活性炭测量系统的最佳条件选择和影响因素

活性灰吸附器测氡法在铀矿勘探中得到了较广泛的应用。作者根据实验室内活性炭吸附器测氡的试验结果,选择了测量系统中装置参数的最佳条件,包括吸附剂类型,干燥剂的性质,吸附系统的灵敏度,吸附器的埋置时间,装置的容积、吸附容量与氧浓度的关系。另外,还研究了活性炭的解吸温度和时间以及温度对活性炭吸附能力的影响。文中详细给出了实验数据。     

Nettle ash as a low cost adsorbent for the removal of nickel and cadmium from wastewater

This study was focused on nettle ash as an alternative adsorbent for the removal of nickel (II) and cadmium (II) from wastewater. Batch experiments were conducted to determine the factors affecting adsorption of nickel (II) and cadmium (II). The adsorption process is affected by various parameters such as contact time, solution pH and adsorbent dose. The optimum pH required for maximum adsorption was found to be 6. The experimental data were tested using Langmuir, Freundlich and Tempkin equations. The data were fitted well to the Langmuir isotherm with monolayer adsorption capacity of 192.3 and 142.8 mg/g for nickel and cadmium, respectively. The adsorption kinetics were best described by the pseudo second order model. The cost of removal is expected to be quite low, as the adsorbent is cheap and easily available in large quantities. The present study showed that nettle ash was capable of removing nickel and cadmium ions from aqueous solution.     

Retention studies of chromium (VI) from aqueous solution on the surface of a novel carbonaceous material

In the present study, the retention capacity of carbonaceous material obtained from the diesel engine exhaust mufflers for Cr(VI) removal has been investigated. The physicochemical properties such as density, pH of aqueous slurry, pH at point of zero charge, ash content, moisture content, volatile matter, surface area, scanning electron microscopy and electron dispersive spectroscopy of the carbonaceous material were determined. The capacity of adsorbent for removal of Cr(VI) from aqueous solution was observed under different experimental condition like contact time, initial concentration of metal ions, pH and temperatures on the adsorption capacity of the adsorbent. Maximum adsorption of Cr(VI) ions was found at low pH. The adsorption process was found to follow second-order kinetics. The rate constant was evaluated at different temperatures along with other thermodynamic parameters like activation energy, Gibbs free energy change, enthalpy change and entropy change. Both Langmuir and Freundlich isotherms were used to describe the adsorption equilibrium of carbonaceous material at different temperatures. Langmuir isotherm shows better fit than Freundlich isotherm at given conditions. The result shows that low-cost carbonaceous material from diesel engine exhaust mufflers can be efficiently used for wastewater treatment containing Cr(VI) ions.     

Pb and Co removal from paint industries effluent using wood ash

The release of heavy metals into the environment is a worldwide major concern. Different studies have demonstrated that natural agents have a high removal capacity for divalent heavy metal ions. Wood ash is a natural adsorbent and, in comparison with others, has a very low price. In this study, the removal of heavy metals (Pb and Co) from Binalood paint industry (Kerman, Iran) effluent was investigated in batch condition. Pb and Co measurement in samples were done with atomic absorption equipment and test methods were adapted from standard methods for the examination of water and wastewater. The effect of pH and the amount of adsorbent was determined and different adsorption isotherms were also obtained. This study shows that the adsorption process follows the adsorption Langmuir isotherm. The amount of wood ash has a great role in the adsorption rate and adsorption rate increased as wood ash increased. In the study, the reactions reached equilibrium in 3 h contact time. The maximum Pb removal efficiency was 96.1 % at pH 2 with a contact time of 3 h and 100 g/L wood ash and the maximum Co removal efficiency was 99 % at pH 2 with a contact time of 3 h and 100 g/L wood ash. According to the results, wood ash is recommended as a low cost and available adsorbent to remove Pb and Co from municipal and industrial wastewaters.     

D2EHPA-impregnated alumina for adsorption of strontium ions in environmental samples

The alumina impregnated by the di-2-ethyl hexyl phosphoric acid was introduced to make more adsorption of strontium as well as to determine the optimal conditions. The influence of various parameters such as pH, equilibrium time, adsorbent mass, interfering ions, and various eluant agents for the desorption of the strontium ions, initial concentration, and temperature was investigated to find out the adsorption behavior of the adsorbent under different conditions. The adsorbent was characterized by the Fourier transform infrared spectroscopy. The experimental data were fitted on the two-parameter and three-parameter adsorption isotherm models. The Freundlich and Redlich–Peterson models have suitable fitting on the experimental data (R ² = 0.9307). The kinetic models of adsorption were analyzed by the pseudo-first- and pseudo-second-order models. The results have been indicated that the pseudo-second-order kinetic model is more appropriate than the others. Advantages of our method were simple operation, less time for preparation of adsorbent, rapid phase separation, and capability to combine with various detection techniques. The method has been utilized to extract and the recovery of strontium ions in environmental aqueous samples.     

Synthesis of poly(amidoamine)-graft-poly(methyl acrylate) magnetic nanocomposite for removal of lead contaminant from aqueous media

Poly(amidoamine)-graft-poly(methyl acrylate) magnetic nanocomposite was synthesized via radical polymerization of methyl acrylate onto modified magnetic nanoparticles followed by the functionalization of the methyl ester groups with poly(amidoamine) dendrimer. The resulting poly(amidoamine)-graft-poly(methyl acrylate) magnetic nanocomposite was then characterized by infrared spectroscopy, transmission electron microscopy, thermogravimetric analysis, scanning electron microscope and X-ray diffraction analysis. Its application as an adsorbent for the removal of Pb(II) ions was studied. The removal capability of the adsorbent was investigated in different pH values, contact time (kinetics) and initial concentration of lead. Moreover, adsorption isotherms were investigated to describe the mechanistic feature of this nanocomposite for adsorption. Accordingly, its high adsorption capacity (310 mg/g) and efficient adsorption toward lead ions in aqueous solution were shown. To further study of the chemistry behind the adsorption process, a comprehensive density functional theory-based study was performed, and a relatively strong interaction between metal ions and adsorbent was observed based on the calculated adsorption free energies.     

Raw and calcination-modified coal waste as adsorbents to remove cadmium from simulated mining wastewater

The adsorption of cadmium from simulated mining wastewater by coal waste (CW) and calcination-modified coal waste (MCW) was investigated. Effects of pH, initial concentration, particle size of adsorbent, adsorbent dosage and temperature were studied in batch experiments. The adsorption efficiency for cadmium increased with increasing pH, and the optimum pH for cadmium adsorption onto MCW and CW was 6.0 and 6.5, respectively. Kinetic experiments showed that the adsorption equilibrium was reached within 120 min and followed pseudo-second-order model well. The adsorption isotherm data fit Langmuir and Freundlich models, and the adsorption capacity of cadmium on the two adsorbents increased with increasing temperature from 298 to 318 K. MCW had a higher adsorption capacity of cadmium than CW, because calcination treatment can make CW to have more loose structure and higher specific surface area. Thermodynamic parameters, the Gibbs free energy change (?G⁰), enthalpy change (?H⁰) and entropy change (?S⁰), were calculated and the results showed that the adsorption of cadmium on CW and MCW was spontaneous and endothermic. Fourier transform infrared studies indicated silanol and aluminol groups were responsible for cadmium binding. The desorption results indicated that the two adsorbents could be used repeatedly at least three times without significant decrease in the adsorption capacity for cadmium. The results suggested that modified CW could have high potential as low-cost adsorbent for cadmium removal.     

Adsorption of lead using a new green material obtained from Portulaca plant

In the present study the potential of a new green material obtained from Portulaca oleracea plant was investigated. The material was used without any chemical treatment to study the adsorption behavior of lead ions from aqueous solution. Various batch experiments were carried out using different experimental conditions such as pH, contact time, adsorbent concentration, and metal ion concentration to identify the optimum conditions. The influence of these parameters on the adsorption capacity was studied. Results showed the optimum initial pH for adsorption as 6. Adsorption equilibrium was reached in 120?min. The adsorption data were modeled using both the Langmuir and Freundlich classical adsorption isotherms. Results show ~78% removal of lead from aqueous solution. The kinetic data corresponded well with pseudo second-order equation. From the initial results, the green material obtained from the waste of Portulaca seems to be a potential low-cost adsorbent for removal of lead ions from water.     

Partitioning of major and trace inorganic contaminants in fly ash acid mine drainage derived solid residues

Acid mine drainage was reacted with coal fly ash over a 24 h reaction time and species removal trends evaluated. The evolving process water chemistry was modeled by the geochemical code PHREEQC using WATEQ4 database. Mineralogical analysis of the resulting solid residues was done by X-ray diffraction analysis. Selective sequential extraction was used to evaluate the transfer of species from both acid mine drainage and fly ash to less labile mineral phases that precipitated out. The quantity of fly ash, volume of acid mine drainage in the reaction mixture and reaction time dictated whether the final solution at a given contact time will have a dominant acidic or basic character. Inorganic species removal was dependent on the pH regime generated at a specific reaction time. Sulphate concentration was controlled by precipitation of gypsum, barite, celestite and adsorption on iron-oxy-hydroxides at pH > 5.5. Increase of pH in solution with contact time caused the removal of the metal ions mainly by precipitation, co-precipitation and adsorption. PHREEQC predicted precipitation of iron, aluminium, manganese-bearing phases at pH 5.53–9.12. An amorphous fraction was observed to be the most important in retention of the major and minor species at pH > 6.32. The carbonate fraction was observed to be an important retention pathway at pH 4–5 mainly due to initial local pockets of high alkalinity on surfaces of fly ash particles. Boron was observed to have a strong retention in the carbonate fraction.     

Single and binary adsorption of lead and cadmium ions from aqueous solution using the clay mineral beidellite

Beidellite, a low-cost, locally available and natural mineral was used as an adsorbent for the removal of lead and cadmium ions from aqueous solutions in batch experiments. The kinetics of adsorption process was tested for the pseudo first-order, pseudo second-order reaction and intra-particle diffusion models. The rate constants of adsorption for all these kinetic models were calculated. Comparison amongst the models showed that the sorption kinetics was best described by the pseudo second-order model. Langmuir and Freundlich isotherm models were applied to the experimental equilibrium data for different temperatures. The adsorption capacities (Q°) of beidellite for lead and cadmium ions were calculated from the Langmuir isotherm. It was found that adsorption capacity was in the range of 83.3–86.9 for lead and 42–45.6 mg/g for cadmium at different temperatures. Thermodynamic studies showed that the metal uptake reaction by beidellite was endothermic in nature. Binary metal adsorption studies were also conducted to investigate the interactions and competitive effects in binary adsorption process. Based on the optimum parameters found, beidellite can be used as adsorbent for metal removal processes.     

Reinventing rice husk ash: derived NaX zeolite as a high-performing CO<Subscript>2</Subscript> adsorbent

In this work, rice husk ash was used as silica source to synthesize NaX zeolite potentially suitable for CO₂ adsorption. The produced material, denoted NaX-RHA, was characterized employing X-ray diffraction, scanning electron microscopy and gas adsorption porosimetry, in order to verify the occurred production of well-crystallized NaX zeolite with a significant degree of purity. CO₂ adsorption isotherms on NaX-RHA were volumetrically evaluated in the 298–348 K temperature range up to standard pressure, revealing performances that are higher than those reported for commercial similar substrates. The experimental data regarding CO₂ adsorption on NaX-RHA were very satisfyingly fitted by the semiempirical Sips model. Analyzing the best fitting values of model parameters allowed to conclude that the synthesized adsorbent could be quite suitable for applications like CO₂ capture from flue gas.     

Application of Bacillus subtilis for reducing ash and sulfur in coal

The replacement of coal with other energy sources is due to the presence of harmful impurities such as sulfur that can lead to emission of harmful and corrosive gases such as H₂S and SO₂. These gases can affect the human health due to its toxicity. Also, the mineral matter (ash) can cause several types of respiratory system diseases due to the presence of heavy metals and formation of hazardous compounds while burning of coal. In order to avoid the production of such emissions, the researchers all over the world were looking for a methodology that can eliminate or reduce these impurities from coal. Therefore, the current study aims at decreasing the sulfur and ash content in Egyptian coal (Maghara coal), using bioflotation technique. The effect of Bacillus subtilis (B. subtilis) on the removal/reduction of sulfur and ash was investigated. The affinity of B. subtilis to coal surface was characterized using zeta-potential, adsorption tests and Fourier transform infrared. The bioflotation results showed that, at optimum conditions, a clean coal contains 0.92 % total sulfur and 1.95 % ash and yield exceeding 72 % was obtained from the starting coal containing 3.3 % sulfur and 6.65 % ash.     

构造抬升过程中煤储层吸附能力的耦合效应及控制因素

煤层气盆地在地史演化过程中几乎都经历了多次抬升作用,构造抬升作用对煤储层吸附能力有着直接的影响。文中通过物理模拟实验和数值模拟对构造抬升过程中煤储层吸附能力的耦合效应和控制因素进行探讨。研究选取高、低煤阶煤储层样品进行等温吸附实验,并假定地温梯度分别为2、4和6 ℃/hm,压力梯度分别为0.3、0.5和1.0 MPa/hm模拟抬升过程中吸附量的变化。研究结果表明,煤储层在构造抬升过程中的吸附能力的变化主要受温压综合作用、煤储层热演化程度和构造抬升强度的控制。构造抬升时,温度作用效果占主导地位,煤储层吸附量增加;反之,压力作用效果占主导地位,煤储层吸附量减少。高煤阶煤层吸附量的变化量大于低煤阶变化量。抬升强度较大时煤层吸附量持续降低,较小时会使吸附量增加。煤层气在抬升过程中可能会出现吸附或解吸,与以往只是解吸的认识不同。当温度作用效果大于压力作用效果,即煤储层吸附量增加时,抬升作用易导致煤储层的含气欠饱和。     

粉煤灰对污水处理的效果及其环境影响试验研究

循环流化床燃烧产生的粉煤灰按不同比例与污水充分混合,其对污水中P的去除率可达90%以上;对COD的去除率为45%左右;对NH3-N的去除效果较差,最高不超过11%。由于粉煤灰含有大量钙,可以与粉煤灰中的磷酸盐形成沉淀,故采用循环流化床产生的粉煤灰可以有效处理含P较高的污水。文章研究了粉煤灰中重金属在污染水中释放规律,如Pb、Cd、Cu、Cr及Ni等,由于粉煤灰与污水浸泡后pH值呈碱性,且污水中含有大量有机物质,使反应体系呈还原状态。因此,粉煤灰中的重金属可以稳定存在,粉煤灰在污水中几乎不释放重金属,所以未加任何处理的粉煤灰在浸泡过程中不会对环境产生重金属污染。为此,粉煤灰可用于井下采空区回填,也可用于路基填充等。由于粉煤灰中少量碱性物质溶于水中,可使地下水pH值升高。     

Application of dried plant biomass as novel low-cost adsorbent for removal of cadmium from aqueous solution

Heavy metals are a threat to human health and ecosystem. These days, great deal of attention is being given to green technologies for purification of water contaminated with heavy metal ions. Biosorption is one among such emerging technologies, which utilizes naturally occurring waste materials to sequester heavy metals from wastewater. Cadmium has hazardous impact on living beings; therefore, its removal through green and economical process is an important task. The aim of the present study was to utilize the locally available Portulaca oleracea plant biomass as an adsorbent for cadmium removal from aqueous solution. The biomass was obtained after drying and grinding the portulaca leaves and stem. No chemical treatment was done on the adsorbent so that it remained green in a true sense. Batch experiments were performed at room temperature. The critical parameters studied were effects of pH, contact time, initial metal ion concentration and adsorbent dose on the adsorption of cadmium. The maximum adsorption was found to be 72 %. The kinetic data were found to best fit the pseudo-second-order equation. High adsorption rates were obtained in the initial 45 min, and adsorption equilibrium was then gradually achieved in about 100 min. Adsorption increased with increase in pH for a range 2 and 6. The equilibrium adsorption results closely followed both the Langmuir and Freundlich isotherms. The values of constants were calculated from isotherms. Results indicated that portulaca plant biomass could be developed as a potential material to be used in green water treatment devices for removal of metal ions.     

煤化工渣高效吸附去除水中全氟辛酸

为高效快速去除水中全氟辛酸,选择工业废物煤化工渣对全氟辛酸进行吸附去除探究。采用不同的处理方法制备了4种煤化工渣（粒径从大到小为CGA1、CGA2、CGA3和CGA4）,研究其在水溶液中的全氟辛酸吸附性能。利用扫描电子显微镜（SEM）、拉曼光谱、傅里叶变换红外光谱（FTIR）和X射线光电子能谱（XPS）对4种煤化工渣的结构特征进行表征分析,并考察了全氟辛酸初始质量浓度和初始pH对吸附进程的影响。实验结果表明：煤化工渣对全氟辛酸有高效的吸附能力,伪二级动力学模型和Langmuir等温模型可以较好地描述4种煤化工渣对全氟辛酸的吸附行为及过程,其中CGA4去除全氟辛酸的最大吸附量为25.51 mg/g;随着全氟辛酸溶液初始质量浓度升高,煤化工渣对全氟辛酸的吸附容量逐渐增加;初始pH对CGA3和CGA4的影响微弱,CGA1和CGA2在酸性条件下显示出更优越的吸附性能。由此得出,4种煤化工材料中粒径最小的CGA4具有最优的全氟辛酸去除能力且基本不受pH限制。FTIR分析表明,吸附过程中氢键的形成占主导地位,XPS和Zeta电位检测结果表明,物理吸附和静电吸附在去除过程中也发挥了重要作用。     

Potentiality of open burnt clay as an adsorbent for the removal of Congo red from aqueous solution

Open burnt clay was studied as a potential adsorbent for the adsorption of Congo red (a reactive dye) from aqueous solution. The effect of contact time, pH, adsorbent dosage and temperature were studied. It was observed that the amount of Congo red retained increase with decreasing pH and increasing initial concentration. Removal percentage at pH 2 and 3 are almost same. The adsorption capacity of regenerated burnt clay was showed more than 98 % recovery of the adsorption efficiency of initial virgin adsorbent. The equilibrium data were described well by both Langmuir and Freundlich isotherm model. The adsorption capacity of some natural adsorbents, namely rice husk, wood charcoal, tea waste etc. were also investigated and compared with that of open burnt clay.     

Emission spectrographic estimation of gold

A procedure for estimating minute quantities (parts per billion) of gold is described, based on dissolution of the sample in aqua regia, adsorption on activated charcoal, arcing of the charcoal ash, and measurement of the intensity of the emitted spectra.     

构造抬升过程中煤储层吸附能力的耦合效应及控制因素

煤层气盆地在地史演化过程中几乎都经历了多次抬升作用,构造抬升作用对煤储层吸附能力有着直接的影响。本文拟通过物理模拟实验和数值模拟对构造抬升过程中煤储层吸附能力的耦合效应和控制因素进行探讨。研究中选取高、低煤阶煤储层样品进行等温吸附实验,并假定地温梯度为分别为2℃/100m、4℃/100m和6℃/100m,压力梯度分别为0.3MPa/100m、0.5 MPa/100m和1.0MPa/100m模拟抬升过程中吸附量的变化。研究结果表明,煤储层在构造抬升过程中的吸附能力的变化主要受温压综合作用、煤储层热演化程度和构造抬升强度的控制。构造抬升时,温度作用效果占主导地位,煤储层吸附量增加;反之,压力作用效果占主导地位,煤储层吸附量减少。高煤阶煤层吸附量的变化量大于低煤阶变化量。抬升强度较大时煤层吸附量持续降低,较小时会使吸附量增加。煤层气在抬升过程中可能会出现吸附或解吸,与以往只是解吸的认识不同。当温度作用效果大于压力作用效果,即煤储层吸附量增加时,抬升作用易导致煤储层的含气欠饱和。     

Dynamic fuzzy neural network for simulating the fixed-bed adsorption of cadmium,nickel, and zinc on bone char

This study introduces the application of a dynamic fuzzy neural network for fitting and simulating the adsorption of nickel, cadmium, and zinc ions in mono- and bi-metallic solutions (nickel–cadmium, nickel–zinc, and cadmium–zinc) using packed-bed columns with bone char. This neural network model has shown a flexible and self-adaptive architecture with a faster learning speed than that of traditional artificial neural approaches. Results showed that this neural network model was reliable for representing the high asymmetry behavior of concentration profiles in both mono- and bi-metallic breakthrough curves where its accuracy was quite reasonable. Breakthrough parameters for mono-component and binary systems of tested heavy metals were calculated and compared. This analysis showed that the removal of these heavy metal ions in binary systems was a strong competitive adsorption process where the presence of co-ions reduced the removal performance of bone char at fixed-bed adsorbers. Results of surface characterization of adsorbent samples with X-ray photoelectron and infrared spectroscopy supported a removal mechanism based on an ion exchange between calcium from hydroxyapatite of bone char and heavy metal ions in the solution forming new metal–phosphate interactions in the adsorbent surface.