颗粒活性炭的特性参数与吸附性能的关系试验

采用活性炭进行饮用水的深度处理,选择适合原水水质的活性炭至关重要,通过6种不同颗粒活性炭特性参数的测试,对饮用水有机物的吸附试验以及吸附等温线的测定,结果表明:针对颗粒活性炭的筛选,碘值,亚甲蓝值,吸附等温线的KF及斜率1/n值均不能单独作为评价筛选活性炭优劣的指标,而应综合考虑颗粒活性炭的孔径分布与原水中有机物的相对分子质量分布相匹配等。研究还表明:碘值,亚甲蓝值,吸附等温线的KF存在一定的相关性,从颗粒活性炭的特性参数和吸附性能参数可以推测活性炭滤柱试验吸附效果。颗粒活性炭用于饮用水深度处理,能去除水中相对分子质量小的有机物,处理的水量为颗粒活性炭体积的4800倍时,对CODMn的去除率为15%左右。     

An inverse method to estimate adsorption kinetics of light hydrocarbons on activated carbon

An inverse algorithm to estimate the adsorption kinetics inside the spherical particles in a constant molar flow (CMF) gas adsorber reservoir by measuring the bulk pressure is developed. The formulation includes Knudsen diffusion, surface diffusion, slip and viscous flows. To obtain an efficient algorithm, the conjugate gradient method (CGM) for optimization procedure and the incremental differential quadrature method (IDQM) for solving the governing equations are adopted. The results show that the Knudsen diffusion, surface diffusion, slip and viscous flows effects depend on the type of adsorbate and adsorbent gases. It is shown that the effective diffusivity is not constant and goes through a minimum at an intermediate pressure. Also, it is found that the Knudsen diffusion and the viscous flow are the dominant parts of the mass transfer process at low and high pressure, respectively, and despite the viscous flow, the Knudsen diffusion is highly sensitive to temperature change.     

甲烷在石墨烯和活性炭上的吸附

以研制新型吸附式天然气(ANG)吸附剂为目的,比较了甲烷在石墨烯和活性炭上的吸附平衡。首先,在温度区间273~293 K、压力范围0~8 MPa,测试甲烷在比表面积分别为300和2074 m²·g^-1石墨烯和活性炭上的吸附平衡数据。其次,应用格子理论导出的通用吸附等温方程,通过吸附平衡态能量分析及10-4-3相互作用势函数求解,确定甲烷分子在石墨烯平面和活性炭上的最大面密度、受到的壁面吸附作用势及其在吸附层内的作用能。结果表明,在相同温度下,吸附甲烷分子在石墨烯上吸附层内的相互作用能较其在活性炭上的大,甲烷分子在石墨烯平面上的集聚更为密集。提高石墨烯的比表面积将有效提高甲烷在其上的吸附容量。     

活性炭的微结构与超级电容器性能的构效关系

以生物质柞木为原料,采用不同活化法制备具有不同结构特征的柞木基活性炭,利用N₂吸附、FT-IR、XPS、XRD、Raman光谱等表征手段对活性炭的微结构特性进行解析,探究活化方式对活性炭微结构性能的影响;微结构与超级电容器性能的构效关系。研究表明： KOH和H₃PO₄-KOH法制备的活性炭微孔发达,炭结构表面缺陷位与杂原子丰富,在低电流密度下表现出更高的比电容;H₃PO₄-KOH法制备的活性炭具备更宽的微介孔分布与孔道连通性,使其具有更好的电容保持率;CO₂、H₃PO₄和H₃PO₄-CO₂法制备的活性炭介孔发达,微孔体积小,孔道连通性差,炭结构相对完整,裸露于炭结构表面的缺陷与杂原子相对较少,尽管电容保持率较高,但比电容较低。因此,高性能的超级电容器活性炭电极应具有发达的微孔结构、较宽的微介孔分布、通畅的微介孔连通结构,同时含有更多的裸露于炭结构表面的结构缺陷与杂原子基团,从而提高超级电容器的能量密度。     

Relation between interfacial energy and adsorption of organic micropollutants onto activated carbon

The adsorption efficacy of 16 pharmaceuticals on six different activated carbons is correlated to the thermodynamic work of adhesion, which was derived following the surface tension component approach. Immersion calorimetry was used to determine the surface tension components of activated carbon, while contact angle measurements on compressed plates were used to determine these for solutes. We found that the acid–base surface tension components of activated carbon correlated to the activated carbon oxygen content. Solute-water interaction correlated well to their solubility, although four solutes deviated from the trend. In the interaction between solute and activated carbon, van der Waals interactions were dominant and explained 65–94% of the total interaction energy, depending on the hydrophobicity of the activated carbon and solute. A reasonable relationship (r² > 70) was found between the calculated work of adhesion and the experimentally determined activated carbon loading.     

污泥基活性炭制备改性及其吸附甲苯性能

以石化企业干化剩余活性污泥为炭源前体、ZnCl₂溶液为活化剂,在613℃条件下炭化70min制得了碘值为683.40mg/g、产率为55.5%的污泥基活性炭（SAC,sludge-based activated carbon）样品,并进一步利用不同浓度的HNO₃、H₂SO₄和H₂O₂溶液为改性剂对SAC氧化改性,通过碘值测定、BET、Boehm滴定、ICP、FTIR、XRD、SEM、TEM等手段对改性前后SAC样品进行了表征分析和对比研究。结果表明,HNO₃和H₂SO₄改性后SAC的BET比表面积、孔容、碘值均明显增加,可有效提高SAC吸附性能,当HNO₃浓度为0.5mol/L、H₂SO₄浓度为1.0mol/L时改性效果最好,动态吸附甲苯的吸附量较改性前分别提高了38.80%和27.19%,吸附穿透时间也明显延长;而对于H₂O₂溶液为改性剂,总体上不利于SAC吸附性能的提高。对甲苯吸附效果最好的几种改性SAC材料进行再生性能测试,均展现了良好的再生循环利用性能。     

The adsorption of bile salts on activated carbon

Activated carbon (AC) has been shown to be effective in reducing serum cholesterol and triglycerides. The mechanism for this action is proposed to be a result of the removal of bile salts in the gut. In this paper, the adsorption of cholate, glycocholate, taurocholate, chenodeoxycholate and deoxycholate on AC is studied in vitro. The results indicate that AC has a high capacity for bile salts, completely removing them from solutions of up to 5 mM and at a rate consistent with physiological activity. Of the 2 types of AC tested, one was shown to exhibit greater capacity and selectivity over the other. A negligible effect was seen with variation of pH through the range 7–9. Desorption occurs in the presence of bile salt-free buffer, but to a minimal extent. Based on these data, the adsorption of bile salts by AC appears to be a likely mechanism for AC-induced reduction of serum lipids.     

Hydrogen adsorption characteristics of activated carbon

Hydrogen adsorption on activated carbons was investigated in the present works up to 100 bars at 298 K. Coconut-shell was activated by potassium hydroxide, resulting in activated carbons with different porosities. All of prepared activated carbons are microporous and show the same adsorption properties. The complete reversibility and fast kinetics of hydrogen adsorption show that most of adsorbed quantity is due to physical adsorption. A linear relationship between hydrogen adsorption capacity and pressure is obtained for the all samples regardless of their porosities. Hydrogen adsorption capacities are linear function of porosities such as specific surface area, micropore surface area, total pore volume, and micropore volume. The maximum hydrogen adsorption capacity of 0.85 wt.% at 100 bars, 298 K is obtained in these materials.     

Multicomponent adsorption equilibria of phenols on activated carbon

Multicomponent adsorption equilibria of phenols on activated carbon were predicted by the ideal adsorbed solution (IAS) theory and results were compared with those calculated from two different Freundlich-type isotherms. Although some deviations between measured and calculated results are observed, the IAS theory permits rapid and relatively accurate predictions of adsorption equilibria for two-and three-component systems comparing with other isotherms. The results obtained show that the IAS theory is quite suitable for the extended application to multicomponent adsorption systems.     

The adsorption of methane-ethane mixtures on activated carbon

The single component adsorption of methane and ethane and also the adsorption of binary mixtures of methane and ethane have been studied in a small fixed isothermal bed containing activated carbon. Results indicate that an empirical Langmuir isotherm fits the experimental data for single components. An extended form of the empirical Langmuir isotherm, in which the parameters are obtained from single component data, satisfactorily describes the adsorption of binary mixtures. The potential theory of Polanyi is also helpful in extending the experimental data. Breakthrough curves of both components from a diluted feed of methane and ethane could be predicted with good precision for the two activated carbons studied. Furthermore, the concentration waves of the components were sufficiently spaced to suggest that these carbons may be of use as a separating agent for methane-ethane mixtures.     

活性炭吸附氯气的性能研究

对活性炭的氯气吸附性能进行了研究。研究表明,活性炭在0.332 MPa、0℃时,对氯气的吸附量(质量分数)可达到40.7%;经过脱附后,可进行多次吸附和脱附,且吸附量没有下降。     

A comparison between catalytic ozonation and activated carbon adsorption/ozone-regeneration processes for wastewater treatment

Two methods based on the use of granular activated carbon (GAC) and ozone to remove organic compounds from water have been investigated. Both methods have been applied to degrade an aqueous solution of gallic acid and a secondary effluent from a wastewater treatment plant (WWTP). One of the methods, namely catalytic ozonation, implies simultaneous ozonation and adsorption onto GAC. This process takes advantage of the oxidizing power of ozone and the adsorption capacity of GAC but also of the catalytic transformation of ozone into secondary oxidants on the GAC surface. The efficiency of catalytic ozonation was compared to those of single adsorption and single ozonation. It was found that the catalytic process highly improves the conversion of total organic carbon (TOC) and makes a more efficient use of ozone than the single ozonation process. To illustrate the reusability of the catalyst, the GAC was reused four times through a series of consecutive experiments. No loss of catalytic activity was observed when treating the WWTP effluent but some deactivation could be appreciated when treating the aqueous solution of gallic acid. This deactivation could be attributed to some porosity destruction and surface oxidation produced as a result of reactions of aqueous ozone on the GAC surface. The other method investigated is an adsorption-regeneration process (namely GAC/O₃-regeneration) that comprises two steps: dynamic adsorption onto GAC and further regeneration of the spent GAC with gaseous ozone. The adsorption stage of the GAC/O₃-regeneration experiments was carried out in a continuous flow adsorption column and breakthrough curves were obtained. It was observed that the GAC used in this work adsorbed gallic acid very efficiently but exhibited limited capacity to remove chemical oxygen demand (COD) from the WWTP effluent. The optimum ozone dose to regenerate the spent GAC after gallic acid adsorption was found to be about 0.4 g O₃/g GAC, with results showing around 90% regeneration efficiency. As a result of incomplete regeneration, the GAC adsorption capacity progressively decreased with the number of adsorption–regeneration cycles. The GAC/O₃-regeneration method was not successful at treating the WWTP effluent as low adsorption uptake was observed. Moreover, the GAC became damaged after regeneration because of excessive oxidation of its surface.     

Electrochemical enhancement of adsorption capacity of activated carbon fibers and their surface physicochemical characterizations

The adsorption of activated carbon fibers (ACFs) and their surface characteristics were investigated before and after electrochemical polarization. The adsorption kinetics of m-cresol showed the dependence on polarized potential, and the adsorption rate constant increased by 77.1%, from 6.38 × 10⁻³ min⁻¹ at open-circuit (OC) to 1.13 × 10⁻² min⁻¹ at polarization of 600 mV. The adsorption isotherms at different potentials were in good agreement with Langmuir isotherm model, and the maximum adsorption capacity increased from 2.28 mmol g⁻¹ at OC to 3.67 mmol g⁻¹ at polarized potential of 600 mV. These indicated that electrochemical polarization could effectively improve the adsorption rate and capacity of ACFs. The surface characteristics of ACFs before and after electrochemical polarization were evaluated by N₂ adsorption-desorption isotherms, scanning electron microscope (SEM), zeta potential and Fourier transform infrared spectroscopy (FTIR). The results showed that the BET specific surface area and pore size increased as the potential rose. However, the surface chemical properties of ACFs hardly changed under electrochemical polarization of less than 600 mV. This study was beneficial to understand the mechanism of electrochemically enhanced adsorption.     

Influence of solvent type on dibenzothiophene adsorption onto activated carbon fiber and granular coconut-shell activated carbon

The adsorption behavior of dibenzothiophene (DBT) on an activated carbon fiber (ACF) and a granular coconut-shell activated carbon (GCSAC) in the solvents n-hexane, n-decane, toluene, and mixture of n-decane and toluene was investigated. The DBT adsorption onto both samples was more active in n-hexane than in n-decane. The lowest DBT adsorption was observed in toluene. Regardless of the type of activated carbons and solvents, all the isotherms fit the Freundlich equation better than the Langmuir equation. At low equilibrium concentrations of <2 mass ppm-S, GCSAC displayed greater capacity for DBT adsorption than did ACF in all the tested solvents. The adsorption kinetics of ACF and GCSAC in all the tested solvents were governed by a pseudo-second-order model.     

有序介孔碳和活性炭对阿莫西林的吸附研究

阿莫西林是废水中一类典型的药品与个人护理品类新型有机污染物,会对周围环境和人体健康造成潜在威胁。以蔗糖为碳源、以SBA-15为模板制备有序介孔碳（OMC）。采用动态吸附法研究其对阿莫西林的吸附行为,并与常规吸附材料商用活性炭（GAC）作对比。探讨了废水中阿莫西林的初始浓度、温度及流速对动态吸附的影响。结果表明：在同等条件下,OMC的吸附能力远强于GAC,以OMC为吸附剂可有效去除废水中的阿莫西林类新型有机污染物。     

Binary vapor adsorption by activated carbon

The adsorption of binary vapor mixtures has been investigated on BPL grade activated carbon. Vapor mixtures include $\text{CNCl}\text{H}{}_2\text{O}$, $\text{HCN}\text{H}{}_2\text{O}$ and $\text{HCN}\text{CNCl}$. Preadsorption of one vapor generally lowers the adsorption of the second vapor below its single vapor isotherm value. Adsorption of CNCl after pre-adsorbing HCN is greater than the adsorption of HCN after pre-adsorbing CNCl. correlating with the higher affinity coefficient observed for CNCl. The adsorption of H₂O vapor is reduced to very low levels by pre-adsorbing HCN or CNCl.