氢氧化钙改性沸石对磷酸盐的吸附特性

采用氢氧化钙对天然沸石进行改性,考察了沸石投加量、初始pH值和吸附时间等对改性沸石吸附磷酸盐的影响,分析了等温吸附及吸附动力学特性,探讨了改性沸石吸附磷酸盐的机理。结果表明,沸石在氢氧化钙浓度为0.25 mol/L,改性时间为24 h的条件下对磷酸盐去除效果最佳;在初始磷酸盐浓度为10 mg/L,沸石投加量为60 g/L,吸附时间为24 h的条件下,改性沸石对磷酸盐的去除率可达97%;改性沸石对磷酸盐的吸附过程符合准一级动力学方程;在20℃时,Freundlich等温方程式能更好地描述改性沸石对磷酸盐的吸附行为,而在30℃时Langmuir等温方程式更适合;改性沸石吸附磷酸盐的主要机理是化学吸附。     

污泥焚烧渣处理含镍废水的模拟实验

污泥焚烧渣具有较大的表面积,对镍离子有一定的吸附能力.本文研究了吸附时间、镍离子初始浓度、废水pH和城市污泥焚烧渣投加量对废水中镍离子吸附率的影响.结果表明,当镍离子初始质量浓度为30 mg/L,废水pH为7.0,吸附时间为6 h,城市污泥焚烧渣投加量为10 g/L时,吸附效果最佳.     

水中Ni~(2+)在粒状沸石/活性炭复合材料上的吸附研究

采用廉价的煤矸石为主要原料,添加一定量的沥青粉制备了沸石NaA/活性炭粒状复合材料,并以此作为吸附剂,研究了水溶液中Ni~(2+)在该复合材料中的吸附行为,考察溶液的初始浓度、吸附时间和pH对吸附的影响.结果表明溶液较高的pH值有利于Ni~(2+)在吸附剂上的吸附;随Ni~(2+)初始浓度的增大复合材料的吸附量增大,而Ni~(2+)的去除率随之减小;Ni~(2+)在复合材料上的吸附接近Langmuir-Freundlich等温吸附模型,反映了吸附表面的多相性及两类吸附中心在复合材料上的共存性;吸附速率遵循准二级吸附动力学模型.     

活性炭吸附处理化学镀镍废液的研究

研究了粉状活性炭对水溶液中低质量浓度柠檬酸络合镍离子的吸附行为,在静态吸附条件下,考察了柠檬酸络合剂质量浓度、吸附剂投加量、pH、温度等因素对粉状活性炭吸附镍离子的影响.试验结果表明,溶液pH和粉状活性炭投加量是影响镍离子吸附的重要因素.溶液初始pH为11.0,ρ(活性炭)为10.0g/L时,镍离子的去除率达到72.3...     

碳羟基磷灰石/钾长石复合材料对镍的吸附性能研究

以钾长石为原料,用液相合成法制备碳羟基磷灰石/钾长石吸附剂（CHAK）去除水中的重金属镍,用静态吸附实验考察了CHAK添加量、溶液初始pH、吸附时间、镍初始浓度等因素对镍去除效果的影响,并结合动力学及热力学拟合探究吸附机理。结果表明：随着CHAK量的增加,对Ni ²⁺的去除率增加,但吸附量会降低;溶液pH=6时吸附效果达到最佳;吸附时间为10 h时吸附达到平衡;Ni ²⁺溶液的初始质量浓度为50~4 000 mg/L时,CHAK对Ni ²⁺的吸附量呈先增长后平稳趋势,饱和吸附量与原材料相比增大7.1倍。动力学及热力学拟合结果显示：准二级模型更符合描述该吸附行为。ΔH>0,表明该吸附过程为吸热反应,升温有利于吸附。ΔG<0,表明该反应能自发进行。     

煤矸石沸石吸附氨氮废水试验研究

以煤矸石和高炉渣为原料合成了2种新型沸石,研究吸附工艺对2种沸石吸附氨氮废水效果的影响并初步研究了吸附机理。实验结果表明:2种沸石吸附氨氮的最佳工艺条件为:沸石投加质量浓度24 g/L,振荡时间分别为60、45 min,废水pH=7;最佳条件下,沸石对氨氮的去除率最高达63%;吸附等温方程表明:Freundlich方程能更好地描述2种合成沸石对氨氮的吸附行为。     

灭活酿酒酵母对水中Ni2+的吸附去除

以灭活酿酒酵母菌为生物吸附剂,研究吸附剂对水中的镍离子吸附。考察了溶液初始pH、菌体投加量、温度等因素对吸附镍离子的影响,并对灭活酿酒酵母菌吸附镍离子的吸附动力学和吸附等温线进行了研究。通过动电电位分析,表明实验用的灭活酿酒酵母等电点介于3～4之间。当溶液的pH为7,吸附能力较好,灭活酵母菌对镍离子吸附量可达128.33 mg/g。随着酵母菌投加量增加,其对镍离子吸附量也随之下降。对灭活酵母吸附Ni~(2+)的数据进行动力学分析,发现灭活酵母菌对Ni~(2+)的吸附符合准二级动力学吸附模型,吸附量理论值q_(cal)为133.33 mg/g。对酵母菌吸附镍离子的等温吸附数据进行分析,表明灭活酵母菌对Ni~(2+)的吸附符合Langmuir等温模型。在30℃时,酵母菌对镍离子的饱和吸附量可达83.33 mg/g。     

片沸石处理氨氮废水的实验研究

以片沸石为吸附剂处理氨氮废水,研究了吸附剂粒径、反应时间、废水pH、氨氮初始含量、沸石投加量对吸附的影响,分析了片沸石的吸附动力学和热力学特征。结果表明,在298K下,当投加沸石质量为8g、粒径为74μm、废水用量为100 mL,初始氨氮质量浓度为50 mg/L、pH为7、吸附时间3 h时,废水中氨氮的去除率可达到70.83%,天然片沸石吸附氨氮符合准2级动力学方程。在温度为298~318 K时,吸附等温线更好地符合Freundlich方程;热力学计算发现ΔH0、ΔG0、ΔS0,表明氨氮在片沸石上的吸附是自发吸热过程,以物理吸附为主。     

活性污泥@PAM对废水中镉的吸附性能

采用活性污泥联合聚丙烯酰吸附去除废水中镉离子,研究活性污泥投加量、溶液pH、温度、PAM投加量对去除镉的影响。结果表明,对于初始浓度100 mg/L的含镉溶液,活性污泥@PAM去除水中镉的最优条件为:污泥投加量0. 54 g,反应pH=5. 686,浓度0. 3%PAM溶液投加量为3. 017 m L,此时水中Cd的去除率可达97. 08%。等温吸附和吸附动力学实验表明,Langmuir等温吸附模型和二级反应动力学模型能够更好地描述镉离子在活性污泥@PAM体系中的吸附行为,表明吸附过程主要以单分子层吸附为主,受到化学吸附机理的控制。     

三聚磷酸铝对水中氨氮的吸附动力学

为研究三聚磷酸铝对铵离子（NH4+）的吸附动力学,通过单因素实验、正交实验研究了铵离子初始质量浓度、溶液pH、三聚磷酸铝用量、吸附温度和吸附时间5个因素对溶液中铵离子去除率的影响。各因素由大到小的影响顺序：三聚磷酸铝用量、吸附温度、铵离子初始质量浓度、吸附时间、溶液pH。最佳吸附条件：铵离子初始质量浓度为50 mg/L,溶液pH为4,吸附剂用量为1.5 g,吸附温度为313 K,吸附时间为70 min。在298 K时,三聚磷酸铝对铵离子的吸附符合三级反应动力学特征,其吸附机理是三聚磷酸铝中的质子氢与其表面吸附的铵离子发生了离子交换。     

Removal of Lead and Nickel Ions Using Zeolite Tuff

The capacity of Jordanian zeolite tuff for the removal of lead and nickel ions from aqueous solutions has been investigated under different conditions, namely zeolite particle size, initial solution pH, initial metal ion concentration, slurry concentration and solution temperature. Equilibrium data obtained have been found to fit both the Langmuir and Freundlich adsorption isotherms. It has been found that this zeolite (phillipsite) tuff is an efficient ion exchanger for removing both lead and nickel ions. Its removal capability is considerably higher for lead ions than for nickel ions under all conditions tested; however, the actual exchange capacities are far below the theoretical values. The finer the zeolite particles used, the higher the metal exchange capacity. An initial solution pH of 4·0 is favourable for obtaining high metal removal. © 1997 SCI.     

Synthesis of NaA zeolite from kaolin source

In this work, zeolite NaA was successfully synthesized by a hydrothermal method using kaolin as a combined source for silica and alumina. Zeolite NaA with high static water adsorption was synthesized from the low-cost raw material, kaolin, and the reaction parameters were optimized. Metakaolin was obtained by calcining kaolin at temperatures ranged from 953 K to 1173 K. The synthesis mixture was pre-crystallized at 343 K and crystallized at 373 K successively. Zeolite NaA was obtained, which was confirmed by SEM, XRD and the water adsorption analysis. The optimized metakaolinization temperature was found at 973 K. The influence of Na₂O/SiO₂ molar ratio, pre-crystallization time and seed on the crystallization of NaA zeolite was investigated. A thorough mixing of metakaolin and NaOH solution was favourable for the nucleation/crystallization rate. The obtained NaA zeolite under the optimized conditions shows excellent crystallinity and static water adsorption of 28.0 wt-%, which was higher than 25.9 wt-% of the commercial NaA zeolite. Kaolin was suggested to be a feasible and economical raw material for the practical industrial applications for NaA zeolite.     

NaA型分子筛膜用于医药工业异丙醇溶媒渗透汽化脱水(英文)

NaA zeolite membranes with 80 cm in length and 12.8 mm in outer diameter were prepared by our research group cooperating with Nanjing Jiusi Hi-Tech Co., China. The influence of dissolved inorganic salts and pH value in the feed of isopropanol (IPA) solution on NaA zeolite membranes was investigated. It was found that both factors exhibited strong influence on the stability of NaA zeolite membranes. A set of pretreatment steps such as pH adjustment and distillation of the IPA solution were proposed to improve stability for pervaporation dehydration. An industrial-scale pervaporation facility with 52 m2 membrane area was built to dehydrate IPA solution from industrial cephalosporin production. The facility was continuously operated at 368-378 K to dehydrate IPA solution from water mass content of 15%-20% to less than 2% with a feed flow rate of 400-500 L·h-1 and an average water flux of 1-1.5 kg·m-2·h-1. The successful application of this facility suggested a promising application of NaA zeolite mem-brane for IPA recovery from pharmaceutical production.     

Maxwell-Stefan理论模拟NaA沸石膜分离一氯甲烷中微量水的渗透特性

通过热浸渍晶种法制备了高质量的NaA沸石膜,并将其应用于蒸汽渗透脱除一氯甲烷中的微量水. 实验结果表明,NaA膜对该体系显示了优异的分离性能,水对一氯甲烷的分离系数高达74831,产品中的水含量从0.2582%(w)降低到0.005%(w). 将基于Maxwell-Stenfan理论和Langmuir理想吸附理论推导的吸附-扩散模型用于模拟水渗透流速与渗透侧真空度和进料温度的关系,预测趋势与实验值吻合很好,且拟合得到的参数与文献报道较接近,表明水蒸汽在NaA沸石膜中的传递为表面扩散机制,水蒸汽的吸附对渗透速率的贡献很大. 水蒸汽的吸附热为-34.15 kJ/mol.     

NaA/MCM-41微介复合分子筛的合成与表征

按n(SiO2)∶n(Na2O)∶n(Al2O3)∶n(H2O)=1∶1.5∶0.5∶100加料,在90℃下水热晶化3 h合成NaA微孔分子筛,再按n(SiO2)∶n(NaOH)∶n(CTAB)∶n(H2O)=1∶0.3∶0.3∶90依次添加到NaA微孔分子筛中,于110℃下水热晶化24 h合成NaA/MCM-41微介复合分子筛,并采用XRD、SEM(EDS)和TEM等方法对其进行了表征。吸附阳离子红X-5GN模拟染料废水结果表明,在50 mLρ(阳离子红X-5GN)=20 mg/L的水溶液中,NaA/MCM-41微介复合分子筛的投加量为0.6 g/L、pH=6、振荡时间为60 min时,脱色率可达到96.4%,比NaA分子筛和MCM-41介孔分子筛独自吸附脱色效果要好。     

Isomerization of n-hexane over nickel-loaded zeolite catalysts

The isomerization of n-hexane to branched-chain isomers was studied over various zeolite supports containing nickel between 1 to 5 wt%. NaA, NaY, CaY and Zeolon 900H were loaded with nickel by an impregnation technique. It was observed that at a nickel content of about 2.5 wt%, all the catalysts showed maximum activity for isomerization. A catalyst containing 1 wt% Ni/CaY gave the maximum selectivity among all the catalysts studied. Increasing the nickel loading beyond 2.5 wt% Ni with CaY and Zeolon 900H led to more hydrocracking. No major change in the activity and selectivity of Ni/NaA catalysts was observed beyond 2.5 wt% Ni, whereas the activity of Ni/NaY catalysts remained almost constant over the range of nickel content studied. A catalyst containing 2.5 wt% Ni on Zeolon 900H gave the maximum yield of isomers at 643°K. The apparent activation energy of the reaction was found to be 48.6 kJ/mol for 1 wt% Ni on Zeolon 900H catalyst.     

Single-step process without organic template for the formation of zeolite A from RHA

Dice-shaped zeolite A (NaA) was prepared via direct dissolution of rice husk ash (96.5% SiO₂) in the presence of NaOH and sodium aluminate solution by autoclave process at 90°C/6 h without using any templating agent. The prepared particles were characterized by DTA/TG, XRD, FTIR, N₂ adsorption-desorption physisorption analysis, FESEM, and TEM. XRD results confirmed crystallization of pure NaA zeolite phase. FTIR study shows the characteristic bands at 554 cm⁻¹ for double 4 membered ring (D4R) of NaA zeolite. The total BET surface area of the product was found to be 31.6 m² g⁻¹. FESEM and TEM images show dice shaped NaA particles of size around 1 μm which is formed via oriented crystalline aggregation of primary particles (30-40 nm). A tentative mechanism was proposed for the formation of NaA crystals through direct dissolution of rice husk ash. The synthesized NaA zeolite could be used for purification of alcohol and separation of toxic and radioactive ions from waste water via a cost-effective process.     

Structure,stability and permeation properties of NaA zeolite membranes for H2O/H2 and CH3OH/H2 separations

NaA zeolite membranes were synthesised in the secondary growth hydrothermal method based on the seeding of the inner surface of a ceramic α-alumina tube. The impacts of crystallisation time and zeolite precursor concentration (in H₂O) were investigated. The structure and stability of the prepared NaA zeolite membranes were also investigated with operating temperatures, times and pressures. The results indicate that the optimal synthesis gel molar composition was 3Na₂O: 2SiO₂: Al₂O₃: 200H₂O. This led to cubic-shaped NaA zeolite which showed good stability. The optimal NaA zeolite membrane had H₂O and CH₃OH fluxes of 2.77 and 0.19 kg/m²h, with H₂O/H₂ and CH₃OH/H₂ separation factors of ∞ and 0.09 at a temperature of 30 °C. The NaA zeolite membrane had high thermal stability, but poor separation performance at high temperature (240 °C). The results suggested that the H₂ permeation flux is significantly influenced by preferential adsorption of vapour in the NaA zeolite membrane.