Polybrominated diphenyl ethers (PBDEs) in dust in typical indoor public places in Hangzhou: Levels and an assessment of human exposure.

Polybrominated diphenyl ethers (PBDEs) are organic pollutants (POPs) with the characteristics of environmental persistence, long-distance transmission in nature, biological accumulation and toxic effects on human health. To investigate the level of contamination due to PBDEs in typical indoor public places in Hangzhou, dust samples were collected from ten supermarkets, three electronic markets and five different areas throughout one commodity market. Based on sample pretreatment and GC-ECD instrumental analysis, the contamination characteristics, sources and the influencing factors of 14 PBDE congeners were analyzed. The results revealed that the mean of ∑14PBDEs in dust in the supermarkets and electronic markets was 546.13 ng/g and 1140.05 ng/g, respectively, while in the commodity market the mean was 1005.42 ng/g and varied in the five different areas as follows: shoe areas (1367.22 ng/g) > parking lot (1001.05 ng/g) > waiting halls (970.31 ng/g) > packet areas (933.23 ng/g) > curtain areas (755.28 ng/g). The high levels of PBDE were attributed to the quantity of electrical appliances in the supermarkets (r = 0.708*, p < 0.05) and the electronic markets (r = 0.799**, p < 0.05) through Spearman correlation coefficient analysis. BDE-209 was the dominant congener, accounting for 53.72% in supermarkets and 64.25% in electronic markets. The calculated inhalation exposure revealed that the exposure level of PBDEs varied in supermarkets, electronic markets and commodity markets, with values of 0.476 ng/day/kg, 0.993 ng/day/kg and 0.876 ng/day/kg, respectively. Moreover, BDE-209's contribution to the total intake of PBDEs was the highest, with a value of 0.072-0.970 ng/day/kg, while the value of BDE-183 was the lowest, with a value of 0-0.020 ng/day/kg. The exposure level of PBDEs in the studied indoor public places was lower than the reference dose of EPA.

[PBDEs Levels in House Dust and Human Exposure to PBDEs via Dust Ingestion in Hangzhou].

In order to evaluate the pollution degree of the dust in Hangzhou City, the indoor dust samples of 19 offices, families and students' dormitories were collected from August to March in 2013 at Hangzhou for evaluating the pollution level of polybrominated diphenyl ethers (PBDEs), to analyze concentrations of 14 PBDEs congeners and congener distribution as well as the possible influencing factors, and to estimate the PBDEs exposure levels of adults and children through the dust intake. The results showed that the average ∑14PBDEs of office was 9.28×102 ng·g-1, and the median was 1.03×103 ng·g-1; the average ∑14PBDEs of family was 7.83×102 ng·g-1, and the median was 9.11×102 ng·g-1; the average ∑14PBDEs of student dormitory was 4.07×102 ng·g-1, and the median was 4.03×102 ng·g-1. The pollution level of the office was higher than that of the living environment. BDE-209 was the largest monomer, and its contribution was 75.48%, followed by BDE-190, BDE-154 and BDE-71.PBDEs exposure levels of adults and children by dust intake were 13.12-32.63 ng·d-1 and 32.40-54.54 ng·d-1, respectively. Children's PBDEs exposure in the dust was higher than that of the adults, mainly because the average dust intake of children was higher than that of adults. The analysis showed that the PBDEs from indoor dust intake was a potential health hazard, and the biggest potential harm to children.

[Pollution status and characteristics of PBDEs in indoor air of Hangzhou].

Pollution Status and characteristics of PBDEs in offices were investigated in Hangzhou. As a result, the total concentration of PBDEs was 40.66-141.00 pg x m(-3), and the mean concentration was 93.22 pg x m(-3), being 1.87 and 5.01 times as high as those in homes and outdoor. In particle and gas phases, BDE-47 and BDE-99 were the most abundant congeners, which accounted for 33.29% and 31.99% of total PBDEs, respectively. Concentration of PBDEs in gas phase was 1.34 times as high as that in particle phase. BDE-28, BDE-47 and BDE-99 mainly existed in the gas phase, while BDE-153 and BDE-183 mainly existed in the particle phase.

[Effect of surfactant on the evaporation of p-chloronitrobenzene and naphthalene in the turbulent process].

Effect of surfactant on the evaporation of p-chloronitrobenzene and naphthalene in the turbulent process was studied in order to understand the effect of surfactant on the evaporation of complex contaminants in dynamic water system. Sodium dodecyl sulfate (SDS), cetyltrimethyl ammonium bromide (CTMAB) and polyethylene glycol sorbitan monolaurate (Tween 20) were used in the experiment. The results showed that the evaporation of p-chloronitrobenzene and naphthalene from surfactant solution in set turbulence intensity followed the first kinetic equation and all the correlation coefficients were above 0.99. The evaporative loss velocity of component was increased in dynamic water,while it decreased in surfactant solution, comparing with static pure water. The combined impact of these two factors was mainly presented promoting. When the turbulence intensity was above 39 r/min and 65 r/min respectively and the concentrations of surfactants were set from 150 mg/L to 2000 mg/L, the corresponding evaporative loss velocity of naphthalene and p-chloronitrobenzene both increased clearly. The evaporative loss velocity of p-chloronitrobenzene and naphthalene in the same turbulence intensity were decreased because of the straining ability of surfactant with the rule: CTMAB > Tween 20 > SDS. The impact of both surfactant and turbulence on naphthalene (with higher H) was more distinct than p-chloronitrobenzene (with lower H).

[Catalytic activity of TiO2 pillared bentonite for degradation of gaseous toluene: relationship between the effect of humidity and the catalyst structure].

Titania pillared bentonite was prepared by the sol method. The results of N2 adsorption-desorption showed that the specific surface areas of the catalysts calcined at 573, 673 and 773 K were 140.15, 110.13 and 88.38 m2/g, respectively. Their catalytic activities were evaluated for the gas phase degradation of toluene. The effects of humidity on the activity were studied in a continuous system. Results indicated that competitive adsorption between toluene and water molecules occurred on the catalyst surface, thus the photoactivities decreased with the increasing humidity. The photodegradation matched well with the Langmuir-Hinshelwood (L-H) kinetic model, and the adsorption constants of water for the catalysts calcined at 573, 673, and 773 K were 2.8 x 10(-5) , 4.1 x 10(-5) and 1.8 x 10(-4) m3 x mg(-1), respectively. The photoactivity of the catalyst calcined at 573 K was worst under low humidity but was best under high humidity compared with those of the catalysts calcined at 673 K and 773 K, suggesting it was most capable of resisting the impact of humidity. The thermal desorption was adopted to analyse the adsorption capability of toluene on catalysts. As the relative humidity increased from 25% to 75%, the adsorption amount of toluene for the catalysts calcined at 573, 673, and 773 K decreased from 184.8 to 3.25 microg/g, 130.5 to 1.92 microg/g, 77.6 to 1.65 microg/g, respectively. Adsorption capability of catalysts increased with the specific surface area, thus the apparent adsorption constant of water was reduced and the ability to resist the effect of humidity was enhanced. Experimental results indicate that during practical application of titania pillared bentonite for gaseous pollutants degradation, the environmental humidity and catalyst structure should be considered to screen out the catalyst with best activity.

[Sorption and mechanism of surfactants on bentonite in combined pollution].

Sorption of cationic surfactant cetyl pyridinium chloride (CPC), anionic surfactant sodium dodecylbenzene sulfonate (SDBS) and nonionic surfactant Triton X-100 (TX-100) on bentonite was studied. The influences of cation-exchange capacity (CEC), temperature and salinity on the sorption of CPC were also discussed. The results indicate that the sorption of CPC on Na-bentonite is greater than that of TX-100 and SDBS, and SDBS hardly shows any sorption. CPC is adsorbed to Na-bentonite through a combination of hydrophobic bonding and cation-exchange. While TX-100 is adsorbed to Na-bentonite via the formation of an adsorption layer of twain surfactant molecule and hydrogenolysis of silicon-oxygen surface of bentonite and TX-100. The amount of SDBS adsorbed on Ca-bentonite increases with increasing surfactant concentration, reaching a maximum at 1.5 critical micelle concentration (CMC), and then decreases with increasing surfactant loading. The mechanism of the retention appears to be formation of a sparingly soluble Ca-SDBS species, and dissolution in the micelle. The amount of CPC adsorbed on bentonite decreases with increasing temperature, and increases with increasing CEC. NaCl can enhance the sorption of CPC on bentonite.

[Effects of Pb(NO3)2 and cetylpyridinium chloride on sorption of p-nitrophenol by sediment].

Sorption behavior of p-nitrophenol by sediment in the presence of both cetylpyridinium chloride (CPC) and Pb(NO3)2 were investigated. The concurrence of Pb(NO3)2 inhibited the enhancement of sorption induced by CPC. The removal effect of pnitrophenol from sediment by compounding of CPC and Pb(NO3)2 presented antagonistic effect. At a given concentration of CPC, the antagonistic effect increased with increasing of the initial concentration of Pb(NO3)2. The antagonistic effect was also dependent on CPC concentrations. At the initial concentration below 3000 mg/L(the equilibrium concentration was below CMC), the antagonistic effect was especially significant. With the increase of the concentration of CPC, the antagonistic effect decreased gradually. Especially at the higher concentration above CMC, the effect went to be an independent effect just induced by CPC. In addition, the study also indicate that Pb2+ and CPC may not compete for the same adsorption sites.

[Effect of surfactant on the evaporation of BTEX from static water].

Effect of surfactant on the evaporative loss of benzene, toluene and ethylbenzene from static water was researched and the mechanism of surfactant was studied, so as try to supply theoretical reference for the effect of surfactant on the evaporation of complex pollution in water system. Sodium dodecylbenzene sulfonate (SDBS), cetyltrimethyl ammonium bromide (CTMAB) and polyoxyethylene(4) lauryl ether(Brij30) were used in the experiment. The results show when the surfactant concentrations exceeded their critical micelle concentrations (CMCs) and were set above 1 000mg/L, 2 000mg/L and 3 000mg/L respectively, the evaporative loss velocity of ethylbenzene, toluene and benzene began to decrease and their half-lives prolonged consequently. The main reason for the decrease of the evaporative loss velocity of BTEX was surfactant micelles formed and it caused the ratio of the concentration of BTEX at the liquid surface to that at the bulk liquid phase to diminish. Comparing CTMAB and Brij30 with SDBS, the evaporative loss of BTEX from static water decreased more evidently in CTMAB and Brij30 solutions. The positive relation was found between the restraining ability of a surfactant and the octanol-water partition coefficients or Henry's law constants of BTEX.

[Adsorption behavior and mechanisms in dual-solutes of Pb2+ and p-nitrophenol by organobentonites].

The sorption behavior for organobentonites to sorb organic pollutants from metal-organic pollutant systems were investigated. The results suggested that in organobentonite/Pb2+/p-nitrophenol solute systems, Pb2+ can slow the sorption velocity of organobentonite to adsorb p-nitrophenol from water. Pb2+ and p-nitriphenol exhibit a competitive effect. The competitive effects were relevant to ration of p-nitrophenol and Pb2+ and adsorption mechanisms of organobentonites. Bentonite modified with TMAB adsorbing contaminants primarily by an adsorption process, and the process exhibits a stonger competitive effect in multi-solute systems.

Sorption of BTEX mixtures to organobenonites.

Organobentonites synthesized by replacing the metal ions in bentonite with cetyltrimethylammonium (CTMA) or tetramethylammonium cation (TMA) were investigated for their behaviors to sorb benzene, toluene, p-xylene from water. The results served to distinguish the sorption mechanisms (adsorption or partition) of the two types of organobentonites. Bentonites modified with short-chain alkyl functional groups (e.g., TMA) sorb organic contaminants primarily by an adsorption process, in which the sorbed amount decreases with increasing steric hindrance of the organic compound and the process exhibits a competitive effect because of steric hindrance in multisolute systems. In contrast, the sorption of contaminants to organobentonites modified with long-chain alkyl groups (e.g., CTMA) occurs by partition process without exhibiting a competitive effect, and the additional organic compounds may induce a cosorptive effect. In the latter case, the measured distribution coefficients of organic compounds between organobentonites and water (log Kd) are positively correlated with the octanol-water partition coefficients of the compounds (logKow) and the sorption process exhibits no competitive effect in multi-solute systems.

Degradation of 4-CP in an internal electrolysis system.

The characteristic and mechanism of parachlorophenol (4-CP) degradation in an internal electrolysis system were investigated. The degradation rate of 4-CP was higher in acid solution than that of in neutral or alkaline solution. Addition of activated carbon could make 4-CP easier be degraded by the surface contact catalysis. The dissolved oxygen in solution could take part in the electrode reaction and intensify the degradation of 4-CP. By the analysis of intermediates of degradation of 4-CP, it could be conferred that 4-CP was broken through the bond beside hydroxy firstly, then the bond beside chloride was broken and the chloride was dechlorinated simultaneously. Most intermediate products were glycerine, ethane diacid and acetic acid, while very few 1,4-butanedial and alcohols were found.

Photochemically enhanced degradation of phenol using heterogeneous Fenton-type catalysts.

The degradation of phenol was carried out using heterogeneous Fenton-type catalysts in the presence of H2O2 and UV. Catalysts were prepared by exchanging and immobilizing Fe2+ in zeolite 13X, silica gel or Al2O3. The concentration of phenol solution was 100 mg/L. The amount of H2O2 added was the stoichiometric amount of H2O2 required for the total oxidation of phenol. Under the irradiation of medium pressure light (300 W) phenol was mineralized within 1 h in the presence of Fe2+/zeolite 13X. The COD removal rate was enhanced in the presence of Fe2+/zeolite 13X compared to that of Fe2+/silica gel or Fe2+/Al2O3. Analogous homogenous photo-Fenton reaction with equivalent Fe2+ was also carried out to evaluate the catalysis efficiency of Fe2+/zeolite 13X. Results showed that the COD removal rate was near to that of homogeneous Fenton, while heterogeneous Fe2+/zeolite 13X catalyst could be recycled.