无机盐对SO2—H2O—CaCO3气液固三相反应系统pH值的影响

研究了硫酸钠、硝酸钠和氯化钠及相应钙盐对石灰石浆液烟气脱硫条件下ＳＯ２－Ｈ２Ｏ－ＣａＣＯ３气、液、固三相反应系统中ｐＨ值的影响。发现硫酸钠能明显提高系统的ｐＨ值，硝酸钠和氯化钠使ｐＨ值提高的幅度不大，而３种钙盐均使ｐＨ值降低。根据膜模型的分析结果，认为无机盐影响该反应系统ｐＨ值的主要原因是无机盐的加入改变了石灰石表面的ｐＨ值。     

WFGD添加剂研究进展与应用探讨

从增效机理和应用两方面总结了国内外WFGD添加剂的研究成果,为实际应用中添加剂的选择提供了借鉴,指出WFGD添加剂的研究发展方向是复合添加剂以及发展化工产业副产品或废料用作添加剂的技术。     

Critical Review of Environmental Forensic Techniques: Part II

A multitude of forensic techniques are available for age dating and source identification, including aerial photography interpretation, corrosion models, the commercial availability of a chemical, chemical associations with discrete types of equipment, chemical profiling, degradation models and contaminant transport models. The success of these techniques in environmental litigation and their applicability to a particular fact situation is rarely discussed in the literature. When these techniques are introduced as scientific evidence, their governing assumptions and the adequacy of the underlying data are rigorously scrutinized and often, successfully challenged. The purpose of this paper is to review selected forensic techniques and discuss their merits so that the user can select the technique or combination of techniques most appropriate for the factual elements of the case.     

尼龙的阻燃研究进展

综述了近年来对尼龙阻燃的最新研究进展，尼龙是相对易燃材料，因此在应用中要进行阻燃处理。主要讨论了关于含卤、含磷、含氮、含硫、含硅、含溴化合物的尼龙的阻燃性研究，也讨论了一些无机添加剂和成炭有机物。可以认为尚未有理想的方法对尼龙阻燃而又不损失其物理性能。低卤和非卤阻燃剂以及多种阻燃剂共同作用的复合型阻燃聚酰胺会越来越得以发展。     

The influence of various additives on coagulation process at different dosing point: From a perspective of structure properties

Structure properties of flocs (size, fractal dimension (D_f), etc.) have a high impact on coagulation efficiency. In this work, the influences of three different additives (ferric salt (Fe), phosphate (P), and citric acid (CA)) on coagulation process/efficiency were investigated. Results showed that a small amount of extra Fe can facilitate the growth of Al flocs by providing more ‘active sites’. Although zeta potential and D_f showed a limited change, the average floc size increased apparently and the increment was more obvious when Fe was added after the formation of the flocs. In contrast, P addition during the rapid mixing period will decrease the final average floc size, while the influence is less significant when P was added after the growth of the flocs. In terms of CA, a more striking negative effect on the growth ability of the flocs was observed compared to P. The strong complexing/coordination interactions between CA and aluminum hydroxide is the main reason behind the influence. CA also significantly decreased the D_f value of the flocs compared to P, and D_f showed a comparatively higher decrease when P or CA was added during the rapid mixing stage compared to the addition after the flocs formation. These results indicated that the addition of CA or P during the rapid mixing stage ‘inactivated’ or occupied more ‘active sites’ on the preliminarily formed Al NPs during the hydrolysis process, and therefore presented stronger impact on the morphology/size of the formed flocs.     

Physical Properties of Chemically Modified Starch(RS4)/PVA Blend Films—Part 1

In this paper, we report on the physical properties of films that have been synthesized by using native corn starch (NS) and chemically modified starch (RS4). NS or RS4/PVA blend films were synthesized by using the mixing process and the casting method. Glycerol (GL), sorbitol (SO), and citric acid (CA) were used as additives. The chemically modified starch (RS4) was synthesized by using sodium trimetaphosphate (STMP) and sodium tripolyphosphate (STPP) as a crosslinker. Then, the RS4 thus synthesized was confirmed by using the pancreatin-gravimetric method, swelling power and an X-ray diffractometer (XRD). Tensile strength (TS), elongation (%E), swelling behavior (SB), and solubility (S) of the films were measured. The result of the measurements indicated the RS4-added film was better than the NS-added film. Especially, the RS4/PVA blend film with CA as an additive showed the physical properties superior to other films.     

Effect of non-solvent additives on the morphology, pore structure, and direct contact membrane distillation performance of PVDF-CTFE hydrophobic membranes

Four common types of additives for polymer membrane preparation including organic macromolecule and micromolecule additives, inorganic salts and acids, and the strong non-solvent H2 O were used to prepare poly(vinylidene fluoride-co-chlorotrifluoroethylene)(PVDF-CTFE) hydrophobic flat-sheet membranes. Membrane properties including morphology, porosity, hydrophobicity, pore size and pore distribution were investigated, and the permeability was evaluated via direct contact membrane distillation(DCMD) of 3.5 g/L Na Cl solution in a DCMD configuration. Both inorganic and organic micromolecule additives were found to slightly influence membrane hydrophobicity. Polyethylene glycol(PEG),organic acids, Li Cl, Mg Cl2, and Li Cl/H2 O mixtures were proved to be effective additives to PVDF-CTFE membranes due to their pore-controlling effects and the capacity to improve the properties and performance of the resultant membranes. The occurrence of a pre-gelation process showed that when organic and inorganic micromolecules were added to PVDF-CTFE solution, the resultant membranes presented a high interconnectivity structure. The membrane prepared with dibutyl phthalate(DBP) showed a nonporous surface and symmetrical cross-section. When H2 O and Li Cl/H2 O mixtures were also used as additives, they were beneficial for solid–liquid demixing, especially when Li Cl/H2 O mixed additives were used. The membrane prepared with 5% Li Cl + 2% H2 O achieved a flux of24.53 kg/(m2·hr) with 99.98% salt rejection. This study is expected to offer a reference not only for PVDF-CTFE membrane preparation but also for other polymer membranes.     

Effect of additives on dechlorination of PVC by mechanochemical treatment

Polyvinyl chloride (–CH₂–CHCl–) _n (PVC) was ground with a powdered inorganic material (CaO, CaCO₃, SiO₂, Al₂O₃, or slag) in a planetary ball mill under atmospheric conditions to investigate the effect of additions on its dechlorination. The grinding causes a dehydrochlorinating reaction, forming a mixture of partially dechlorinated PVC and inorganic chloride, depending on the grinding time. The dechlorination increases as the grinding progresses, and is improved with increasing amounts of additives. The most effective additive is a mixture of CaO, SiO₂, and Al₂O₃, which has the same constituent components as blast furnace slag. CaO, a mixture of CaO, SiO₂, and blast furnace slag, are also effective, but CaCO₃ is the least effective additive tired. Received: August 3, 2000 / Accepted: September 21, 2000     

Intensification of degradation of aqueous solutions of rhodamine B using sonochemical reactors at operating capacity of 7 L

In the present work, degradation of rhodamine B, a typical dye effluent commonly observed in chemical processing wastewaters has been investigated using a sonochemical reactor with capacity of 7 L. The reactor consists of an ultrasonic bath equipped with a single large transducer having longitudinal vibrations with operating frequency of 25 kHz and rated power output of 1 kW. The effect of operational conditions such as the rhodamine B initial concentration, operating pH and use of additives such as H(2)O(2), CCl(4) and TiO(2) has been investigated initially. A mathematical model has also been fitted to estimate the rate constant for rhodamine B removal under different operating conditions. Intensification studies have been carried by combining sonochemical oxidation with photocatalytic oxidation under optimized conditions. In all the investigated systems, complete removal of rhodamine B (10 ppm initial concentration) was obtained using a combination of sonochemical reactor and CCl(4). Sonocatalysis (in the presence of TiO(2)) of rhodamine B showed 92% degradation, while sonophotocatalysis gave degradation of 93%. TOC analysis at various optimum conditions was also performed to quantify the extent of mineralization and it was observed that the extent of mineralization is always lower than the extent of removal of parent compound.     

Photolysis of Enrofloxacin in aqueous systems under simulated sunlight irradiation: Kinetics, mechanism and toxicity of photolysis products

Photolysis of Enro in water was investigated under simulated sunlight irradiation using a Xenon lamp. The results showed that Enro photolysis followed apparent first-order kinetics. Increasing Enro concentration from 5.0 to 40.0 mg L⁻¹ led to the decrease of the photolysis rate constant from 1.6 × 10⁻² to 3.0 × 10⁻³ min⁻¹. Compared with the acidic and basic conditions, the photolysis rate was faster at neutral condition. Both of nitrate and humic acid can markedly decrease the photolysis rate of Enro because they can competitively absorb photons with Enro. The electron spin resonance and reactive oxygen species scavenging experiments indicated that Enro underwent self-sensitized photooxidation via OH and ¹O₂. After irradiation for 90 min, only 13.1% reduction of TOC occurred in spite of fast photolysis of 58.9% of Enro, indicating that Enro was transformed into intermediates without complete mineralization. The photolysis of Enro involved three main pathways: decarboxylation, defluorination, and piperazinyl N⁴-dealkylation. The bioluminescence inhibition rate using Vibrio fischeri increased to 67.2% at 60 min and then decreased to 56.9% at 90 min, indicative of the generation of some more toxic intermediates than Enro and then the degradation of the intermediates. The results will help us understand fundamental mechanisms of Enro photolysis and provide insight into the potential fate and transformation of Enro in surface waters.