Co-BTC脱除噻吩性能研究

基于溶剂热法合成出金属有机骨架材料Co-BTC,通过XRD、IR表征其结构。采用固定床吸附穿透实验,考察了不同的空速条件及溶解水对Co-BTC吸附分离噻吩的影响,并用甲苯溶剂洗涤进行吸附剂再生。结果表明,Co-BTC对模型油中噻吩的穿透容量及饱和吸附量分别为0.98%,2.05%(wt);Co-BTC在含溶解水和纯模型油中硫的饱和容量分别是1.50%,2.05%,饱和吸附容量降低了27%,运用分子筛分层填装吸附柱技术能将Co-BTC的饱和吸附容量提高到2.02%;再生的吸附剂对模型油中噻吩硫的饱和吸附容量为2.02%,再生率达到99%。     

一步快速活化法制备生物质活性炭及其对乙酸乙酯的吸附再生

活性炭吸附法因技术成熟、简单易行、吸附效率高等优点而被广泛应用于挥发性有机化合物（VOCs）的处理中。本文以山林废弃物的野山桃核为原料,烟道废气及硝酸铁为活化剂,制备了一系列生物质活性炭,并利用固定床吸附装置对其吸附、再生性能进行了研究。利用二氧化碳和水蒸气模拟烟气,在固定流量的烟气活化氛围中进行活化,并探讨了不同硝酸铁的量对活性炭的孔隙结构及其吸附再生性能的影响。利用N₂ 吸附-脱附实验、扫描电镜、拉曼光谱和红外光谱等技术研究了活性炭详细特征。结果表明：当硝酸铁的质量分数为0.2% 时,所制备的活性炭AC-3具有最大的比表面积和平均孔径,分别为923m2/g及2.57nm。其对乙酸乙酯的饱和吸附量也最大,为973.04mg/g。利用烟气对AC-3活性炭进行活化再生处理,经过3次重复吸附-解吸再生实验,其饱和吸附能力仍可达91.5％以上,实现了废弃烟气资源化利用及活性炭的循环回收,从而达到废气治理的目标。     

The defluoridation of water by acidic alumina

Fluoride is considered as a major inorganic pollutant present in drinking water. To remove this excess fluoride, defluoridation was done by alumina. In the present study, alumina used was acidic in nature and hence considered as a good fluoride removing adsorbent. Characterization of the adsorbent was done by XRD, SEM, BET and FTIR with BET surface area of 144.27 m²/g. Systematic adsorption experiments were carried out with different process parameters such as contact time, adsorbent mass, pH, temperature and stirring speed. Fluoride adsorption by alumina was highly pH dependent. Maximum fluoride was removed from water at pH 4.4. At very low and very high pH, fluoride removal efficiency was affected. The study of thermodynamic parameters inferred that physical adsorption was dominant with activation energy of 95.13 kJ/mol and endothermic behavior of the process. The kinetics study concluded that pseudo second order kinetics was followed by the adsorption process. Adsorption equilibrium was studied with Langmuir and Freundlich isotherm models. The adsorption process followed Langmuir isotherm with an adsorption capacity of 8.4 mg/g. A regeneration study was proposed in order to reuse the adsorbent for better economy of the process. Finally, a process design calculation was reported to know the amount of adsorbent required for efficient removal of fluoride from aqueous medium.     

Removal of Tartrazine From Water by Adsorption with Electrochemical Regeneration

An innovative process has been developed at University of the Manchester in order to remove organic contaminants from wastewater using graphite intercalation compounds (GICs) as adsorbents with electrochemical regeneration. The present study has demonstrated the removal of tartrazine, from water by adsorption and electrochemical regeneration. The adsorption of tartrazine onto GIC adsorbent was shown to be a quick process, however, with extremely low adsorption capacity compared to porous adsorbents. Low adsorption capacity of the adsorbent is being compensated by rapid electrochemical regeneration associated with low energy consumption that makes the process cost-effective. Regeneration efficiency of around 100% could be obtained in an electrochemical cell by passing a charge of 18 C g^?1 for 18 min through a 10-mm thick adsorbent bed. A series of adsorption and regeneration cycles showed that there was little loss in adsorbent capacity, demonstrating that tartrazine loaded GIC adsorbent could be effectively regenerated electrochemically.     

活性炭填充床脱除水中苯酚及填充床的再生

实验研究了活性炭填充床脱除水中苯酚的吸附性能,探讨其饱和吸附填充床的再生方法,结果表明当平衡浓度范围为0－0．8kg/m^3时,活性炭对水中苯酚的吸附能力达230kg/kg（吸附剂）,吸附等温线符合Langmuir型,填充床的穿透曲线和穿透时间强烈依赖于实验条件,较高的进料浓度,较大的进料速度,以及较短的床层长度都将使填充床穿透较快;用热的NaOH稀溶液可再生被苯酚饱和的活性炭纤维填充床,再生效率达90％以上。     

Process analysis of temperature swing adsorption and temperature vacuum swing adsorption in VOCs recovery from activated carbon

In order to better guide the design of industrial process for purification and recovery of VOCs, temperature swing adsorption (TSA) and temperature vacuum swing adsorption (TVSA) process for VOCs purification and recovery were studied systematically with activated carbon adsorbent. The adsorption and desorption behaviors of benzene on activated carbon in above two processes were investigated systematically. Effects of operating parameters on process performances were further analyzed, including as regeneration temperature, purging feed ratio and hot–cold purging ratio. The results showed that the increase of hot–cold purging ratio (HP/CP) could obtain the same regeneration effect as the increase of desorption temperature. Increasing the feed purge ratio without increasing the hot–cold purging ratio is not conducive to bed regeneration, because a large number of cold purge gases cannot utilize the residual heat of temperature wave, thus reducing the desorption effect of the cooling step on the bed. In addition, the vacuum step can enhance the regeneration ability of hot nitrogen to the bed at the same regeneration temperature, making the bed regeneration of TVSA process more thorough. Temperature in the middle and lower part of the bed in TVSA process was higher and the regeneration was more thorough. In conclusion, TVSA has more obvious advantages than TSA in terms of energy consumption, hot or cold purge volume and bed regeneration.     

Removal of fluoride from drinking water by adsorption onto alum-impregnated activated alumina

The ability of the alum-impregnated activated alumina (AIAA) for removal of fluoride from water through adsorption has been investigated in the present study. All the experiments are carried out by batch mode. The effect of various parameters viz. contact time, pH effect (pH 2–8), adsorbent dose (0.5–16 g/l), initial fluoride concentration (1–35 mg/l) has been investigated to determine the adsorption capacity of AIAA. The adsorbent dose and isotherm data are correlated to the Bradley equation. The efficacy of AIAA to remove fluoride from water is found to be 99% at pH 6.5, contact time for 3 h, dose of 8 g/l, when 20 mg/l of fluoride is present in 50 ml of water. Energy-dispersive analysis of X-ray shows that the uptake of fluoride at the AIAA/water interface is due to only surface precipitation. The desorption study reveals that this adsorbent can be regenerated following a simple base–acid rinsing procedure, however, again impregnation of the regenerated adsorbent (rinsed residue) is needed for further defluoridation process.     

超声辅助熔融草酸法高效绿色再生饱和活性炭

饱和活性炭的高效绿色再生对活性炭在污染物吸附过程中的循环利用是非常重要的。本文利用超声波辅助熔融草酸的方法对饱和活性炭进行高效绿色再生，讨论了温度、时间、超声振幅和固液比对饱和活性炭再生效率的影响。结果表明，在超声辅助作用下，熔融草酸可在20min内使饱和活性炭得到快速再生，再生效率高达94.72%。通过5次吸附-脱附循环后，再生效率仍可达到78.02%，与此同时有机酸的回收率极高，平均达到98.35%，再生过程十分绿色环保。在超声的辅助作用下，强氢键缔合能力的熔融草酸更充分地与焦糖反应，形成草酸-焦糖强氢键缔合体系，降低焦糖与活性炭表面的亲和力，将焦糖解吸，实现活性炭的再生。该法可为绿色高效的活性炭再生方法的研究开发提供新思路。     

Column breakthrough studies for the removal and recovery of phosphate by lime-iron sludge: Modeling and optimization using artificial neural network and adaptive neuro-fuzzy inference system

Increases in the treatment of water to meet the growing water demand ultimately result in unmanageable quantities of residuals, the handling, and disposal of which is a major environmental issue. Consequently, research into beneficial reuse of water treatment residuals continues unabated. This study investigated the applicability of lime-iron sludge for phosphate adsorption by fixed-bed column adsorption. Laboratory-scale experiments were conducted at varying flow rates and bed depths. Fundamental and empirical models(Thomas, Yan,Bohart-Adams, Yoon-Nelson, and Wolboroska) as well as artificial intelligence techniques(Artificial neural network(ANN) and Adaptive neuro-fuzzy inference system(ANFIS)) were used to simulate experimental breakthrough curves and predict column dynamics. Increase in flow rate resulted in reduced adsorption capacity.However, adsorption capacity was not affected by bed depth. ANN was superior in predicting breakthrough curves and predicted breakthrough times with high accuracy(R~20.9962). Na OH(0.5 mol·L~(-1)) was successfully used to regenerate the adsorption bed. After nine cyclic adsorption/desorption runs, only a marginal decrease in adsorption and desorption efficiencies of 10% and 8% respectively was observed. The same regenerate Na OH solution was reused for all desorption cycles. After nine cycles the eluent desorbed a total of 1550 mg phosphate exhibiting potential for further reuse.     

活性炭吸附法分离纯化ADN

采用静态吸附试验,研究了3种活性炭(AC、BC、CC)的静态吸附与解吸,筛选出一种较好的活性炭AC;通过动态吸附和解吸实验,对二硝酰胺铵(ADN)的吸附、解吸工艺条件进行了优化。结果表明,AC的吸附能力与解吸能力均优于活性炭BC与CC,是分离纯化ADN的理想吸附剂;当上样溶液质量浓度为30 155.32mg/L、流速为5mL/min时,活性炭AC对ADN的吸附量较大。以80℃热水为洗脱溶剂,洗脱至第10个柱体积时,总洗脱率达95.64%。     

Pollutant adsorption during activated carbon and steam regeneration in technical columns (experiments, modelling): Part 2. Influence of process parameters during steam regeneration of activated carbon beds on pollutant exit concentration

Experiments in activated carbon columns of technical scale with upstream adsorption and downstream steam regeneration showed that pollutant exit concentration of waste gas can be markedly decreased if the upper zone of the fixed bed is preheated to 120 °C before desorption and, additionally, if the bed is desorbed with superheated steam with a temperature 150 °C. With this improved steam regeneration technique a decrease in pollutant exit concentration is achieved: for example, from 20 to 3 mg m⁻³ toluene. An increase in adsorption time before pollutant breakthrough from 12 to 19 h is also noted.

During regeneration of a cold bed of activated carbon with saturated steam the particles will become wetted with condensate outside and adsorbed steam inside. These water condensation/adsorption effects are markedly reduced by preheating the particles to temperatures so far above that of steam condensation that steam adsorption is prevented too. Additionally the regeneration steam is superheated so that the temperature drop caused by heat of pollutant desorption is not so great that steam adsorption occurs.

The whole desorption-adsorption cycle in a technical scale bed, including the effects of Steam condensation/ adsorption, flux and suction of condensate, hetero-azeotropic pollutant distillation and evaporation of condensate was modelled.

Radial maldistribution effects (discussed in part 1 of this paper, Chem. Eng. Proc., 32 (1993) 359) have not been taken into account here.

The calculated flux rates of pollutant in the gas mixture leaving the bed during desorption and the pollutant breakthrough curves at the following adsorption step correlate quite well with experimental results.     

Granulation of Fe-Al-Ce nano-adsorbent for fluoride removal from drinking water by spray coating on sand in a fluidized bed

A technology for the granulation of Fe-Al-Ce nano-adsorbent (Fe-Al-Ce) in a fluidized bed was developed. The coating reagent, a mixture of Fe-Al-Ce and a polymer latex, was sprayed onto sand in a fluidized bed. The granule morphology, coating layer thickness, granule stability in water and adsorption capacity for fluoride was investigated by analyzing samples for different coating time. The coating amount was from 3% to 36%. With increasing coating amount, granule stability decreased and adsorption capacity increased. FTIR analysis showed that the latex can react with active hydroxyl on the Fe-Al-Ce adsorbent, which led to a decrease of the adsorption capacity. Coated granules with a coating amount of 27.5% had a fluoride adsorption capacity of 2.22 mg/g (coated granules) at pH 7 and initial fluoride concentration of 0.001 M. A column test showed that 300 bed volumes can be treated with the effluent under 1.0 mg/L at an initial fluoride concentration of 5.5 mg/L, space velocity of 5 h^− 1 and pH of 5.8. The coating granulation of the Fe-Al-Ce adsorbent can produce granules that can be used in a packed bed for the removal of fluoride from drinking water.     

超声波振荡对活性氧化铝除氟性能的影响

在超声波振荡搅拌下,实验研究了活性氧化铝对氟离子的吸附性能,分析了活性氧化铝颗粒大小、超声波振荡时间、pH、活性氧化铝加入量及原水氟浓度对吸附性能的影响。研究结果表明：活性氧化铝结晶不完整及晶格的无序使得它具有更大的比表面积;使用超声波振荡时,其除氟速率比机械搅拌快得多,除氟前期其平均除氟速率达0.93 mg/min,是机械搅拌除氟速率的5.8倍。同时,采用超声波振荡达到平衡的时间是机械搅拌的1/7,其饱和吸附容量也有所提高;pH在5～7时,活性氧化铝的吸附容量大、除氟速率高;另外,活性氧化铝的加入量及原水氟浓度对除氟速率和吸附容量也有重要影响。     

DYNAMIC MODELLING OF WATER VAPOR ADSORPTION BY ACTIVATED ALUMINA

Prediction of water vapor adsorption by activated alumina in a packed bed operated adiabatically is accomplished through the use of a simplified mathematical model. The model accounts for the heat and mass convection in the axial direction, and characterizes the heat and mass transfer associated with the adsorption process by a linear driving force. A linear isotherm was applied to approximate the equilibrium relationship of water vapor on activated alumina. Experimental data using Alcoa's commercial activated alumina, obtained from a 6 x 48 inch adiabatic column, were compared with model prediction; and a reasonably good agreement between these two was obtained. @KEYWORDS: Mathematical modeling, Adsorption, Activated alumina, Gas drying, Desiccant, Packed column.     

胶原纤维负载锆对废水中氟的去除

以胶原纤维为基质负载Zr(Ⅳ)制备新型吸附剂胶原纤维负载锆(ZrCF),将其用于高浓度含氟冶炼废水中氟的去除,考察了盐度、硬度对除氟效果的影响,优化了吸附剂用量、吸附次数、初始pH值、接触时间等工艺条件,并进行了固定床吸附实验.结果表明,盐度、硬度对除氟效果影响不大;连续8次投加ZrCF0.1 g可以使出水氟离子浓度达...     

Surfactant‐Enhanced Carbon Regeneration in a Vapor‐Phase Application

Abstract

Coal‐based granular activated carbon (GAC) is saturated with trichloroethylene (TCE) by passing air through a fix bed adsorber. In surfactant‐enhanced carbon regeneration, an aqueous solution of anionic surfactant, sodium dodecyl sulfate (SDS), is passed through the bed to induce desorption of TCE. More than 95% of the sorbed TCE was removed in the desorption operation with a 0.1 M SDS solution at a superficial flow rate of 1 cm/min. The desorption rate of TCE from pores of GAC is limited by pore diffusion and not significantly affected by either the concentration of SDS in the regenerant (when well above the critical micelle concentration) or its flow rate. From the breakthrough curve of a subsequent adsorption cycle without a flushing step following the desorption, only 7% of the virgin carbon effective adsorption capacity is observed for the regenerated carbon. With a water flushing step following the regeneration step, the effective adsorption capacity is significantly improved to about 15% of that of virgin carbon. Increased temperature of the flushing water also enhances the effective adsorption capacity of the regenerated GAC. Separate batch adsorption‐desorption isotherms of SDS on GAC support the enhanced desorption of SDS at elevated temperatures. The drastic reduction in the effective adsorption capacity of regenerated GAC results from the residual SDS remaining in the pores of GAC as confirmed by thermal gravimetric analysis. Both the regeneration and water flush steps are rate limited under conditionsused here.     

胶原纤维负载锆处理高浓度砷(Ⅴ)氟废水的研究

将胶原纤维负载锆(ZrCF)用于高浓度砷(Ⅴ)、氟废水的处理。研究了ZrCF对砷(Ⅴ)、氟共存溶液的吸附,并以化肥厂高浓度砷(Ⅴ)氟废水为例,考察了吸附剂用量、pH、接触时间对吸附性能的影响,进行了固定床吸附实验。结果表明,相同浓度下ZrCF对砷(Ⅴ)的亲和作用优于对氟离子(F)的作用;吸附剂用量超过0.8 g,化肥厂出水的砷(Ⅴ)、氟浓度同时达到排放标准;处理的最佳酸度值是pH=6.0,满足出水浓度限值的反应时间为6 h;流出液体积为4.68 L时,固定床对氟、砷(Ⅴ)均达到饱和。ZrCF可以高效地联合去除废水中的砷(Ⅴ)和氟。     

Removal of Fluoride from Aqueous Solution Using Aluminum-Impregnated Chitosan Biopolymer

Abstract

Aluminum impregnated chitosan (AIC) was prepared and applied as an adsorbent for the removal of fluoride from aqueous solutions. The process involved two stages: (i) isolation of chitosan from chitin, (ii) impregnation of aluminum in isolated chitosan at fixed pH. SEM and EDS techniques were used to characterize the composition of adsorbent AIC. Dynamic adsorption experiments on AIC were carried out at various pH, contact times, adsorption dosages, and initial fluoride concentration to determine optimum adsorption properties. The experimental data were analyzed using two adsorption models, Langmuir and Freundlich, with the later system providing the best fit. Thermodynamic parameters showed the adsorption process as spontaneous and endothermic. The adsorption process follows first-order kinetics for which a mechanism has been proposed. Reusability of the AIC was tested up to four consecutive cycles. The desorption experiment showed 92% elution of adsorbed fluoride at a pH of 12. Finally, the performance of the adsorbent material was studied on field water samples collected from a fluorosis endemic-region.