TiO2/柚子皮生物质活性炭复合材料的制备和吸附光降解性研究

本文以自制柚子皮生物质活性炭为原料,采用凝胶-溶胶法合成TiO2/柚子皮生物质活性炭复合材料(TiO2/BAC)。对复合材料进行SEM、FTIR、XRD等表征,并研究该复合材料对中性红、亚甲基蓝染料及甲醛的吸附降解性能。结果表明,在复合材料中柚子皮生物质活性炭的添加量为7 g、预吸附时间为2 h时,对染料具有最佳的吸附降解效果,复合材料在循环使用5次后对染料的吸附降解率仍达到了80 %以上。当活性炭的添加量为6 g、复合材料的添加量为2 g时,复合材料对甲醛的吸附降解达到最大,可达61%。表明该复合材料对中性红、亚甲基蓝染料及甲醛具有良好的吸附降解效果,有望用于废水染料的去除和家居甲醛净化。     

TiO_2/生物质活性炭复合材料的制备和吸附光降解性能

本文以自制生物质活性炭(BAC)为原料,采用凝胶-溶胶法合成TiO_2/BAC复合材料。对复合材料进行扫描电镜、傅里叶变换红外光谱、X射线衍射和N_2吸附等表征;并研究该复合材料对中性红、亚甲基蓝染料及甲醛的吸附降解性能。结果表明,当复合材料制备时BAC的添加量为7g(即BAC与(BuO)_4Ti的质量体积比为1∶5)、复合材料的用量为0.7g、预吸附时间为2h时,对染料具有最佳的吸附降解效果,复合材料在循环使用5次后对染料的吸附降解率仍达到80%以上。当复合材料制备时BAC的添加量为6g、复合材料的添加量为2g时,其对甲醛的吸附降解达到最大,可达63.41%。该复合材料有望用于废水中亚甲基蓝、中性红等染料的去除及家居甲醛的净化。     

关于亚甲基蓝在活性炭表面吸附投影面积σA的探讨

溶液吸附法测定活性炭比表面积是大学本科基础物理化学实验中一个较重要的实验.亚甲基蓝在活性炭表面的吸附符合Langmuir单分子层吸附,但按照实验教科书及文献介绍的溶液吸附法测定活性炭比表面积的方法,大量学生实验的测定结果比活性炭实际比表面积偏低很多.本文以BET表面吸附装置测定活性炭比表面积,再以溶液吸附法测定了亚甲基蓝在活性炭表面的最大吸附量Γ∞,计算了亚甲基蓝在活性炭表面吸附投影面积σA.结果表明亚甲基蓝在活性炭表面可能不是端基吸附,而是平面吸附,分子的投影面积σA应为1.35×10-18 m2.     

KOH活化木屑生物炭制备活性炭及其表征

以木屑热裂解的生物质炭为原料,氢氧化钾为活化剂,采用化学活化法制备活性炭,探讨了碱炭比、活化温度和活化时间对活性炭吸附亚甲基蓝吸附值的影响。 利用N2吸附实验、XRD和FTIR等实验技术,对原料与制备活性炭的结构与性能进行了表征。 结果表明,在碱炭质量比为1.5、活化温度750 ℃、活化时间2 h的条件下,所制备的活性炭对亚甲基蓝吸附值为255 mg/g,BET总比表面积为1514 m2/g,中孔比表面积为110 m2/g,吸附总孔容为0.821 cm3/g,中孔孔容为0.117 cm3/g,吸附平均孔径为2.170 nm。     

明胶改性磁性石墨烯对亚甲基蓝的吸附性能研究

采用化学还原法制备了一种新型的明胶掺杂磁性石墨烯复合材料(gelatinMGO),并进一步研究了pH值、接触时间和温度对该材料吸附亚甲基蓝的影响。亚甲基蓝吸附实验结果表明,gelatin-MGO对亚甲基蓝有较大的吸附能力,最大吸附容量可达210.5mg/g,吸附为自发吸热过程,在pH值为6.5时去除率最大,其吸附过程符合拟二级反应动力学方程和Langmuir吸附模型,解吸实验表明,明胶改性石墨烯的再生性能优异,重复使用5次去除率仍为85%以上,该材料适合作为吸附剂去除废水中的亚甲基蓝。     

KOH活化糠醛渣制备活性炭机理与表征

以糠醛渣为原料、KOH为活化剂,采用两步活化法制备了活性炭。考察了活化温度、活化时间、碱炭比和浸渍时间对活性炭孔结构及吸附性能的影响。采用低温N2吸附、BET、BJH及DFT理论对活性炭孔结构进行了表征分析,利用傅里叶变换红外-拉曼光谱仪检测其表面官能团,分别使用扫描电镜和X射线衍射对其进行表观形貌观察和晶型分析。结果表明,制备活性炭的最佳工艺条件为:活化温度800℃、活化时间3h、碱炭比3∶1、浸渍时间12h。所制备的糠醛渣活性炭的吸附孔径分布集中,吸附孔容为0.8825cm2/g,DFT总比表面积为3290.5m2/g,其碘吸附值和亚甲基蓝吸附值分别为2107.32mg/g和39.67mL/0.1g。     

KOH活化糠醛渣制备活性炭及其表征

以糠醛渣为原料、KOH为活化剂,采用两步活化法制备了活性炭。考察了活化温度、活化时间、碱炭比和浸渍时间对活性炭孔结构及吸附性能的影响。采用低温N2吸附、BET、BJH及DFT理论对活性炭孔结构进行了表征分析,利用傅里叶变换红外-拉曼光谱仪检测其表面官能团,分别使用扫描电镜和X射线衍射对其进行表观形貌观察和晶型分析。结果表明,制备活性炭的最佳工艺条件为:活化温度800℃、活化时间3h、碱炭比3∶1、浸渍时间12h。所制备的糠醛渣活性炭的吸附孔径分布集中,吸附孔容为0.8825cm2/g,DFT总比表面积为3290.5m2/g,其碘吸附值和亚甲基蓝吸附值分别为2107.32mg/g和39.67mL/0.1g。     

超细粉煤灰吸附亚甲基蓝的机理研究

以西安西郊热电厂粉煤灰(XFA),西安灞桥热电厂粉煤灰(BFA)和陕西渭河电厂粉煤灰(WFA)为原料,球磨后经旋风分级再用布袋收集逸出物分别得到超细粉煤灰XUFA、BUFA和WUFA。研究了超细粉煤灰对亚甲基蓝的吸附动力学、热力学以及pH值对吸附的影响。结果表明,超细粉煤灰对亚甲基蓝的吸附性能明显好于原粉煤灰。超细粉煤灰对亚甲基蓝的吸附性能按顺序为WUFA>XUFA>BUFA。粉煤灰颗粒粒度、比表面积和活性组分(SiO2 Al2O3)含量是影响粉煤灰吸附性能的主要因素。WUFA对亚甲基蓝的吸附符合Langmuir吸附等温式,而XUFA和BUFA对亚甲基蓝的吸附符合Freundlich吸附等温式。超细粉煤灰对亚甲基蓝的吸附均符合二级吸附动力学模型,吸附过程由颗粒内扩散过程控制。当溶液pH由2增加到8时,超细粉煤灰吸附量增加,后随pH值增加,吸附量略有下降。     

高介孔率烟梗基活性炭的优化制备

采用ZnCl_2对废弃烟梗进行活化制备高介孔活性炭,通过Minitab软件设计2~3全因素实验优化活性炭介孔率,并分析影响活性炭介孔率的主要因素间的次序及交互作用,采用帕累托图、交互作用图和正常概率图分析数据,并通过微孔材料吸附仪、傅立叶红外光谱仪和扫描电镜仪表征活性炭孔结构和表面化学基团。在节约能耗前提下,设计单因素实验,并以亚甲基蓝为吸附质检测活性炭品质。结果表明所有因素及其交互作用都为显著因素(P0.05),活化剂浓度对介孔率影响远高于其他因素,扩大浓度范围设计单因素实验制备出介孔率高达95.1%的高介孔活性炭,孔容为1.81 cm~3,亚甲基蓝吸附值为463 mg/g。     

铁酸锰/腐植酸复合材料制备及其对亚甲基蓝吸附性能

采用化学共沉淀法合成了一种腐植酸(Humic Acid,HA)包覆铁酸锰型磁性复合材料(MnFe₂O₄/HA)。采用扫描电子显微镜(SEM)、粉末X射线衍射(XRD)和傅里叶变换红外光谱(FT-IR)等技术手段对其进行表征和分析表明,合成产物颗粒大小约200 nm,具有典型的尖晶石结构,腐植酸成功包覆在MnFe₂O₄颗粒表面,饱和磁化强度为34.01 A·m²/kg,在外界低磁场作用下30 s内便可从水溶液分离。 MnFe₂O₄/HA对亚甲基蓝的吸附是一个准二级动力学过程,在2 h达到平衡,较好的符合Langmuir吸附模型。 与MnFe₂O₄相比其对亚甲基蓝的吸附能力显著增强,室温下pH=9时最大吸附量可以达到29.94 mg/g。 MnFe₂O₄/HA可以作为一种有效去除水体中亚甲基蓝污染物的吸附材料。     

Recovery of gold from gold slag by wood shaving fly ash

Wood shaving fly ash was used as an alternative adsorbent for gold preconcentration from gold slag. The maximum gold adsorption capacity of wood shaving fly ash washed with tap water (WSFW) at 20, 30, 40, and 60 degrees C was 8.68, 7.79, 7.44, and 7.25 mg(Au)/g(adsorbent), respectively, while of activated carbon it was 76.78, 60.95, 56.13, and 51.90 mg(Au)/g(adsorbent), respectively. Deionized water at 100 degrees C could elute gold adsorbed onto WSFW to 71%. The effect of the increasing temperature of water, 30, 60, and 100 degrees C, implied that the adsorption mechanism was mainly physical adsorption. The negative values of enthalpy change (DeltaH) and free energy change (DeltaG) indicated an exothermic and spontaneous process, respectively. The positive values of entropy change (DeltaS) indicated increasing disorder of the system. The advantages of wood shaving fly ash are the purification of gold and the easier recycling of gold from the gold-adsorbed adsorbent.     

Adsorption of Copper (II) onto Different Adsorbents

Removal of copper (II) from aqueous solution of CuCl₂·2H₂O by different adsorbents, namely, sissoo sawdust, activated carbon, and fly ash were investigated. Adsorption of copper (II) on sissoo sawdust, activated carbon, and fly ash has been studied using batch techniques. Kinetic and isotherm studies were determined as a function of the solution pH, temperature, contact time, adsorbent dosage, and initial adsorbate concentration. Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin isotherms were used to analyze the equilibrium data at different temperatures. The maximum adsorption capacities for copper (II) on sissoo sawdust, activated carbon, and fly ash adsorbents at 30, 40, and 50°C temperatures were found to be 263.2, 166.6, and 142.8; 125.0, 88.49, and 72.46; 69.93, 181.8, and 111.1 mg/g, respectively. The thermodynamics of copper (II) adsorption on sissoo sawdust, activated carbon, and fly ash indicates its spontaneous and endothermic nature. Kinetic studies showed that the adsorption followed a pseudo-second-order kinetic model.     

Specific features of adsorption of azo dyes on fly ash

A possibility to utilize fly ash (FA) formed at coal-fired power plants as a cheap adsorbent for the purification of wastewater containing azo dyes methylene blue (MB) and methyl red (MR) was considered. The effect of an FA additive on the adsorption capacity of active carbon was studied. The efficiency of FA as an adsorbent for the purification of aqueous solutions from MB and MR was shown. The adsorption is also fairly efficient when active carbon is partially replaced by FA. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 545–548, March, 2007.     

Coal fly ash decomposes diethyl phthalate

Decomposition of diethyl phthalate (DEP) exposed to a coal fly ash has been investigated in water by measuring UV-VIS spectra and GC-MS. Alkaline constituents eluted from the fly ash in the liquid phase gradually hydrolyzed DEP to produce monoethyl phthalate and/or phthalic acid. These products were adsorbed on the fly ash and decarboxylated into ethyl benzoate and benzoic acid, respectively, followed by decomposition into benzenes and/or the other compounds of lower molecular weight. The fly ash acts as not only an adsorbent but also a decomposer.     

Synthesis of NiO coated chitosan-cenosphere buoyant composite for enhanced adsorptive removal of methylene blue

The objective of the present study is to utilize fly ash cenosphere to remove methylene blue (MB) from the water streams. Nickel oxide is a typical semiconductor used as proficient adsorbent material for degradation of dye with environment friendly applications due to its excellent chemical stability and high catalytic activity. The chitosan cenosphere buoyant composite coated with NiO was synthesized with hydrothermal grafting reaction using silane coupling agent and epichlorohydrin as a cross-linking reagent. The batch adsorption experiments were carried out with a cationic dye, methylene blue as a representative organic pollutant to investigate the adsorptive capabilities of the composite as adsorbent. The influence of pH (2-12), initial concentration of dye (50–200 mg/L), temperature (37–47 °C) and contact time (0–24 h) were taken as parameters in the study. On the relative elimination of MB, the effect of time and temperature were investigated. The adsorption kinetics for MB was correlated and found to observe the pseudo-second order kinetic model, whereas the equilibrium adsorption isotherm follows the Langmuir model (R² > 0.99). The results indicate that the floating fly ash cenosphere coated with NiO proved to be more responsive for enhanced degradation of methylene blue.     

燃烧福建无烟煤的循环流化床锅炉飞灰及其未燃炭分析

以三个燃烧福建无烟煤的商业CFB锅炉电厂飞灰为研究对象，分析飞灰的粒径和含碳量分布；观察并区分了飞灰中煤炭、烟怠、半焦和灰渣等颗粒的表面形貌；测定了飞灰炭的反应活性并与入炉煤作比较；并研究了飞灰炭的来源。结果表明，采用单级分离装置的CFB锅炉，粒径在0.0385mm～0.0500mm的飞灰质量最多，未燃炭份额也最高；而采用双级分离装置的CFB锅炉，飞灰质量分布和飞灰炭份额的峰值则出现在粒径为0.0500mm~0.0750mm处。飞灰主要由三种形貌的颗粒组成，颗粒状的未燃炭、絮团状的灰渣、和介于两者之间的半焦。与入炉煤相比，飞灰炭的反应活性较高，主要来源于入炉煤中的细粉和燃烧早期因破碎和磨蚀而产生的、来不及在炉膛中燃尽的细小含炭颗粒。入炉煤中易破碎、反应性较高的亮煤是构成电厂CFB锅炉飞灰炭的主要成分。     

强力霉素废水的吸附-混凝预处理研究

根据强力霉素废水的特点,采用吸附-混凝联合处理工艺对其进行预处理研究。筛选出最佳吸附剂、混凝剂、助凝剂,考察了其投加量、pH、反应时间、搅拌强度等因素对处理效果的影响。实验表明,选用粉煤灰作为吸附剂、聚合氯化铝(PAC)作为混凝剂、羟乙基田菁胶(ESG)作为助凝剂,F-去除率达到99.9%,氟浓度降至10mg/L以下;化学需氧量(CODCr)去除率达到37.5%,生化需氧量/化学需氧量(BOD5/CODCr)由原来的小于0.1提高至0.16,提高了原废水的可生化性。而且处理后的灰渣烧制成砖块,不会对环境造成二次污染,达到了以废治废的目的。     

Humic acid adsorption on fly ash and its derived unburned carbon

Fly ash is solid waste from combustion process, containing oxide minerals and unburned carbon. In this investigation, fly ash has been separated into metal oxide mineral section and unburned carbon. The fly ash with different contents of unburned carbon was employed for humic acid adsorption to investigate the influence of unburned carbon on adsorption. It is found that metal oxides and unburned carbon in fly ash exhibit significant difference in humic acid adsorption. The unburned carbon plays the major role in adsorption. Higher content of unburned carbon in fly ash results in higher surface area and thus higher humic acid adsorption. Fly ash and unburned carbon exhibit adsorption capacity of humic acid of 11 and 72 mg/g, respectively, at 30 degrees C, pH 7. Humic acid adsorption is also affected by ion strength, pH, and temperature. The thermodynamic calculations indicate that the adsorption is endothermic nature with DeltaH(0) and DeltaS(0) as 5.79 kJ/mol and 16.0 J/K mol, respectively.     

A New Organophosphorus Insecticides Removal Process Using Fly ASH

Abstract

Fly ash and soil mixtures with a range of fly ash content from 1 to 100% were used to study adsorption and desorption of four organophosphorus insecticides, ethyl parathion, methyl parathion, fenitrothion and fenthion, in batch experiments. The object of the study was to develop a treatment process using fly ash as sorbent material to isolate/immobilize organic contaminants from aqueous solutions. The adsorption isotherms fit the Freundlich equation x/m=K_dC^1/n. The K_d values increase with the increase of the fly ash content. The isotherms seem to fit the S type, in mixtures of soil with a fly ash content from 0 to 10%, which implies that adsorption becomes easier as the concentration in the liquid phase increases. In mixtures of soil with a fly ash content from 25 to 50% the isotherms become L type and correspond to a decrease of site availability as the solution concentration increases. Finally in mixtures of soil with a fly ash content over 50%, C type adsorption was observed which correspond to a constant partition of the insecticides between the bulk solution and the adsorbent. Mass balance estimations show that the mean percent amounts of insecticides for a range of concentration 0.5–15 mg/l, removed by adsorption in the soil sample are 81.56 % for ethyl parathion, 48.97 % for methyl parathion, 67.06 % for fenitrothion and 86.65 % for fenthion. The adsorption increases as the fly ash content increased and reach the 100% in the “pure” fly ash. The adsorbed amounts of insecticides in mixtures of soils with >50% fly ash content, are up to 99%. In contrast, the amounts of desorption in water decrease as the fly ash content increase.

The results of this research demonstrate that the fly ash shows a significant capacity for adsorption of organophosphorus compounds from aqueous solution and can be used for pesticide removal process.     

Unburned carbon as a low-cost adsorbent for treatment of methylene blue-containing wastewater

Fly ash, natural zeolite, and unburned carbon separated from fly ash have been employed as low-cost adsorbents for dye adsorption in methylene blue-containing wastewater. It is found that the unburned carbon exhibits a much higher adsorption capacity than raw fly ash and natural zeolite. The adsorption capacities of fly ash, natural zeolite, and unburned carbon for methylene blue are 2 x 10(-5), 5 x 10(-5), and 2.5 x 10(-4) mol/g, respectively. Investigation also indicates that adsorption is influenced by initial dye concentration, particle size, dye solution pH, and adsorption temperature. Adsorption on unburned carbon increases with the initial dye concentration, solution pH, and temperature, but reduces with the increasing particle size. Kinetic studies show that adsorption of methylene blue on fly ash, natural zeolite, and unburned carbon can be best described by the pseudo-second-order adsorption model and that adsorption is a two-step diffusion process. The apparent activation energies for methylene blue adsorption on unburned carbon in the first and second diffusion processes are 12.4 and 39.3 kJ/mol, respectively.