerate the Fe(III)/Fe(II) cycle to enhance the ·OH generation. Meanwhile, the Fe(III)/PCA/H2O2 system could also work well at near natural pH even in the case of PCA concentration as low as 0.1 mmol/L. More importantly, both alachlor and PCA could be effectively mineralized in this Fenton system, suggesting the environmental benignity of PCA/Fe(III)/H2O2 Fenton system. We employed gas chromatography-mass spectrometry to identify the degradation intermediates of alachlor and then proposed a possible alachlor degradation mechanism in this novel Fenton oxidation system. This study provides an efficient way to remove chloroacetanilide herbicides, and also shed new insight into the possible roles of widely existed phenolic acids in the conversion and the mineralization of organic contaminants in natural aquatic environment.

Sulfur‐replaced Fenton systems: can sulfate radical substitute hydroxyl radical for advanced oxidation technologies?

AbstractSulfate radicals (SO4•−) and hydroxy radicals (HO•) are the major radicals used in advanced oxidation technologies (AOTs) for the removal of contaminants. Although SO4•− reacts with organic or inorganic compounds with rate constants comparatively lower than that of HO•, AOTs based on SO4•− (abbreviated as SR‐AOTs) have gained lots of attention due to the selective oxidation and non‐pH‐dependence. A series of systems using persulfate (PS) or peroxymonosulfate (PMS) instead of H2O2 is designated as a sulfate radical‐Fenton system or sulfur‐replaced Fenton system (SR‐Fenton). Comparisons and analogies between Fenton (Fenton‐like) systems and SR‐Fenton systems are made and some new SR‐AOTs systems without PS or PMS are introduced. The possibility for the substitution of HO• by SO4•− for AOTs is discussed. Most likely in the future, efforts will be concentrated on product‐oriented AOTs with the purpose of recovery of chemical products rather than mineralization of organic contaminants, producing greenhouse gas CO2. Moreover, such SR‐Fenton system may be more atomically economical. © 2014 Society of Chemical Industry

Catalytic Wet Peroxide Oxidation Technique for the Removal of Decontaminating Agents Ethylenediaminetetraacetic Acid and Oxalic Acid from Aqueous Solution Using Efficient Fenton Type Fe-MCM-41 Mesoporous Materials

Catalytic wet peroxide oxidation (CWPO) of organic contaminants may have a possible path for the treatment of decontamination waste containing chelating agents that cause a complex with radioactive cations leading to interferences in their removal by various techniques and may pose a hazard to the environment. The aim of the present work was to synthesize and characterize the mesoporous Fe-MCM-41 with various Si/Fe ratios for evaluating the removal of organic contaminants such as ethylenediaminetetraacetic acid (EDTA) and oxalic acid in aqueous solution. The influence of reaction parameters such as time, pH, and temperature was studied to achieve efficient removal of organic contaminant. Among the catalysts studied, Fe-MCM-41 (Si/Fe = 25) provides high-percentage removal of total organic carbon in aqueous solution. The mineralization of organic contaminants was found to be higher in heterogeneous catalysis than homogeneous catalysis (Fe3+). Further, after the reaction, only a minimum percentage (2%) of Fe...

Mineralization of organic contaminants under aerobic and anaerobic conditions in sludge-soil mixtures

Background and Main Features The mineralization of eight organic chemicals (surfactants, substituted aromatic compounds, di(2-ethylhexyl)phthalate and phenanthrene) was examined in sludge-soil mixtures under aerobic, denitrifying and methanogenic conditions.

Mineralization of organic contaminants in sludge-soil mixtures

The mineralization of 14C-labeled linear alkylbenzene sulfonate (LAS), nonylphenol (NP), nonylphenol-di-ethoxylate (NP2EO), di-(2-ethylhexyl)phthalate (DEHP), pyrene, and 1,4-dichlorobenzene (DCB) was investigated in different sludge-soil mixtures and soils. Under aerobic conditions, the mineralization of LAS, NP, and NP2EO was between 50 and 81% of the added amounts after two months, while DEHP and pyrene were mineralized more slowly. The mineralization of the model chemicals was indirectly affected by the amount of sludge in the test mixtures. A higher content of sludge in the mixtures reduced the overall concentration of oxygen, which resulted in a decrease of the mineralization of several of the model chemicals. In sludge-soil mixtures with predominantly anaerobic conditions, the mineralization was slower for all of the chemicals with the exception of DEHP and DCB. The mineralization of DCB was enhanced in mixtures with a high sludge content. No pronounced difference in the mineralization of the model chemicals (except DEHP) was observed when the sludge was mixed with three different agricultural soils.

Mineralization of organic contaminants in sludge-soil mixtures.

The mineralization of 14C-labeled linear alkylbenzene sulfonate (LAS), nonylphenol (NP), nonylphenol-di-ethoxylate (NP2EO), di-(2-ethylhexyl)phthalate (DEHP), pyrene, and 1,4-dichlorobenzene (DCB) was investigated in different sludge-soil mixtures and soils. Under aerobic conditions, the mineralization of LAS, NP, and NP2EO was between 50 and 81% of the added amounts after two months, while DEHP and pyrene were mineralized more slowly. The mineralization of the model chemicals was indirectly affected by the amount of sludge in the test mixtures. A higher content of sludge in the mixtures reduced the overall concentration of oxygen, which resulted in a decrease of the mineralization of several of the model chemicals. In sludge-soil mixtures with predominantly anaerobic conditions, the mineralization was slower for all of the chemicals with the exception of DEHP and DCB. The mineralization of DCB was enhanced in mixtures with a high sludge content. No pronounced difference in the mineralization of the model chemicals (except DEHP) was observed when the sludge was mixed with three different agricultural soils.