A Novel Concept for the Removal of Solvent Vapors from Exhaust Air

The emission of large amounts of solvent vapors with exhaust air from industrial production into the environment is a serious problem. In Germany, industry‐sector‐specific threshold values are applied and technical measures for pollution reduction are required. Different techniques for exhaust air cleaning are in use but still posing problems concerning costs and reliability. For these reasons, the development of processes for exhaust air treatment is the subject of the current research. A new concept for exhaust air cleaning is introduced that combines absorption of a solvent vapor by an organic fluid and a subsequent adsorption by a molecular sieve placed in the absorber. It was managed to close the loops of solvent recovery and sorbents regeneration. In laboratory‐scale experiments it was possible to reduce an initial ethylacetate pollution of 800 mg/m³ or 349 mg C/m³ below the limit value of 75 mg C/m³ over 60 h duration. Thermogravimetric measurements assisted to define optimum conditions for solvent recovery at 180°C from the molecular sieve. One unexpected positive finding was the considerable increase in the solvent release in the presence of the absorption fluid while adsorption isotherms revealed first insight into this process.     

Removal of Organochlorine Pesticides from Aqueous Solution by Using Neutralized Red Mud

This work describes the potential usability of neutralized red mud for the removal of organochlorine pesticides (OCPs) from aqueous solutions. After examination on the adsorption capability of neutralized red mud for all studied OCPs, the experiments were performed by employing aldrin as a model compound. The effect of several parameters, such as contact time, pH of the solution, initial aldrin concentration, and dosage of the adsorbent was evaluated by batch experiments. The determination of OCPs was carried out using traditional liquid–liquid extraction followed by a GC coupled with µ‐electron capture detector (GC‐µECD). The results showed that adsorption equilibrium time depended upon the initial aldrin concentration and adsorption followed the second‐order kinetic model. Kinetic study also indicated that the film diffusion mechanism was a main rate control mechanism. The removal was explained by considering the electrostatic interactions between metal oxides surface of the neutralized red mud and inductively charged centers (negative charge (d?) of chlorine atoms and positive charge (d+) of π‐cloud aromatic ring) of the aldrin molecules. In comparison to the Langmuir isotherm model, the Freundlich model better represented the adsorption data. The neutralized red mud was also succesfully employed for the removal of OCPs from real water samples, including tap water and surface (lake) water, fortified with studied OCPs.     

Characterization and Application of Dried Plants to Remove Heavy Metals,Nitrate, and Phosphate Ions from Industrial Wastewaters

Low cost adsorbents were prepared from dried plants for the removal of heavy metals, nitrate, and phosphate ions from industrial wastewaters. The efficiency of these adsorbents was investigated using batch adsorption technique at room temperature. The dried plant particles were characterized by N₂ at 77 K adsorption, scanning electron microscopy, energy dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy, and phytochemical screening. The adsorption experiments showed that the microparticles of the dried plants presented a good adsorption of heavy metals, phosphate, and nitrate ions from real wastewaters. This adsorption increased with increasing contact time. The equilibrium time was found to be 30 min for heavy metals and nitrate ions and 240 min for phosphate ions. After the adsorption process, the Pb(II) concentrations, as well as those of Cd(II), Cu(II), and Zn(II) were below the European drinking water norms concentrations. The percentage removal of heavy metals, nitrates, and phosphates from industrial wastewaters by dried plants was ～94% for Cd²⁺, ～92% for Cu²⁺, ～99% for Pb²⁺, ～97% for Zn²⁺, ～100% for ${\rm NO}_{{\rm 3}}^{{-} } $ and ～77% for ${\rm PO}_{{\rm 4}}^{3{-} } $ ions. It is proved that dried plants can be one alternative source for low cost absorbents to remove heavy metals, nitrate, and phosphate ions from municipal and industrial wastewaters.     

Removal of Ni(II) Using Cation Exchange Resins in Packed Bed Column: Prediction of Breakthrough Curves

Sorptive removal of Ni(II) from electroplating rinse wastewaters by cation exchange resin Dueolite C 20 was investigated at the temperature of 30°C under dynamic conditions in a packed bed. The effects of sorbent bed length 0.1–0.2 m, fixed flow rate 6 dm³ min^?1, and the initial rinse water concentration (C₀) 53.1 mg L^?1 on the sorption characteristics of Dueolite C 20 were investigated at an influent pH of 6.5. More than 94.5% of Ni(II) was removed in the column experiments. The column performance was improved with increasing bed height and decreasing the flow rate. The Thomas, Yoon–Nelson, Clark, and Wolborska models were applied to the experimental data to represent the breakthrough curves and determine the characteristic design parameters of the column. The sorption performance of the Ni(II) ions through columns could be well described by the Thomas, Yoon–Nelson, and Wolborska models at effluent‐to‐influent concentration ratios (C/C₀) >0.03 and <0.99. Among the all models, the Clark model showed the least average percentage time deviation. The sorptive capacity of electroplating rinse water using Ni(II) was found to be 45.98 mg g^?1.     

Adsorption of Chromium(III), Nickel(II), and Copper(II) from Aqueous Solution by Activated Alumina

The possible use of activated alumina powder (AAP) as adsorbent for Cr(III), Ni(II), and Cu(II) from synthetic solutions was investigated. The effect of various parameters on batch adsorption process such as pH, contact time, adsorbent dosage, particle size, temperature, and initial metal ions concentration were studied to optimize the conditions for maximum metal ion removal. Both higher (molar) and lower (ppm) initial metal ion concentration sets were subjected to adsorption on AAP. Adsorption process revealed that equilibrium was established in 50 min for Cr(III) at pH 4.70, 80 min for Ni(II) at pH 7.00, and 40 min for Cu(II) at pH 3.02. Percentage removal was found to be highest at 55°C for Cr(III) and Ni(II) with 420 µm and 45°C for Cu(II) with 250‐µm particle size AAP. A dosage of 2 g for Cr(III), 8 g for Ni(II), and 10 g Cu(II) gave promising data in the metal ion removal. The adsorption process followed Langmuir as well as Freundlich models. The thermodynamics of adsorption of these metal ions on activated aluminum indicated that the adsorption was spontaneous and endothermic in nature. Present study indicates that AAP can act as a promising adsorbent for industrial wastewater treatment.     

Cotton Fiber/ZrO2, A New Material for Adsorption of Cr(VI) Ions in Water

The natural cotton fiber was used to synthesize an anion exchange, containing ZrO₂ film on its surface, NCFZC (natural cotton fiber/ZrO₂ composite). This anion exchanger was produced by the reaction of the zirconium oxychloride and hydroxyl groups on surface of the natural cotton fiber. The material was used for Cr(VI) ions adsorption studies. Adsorption equilibrium time and optimum pH for Cr(VI) adsorption were found to be 6 h and 4.0, respectively. The Langmuir and Temkin isotherms were used to models adsorption equilibrium data. The adsorption capacity of NCFZC was found to be 1.33 mmol/g. Kinetic studies showed that the rate of adsorption of Cr(VI) on NCFZC obeyed a pseudo‐second‐order kinetic model.     

铵在中砂上的3种吸附形态研究

通过动力学和等温吸附实验,研究了不同初始氨氮浓度下水溶铵、交换铵和固定铵在中砂上的吸附规律。结果表明,吸附平衡时各种形态铵含量随初始氨氮浓度增加而增大。3种形态铵吸附行为符合准二级动力学方程。吸附速率常数K大小顺序为：固定铵〉交换铵〉水溶铵,初始速率：固定铵〈交换铵〈水溶铵。随着初始氨氮浓度的增加,水溶铵占总铵的比重由40%上升到65%,其吸附的主要限制步骤为颗粒间扩散。交换铵对总铵的贡献率维持在25%左右,吸附饱和后有所降低,初始氨氮浓度为交换铵吸附的主要限制步骤。固定铵达到饱和时,吸附量只有26.18 mg/kg,对总铵的贡献率由33%下降到9%。     

The Impact of Aqueous Medium on Gas Yields and Kinetic Behaviors of Hydrogen Isotope Fractionation during Organic Matter Thermal Degradation

In order to recognize the impact of aqueous medium on gas yields and the kinetic behaviors of hydrogen isotope fractionation during organic matter thermal degradation, the gold tube apparatus was used to conduct thermal simulation experiments by mixing the nC18 with the water of different properties and proportions. The yields of natural gas components, the relation among hydrogen isotope composition of each component and the experimental temperatures vs. heating rates have been obtained, and the results indicate that under the higher temperature conditions, the hydrous experiment has obvious impact on gas yields, such as when more water is added, higher amounts of hydrocarbon gas and H2 are yielded, and the existence of water obviously prolongs the temperature interval with the existence of heavy hydrocarbon gas. It also shows that the hydrogen isotope of hydrocarbon gas generated by the hydrous experiment is obviously lighter than that generated by the anhydrous experiment, and with the increasing amount of added water, the δD value of hydrocarbon gas gradually decreases. Compared with gas yields, the variation of δD value is more sensitive to aqueous medium in the thermal simulation experiment. However, compared with the amount of the added water, the aqueous medium property has smaller impact on the gas yields, which still shows the inherit effect on hydrogen isotope composition of aqueous medium. Through the model simulation and the isotope fractionation behavior analysis, it is validated that the hydrogen isotope fractionation process can be well described by the chemical kinetic model. The difference of reaction fraction of normal methane and D-containing methane is large, corresponding to the same activation energy. The content of normal methane is obviously higher in the part with lower activation energy, while the content of D-containing methane is higher in the part with higher activation energy. Therefore, it will result in larger hydrogen isotope fractionation amplitude, and the δD values will be more sensitive to the variation of maturity. Meanwhile, the average activation energy of methane generation from nC18 in the hydrous experiment is higher than that in the anhydrous experiment, and the greater amount of added water, the larger the average activation energy of methane generation reaction. This has laid foundation for its exploratory application in the study of gas reservoir forming history and the gas-source correlation, which indicates the research and application prospects in this orientation.     

Water Role and Its Influence on Hydrogen Isotopic Composition of Natural Gas during Gas Generation

In order to discuss the role and influence of water during the generation of natural gas, the participation mechanism of water during the evolution of organic matter and its influences were summarized. In addition, we carried out an anhydrous cracking experiment of oil extracted from the Feixianguan Formation source rock in a closed system, which led to the establishment of the kinetic models for describing carbon and hydrogen isotopic fractionation during gas generation from organic matter. The models were calibrated and then applied to the northeastern Sichuan Basin. By combining a series of gas generation experiments from octadecane pyrolysis without water or with distilled water in varying mass proportions, several results were proved: (1) the hydrogen isotopic composition of natural gas becomes lighter with the participation of formation water; (2) we can quantitatively study the hydrogen isotopic fractionation with the kinetic model for describing carbon isotopic fractionation; (3) more abundant and reliable geological information can be obtained through the combined application of carbon and hydrogen isotopic indices.     

Kinetic simulation of hydrocarbon generation from lacustrine type I kerogen from the Songliao Basin: Model comparison and geological application

Eight lacustrine Type I kerogen samples from the Songliao Basin were pyrolyzed using the Rock-Eval equipment, and parallel first-order reaction models including the model with a single frequency factor and a discrete distribution of activation energies (SFF model) and the model with multiple frequency factors and a discrete distribution of activation energies (MFF model) were adopted to analyze kinetic characteristics of hydrocarbon generation of the Type I kerogen samples. The results show that the MFF and SFF models can satisfactory simulate hydrocarbon generation under laboratory conditions and the Type I kerogen shows relatively concentrated activation energy distributions (activation energies of MFF model range from 190 kJ/mol to 250 kJ/mol, activation energies of SFF model range from 220 kJ/mol to 240 kJ/mol), which indicates a homogeneous chemical bond structure of the Type I kerogen. The hydrocarbon generated curves from Type I kerogen were calculated by using the two models with a linear heating rate (3.3 K/Ma). It indicates that the hydrocarbon generation potentials (reaction fractions) are underestimated by using the SFF model during the kerogen thermal degradation for the components with chemical bond of lower and higher activation energies, while this problem can be avoided by using the MFF model. The calculated temperatures for 50% transformation ratio (TR) of all samples differ by as much as 20 °C. For the SFF model, the hydrocarbon generation curve obtained by using the weighted averaged kinetic parameters and the SFF model almost includes every curve calculated by using its own kinetic parameters. While the curve obtained by using the weighted averaged kinetic parameters and the MFF model cannot include every curve for all samples, it lies at the position of the averaged curve of all samples. The application of the MFF model in Songliao Basin shows that if TR 10% is taken as the onset of hydrocarbon generation, the threshold depth of hydrocarbon generation is about 1700 m, which is consistent with other geochemical parameters, such as S₁/TOC, S₁/(S₁ + S₂) and HC/TOC.