Selective Removal of Nitrogen-Containing Heterocyclic Compounds from Transportation Diesel Fuels with Reactive Adsorbent

This paper presents a new selective adsorbent to remove nitrogen-containing heterocyclic compounds from model and commercial transportation diesel fuels based on characteristic reaction designed to occur in the pores of substrate. This reactive adsorbent is composed of formaldehyde, phosphotungstic acid and Santa Barbara USA (SBA)-15. The experiment was based on assumed hydroxymethylation reaction of nitrogen-containing heterocyclic compounds with formaldehyde using phosphotungstic acid as catalyst in batch and fixed-bed systems. The nitrogen concentration in the model fuel was 237.33 ng·μl^-1, carbazole and toluene were used as model nitrogen-containing heterocyclic compound and solvent, respectively. The effectiveness of reactive adsorbent for removal of nitrogen-containing heterocyclic compounds from commercial 0^# diesel fuel containing 224.86 ng·μl^-1 nitrogen was examined in a fixed-bed reactor at 70 ℃. The results showed that nitrogen in the model fuel was very low and the nitrogen concentration in the commercial diesel reduced to 2.44 ng·μl^-1. The demand for transportation fuel with ultra-low nitrogen is satisfied.     

Separation of Nitrogenous-Type Compounds from Synthetic Crudes

Abstract

This study describes the use of model compounds combined with gas chromatography analysis as a simple method to characterize complex adsorption systems and to obtain information on the adsorption mechanism. The possibility of using adsorbents for the selective removal of nitrogenous compounds from petroleum fractions is demonstrated. The adsorbent chosen in this study is ilmenite treated with bromide. The extent of removal is high for basic nitrogenous compounds but low for acidic/neutral nitrogenous compounds.     

Removal of Metal Cations from Water Using Zeolites

Abstract

Zeolites from abundant natural deposits were investigated by the Bureau of Mines for efficiently cleaning up mining industry wastewaters. Twenty-four zeolite samples were analyzed by x-ray diffraction and inductively coupled plasma. These included clinoptilolite, mordenite, chabazite, erionite, and phillipsite. Bulk densities of a sized fraction (-40, +65 mesh) varied from 0.48 to 0.93 g/mL. Attrition losses ranged from 1 to 18% during an hour-long shake test. The 24 zeolites and an ion-exchange resin were tested for the uptake of Cd, Cu, and Zn. Of the natural zeolites, phillipsite proved to be the most efficient, while the mordenites had the lowest uptakes. Sodium was the most effective exchangeable ion for exchange of heavy metals. Wastewater from an abandoned copper mine in Nevada was used to test the effectiveness of clinoptilolite for treating a multi-ion wastewater. The metal ions Fe³⁺, Cu²⁺, and Zn²⁺ in the copper mine wastewater were removed to below drinking water standards, but Mn²⁺ and Ni²⁺ were not. Calcium and NH₄ ⁺ interfered with the uptake of heavy metals. Adsorbed heavy metals were eluted from zeolites with a 3% NaCl solution. Heavy metals were concentrated in the eluates up to 30-fold relative to the waste solution. Anions were not adsorbed by the zeolites.     

Removal of Heavy Metals and Other Cations from Wastewater Using Zeolites

Abstract

Zeolites from abundant natural deposits were investigated by the Bureau of Mines for efficiently cleaning up mining industry wastewaters. Twenty-two zeolites were analyzed by X-ray diffraction and inductively coupled plasma analysis (ICP). These included clinoptilolite, mordenite, chabazite, erionite, and phillipsite. The zeolites were primarily in the sodium or calcium form, but potassium and magnesium counter ions were also present. Bulk densities of a sized fraction (minus 40, plus 65 mesh) varied from 0.48 to 0.93 g/cc. Heavy metal ion exchange loading values on two clinoptilolites ranged from 1.6 meq/g for lead to 0 meq/g for mercury in single ion tests. The selectivity series was determined to be Pb>Cd>Cs>Cu(II)>Co(II)>Cr(III)>Zn>Ni(II)>Hg(II). Sodium was the most effective exchangeable ion for ion exchange of heavy metals. Wastewater from an abandoned copper mine in Nevada was used to test the effectiveness of clinoptilolite for treating a multiion wastewater. Aluminum, Fe(III), Cu(II), and Zn in the copper mine wastewater were removed to below drinking water standards, but Mn(II) and Ni(II) were not. Calcium and NH₄ were absorbed preferentially to all heavy metal cations except Pb. Adsorbed heavy metals were eluted from zeolites with 3-pct NaCl solution. Heavy metals were concentrated in the eluates up to 30-fold relative to the waste solution. Anions were not adsorbed by the zeolites.     

改性沸石去除水中有机污染物的研究进展

概述了沸石的物理、化学性质及结构特征,介绍了采用沸石处理有机污染物时所采用的不同改性方法以及改性后对不同有机物的去除效果。综述了沸石在改性和处理有机污染物过程中所涉及到的反应机理及相关理论,总结了沸石改性和应用方面存在的问题及今后研究的方向。     

沸石对主流烟气中挥发性亚硝胺及NOx的吸附去除

采用程序升温脱附(TPD)及程序升温表面反应(TPSR)技术研究了NaY、NaZSM—5、NaA等分子筛对NO2、亚硝胺和香烟主流烟气的吸附作用。沸石对NO2、亚硝胺NPYR具有独特的吸附和催化能力,孔径、比表面是影响吸附量的重要因素。沸石对于主流烟气中NOx和亚硝胺的吸附比例关系受到孔径的制约。     

Removal of Volatile Organic Compounds from Water by Pervaporation Using Polyetherimide-Polyethersulfone Blend Hollow Fiber Membranes

Abstract

Removal of volatile organic compounds (VOCs) such as 1,2-dichloroethane, trichloroethylene, chlorobenzene and toluene from water solutions through polyetherimide (PEI)-polyethersulfone (PES) blend hollow fiber membranes was investigated by pervaporation (PV) in this work. The separation performances of the membranes were researched by varying the spinning conditions (such as coagulation temperature and air gap distance) for the preparation of the hollow fibers and the operation conditions (such as velocity, concentration, and temperature of feed liquids). For the PEI-PES blend hollow fiber membrane prepared when the air gap was 7 cm and the temperature of coagulation bath was 45°C, it possessed high selectivity to the aqueous solutions containing 0.04 wt.% of VOCs at 20°C. The separation factors to 1,2-dichloroethane, trichloroethylene, chlorobenzene and toluene were 7069, 5759, 3952, and 3205, respectively. It was found that the pervaporation performance of the blend hollow fiber membrane was strongly related to the molecular size of the VOCs. The order of the selectivities was 1,2-dichloroethane > trichloroethylene > chlorobenzene > toluene.     

Removal of Aromatic Nitro Compounds from Water by Ozonation

Experimental studies were carried out on the removal of five species of aromatic nitro hydrocarbons by ozonation. Ultraviolet spectrograms with distinct absorption peaks were plotted for each of them. It has been found that the absorbances of aqueous solutions containing the single compounds mentioned above increase to different extents at the wave lengths ranging from 200 to 230 nanometers with increase of ozone dosages. This is ascribed to the nitrite ions splitting out of the benzene rings and being further oxidized to nitrate ions by ozonation.

It has been indicated that the removal of the five species of aromatic nitro compounds by ozonation can well be expressed mathematically by first order reaction equations. Besides, the reaction constants and half-life periods for various species of the tested nitro compounds were calculated at different temperatures and pH.

An ozonation effect index (OI) was developed in the study to express the degree of degradation of substrates by ozonation, by means of which the five aromatic nitro hydrocarbons were compared with each other and finally ranked in the following order from greatest to smallest degrees of degradation:

p-nitroaniline > nitrobenzene > p-dinitrobenzene > p-nitrotoluene > m-dinitrobenzene

It has also found that the CODm/M ratio increases with ozone doses. This means that some easily degradable intermediates are produced, and increase in concentration with increase of ozone dose in the ozonation process.

The mechanisms of removing the five aromatic nitro hydrocarbons are discussed from the viewpoint of orienting effects of substituent groups on the aromatic rings.     

Dual‐Layer Hollow Fibers for Sulfur Removal from Fuels

Emission of sulfur compounds to the atmosphere is universally recognized as one key target to be reduced. For membrane pervaporation which is considered as a potential purification process of fuels, dual‐layer polyurethane (PU)/polyethersulfone hollow‐fiber membranes were prepared. A novel fabrication technique is proposed using a quadruple spinneret to produce the fiber with such morphology by simultaneous spinning of two polymer solutions in the presence of two corresponding precipitation media. Activated carbon was added into the PU solution to improve the transport properties of the selective layer. Resulting hollow‐fiber membranes showed very good adhesion between the selective layer and its support, in addition to an effective removal of a sulfur compound such as 2‐methyl thiophene from a typical model fuel, an indication of good prospects for both the fabrication technique and for sulfur removal by pervaporation of fuels.     

Removal of Trace Levels off Phenols from Aqueous Solution by Foam Flotation

Abstract

Peritachlorophenol (PCP) was removed from water by foam flotation with the cationic surfactant cetyltrimethylammonium bromide (CTAB). With initial PCP concentrations of 20 ppm or less, residual PCP concentrations of less than 0.05 ppm were obtained after 5 min flotation. The CTAB concentration and flotation time are directly related to the amount of PCP removed. PCP removal is most efficient at neutral to basic pH and at low ionic strength. PCP removal is less effective with sodium dodecyl sulfate. As much as 80% of the CTAB can be replaced by dodecylamine without inhibiting PCP removal. Alcohols up to 10% by volume do not affect PCP removal. Other phenols can also be removed equally well by foam flotation if the phenol is in the anionic form during flotation.     

利用微藻去除污水中的汞

开展了利用小球藻和斜生栅藻去除污水中无机汞的实验研究。研究结果表明,在实验浓度条件下,无机汞未对微藻的生长产生明显的抑制作用。两种微藻均可以快速、高效地去除培养基和生活污水中的无机汞,去除效率在90%以上。     

Removal of 1,4-Dioxane and Volatile Organic Compounds from Groundwater Using Ozone-Based Advanced Oxidation Process

Ozone and ozone/peroxide processes were evaluated for the removal of 1,4-dioxane from laboratory water and site groundwater. The effect of process parameters such as solution pH and dosage of peroxide was studied. Ozone alone was not very effective in removing 1,4-dioxane from water (≤ 20% removal). Enhanced oxidation of 1,4-dioxane was achieved by increasing the solution pH or by adding peroxide at neutral pH. Pseudo–first-order rate constants were calculated for the removal of 1,4-dioxane using ozone. Correlations were developed for the consumption of ozone per 1,4-dioxane removed. Acidic and neutral pH conditions resulted in higher consumption of ozone per dioxane removed. Basic solution pH and presence of hydrogen peroxide enhanced the dioxane removal, which resulted in lower consumption of ozone per dioxane removed. Following the lab study, ozonation was used for the remediation of site groundwater contaminated with 1,4-dioxane and chlorinated volatile organics. Presence of 5 mg/L of hydrogen peroxide during ozonation resulted in simultaneous removal of 1,4-dioxane and volatile organics from groundwater to target levels. For the AOP process, removal kinetics was approximately 50% slower in groundwater compared to the lab DI water.     

Selective Removal of Cadmium from Mixed Metal Solution by Carbonate Infusion

Abstract

The purpose of this study is to develop the technology of selective precipitation of a single metal from a mixed solution by carbonate infusion. Experiments were conducted in Pyrex reactors and jar testers. Synthetic wastewater of cadmium and copper mixed solution was used in this study. Initial cadmium and copper concentrations were 10^?5, 10^?4, and 10^?3 M, which are the concentrations commonly occurring in electroplating rinsewater. The effects of pH, carbonate concentration, and mixing rate on copper and cadmium hydrolysis were investigated. The optimum conditions of selective precipitation for the cadmium form mixed solutions were around pH 9, and the mixing rate was 100 rpm.     

Selective Removal of Copper from an Aqueous Solution Using Ligand-Modified Micellar-Enhanced Ultrafiltration Using an Alkyl-β-diketone Ligand

Abstract

The semiequilibrium dialysis technique has been used to investigate the concentration of Cu²⁺ using a water-insoluble liquid ion exchanger or ligand with cationic surfactant in a ligand-modified micellar-enhanced ultrafiltration (LM-MEUF) process. In LM-MEUF the surfactant and the ligand are added to an aqueous solution containing ions of like charge, one of which needs to be selectively removed. The ligand forms a complex with the target ion of interest and solubilizes or dissolves inside the organic interior of the micelles. Therefore, it is possible to replace typical solvent extraction solvents such as kerosene by micelles. In this study copper chloride/calcium chloride solutions were treated for the extraction of copper using a commercially available ligand, 1-phenyl-3-isoheptyl-1,3-propane dione in cetyltrimethylammonium bromide (CTAB), a cationic surfactant. The effect of pH and the concentrations of copper, calcium, surfactant, and ligand on the efficiency of copper removal from water are discussed. Copper rejections greater than 99% were obtained even in the presence of calcium. In studies of regeneration of surfactant and ligand from the retentate stream containing rejected species, stripping of copper from the retentate was achieved using sulfuric acid. Stripping efficiencies greater than 94% were attained in three to four stages, demonstrating the feasibility of this regeneration scheme.     

Selective Removal of Hydrogen Sulfide from Gases Containing Hydrogen Sulfide and Carbon Dioxide Using Diethanolamine

Abstract

It is sometimes necessary to selectively remove hydrogen sulfide from gases containing carbon dioxide. This may be the case for example in the production of sulfur using the Claus process. When two gases are simultaneously absorbed into a solution containing a reactant with which each gas can react, the rate of absorption of each component is affected by the presence of the other gas. For the absorption of hydrogen sulfide into primary and secondary amines, the reaction which occurs can usually be considered to be instantaneous. An instantaneous reaction is diffusion-limited since the reaction occurs so rapidly that the liquid phase reactant and the absorbed gas cannot coexist in the same region of the liquid. For primary and secondary amines used for gas treatment, the reaction with carbon dioxide is much slower than for hydrogen sulfide and can often be considered to be second order.

In this work the simultaneous absorption of two gases into a liquid containing a reactant with which both gases can react is modeled using penetration theory. It is assumed that one gas reacts instantaneously and the other gas undergoes a second order reaction. Parameters used in the calculations are those available in the literature corresponding to the absorption of hydrogen sulfide and carbon dioxide in diethanolamine.     

利用煤中SO3节约石膏技术的探索与应用

利用高硫煤中的SO3替代石膏中的SO3进行生料配料,在理论上是可行的。本文从实际出发,以如何优化配料方案,通过试验研究,找到配料与实际生产的结合点,以求达到既能满足熟料煅烧的要求,又节约石膏,降低成本,提高效益的目的。     

The Potential Use of Ozone and Peroxidase for Removal of Aromatic Compounds from Water by Polymerization

Oxidation organics by ozone has been the object of extensive studies. A great number of these concern the aromatic ring cleavage, but polymerization by ozone or enzyme, such as peroxidase, was not greatly studied. In this paper, the effects of ozone or enzyme on the polymerization of dichlorophenol, under the conditions of potable water treatment are studied using HPLC, scintillation counting, exclusion chromotography, and GC-MS. These techniques permit the characterization and identification of polymers.Even at low concentrations these compounds may cause taste and odor problems, or represent a health risk based on toxic and mutagenic considerations.     

Affinity of Clinoptilolite‐based Zeolites towards Removal of Cd from Aqueous Solutions

Abstract

Cd removal from aqueous solutions using as‐received and pretreated forms of two different clinoptilolite samples (denoted GC and BC) was investigated and dissimilar sorption affinities were revealed. Equilibrium behavior of systems were modeled using six different adsorption isotherms. The maximum sorption capacities, as obtained from the solubility‐normalized Dubinin‐Astakhov model for as‐received samples, were determined as 0.18 meq/g and 0.12 meq/g for GC and BC, whereas 0.72 meq/g and 0.41 meq Cd/g was determined for their pretreated forms, respectively. Examination of the release of exchangeable cations into the solution at equilibrium and the change of pH were discussed in terms of varying prevalence of ion exchange, dissolution of the sorbent and adsorption.     

粗TiCl4有机物除钒的研究

在粗TiCl4的几种主要除钒方法中,有机物除钒法是一种比较理想的除钒方法.介绍了粗TiCl4除钒的国内外现状,有机物除钒的基本原理,着重从热力学方面和动力学方面对有机物与VOCl3相互作用进行了分析.