Sorption of aromatic organophosphate flame thermally and hydrothermally produced retardants on biochars

Aromatic organophosphate flame retardant(OPFR)pollutants and biochars are commonly present and continually released into soils due to their increasingly wide applications.In this study,for the first time,the sorption of OPFRs on biochars was investigated.Although triphenyl phosphate(TPhP)and triphenylphosphine oxide(TPPO)have similar molecular structures and sizes,TPhP exhibited much faster and higher sorption than TPPO due to its stronger hydrophobicity,suggesting the dominant role of hydrophobic interactions in TPhP sorption.Theπ-πelectron donor-acceptor(EDA)interactions also contributed to the sorption process,as suggested by the negative correlation between the sorption capacity of the aromatic OPFRs and the aromatic index(H/C atomic ratios)of biochar.Density functional theory calculations further showed that one benzene ring of aromatic OPFRs has no electrons,which may interact with biochar viaπ-πEDA interactions.The electrostatic attraction between the protonated P=O in OPFRs and the negatively charged biochar was found to occur at pH below 7.This work provides insights into the sorption behaviors and mechanisms of aromatic OPFRs by biochars.

Effect of allelochemicals sustained-release microspheres on the ingestion, incorporation, and digestion abilities of Daphnia magna Straus

Allelochemicals sustained-release microspheres(ACs-SMs)exhibited great inhibition effect on algae,however,few studies have focused on ACs-SMs toxicity on invertebrate.In this study,the effects of single high-concentration ACs(15 mg/L,SH-ACs),repeated lowconcentration ACs(3×5 mg/L,RL-ACs)and ACs-SMs containing 15 mg/L ACs exposure on the ingestion,incorporation,and digestion of Daphniamagna Straus(DS)were investigated by stable isotope 15N labeling method.Meanwhile,the diversity and abundance of microflora in DS guts were determined by 16S rRNA genes and cloning methods.The results showed that SH-ACs exposure caused 50%and 33.3%death rates for newborn and adult DS,while RL-ACs exposure caused 10%death rate for newborn DS and no obvious effect on the activity of adult DS.And ACs-SMs exposure did not diminish the motility of both newborn and adult DS,indicating the lower acute toxicity of ACs-SMs.Furthermore,SH-ACs inhibited the ingestion(-6.45%),incorporation(-47.1%)and digestion(-53.8%)abilities of DS and reduced the microbial abundance(-27.7%)in DS guts.Compared with SH-ACs,RL-ACs showed relatively low impact on the ingestion(-3.23%),incorporation(-5.89%)and digestion(-23.9%)abilities of DS.Interestingly,ACs-SMs enhanced the ingestion(+9.68%),incorporation(+52.9%)and digestion(+51.3%)abilities of DS and increased the microbial abundance(+10.7%)in DS guts.Overall ACs and ACs-SMs reduced the diversity of microflora in DS guts.In conclusion,ACs-SMs can release ACs sustainably and prolong the sustained release time,which not only effectively reduce the toxicity of ACs,but also had positive effects on DS.

Adsorption of emerging sodium p-perfluorous nonenoxybenzene sulfonate(OBS) onto soils: Kinetics, isotherms and mechanisms

The widespread use of sodium p-perfluorous nonenoxybenzene sulfonate(OBS), a typical alternative to perfluorooctane sulfonate, has resulted in potential threats to the environment, but the adsorption behavior of OBS in soils has not yet been reported. In this study, the adsorption behaviors of OBS on five soils with different physicochemical properties were investigated. The rate of OBS adsorption was fast, and most of the OBS uptake was completed within 12 h. The good model fit of OBS adsorption to the pseudo-second-order and Elovich models indicated the occurrence of chemical adsorption. The adsorption isotherms of OBS on the soils were better described by the Freundlich model than by the Langmuir model, suggesting that the OBS adsorption sites on the soils were heterogeneous. This is possibly associated with various adsorption mechanisms including hydrophobic, π-π, hydrogen bonding, and electrostatic interactions,further confirmed by the good model fit to the D-R isotherm. Adsorption of OBS occurred on the soils, and the adsorption process was spontaneous and endothermic. In addition, the soils were more suitable for OBS adsorption at lower pH values due to the stronger electrostatic adsorption. The OBS adsorption on the soils decreased with the increase of soil depth from 0 to 30 cm. Moreover, the presence of organic matter and ammonia nitrogen in the soils was favorable for OBS adsorption, and these parameters decreased with increasing soil depth, making OBS adsorption less prominent in the deeper soil. This study indicates that OBS is easily enriched in surface soils, and that soil organic matter and ammonia nitrogen significantly affect OBS migration in soil.

Removal efficiencies of natural and synthetic progesterones in hospital wastewater treated by different disinfection processes

Progesterones are ubiquitous in hospital wastewater(HWW)with concentrations much higher than those of estrogens and androgens.To ensure that these water systems are safe to use,disinfection is crucial during HWW treatment by providing"front line"defense against biological contaminations.Here,five disinfection processes,namely,chlorine(Cl_(2)),chlorine dioxide(ClO_(2)),ozone(O_(3)),ultraviolet(UV)),and UV/chlorine(UV/Cl_(2)),were selected to investigate their removal efficiencies for progesterones in primary filtration and secondary biological treatment effluents.There were 61 natural and synthetic progesterones detected in HWW,with the natural progesterones being the main components with a concentration of 845.51 ng/L and contributing to 75.08%of the total proge-sterones.The primary filtration treatment presented insignificant removal effects on the progesterones,while the secondary biological treatment significantly reduced the progesterone content by biode-gradation.The order of removal efficiencies of total progesterones by different disinfection processes was UV/Cl_(2)>Cl_(2)>O_(3)>ClO_(2)>UV.UV/Cl_(2)showed the highest removal efficiency against progesterones mainly due to the activation of Cl_(2)by ultraviolet(UV)photolysis,which helps open the heterocyclic,aromatic,and phenolic rings,thus accelerating progesterone degradation.In addition,the removal efficiencies of natural progesterones in the five disinfection processes were higher than those of synthetic progesterones(progesterone derivatives,19-nortestosterone derivatives,and 17α-hydroxyprogesterone derivatives).

Occurrence and migration of microplastics and plasticizers in different wastewater and sludge treatment units in municipal wastewater treatment plant

Microplastics(MPs)and plasticizers,such as phthalate esters(PAEs),were frequently detected in municipal wastewater treatment plants(MWTP).Previous research mainly studied the removal of MPs and PAEs in wastewater.However,the occurrence of MPs and PAEs in the sludge was generally ignored.To comprehensively investigate the occurrence and the migration behaviors of MPs and PAEs in MWTP,a series of representative parameters including the number,size,color,shape of MPs,and the concentrations of PAEs in wastewater and sludge were systematically investigated.In this study,the concentrations of MPs in the influent and effluent were 15.46±0.37 and 0.30±0.14 particles/L.The MP removal efficiency of 98.1%was achieved and about 73.8%of MPs were accumulated in the sludge in the MWTP.The numbers of MPs in the sludge before and after digestion were 4.40±0.14 and 0.31±0.01 particles/g(dry sludge),respectively.Fourier Transform Infrared Spectroscopy(ATR FT-IR)analysis showed that the main types of MPs were polyethylene terephthalate(PET),polypropylene(PP),polyethylene(PE),and polystyrene(PS).Six PAEs,including phthalate(DMP),diethyl phthalate(DEP),diisobutyl phthalate(DIBP),ortho dibutyl phthalate(DBP),butyl benzyl phthalate(BBP),and bis(2-ethyl)hexyl phthalate(DEHP),were detected in the MWTP.The concentrations of total PAEs(ΣPAEs)in the influent and effluent were 76.66 and 6.28μg/L,respectively.The concentrations ofΣPAEs in the sludge before and after digestion were 152.64 and 31.70μg/g,respectively.In the process of thermal hydrolysis,the number and size of MPs decreased accompanied by the increase of the plasticizer concentration.