低床层烟炱和石灰粉混合物吸附脱硫试验研究

利用燃油锅炉本身排出的烟炱和石灰粉的混合物作脱硫吸附,在布袋除尘器内进行烟气脱硫试验。结果表明,在烟气温度110℃、过滤风速0．6－0．7m/min、吸附床层厚度为2－3mm等工艺条件下,烟炱和石灰粉的较佳混合比为5：1,吸附时间在60min内的平均脱硫70．54％。     

活性炭纤维对染料的吸附性能研究

研究了聚丙烯腈活性炭纤维（P－ACF）、粘胶活性炭纤维（R－ACF）和颗粒活性炭（GAC）对5种红色染料的吸附能力,通过简单的模型,算出5种染料在两种活性炭纤维上的吸附速率常数。结果表明,尽管吸附能力随染料种类不同而有一定的差别,但总体上,聚丙烯腈活性炭纤维的吸附能力略低于颗粒活性炭,而粘胶活性炭纤维的吸附能力则远远优于前两种,对染料有着较大的吸附容量和较快的吸附速率。     

Utilization of sepiolite materials as a bottom liner material in solid waste landfills

Landfill bottom liners are generally constructed with natural clay soils due to their high strength and low hydraulic conductivity characteristics. However, in recent years it is increasingly difficult to find locally available clay soils that satisfy the required engineering properties. Fine grained soils such as sepiolite and zeolite may be used as alternative materials in the constructions of landfill bottom liners. A study was conducted to investigate the feasibility of using natural clay rich in kaolinite, sepiolite, zeolite, and their mixtures as a bottom liner material. Unconfined compression tests, swell tests, hydraulic conductivity tests, batch and column adsorption tests were performed on each type of soil and sepiolite–zeolite mixtures. The results of the current study indicate that sepiolite is the dominant material that affects both the geomechanical and geoenvironmental properties of these alternative liners. An increase in sepiolite content in the sepiolite–zeolite mixtures increased the strength, swelling potential and metal adsorption capacities of the soil mixtures. Moreover, hydraulic conductivity of the mixtures decreased significantly with the addition of sepiolite. The utilization of sepiolite–zeolite materials as a bottom liner material allowed for thinner liners with some reduction in construction costs compared to use of a kaolinite-rich clay.     

硬脂酸改性磁铁矿对石油污水的处理研究

研究硬脂酸改性磁铁矿对石油污水中油类物质的吸附,通过改变温度、超声振荡时间和磁铁矿与硬脂酸的质量比等因素,在最佳的改性条件下制得改性磁铁矿。将改性后的磁铁矿应用于石油污水处理,改变震荡时间,用红外分光测油仪得出吸附结果。结果表明:当改性温度为35℃、改性时间为35min、硬脂酸与磁铁矿质量比为3.5%时磁铁矿改性效果最佳,当吸附时间为8min时,对石油炼化污水中油类物质的吸附效果最好,吸附量为216.65mg/g。     

Low-temperature (NO + O2) adsorption performance of alkaline earth metal-doped C-FDU-15

To improve the removal capacity of NO + O₂ effectively, the alkaline earth metal-doped order mesoporous carbon (A-C-FDU-15(0.001) (A = Mg, Ca, Sr and Ba)) and Mg-C-FDU-15(x) (x = 0.001?0.003) samples were prepared, and their physicochemical and NO + O₂ adsorption properties were determined by means of various techniques. The results show that the sequence in (NO + O₂) adsorption performance was as follows: Mg-C-FDU-15(0.001) (93.2 mg/g) > Ca-C-FDU-15(0.001) (82.2 mg/g) > Sr-C-FDU-15(0.001) (76.1 mg/g) > Ba-C-FDU-15(0.001) (72.9 mg/g) > C-FDU-15 (67.1 mg/g). Among all of the A-C-FDU-15(0.001) samples, Mg-C-FDU-15(0.001) possessed the highest (NO + O₂) adsorption capacity (106.2 mg/g). The species of alkaline earth metals and basic sites were important factors determining the adsorption of NO + O₂ on the A-C-FDU-15(x) samples, and (NO + O₂) adsorption on the samples was mainly chemical adsorption. Combined with the results of (NO + O₂)-temperature-programmed desorption ((NO + O₂)-TPD) and in situ diffused reflectance infrared Fourier transform spectroscopy (DRIFTS) characterization, we deduced that there were two main pathways of (NO + O₂) adsorption: one was first the conversion of NO and O₂ to NO₂ and then part of NO₂ was converted to NO₂^? and NO₃^?; and the other was the direct oxidation of NO to NO₂^? and NO₃^?.     

Graphitic carbon nitride/biochar composite synthesized by a facile ball-milling method for the adsorption and photocatalytic degradation of enrofloxacin

In order to enhance the removal performance of graphitic carbon nitride (g-C₃N₄) on organic pollutant, a simultaneous process of adsorption and photocatalysis was achieved via the compounding of biochar and g-C₃N₄. In this study, g-C₃N₄ was obtained by a condensation reaction of melamine at 550°C. Then the g-C₃N₄/biochar composites were synthesized by ball milling biochar and g-C₃N₄ together, which was considered as a simple, economical, and green strategy. The characterization of resulting g-C₃N₄/biochar suggested that biochar and g-C₃N₄ achieved effective linkage. The adsorption and photocatalytic performance of the composites were evaluated with enrofloxacin (EFA) as a model pollutant. The result showed that all the g-C₃N₄/biochar composites displayed higher adsorption and photocatalytic performance to EFA than that of pure g-C₃N₄. The 50% g-C₃N₄/biochar performed best and removed 45.2% and 81.1% of EFA (10 mg/L) under darkness and light with a dosage of 1 mg/mL, while g-C₃N₄ were 19.0% and 27.3%, respectively. Besides, 50% g-C₃N₄/biochar showed the highest total organic carbon (TOC) removal efficiency (65.9%). Radical trapping experiments suggested that superoxide radical (?O₂^?) and hole (h⁺) were the main active species in the photocatalytic process. After 4 cycles, the composite still exhibited activity for catalytic removal of EFA.     

A highly porous animal bone-derived char with a superiority of promoting nZVI for Cr(VI) sequestration in agricultural soils

Paddy soil and irrigation water are commonly contaminated with hexavalent chromium [Cr(VI)] near urban industrial areas, thereby threatening the safety of agricultural products and human health. In this study, we develop a porous and high specific area bone char (BC) to support nanoscale zero-valent iron (nZVI) and apply it to remediate Cr(VI) pollution in water and paddy soil under anaerobic conditions. The batch experiments reveal that BC/nZVI exhibits a higher removal capacity of 516.7 mg/(g?nZVI) for Cr(VI) than nZVI when normalized to the actual nZVI content, which is 2.8 times that of nZVI; moreover, the highest nZVI utilization is the nZVI loading of 15% (BC/nZVI15). The Cr(VI) removal efficiency of BC/nZVI15 decreases with increasing pH (4 – 10). Coexisting ions (phosphate and carbonate) and humic acid can inhibit the removal of Cr(VI) with BC/nZVI15. Additionally, BC exhibits a strong advantage in promoting Cr(VI) removal by nZVI compared to the widely used biochar and activated carbon. Our results demonstrate that reduction and coprecipitation are the dominant Cr(VI) removal mechanisms. Furthermore, BC/nZVI15 shows a significantly higher reduction and removal efficiency as well as a strong anti-interference ability for Cr(VI) in paddy soil, as compared to nZVI. These findings provide a new effective material for remediating Cr(VI) pollution from water and soil.     

Remediation of preservative ethylparaben in water using natural sphalerite: Kinetics and mechanisms

As a typical class of emerging organic contaminants(EOCs), the environmental transformation and abatement of preservative parabens have raised certain environmental concerns. However, the remediation of parabens-contaminated water using natural matrixes(such as, naturally abundant minerals) is not reported extensively in literature. In this study, the transformation kinetics and the mechanism of ethylparaben using natural sphalerite(NS) were investigated. The results show that around 63% of ethy...     

Evaluation of offline sampling for atmospheric C3-C11 non-methane hydrocarbons

The concentration variation of C3-C11 non-methane hydrocarbons(NMHCs) collected in several types of commercial flexible bags and adsorption tubes was systematically investigated using a gas chromatography-flame ionization detector(GC-FID) system. The percentage loss of each NMHC in the polyvinyl fluoride(PVF) bags was less than 5% during a 7-hr storage period; significant NMHCs loss was detected in aluminum foil composite film and fluorinated ethylene propylene bags. The thermal desorption effic...     

A mechanistic study of ciprofloxacin adsorption by goethite in the presence of silver and titanium dioxide nanoparticles

The adsorption behaviors of ciprofloxacin (CIP), a fluoroquinolone antibiotic, onto goethite (Gt) in the presence of silver and titanium dioxide nanoparticles (AgNPs and TiO₂NPs) were investigated. Results showed that CIP adsorption kinetics in Gt with or without NPs both followed the pseudo-second-order kinetic model. The presence of AgNPs or TiO₂NPs inhibited the adsorption of CIP by Gt. The amount of inhibition of CIP sorption due to AgNPs was decreased with an increase of solution pH from 5.0 to 9.0. In contrast, in the presence of TiO₂NPs, CIP adsorption by Gt was almost unchanged at pHs of 5.0∼6.5 but was decreased with an increase of pH from 6.5 to 9.0. The mechanisms of AgNPs and TiO₂NPs in inhibiting CIP adsorption by Gt were different, which was attributed to citrate coating of AgNPs resulting in competition with CIP for adsorption sites on Gt, while TiO₂NPs could compete with Gt for CIP adsorption. Additionally, CIP was adsorbed by Gt or TiO₂NPs through a tridentate complex involving the bidentate inner-sphere coordination of the deprotonated carboxylic group and hydrogen bonding through the adjacent carbonyl group on the quinoline ring. These findings advance our understanding of the environmental behavior and fate of fluoroquinolone antibiotics in the presence of NPs.