空分设备基础知识讲座 第三讲 空气净化设备(二)

本部分为空气中水份的净除。讲了吸附法干燥空气; 吸附剂的种类和性能;吸附原理; 固定床吸附;吸附剂再生; 吸附容量; 吸附器;吸附法净化空气的进展。图23表6。     

变压吸附PSA净化天然气技术

为了满足天然气净化过程符合小型LNG装置机动灵活、开停方便的要求,采用PSA变压吸附法对天然气进行液化前的预处理。变压吸附法的关键在于吸附剂的选择。通过综述各种变压吸附法对天然气的净化处理,包括脱水、脱氮、脱碳、脱硫、脱汞等,探讨各种吸附剂的吸附能力以及吸附效果。最后,对变压吸附的前景进行了展望。     

复合吸附剂麦饭石-壳聚糖的制备及对Zn~(2+)的吸附性能

含重金属离子的废水对人体和环境有极大的影响,采用吸附法对其进行处理,效果较好,但成本高,不易推广.为此,利用麦饭石负载壳聚糖制备了一种价廉的复合吸附剂.通过X射线衍射(XRD)和扫描电子显微镜(SEM)对其结构进行了表征,研究了不同pH值、不同吸附时间、不同吸附剂投加量对复合壳聚糖吸附Zn2+的影响.结果在pH值为6～8、吸附时间为40 min、复合吸附剂的投加量为4.0 g/L的条件下,复合吸附剂对Zn2+的吸附率达到95%以上,达到国家污水综合排放标准.通过对试验数据运用相关数学模型拟合,复合吸附剂对Zn2+的吸附符合Langmuir吸附等温式,其相关系数R2为0.965 1.因而复合吸附剂麦饭石-壳聚糖可有效地处理含锌废水.     

用活性炭吸附二氧化硫模拟实验

目前净化烟气的方法很多,主要有吸附法、吸收法、催化法、冷凝法和燃烧法。其中吸附法由于固体吸附剂吸附量小,需要的吸附剂量大,设备就大,一次性投资大,所以存在一些弊端。但是吸附法具有选择性高,净化效率高,吸附剂能再生,能实现自动控制等优点,在世界各国环境工程中得到了广泛的应用。随着我国经济的增长,人们生活水平的提高,人们对生存环境的质量要求越来越高,吸附法在我国得到了广泛的应用和推广。     

气体纯化技术—分子筛吸附性能试验

以5A 分子筛、4A 分子筛、活性碳二种吸附剂分别对 O_2、N_2、CO_2、C_2H_2进行吸附试验。通过试验进一步了解分子筛及活性碳在不同温度、不同压力下对各种气体的吸附能力。选择最佳吸附系件,找出分子筛的吸附规律及持续吸附时间.使其在空分原料气净化、气体纯化中发挥更大的作用。     

氯化钠改性5A分子筛吸附剂的实验研究

采用氯化钠浸渍法改性5A分子筛，并吸附净化泥磷制取次磷酸钠产生的含PH。气体，选择吸附效率和吸附容量进行吸附剂吸附效果的判定。主要考察了氯化钠浸渍液的浓度、吸附剂的干燥温度、焙烧温度对吸附效果的影响，确定了最适宜的吸附剂制备条件：在浸渍液浓度0．3mol／L、干燥温度110~C、焙烧温度为300℃的条件下，吸附容量为2...     

变压吸附系统吸附剂吸附容量的实验研究

运用实验的方法对变压吸附系统中吸附剂的吸附容量进行了研究.分析不同因素对吸附剂吸附容量的影响,包括吸附温度、吸附压力,给出吸附容量在这些因素影响下的变化规律,同时比较了不同吸附剂的吸附容量.实验结果可对工业选用吸附剂以及变压吸附系统的优化设计提供必要的数据.     

氯化钠改性5A分子筛吸附剂的实验研究

采用氯化钠浸渍法改性5A分子筛,并吸附净化泥磷制取次磷酸钠产生的含PH₃气体,选择吸附效率和吸附容量进行吸附剂吸附效果的判定。主要考察了氯化钠浸渍液的浓度、吸附剂的干燥温度、焙烧温度对吸附效果的影响,确定了最适宜的吸附剂制备条件:在浸渍液浓度0.3mol/L、干燥温度110℃、焙烧温度为300℃的条件下,吸附容量为20mg/g,穿透时间可达6h。     

城市污泥改性物对电镀废水中Cr(Ⅵ)的吸附研究

在静态条件下,进行了以城市污泥改性物(MSMP)作吸附剂净化含Cr(Ⅵ)废水的试验.研究了含Cr(Ⅵ)废水的pH值、浓度、接触时间和吸附剂的投加量等因素对MSMP吸附Cr(Ⅵ)的影响,确定了MSMP净化含Cr(Ⅵ)废水的最佳条件为:吸附时间20 min,pH值为中性,Cr(Ⅵ)起始浓度不超过50 mg/L,温度为30℃.结合对实际含Cr(Ⅵ)废水的吸附净化处理,证实了MSMP可用于电镀废水中Cr(Ⅵ)的吸附处理.     

低浓度甲醛吸附材料的研究进展

室内空气质量直接关乎人体健康,甲醛属于室内空气质量标准严控污染物之一.室内甲醛浓度低但危害大,对于大风量低浓度甲醛治理,吸附技术是主流技术之一,吸附材料又是该技术的核心.综述了国内外关于室内低浓度甲醛净化吸附材料及其吸附机理的最新研究进展,对比研究了碳基吸附剂、硅基吸附剂以及MOFs及POPs材料对甲醛的吸附相平衡和动...     

多晶硅生产中氢气的来源与净化

简述了多晶硅生产过程中氢气的几个来源,并比较了采用电解、裂解或工业尾气净化回收氢气作为多晶硅生产补充氢气来源的技术、经济性。提出了采用特定吸附剂,变压吸附净化回收可重复利用氢气的新方法。对比了几种氢气的净化回收技术的优势,认为采用变压吸附（PSA）氢气净化工艺过程最优,能耗最低,经济效益最好。     

Studies on the adsorption of reactive brilliant red X-3B dye on organic and carbon aerogels

Organic aerogels (AGs) and carbon aerogels (CAs) as adsorbents were successfully fabricated by a sol-gel polymerization method. The BET specific surface area and pore size distribution of the samples were analyzed by N(2) adsorption measurements. The adsorption efficiency of prepared samples towards reactive brilliant red X-3B dye (RBRX) was investigated. The adsorption of dye was found to follow the Langmuir and Freundlich models. The thermodynamic parameters, such as the change of free energy, enthalpy and entropy were calculated from equilibrium constants. Kinetic studies indicated that the adsorption of CA followed pseudo first and second order kinetic model, but the adsorption of AG only followed pseudo first order kinetic model. Batch adsorption studies were conducted to evaluate the effects of main preparation and adsorption conditions such as R/C (molar ratio of resorcinol (R) to surfactant (CTAB)) of adsorbent, pH, adsorbent dose and adsorbent particle size on the adsorption of RBRX on AG and CA. The results showed that the adsorption capacity of dye increased with the decrease in dose and particle size of the adsorbent. Maximum adsorption of AGs and CAs was observed at R/C=200. The adsorption capacity of AG and CA would increase largely when pH<4 or pH>12.     

胶原纤维吸附剂对芹菜素的分离纯化性能研究

以戊二醛交联胶原纤维为吸附剂,通过柱层析研究其对芹菜素、槲皮素和杨梅素组成的三元黄酮类混合物中芹菜素的分离纯化特性。结果表明胶原纤维吸附剂对3种黄酮化合物表现出一定的吸附差异,对芹菜素的吸附作用最小;用100%～70%乙醇水溶液分步淋洗,能够从混合物中分离得到芹菜素,其纯度为98.03%,回收率为100%;用40%～60%乙醇水溶液分步淋洗,能够分离得到芹菜素和槲皮素,产物纯度分别为99.16%和99.47%,回收率分别为100%和91.22%;适当增大吸附柱的柱高,有助于提高芹菜素的纯度;在5次重复分离实验中,胶原纤维吸附剂的分离性能无明显降低,具有较好的重复使用性。因此,胶原纤维吸附剂可用于黄酮类混合物中芹菜素的分离纯化。     

Adsorption of Chrysoidine R by using fly ash in batch process

This investigation deals with effective utilization of fly ash as adsorbent for the removal of Chrysoidine R from the aqueous solution. The fly ash is a major byproduct generated in coal-based thermal power plants and has good potential for use as an adsorbent. A series of experiments were carried out in a batch adsorption technique to obtain the effect of process variables viz. contact time, pH (2, 4, 6 and 8) initial concentration of the dye (400, 600, 800 and 1000mgL(-1)), amount of the adsorbent (125, 250, 375 and 500mgL(-1)), and temperature (303, 313, 323 and 333K) on adsorption. The concentration of dye was determined by spectrophotometer. The results showed that as the amount of the adsorbent was increased, the percentage of dye removal increased accordingly; higher adsorption percentage was observed at lower concentration of chrysoidine. The adsorption data were analyzed using Langmuir and Freundlich isotherms. The adsorption was found to obey pseudo-first order kinetics. An intra particle diffusion model was used to fit the experimental data. The thermodynamic parameters such as standard change in free energy, enthalpy and entropy of adsorption have been calculated. Adsorption of Chrysoidine R on fly ash was found to be an exothermic reaction.     

The effect of pH in the adsorption of Alizarin and Eriochrome Blue Black R onto iron oxides

The adsorption process of two dyes as a function of pH on three different adsorbents (goethite, Co-goethite, and magnetite) has been analyzed. Typical anionic adsorption behavior was observed for both dyes onto goethite and Co-goethite. The adsorption level was practically constant in the range of pH studied when the adsorbent was magnetite. The constant capacitance model (CCM) was employed to fit the experimental results. The surface complexes proposed from the adsorption data were in agreement with the patterns obtained from FTIR spectroscopy and a molecular mechanics calculation. Goethite has very good performance as adsorbent of Alizarin and Eriochrome Blue Black R. The presence of a foreign cation in Co-goethite does not improve the adsorption abilities of goethite. At low pH, the amounts of Alizarin and Eriochrome Blue Black R adsorbed on goethite and Co-goethite are similar. However, a higher dependence with the increase of pH is observed by Eriochrome Blue Black R. On magnetite, the dye adsorption shows less affinity for both dyes. Electronic and steric considerations can explain the trends found in the adsorption of the two dyes on the three iron oxides studied in this work.     

Application of grass char for Cd(II) treatment in column leaching test

Various adsorbents as well as toxicants have been investigated regarding the adsorption behaviors and mechanisms. However, most of these reports were based on batch test. The discrepancy in adsorption behaviors between batch test and column test has been recognized recently. This study was to investigate the sorption behavior of Cd(II) in a novel adsorbent made from Reed char. Batch adsorption test and column leaching test were both conducted. Various influence factors including confining pressure, pH, velocity, concentration and ionic strength were studied. The velocity was found to have negligible effect on the breakthrough of Cd(II). The adsorption affinity was observed for the first time to decrease from a high value (R(d) = 130.00) to a negligible one (R(d) = 1.20) with increasing confining pressure from 0 to 100.00 kPa. The breakthrough of acid Cd(II) solution was earlier for solutions with less pH and higher ionic strength. The Cd(II) laden adsorbent was reclaimed by flushing chelants through the column. The recycled adsorbent appeared to be applicable in the following adsorption treatment. Suggestions were provided regarding the potential engineering applications.     

Reuse of waste silica as adsorbent for metal removal by iron oxide modification

Silica gel is widely used in research laboratories, especially for the purification of organic compounds. Consequently, waste silica gel is generated in increasing amounts. In this work, waste silica was modified by coating its surface with iron oxide aiming to obtain an effective adsorbent for metal removal from wastewater. In the preparation of the adsorbent, the optimal pretreatment temperature and iron concentration were investigated. The coated waste silica was characterized for BET surface area, pore size, specific pore volume and iron content. Iron oxide-coated waste silica was tested for the adsorption of Pb(II), Cu(II), Cd(II) and Ni(II) from solutions in a batch system. The effect of contact time, pH and salt concentration on metal adsorption was investigated. It was found that the adsorption of metals occurred rapidly and reached equilibrium within 30 min. The pH suitable for metal adsorption was between 6 and 7 and leaching of iron from the coating was observed only at pH 3 or lower. The presence of salt reduced the adsorption efficiency of the adsorbent. The adsorption behavior followed both Langmuir and Freundlich isotherms (25 degrees C). Finally, the efficacy of the adsorbents was investigated using aqueous lab waste where removal efficiencies ranging from 62 to 89% were achieved when the initial metal concentrations ranged from 13 to 42 mg L(-1).     

Adsorption of Cr(VI) using silica-based adsorbent prepared by radiation-induced grafting

Silica-based adsorbent was prepared by radiation-induced grafting of dimethylaminoethyl methacrylate (DMAEMA) onto the silanized silica followed by a protonation process. The FTIR spectra and XPS analysis proved that DMAEMA was grafted successfully onto the silica surface. The resultant adsorbent manifested a high ion exchange capacity (IEC) of ca. 1.30 mmol/g and the Cr(VI) adsorption behavior of the adsorbent was further investigated, revealing the recovery of Cr(VI) increased with the adsorbent feed and the equilibrium adsorption could be achieved within 40 min. The adsorption capacity, strongly depended on the pH of the solution, reached a maximum Cr(VI) uptake (ca. 68 mg/g) as the pH was in the range of 2.5–5.0. Furthermore, even in strong acidic (4.0 mol/L HNO₃) or alkaline media (pH 11.0), the adsorbent had a sound Cr(VI) uptake capacity (ca. 22 and 30 mg/g, respectively), and the adsorption followed Langmuir mode. The results indicated that this adsorbent, prepared via a convenient approach, is applicable for removing heavy-metal-ion pollutants (e.g. Cr(VI)) from waste waters.     

Dye adsorption by calcium chloride treated beech sawdust in batch and fixed-bed systems

Batch and column kinetics of methylene blue and red basic 22 adsorption on CaCl(2) treated beech sawdust was investigated, using untreated beech sawdust as control, in order to explore its potential use as a low-cost adsorbent for wastewater dye removal. The adsorption capacity, estimated according to Freundlich's model, and the adsorption capacity coefficient values, determined using the Bohart and Adams' bed depth service model indicate that CaCl(2) treatment enhanced the adsorption properties of the original material.     

Removal of chromium (VI) from aqueous solution using treated oil palm fibre

This study proposed an oil palm by-product as a low-cost adsorbent for the removal of hexavalent chromium [Cr (VI)] from aqueous solution. Adsorption of Cr (VI) by sulphuric acid and heat-treated oil palm fibre was conducted using batch tests. The influence of pH, contact time, initial chromium concentration and adsorbent dosage on the removal of Cr (VI) from the solutions was investigated. The optimum initial pH for maximum uptake of Cr (VI) from aqueous solution was found to be 1.5. The removal efficiency was found to correlate with the initial Cr (VI) concentration, adsorbent dosage as well as the contact time between Cr (VI) and the adsorbent. The adsorption kinetics tested with pseudo first order and pseudo second order models yielded high R(2) values from 0.9254 to 0.9870 and from 0.9936 to 0.9998, respectively. The analysis of variance (ANOVA) showed significant difference between the R(2) values of the two models at 99% confidence level. The Freundlich isotherm (R(2)=0.8778) described Cr (VI) adsorption slightly better than the Langmuir isotherm (R(2)=0.8715). Difficulty in desorption of Cr (VI) suggests the suitability of treated oil palm fibre as a single-use adsorbent for Cr (VI) removal from aqueous solution.