Degradation of chlorine dioxide bleaching wastewater and response of bacterial community in the intimately coupled system of visible-light photocatalysis and biodegradation.

Intimate coupling of visible-light photocatalysis and biodegradation (ICPB) offers potential for degrading chlorine dioxide bleaching wastewater. In this study, we reported a TiO2-coated sponge biofilm carrier with significant adhesion of TiO2 and the ability to accumulate biomass in its interior. Four mechanisms possibly acting in ICPB were tested separately: adsorption of chlorine dioxide bleaching wastewater to the carrier, photolysis, photocatalysis, and biodegradation by the biofilm inside the carrier. The carrier had an adsorption capacity of 17% and 16% for CODcr and AOX, respectively, in the wastewater. The photodegradation rate of wastewater was very low and could be ignored. Both biodegradation (AOX 30.1%, CODcr 33.8%, DOC 26.2%) and photocatalysis (AOX 65.1%, CODcr 71.2%, DOC 62.3%) possessed a certain degradation efficiency of wastewater. However, the removal rate of AOX, CODcr, and DOC in wastewater treatment by protocol ICPB reached 80.3%, 90.5%, and 86.7%. FT-IR and GC-MS analysis showed that the ICPB system had photocatalytic activity on the surface of the porous carrier in vitro, which could transform organic into small molecules for microbial utilization or complete mineralization. Moreover, the biofilm in the interior of the TiO2-coated sponge carrier could mineralize the photocatalytic products, which enhanced the removal of AOX, CODcr, and DOC by more than 15.2%, 20.0%, and 24.0%, respectively. The biofilm in the carrier of the ICPB system evolved, enriched in Proteobacteria, Chloroflexi, Bacteroidetes, and Actinobacteria, microorganisms known to play active roles in the biodegradation of papermaking wastewater.

Influence of organic matters on the adsorption-desorption of 1,2-dichloroethane on soil in water and model saturated aquifer.

1,2-Dichloroethane (1,2-DCA) is a typical organic chlorinated compound largely utilized in chemical manufacturing and industrial production and also a common pollutant in organically contaminated sites. The adsorption of 1,2-DCA on soil grains significantly influences its environmental fate and removal process. This study investigated the influence of fulvic acid (FA) and humic acid (HA) on the adsorption-desorption of 1,2-DCA in solid-liquid interfaces in water or constructed porous media. Experimental findings demonstrated the influence of organic matter on the adsorption of 1,2-DCA at the solid-water interface. 1,2-DCA adsorption increased in the FA or HA-treated soils when organic matter was present on the solid surfaces. The 1,2-DCA adsorption in the mixture of FA and HA was slightly lower than that in single organic acids, depending on the binding of FA and HA to the soil grains/colloids. Basic conditions reduced the adsorption of 1,2-DCA on soils, whereas acidic conditions enhanced adsorption due to the increased interactions via adsorption sites and hydrogen bonds. Conversely, the presence of organic matter in solutions (liquid phase in constructed porous media) will reduce the adsorption of 1,2-DCA on solid surfaces and increase the transport in the model aquifer. The combination of FA, HA, and rhamnolipids is helpful for the removal of 1,2-DCA from solid surfaces. Additionally, because of the enhanced desorption, the risk of 1,2-DCA contamination in groundwater can be increased when the organic matter or surfactant is present in the liquid phase if the eluent is not collected. This study helps to better understand the cooperative interaction of soil organic matter and chlorinated hydrocarbons at solid-water interfaces and the environmental fate and potential removal strategies of chlorinated hydrocarbons in contaminated sites.

Photodegradation performance and mechanism of sulfadiazine in Fe(III)-EDDS-activated persulfate system.

In order to overcome the shortcomings in the traditional Fenton process, Fe(III)-EDDS-activated persulfate advanced oxidation process under irradiation is carried out as a promising technology. The photodegradation of sulfadiazine (SD) in Fe(III)-EDDS-activated persulfate system was investigated in this paper. The results showed that SD could be effectively degraded in Fe(III)-EDDS/S2O82-/hv system. The effects of Fe(III):EDDS molar ratio, the concentration of Fe(III)-EDDS, and the concentration of S2O82- on SD degradation were explored. At neutral pH, when Fe(III):EDDS = 1:1, Fe(III)-EDDS = 0.1 mM, S2O82- = 1.5 mM, the best SD degradation was achieved. The experiment of external influence factors showed that the degradation of SD could be obviously inhibited by the presence of CO32-, SO42-, whereas the degradation of SD was almost unaffected by the addition ofCl-. The degradation of SD could be slightly inhibited by the presence of humic acid and NO3-. The effect of pH on SD degradation was investigated, and SD could be degraded effectively in the pH range of 3-9. ESR proved that 1O2, ·OH, SO4-, and O2- were produced in the process. SO4- and ·OH were identified as the main radicals while O2·- also played non-ignorable role. Eleven intermediate products of SD were analysed. The C = N, S-N, and S-C bonds of SD were attacked by radicals firstly, leading to a series of reactions that eventually resulted in the destruction of SD molecules and the formation of small organic molecules.

A kinetic model for oxidative degradation of bagasse pulp fiber by sodium periodate.

In this paper, some key parameters, such as the system pH, the periodate concentration, and the reaction temperature, on the influence of the bagasse fiber degradation were studied based on the oxygenant of periodate. And the feasible reaction mechanism was also discussed through the FTIR characterization for bagasse fiber before and after the oxidizing reaction. As the results shown, the crystallinity of bagasse fiber decreased with the oxidation level increasing. It was interesting that the aldehyde content of the reaction system rose gradually along with cellulose degradation. Based on this result, the selective oxidation kinetics was constructed by introducing of variable factor R (the ratio of aldehyde content to the degradation of cellulose fiber), and the results shown that there was a better correlation between the dynamic model and the experimental data, so the oxidation degree of bagasse fiber oxidized by periodate can be quantitative evaluated based on this model.

Anaerobic Co-Digestion with Food Waste: A Possible Alternative to Overcome the Energy Deficit of Sludge Thermal Pretreatment.

Thermal pretreatment (TP) was an effective method to improve the anaerobic digestion of waste-activated sludge. In order to balance the energy consumption of sludge TP integrated with anaerobic digestion, food waste was introduced as a co-substrate to achieve an energy self-sustainable sludge treatment system. An anaerobic biodegradability test was performed using thermal pretreated sludge and food waste in order to clarify the kinetics and mechanism of co-digestion, especially the synergetic effect on specific methane yield. The prominent synergetic effect was an initial acceleration of cumulative methane production by 20.7-23.8% observed during the first 15 days. The modified Gompertz model presented a better agreement of the experimental results, and it was a suitable tool for methane production prediction of mono- and co-digestion. The energy assessment showed that co-digestion with food waste was a sustainable solution. When the moisture content of the TP sludge was 80-90%, the energy compensation required was about 0.04-0.22 t VSFoodwaste/t VSSludge, which could maintain the integration of neutral or even positive energy between TP and anaerobic digestion.

Catalytic removal of attached tetrabromobisphenol A from microplastic surface by biochar activating oxidation and its impact on potential of disinfection by-products formation.

There are numerous studies concerning the impacts of widespread microplastic pollution on the ecological environment, and it shows synergistic effect of microplastics and co-exposed pollutants in risk enhancement. However, the control methods for removing harmful pollutants from microplastic surface to reduce their ecological toxicity has rarely been explored. In this paper, magnetic graphitized biochar as a catalyst is shown to achieve 97% removal of tetrabromobisphenol A (TBBPA) from microplastics by biochar mediated electron transfer. The changes in the surface and structure of microplastics caused by various aging processes affected the pollutant attachment and subsequent removal efficiency. After chlorination, the highest disinfection by-product (DBP) generation potential was observed by the group of microplastics attached with TBBPA. The oxidation system of biochar activating peroxodisulfate (PDS) can not only reduce the kinds of DBPs, but also greatly reduce the total amount of detected DBPs by 76%, as well as reducing the overall toxicity. This paper highlights an overlooked contribution of pollutant attachment to the potential risks of DBP generated from natural microplastics during chlorination process, and provides the underlying insights to guide the design of a biochar-based catalyst from wastes to achieve the removal of TBBPA from microplastics and reduce the risks and hazards of co-contamination.

Visible light driven antibiotics degradation using S-scheme Bi2WO6/CoIn2S4 heterojunction: Mechanism, degradation pathways and toxicity assessment.

S-scheme heterojunction photocatalysts with strong redox ability and excellent photocatalytic activity are highly desired for photocatalytic degradation of pollutants. Herein, S-scheme Bi2WO6/CoIn2S4 heterojunctions were synthesized using hydrothermal method. The photo-induced carriers transfer mechanism of the S-scheme Bi2WO6/CoIn2S4 heterojunction was clarified by band structure analysis, ultraviolet photoelectron spectrometer (UPS), electron spin resonance (ESR) and radical trapping experiments. Significant enhance of light absortion, and more efficient carriers separation were observed from the Bi2WO6/CoIn2S4 with CoIn2S4 nanoclusters growing on the surface of petal-like Bi2WO6 nanosheets. TC degradation efficiency of 90% was achieved by Bi2WO6/CoIn2S4 (15:1) within 3 h of irradiation, and ·O2-and ·OH radicals were dominated contributors. Possible decomposition pathways of TC were proposed, and ECOSAR analysis showed that most of the intermediates exhibited lower ecotoxicity than TC. This work provides reference on the constructing ternary-metal-sulfides-based S-scheme heterojunctions for improving photocatalytic performance.

Pollution and ecological risk assessment, and source identification of heavy metals in sediment from the Beibu Gulf, South China Sea.

The Beibu Gulf is an important passageway between China and the Association of Southeast Asian Nations, where there has been an increase in pollution of heavy metals (HMs). High concentrations of Pb, Cr, Cd, Cu, Zn, As, and Hg in surface sediment were found in Qinzhou Bay, Fangchenggang, and other coastal areas. Stochastic geo-accumulation analyses identified the pollution to be "uncontaminated"; however, it had an 18% probability of deterioration. The Cd, Hg, and As pollution were relatively serious. Principal component analysis, positive matrix factor model, and mercury isotopes demonstrated that the HMs could mainly be attributed to industrial sources including petrochemical, coal-fired, metal and metalloid processing, leather tanning, and human activities: anthropogenic sources accounted for approximately 70% of all the contaminations. This study demonstrates the contribution of terrigenous input to HMs even at a low level and provides basic data for the coordinated development of land and marine resources.

Coupling Interface Constructions of FeNi3-MoO2 Heterostructures for Efficient Urea Oxidation and Hydrogen Evolution Reaction.

Urea electrolysis has prospects for urea-containing wastewater purification and hydrogen (H2) production, but the shortage of cost-effective catalysts restricts its development. In this work, the tomentum-like FeNi3-MoO2 heterojunction nanosheets array self-supported on nickel foam (NF) as bifunctional catalyst is prepared by facile hydrothermal and annealing method. Only 1.29 V and -50.8 mV is required to obtain ±10 mA cm-2 for urea oxidation and hydrogen evolution reaction (UOR and HER), respectively, showing great bifunctional catalytic activity. For overall urea electrolysis, it only needs 1.37 V to reach 10 mA cm-2 and can last at 100 mA cm-2 for 70 h without obvious activity attenuation, showing outstanding durability. Coupling interface constructions of FeNi3-MoO2 heterostructures, novel morphology with a mesoporous and self-supporting structure could be the reason for this good performance. This work thus proposes a promising catalyst for boosting UOR and HER to realize efficient overall urea electrolysis.

Prussian blue modified CeO2 as a heterogeneous photo-Fenton-like catalyst for degradation of norfloxacin in water.

The heterogeneous photo-Fenton-like process is emerging as a promising treatment of antibiotics-containing wastewater. The preparation of new efficient and stable catalysts is one of the research fields. A composite catalyst, prussian blue (PB) modified CeO2 was prepared, characterized, and applied for photo-Fenton oxidation of norfloxacin (NOR) in this study. It was found that chemical doping of PB leaded to more oxygen vacancies and increased the surface area of CeO2 obviously. PB/CeO2 with more Ce3+ facilitated electron transfer between Fe3+/Fe2+ with Ce3+/Ce4+. PB could also improve the separation rate of photoexcited electron-hole pairs in CeO2 nanostructures. When the doping ratio of PB and CeO2 was 10%, PB/CeO2 show the highest catalytic degradation ability and 88.93% of NOR could be degraded within 30 min. PB/CeO2 composite showed well reactivity at the wide pH value range of 3-8. The reusable experiments and low iron dissolution with less than 1 mg/L indicated that PB/CeO2 could be employed as an efficient heterogeneous photo-Fenton-like catalyst in organic contaminants degradation.

Oxygen vacancy enhancing Fenton-like catalytic oxidation of norfloxacin over prussian blue modified CeO2: Performance and mechanism.

To develop an efficient heterogeneous Fenton-like catalyst is of great importance for degrading organic pollutants. CeO2 was selected as the catalyst carrier. Prussian blue (PB) was chose as the iron resource for its sensitivity to H2O2 and low toxicity. PB modified CeO2 composite was successfully fabricated and used for Fenton-like oxidation of norfloxacin (NOR) in this study. The characteristics of the catalysts demonstrated that the doping of PB distorted the lattice locally and increased the surface area of CeO2 obviously. The XPS analysis also indicated that chemically supported catalysts PB/CeO2 with more Ce3+ was beneficial to Fenton-like catalytic reaction. The degradation tests showed that the PB/CeO2 significantly enhanced the removal of NOR which indicated a synergistic effect between PB and CeO2. The reason should be mainly attributed to the synergetic catalysis of H2O2 by Fe3+/Fe2+ and Ce3+/Ce4+ redox couples. At the same time, PB/CeO2 composite showed well reusability and wide pH value range of 2-9 with fairly low concentration of iron ions. The reaction mechanisms were identified to be OH oxidation and improvement of oxygen vacancies (OVs).

From Cellulose to Cellulose Nanofibrils-A Comprehensive Review of the Preparation and Modification of Cellulose Nanofibrils.

This review summarizes the preparation methods of cellulose nanofibrils (CNFs) and the progress in the research pertaining to their surface modification. Moreover, the preparation and surface modification of nanocellulose were comprehensively introduced based on the existing literature. The review focuses on the mechanical treatment of cellulose, the surface modification of fibrillated fibers during pretreatment, the surface modification of nanocellulose and the modification of CNFs and their functional application. In the past five years, research on cellulose nanofibrils has progressed with developments in nanomaterials research technology. The number of papers on nanocellulose alone has increased by six times. However, owing to its high energy consumption, high cost and challenging industrial production, the applications of nanocellulose remain limited. In addition, although nanofibrils exhibit strong biocompatibility and barrier and mechanical properties, their high hydrophilicity limits their practical application. Current research on cellulose nanofibrils has mainly focused on the industrial production of CNFs, their pretreatment and functional modification and their compatibility with other biomass materials. In the future, with the rapid development of modern science and technology, the demand for biodegradable biomass materials will continue to increase. Furthermore, research on bio-based nanomaterials is expected to advance in the direction of functionalization and popularization.

Photocathode optimization and microbial community in the solar-illuminated bio-photoelectrochemical system for nitrofurazone degradation.

To further enhance the bio-photoelectrochemical system (BPES) performance for nitrofurazone (NFZ) degradation and current output, the g-C3N4/CdS photocathode was optimized, and microbial community shift from inoculation to the BPES was analyzed. Results showed that photocathode with g-C3N4/CdS (mass ratio of 1:9) loading of 7.5 mg/cm2 exhibited the best performance, with NFZ removal of 83.14% (within 4 h) and current of ~9 mA in the BPES. Proteobacteria accounted for the largest proportion: 66.53% (inoculation), 71.89% (microbial electrolysis cell (MEC) anode), 74.67% (BPES anode) and 57.31% (BPES cathode), respectively. In addition, Geobacter was the most dominant genus in MEC and BPES anode and cathode, which occupied 31.64%, 67.73% and 41.34%, respectively. The microbial compositions of BPES anode and cathode were similar, but different from that of MEC anode. Notably, Rhodopseudomonas, a photosynthetic species, was detected in the BPES. Cognition of microbial community in the BPES is important for advancing its development.