微孔分布对凹凸棒石吸附剂吸附油脂色素的影响

凹凸棒石吸附剂属于多孔固体吸附剂,微孔分布在其吸附过程中发挥了重要作用.对不同来源矿物制备吸附剂样品后发现,凹凸棒石吸附剂存在着跨越一定孔径范围的微孔,胁UrICUich吸附等温线研究结果也表明,不同微孔分布的凹凸棒石吸附剂N值和K值具有明显规律性,但其吸附性质相同.吸附剂的微孔与色素类分子直径越接近,其吸附量会越大,在凹凸棒石对油中色素类物质的吸附的过程中,吸附剂对色素类物质的分子筛分作用不是最重要的.     

凹凸棒石油脂脱色行为及其机理

以凹凸棒石为大豆油脱色吸附剂,通过对其物理特性、脱色热力学和吸附动力学分析,探讨凹凸棒石吸附剂的吸附行为与脱色机理。结果表明,凹凸棒石吸附剂主要为短晶束和单晶形,其孔径集中分布于1.5～10.0?nm的范围内;脱色热力学分析表明,随着脱色温度升高,凹凸棒石的色素吸附能力逐渐增强,但温度不能改变吸附剂对色素类物质的作用方式;吸附动力学分析表明,叶绿素等微量成分在凹凸棒石上的吸附速率较快,正己烷纯溶液体系中吸附速率依次为叶绿素＞亚油酸＞磷脂＞类胡萝卜素,而大豆油体系中吸附速率依次为叶绿素＞类胡萝卜素＞游离脂肪酸＞磷脂。由此可知,凹凸棒石油脂脱色主要通过孔径填充吸附,并伴随有部分氢键吸附和化学吸附。     

凹凸棒石吸附剂特征及其在油脂脱色过程中的应用研究

凹凸棒石粘土是我国特色非金属资源,具有纤维结构特点并具有明显的层状外观,改性后具有优良的吸附性能。对凹凸棒石吸附剂的形貌、矿物组成、BET比表面、孔径分布、表面酸性点等理化特征进行了系统分析,并对凹凸棒石吸附剂在油脂脱色过程中的应用进行了初步研究。研究表明,温度、吸附时间和吸附剂用量对色素的吸附都具有明显的影响。另外,结合凹凸棒石吸附剂特征对吸附过程的现象进行了解释。     

Freundlich方程在不同吸附剂的油脂脱色体系中的应用

油脂脱色体系属于稀溶液吸附体系，该体系中的吸附等温式最常用的是Langmuir方程和Freundlich方程，其中Freundlich方程更适合植物油脂脱色体系。作者对植物油脂脱色工艺中常用的3种吸附剂进行了研究，结果表明：在低浓度区时3种吸附剂都符合Freundlich吸附等温方程，K凹〉K膨〉K活，N凹〉N膨〉N活。凹凸棒石的K值和N值均为最大，大孔径范围的孔道和较多的表面酸性点使凹凸棒石不仅具有较强的吸附能力，而且具有较高的吸附强度。     

大豆油吸附脱色过程氯离子含量变化及对脱臭油中 3-氯丙醇酯和缩水甘油酯的影响

参照土壤中氯离子检测方法,对常见油脂脱色吸附剂中氯离子的超声提取时间进行优化,并对其氯离子含量进行检测。利用常见的吸附剂对大豆油进行吸附脱色,检测吸附脱色前后油脂中氯离子含量,对不同吸附剂脱色后的油脂进行蒸馏脱臭,检测脱臭油中3-氯丙醇酯(3-MCPD酯)和缩水甘油酯(GEs)含量,分析研究不同吸附剂对油脂吸附脱色过程氯离子含量的影响以及对脱臭油中3-MCPD酯和GEs的影响。结果表明:吸附剂中氯离子的最佳超声提取时间为30 min,10个吸附剂样品中氯离子含量为11. 93～187. 881 mg/kg,差异很大;几种吸附剂在油脂吸附脱色过程对氯离子有不同程度的脱除作用,其中脱除效果最好的YS-900活性炭能使油脂中氯离子含量降低83. 21%。对比未进行吸附脱色处理的大豆油,经吸附脱色的大豆油再经脱臭后3-MCPD酯与GEs生成量均有所降低,并且随吸附过程氯离子降低幅度不同,脱臭油中3-MCPD酯与GEs生成量不同:当脱色油中氯离子含量降幅较小时,经脱臭过程GEs生成量明显低于3-MCPD酯;当脱色油中氯离子含量降幅很大时,经脱臭过程3-MCPD酯的生成量低于GEs。以同时降低脱臭过程3-MCPD酯和GEs的生成量为目标,H-2活性炭作为吸附剂是最好的。     

关于活性碳再次活化的初步研究

活性碳是一种重要的吸附剂,它比较普遍地用于糖浆脱色。目前,国内许多食品厂都利用活性碳吸附。在吸附操作中,将液相或气相中含有的杂质、色素、臭味等舍弃物,吸附于固态吸附剂的表面上,以达到同糖类物质分离的目的。 多年来,我们牡丹江市国营第一食品厂淀粉糖化车间,糖浆脱色都采用非极性固体吸附剂——303型粉状活性碳。此种吸附剂的脱色力在95％以上,适用于糖浆脱色。但只能使用一次     

树脂对灵芝多糖色素吸附研究

分别从树脂极性、离子型、比表面积和平均孔径等特征,研究比较了八种大孔吸附树脂和四种离子交换树脂对灵芝多糖溶液脱色性能的影响,得出色素主要为阴离子型分子,同时还有少量的非极性和弱极性分子,比表面>180m2/g,孔径>20nm的大孔吸附树脂和功能基团-NH2阴离子交换树脂为适宜脱色树脂,筛选出D392阴离子交换树脂为较好的吸附灵芝多糖色素树脂,从不同温度,不同树脂用量下研究静态脱色工艺,进一步研究得出色素类型粗略含量和适宜的pH,最终确定D392阴离子交换树脂吸附灵芝多糖色素的静态工艺.     

凹凸棒石脱色大豆油的热力学研究

本实验研究了在一定的脱色条件下,大豆油中色素类物质在活化过的凹凸棒石上的吸附平衡热力学特性。实验得出353～383K热力学曲线,计算出这些物质在凹凸棒石上的吸附焓变在-0.0434～-0.0036kJ/mol范围内;吸附Gibbs自由能变在-10.23～11.77kJ/mol之间;熵变在-33.34～27.78J/mol·K范围内。证明活化凹凸棒石对大豆油中色素类物质的吸附反应为放热反应,温度升高和吸附剂添加量的增多有利于吸附作用的进行,在该温度范围内的吸附作用主要是熵趋动的过程。     

废混合吸附剂脱脂溶剂的选择及工艺的研究

混合吸附剂价格高,用于物理精炼或质量较差的油脂脱色,其废吸附剂中含油较高,采用不同的溶剂萃取,可以脱除其中的油脂和色素,实现中性油的回收或吸附剂的再生。研究表明,丙酮具有最好的脱脂效果,同时又能萃取出色素,适合于吸附剂再生;如果仅仅考虑回收中性油则正己烷是较理想的选择;废混合吸附剂比废白土含油高,且萃取更困难;确定废吸附剂脱脂后的残油率要考虑其来源。     

一种新型油脂吸附脱色剂──酸化稻壳灰

一种新型油脂吸附脱色剂──酸化稻壳灰马云肖油脂的脱色主要去除油脂中的天然色素如叶绿素、胡萝卜素和叶黄素等，从而使油品外观得以改善，提高油脂的质量。油脂脱色常用的方法为吸附法，它是利用某些对色素具有较强选择性作用的物质（吸附剂）来吸附除去油脂内的色素。...     

Approaches to mitigate the impact of dissolved organic matter on the adsorption of synthetic organic contaminants by porous carbonaceous sorbents

Adsorption of trichloroethylene (TCE) and atrazine, two synthetic organic contaminants (SOCs) having different optimum adsorption pore regions, by four activated carbons and an activated carbon fiber (ACF) was examined. The selected adsorbents had a wide range of pore size distributions but similar surface acidity and hydrophobicity. Single solute and preloading (with a dissolved organic matter (DOM)) isotherms were performed. Single solute adsorption results showed that (i) the adsorbents having higher amounts of pores with sizes about the dimensions of the adsorbate molecules exhibited higher uptakes, (ii) there were some pore structure characteristics, which were not completely captured by pore size distribution analysis, that also affected the adsorption, and (iii) the BET surface area and total pore volume were not the primary factors controlling the adsorption of SOCs. The preloading isotherm results showed that for TCE adsorbing primarily in pores < 10 angstroms, the highly microporous ACF and GACs, acting like molecular sieves, exhibited the highest uptakes. For atrazine with an optimum adsorption pore region of 10-20 angstroms, which overlaps with the adsorption region of some DOM components, the GACs with a broad pore size distribution and high pore volumes in the 10-20 angstroms region had the least impact of DOM on the adsorption.     

Enhancement of the performance of activated carbons as municipal odor removal media by addition of a sewage-sludge-derived phase

Two commercial low-cost activated carbons and wood-based char were mixed with dewatered sludge and pyrolized at 950 degrees C. The sludge content on a dry basis was 23%. The obtained composite adsorbents were characterized from the point of view of surface chemistry (pH) and texture (adsorption of nitrogen at its boiling point: surface area, pore volume, pore size distributions). Then hydrogen sulfide breakthrough capacities were measured using the home-designed dynamic test. The results revealed a significant increase in the capacity of the composite adsorbents compared to the unmodified carbons. Moreover, that increase was a few times greater than the hypothetical one predicted when desulfurization performance would be the sum of the contributions of both the sludge-derived and carbon phases. This is attributed to a synergetic effect related to the dispersion of the catalysts and the presence of small pores. Mixing activated carbon provides the active centers for oxidation (coming from sludge) and the developed pore system (from the activated carbon) where products of oxidation can be stored. Moreover, in the hydrophobic pore space the volatile organic compounds present in effluent air from a municipal waste treatment plant can be adsorbed. The selectivity for H2S oxidation, as in the case of pure activated carbon, depends on the pore sizes. Smaller pores lead to a higher yield of sulfuric acid; larger pores lead to a higher yield of sulfur.     

Fundamental adsorption characteristics of carbonaceous adsorbents for 1,2,3,4-tetrachlorobenzene in a model gas of an incineration plant

Carbonaceous adsorbents such as activated carbon have been used to reduce the emission of organic pollutants from incineration plants. However, with this method, the amount and type of adsorbent to be used are based only on empirical results, which may lead to overuse of the adsorbents. The fundamental adsorption characteristics of several kinds of activated carbon, activated coke, and carbide wood were examined using 1 ,2,3,4-tetrachlorobenzene as an adsorbate. The removal performance and various equilibrium adsorption characteristics of these adsorbents were analyzed using laboratory-scale adsorption equipment. The equilibrium adsorption amount increased by a factor of 1.9-3.2 at 150 degrees C compared with that at 190 degrees C. The effect of the moisture content on adsorption capacity was relatively small in comparison with that of the temperature. The micropore volume for pore diameters of 2 nm or less was the most important factor governing the adsorption capacity for all adsorbents. Activated carbon showed superior adsorption ability compared to activated coke and carbide wood, although all adsorbents were sufficient for practical use.     

Effects of powdered activated carbon pore size distribution on the competitive adsorption of aqueous atrazine and natural organic matter

The pore size distribution (PSD) of adsorbents has been found to be an important factor that affects adsorption capacity for organic compounds; consequently, it should influence competitive adsorption in multisolute systems. This research was conducted to show howthe PSD of activated carbon affects the competition between natural organic matter (NOM) and the trace organic contaminant atrazine, with a primary emphasis on quantifying the pore blocking mechanism of NOM competition. Isotherm tests were performed for both atrazine and NOM from a groundwater on five powdered activated carbons (PACs) with widely different PSDs. The capacity for NOM correlated best with the surface area of pores in the diameter range of 15-50 A, although some NOM also adsorbed in the smaller pores as evidenced by a reduction in capacity for atrazine when NOM was present. Kinetic tests for atrazine on PACs with various levels of preadsorbed NOM showed that the magnitude of the pore blockage effect by NOM was lower for PACs with higher surface area of pores with diameter in the range of 15-50 A. Therefore increasing pores in the size range where NOM adsorb can reduce the extent of the pore blockage competitive effect on the target compound atrazine. The effect of PSD was further studied with a flow-through PAC-membrane hybrid watertreatment system, in which experimental results successfully verified model simulations by the COMPSORB model.     

高中空生物质活性碳纤维制备及其对亚甲基蓝的吸附性能

为提高活性碳纤维对有色废水的吸附效率,以牛角瓜纤维为前驱体,采用磷酸活化、高温炭化工艺制备了具有高中空结构的活性碳纤维。采用扫描电镜/能谱仪、红外光谱仪等表征其微观形貌及化学结构,分析了所制备活性碳纤维对水溶液中亚甲基蓝的吸附性能与吸附机制。结果表明:牛角瓜活性碳纤维的平均中空度大于92%,具有粗糙表面和发达介孔结构,比表面积和平均孔径分别为1 244.812 m ²/g和3.744 nm;活性碳纤维表面富含O、P元素,构成了活性表面;亚甲基蓝溶液(100 mg/L)的饱和吸附量为198.840 mg/g,该吸附满足准二级动力学方程,同时符合Freundlich模型,以多层吸附为主。     

CO_2固体吸附剂研究述评

由于介孔材料具有比表面积大和空隙较多等优点,被广泛地应用于对空气中或工业废气中的CO2的吸附.活性炭、沸石、硅胶等传统的吸附剂具有制备方法简单、制造工艺成熟、成本低廉等优点,是吸附空气中CO2的首选材料,但较强的吸湿性使其不能用于高湿度的吸附环境等,而通过对传统的介孔材料进行表面改性,接枝胺类等碱性物质,将单纯的物理吸附转变为物理吸附和化学吸附共同作用的吸附方式,在改善吸附剂适应环境能力的同时也能增加吸附量.开发具有最佳结构且物理及化学性能稳定的功能复合吸附剂将是该领域的研究热点和主要方向.     

废弃棉/亚麻混纺织物制备活性炭的性能

为实现废弃织物的综合利用,以废弃的棉／ 亚麻（50／50）混纺织物为原料,以氮气为载体,将水蒸气送入高温管式炉中进行活化制备活性炭。研究了活化温度、活化时间和水蒸气的载体流速对活性炭的比表面积、孔径分布的影响;利用废弃棉／ 亚麻活性炭的碘吸附量来表征其吸附能力,分析结构性能与吸附性能之间的关系。试验结果表明：随着活化温度、活化时间、水蒸气载体流速的增加,活性炭碘吸附量先增大后减小,而孔直径不断增大;当活化温度为800 ℃、活化时间为50min、水蒸气载体流速为240L／h时,活性炭比表面积及孔容达到最大,分别为1047.34ｍ２／g和1.25ｃｍ３／g,孔直径在18nm左右,碘吸附量为805.16mg／g;当活化温度为750 ℃,活化时间为50min,水蒸气载体流速为240L／h 时,活性炭比表面积为648.25m2／g,孔直径为4nm左右,此时碘吸附量达到最大值,为1079.39mg／g。     

基于吸附理论分析活性炭对卷烟烟气的吸附

为了解活性炭孔隙结构及被吸附化合物的性质对吸附效率的影响,测定了纯丙酮气体在活性炭上的吸附特性及不同结构活性炭对烟气羰基物的吸附效率。分别用Langmuir模型和D-R模型对活性炭上丙酮气体的吸附数据进行拟合,从模型拟合精度及吸附热预测角度对Langmuir模型及D-R模型进行了比较。进一步分析了吸附效率与模型参数间的关系以及模型参数与活性炭结构和被吸附化合物性质间的关系。结果表明:①与Langmuir模型相比,D-R模型对活性炭上纯丙酮气体吸附数据的拟合相关系数更高,平均相对标准偏差更低,拟合结果更好。②由10-4-3型势函数计算得到活性炭上纯丙酮气体的理论吸附热为17.9 kJ/mol,吸附热较小,说明此吸附以物理吸附为主。D-R模型吸附热预测值为15.8 kJ/mol,与理论计算值较为接近;Langmuir模型吸附热预测值为40.7 kJ/mol,比理论计算值偏大较多。③实现活性炭对不同化合物吸附效率预测的关键是对化合物吸附热的预测。吸附效率主要与吸附温度,活性炭的用量、孔容,化合物的分子量,碰撞直径和能量参数有关。通过分析吸附能可以推断孔径对吸附效率及吸附选择性的影响。     

活性炭微观结构对玉米朊脱色效果的影响

为研究国内外活性炭在玉米朊脱色过程中吸附色素特性的差异,以玉米朊的乙醇萃取溶液和商业玉米朊 产品乙醇复溶溶液为研究对象,分别采用国产活性炭（ACP）和进口活性炭（ACD）对比研究其对玉米朊的脱色效 果,并对活性炭的微观结构进行表征。静态吸附实验结果表明,活性炭对玉米朊复溶溶液和萃取液的脱色效果没有 明显差异;ACP对玉米朊溶液中色素的吸附率（77.31%）略高于ACD（67.27%）。扫描电子显微镜分析表明,ACP 结构向内延伸而ACD表面凹陷孔结构不明显;比表面积和孔隙结构分析表明,ACP的比表面积（1 438.082 m2/g） 和总孔容积（1.310 cm3/g）大于ACD（779.809 m2/g、0.626 cm3/g）,且ACP具有更多的微孔和中孔结构。ACD表 面含有较多的羧酸和内酯类官能团,可与色素分子中的羟基结合,从而有效增强活性炭的化学吸附效果。ACD粒 径分布更加集中,有利于脱色后的固-液分离。综合以上因素考虑,ACD更适合用于黄色玉米朊的脱色处理。     

活性炭纤维形态对吸附性能的影响

比表面积和孔结构是影响活性炭纤维吸附性能的重要因素。选用相同的活化工艺,制备相似孔结构和比表面积的活性炭毡和活性炭布,讨论在比表面积相近的情况下,活性炭纤维的形态和厚度对吸附性能的影响。结果表明:在一定条件下,活性炭毡的吸附性能略优于活性炭布,活性炭纤维的吸附能力并不随着活性炭织物厚度的增加而线性增强。