Ce掺杂Fe-Sn负载斜发沸石电催化氧化含酚废水

采用浸渍焙烧法制备了以斜发沸石为载体,Ce掺杂Fe、Sn氧化物的负载型催化剂,用扫描电子显微镜(SEM)和X射线衍射(XRD)对催化剂的表面形貌、晶相结构进行了表征,以苯酚为模拟含酚废水对催化剂的电催化性能进行了测定,并探讨了催化剂投加量、电流密度、溶液初始pH对苯酚降解过程的影响。结果表明,当负载催化剂活性组分Fe、Sn、Ce的摩尔比为6:3:1时,在催化剂的表面形成了明显的Fe、Sn、Ce氧化物衍射峰;该催化剂在三维电催化降解苯酚体系中,当苯酚初始质量浓度为100 mg/L、pH为5、催化剂投加量为15 g/L、电流密度为42.6 mA/cm2、曝气体积流量为0.1 m3/h、电解60 min时,苯酚和TOC去除率分别达93.03%和80.34%;重复使用6次的催化剂仍具有很好的催化活性,苯酚去除率和TOC去除率仍可达到80.31%和75.56%。     

Porosity on External Surface of H-Clinoptilolite Sorption of CCI4 and n-C6H14

CCl4 （carbon tetrachloride） and n-C6H14 （n-hexane） sorption studies have been carried out on natural and dealuminated clinoptilolite-type zeolites. External surface area of the materials has been assessed using the αs-plots method. The high resolution αs-plots show that the isotherms are divided into four parts corresponding to adsorption in ultramicropores, intersections, supermicropores and external surface area, respectively. The mineralogies of natural zeolites are determined by X-ray analysis. N： low-pressure hysteresis loops, displayed by some substrata, are related to the micropore structure and to the ion-exchange treatment at which the natural precursors were subjected. The adsorption behavior of these substrata was examined in the range of relative pressures between 10^-5-1. Natural samples were used as reference materials to carry out the sorption analyses of the dealuminated samples. The effect of narrow micropore constrictions on the adsorption behavior of clinoptilolites was explored. The occurrence of a low-pressure hysteresis loop on the sorption isotherm of a modified sample is associated to the strong adsorption of the adsorbate molecules at the entrance of the necked-shape micropores, which interfere with the diffusion of the adsorbate molecules inside the porous structure.     

Isomerization,Disproportionation and Hydrocracking of 1,3,5-Trimethylbenzene and n-Decane Mixture Over Natural Clinoptilolite Zeolites

Abstract

Five different catalysts were prepared from the ammonium form of the dealuminated natural zeolite clinoptilolite occurs in Gördes, Turkey. The effect of reaction temperature on the activity and selectivity is studied over each catalyst by employing 1,2,3 Trimethylbenzene (1,2,3-TMB) and n-decane (90:10) model mixture as feedstock. Effects of the catalyst type and reaction temperature on the isomerization, disproportionation, and hydrocracking reactions are discussed. The 1,3,5-TMB conversion increased by the temperature increment for all catalysts. Highest 1,3,5-TMB conversion (> 40%) and highest selectivity for the isomerization (> 80%) was reached over the dealuminated and nickel-deposited clinoptilolite catalyst (NiDK).     

磷改性斜发沸石的组成和结构表征

采用焙烧法、微波法固固相同晶取代反应对斜发沸石骨架进行磷改性 ,并用化学分析、XRD、FT -IR和2 9Si、2 7Al、3 1 PMASNMR等手段对其化学组成和骨架结构进行表征。结果表明 ,通过骨架脱Al或占据晶格空穴 ,P进入沸石骨架形成八面体硅的Si(Oct)—O—P结构及Si端位磷氧基团 ;也可以通过Si、Al、P结构重排形成Al—O—P结构。由于P的进入 ,沸石骨架扭曲 ,矿样结晶度降低 ,主衍射峰位移。但是 ,磷改性并未破坏斜发沸石的基本骨架结构 ,仍属于斜发沸石单斜晶系。由于微波对矿样有较强的穿透能力 ,微波法骨架上P的同晶取代效果优于焙烧法。     

NATURAL ZEOLITES IN AIR DRYING

ABSTRACT

The local clinoptilolite from Bigadis region in Turkiye, was used for air drying in packed column. The effective diffusion coefficient of water in natural zeolite was found as 5×10^?10 m² s^?1 from isothermal uptake measurements. Effects of packing height and airvelocity on breakthrough curves were studied.     

合成斜发沸石影响因素的研究

在不同摩尔配比的条件下水热合成出较高纯度斜发沸石,系统研究了斜发沸石合成的各种影响因素.结果表明,在140、160和180℃条件下均能合成出斜发沸石,且提高温度可以缩短沸石的晶化时间;合成配料的硅铝摩尔比应控制在10-12之间;碱度的降低会导致成核时间延长,过高的碱度则导致晶种溶解.     

改性斜发沸石对OH~-吸附动力学的研究

以5种改性斜发沸石为原料,通过吸附不同碱溶液中的OH-,确定了最佳的碱溶液和改性沸石,并对OH-浓度和吸附动力学进行了研究.研究表明:钙改性沸石和镁改性沸石对Ca(OH)2溶液中OH-的单位吸附量最大;在25℃下,钙改性沸石的全吸附容量为22.21mg/g,镁改性沸石的全吸附容量为25.30mg/g;通过动边界模型理论可确定在25℃下钙改性沸石和镁改性沸石吸附OH-的动力学吸附过程主要由颗粒扩散控制.     

The adsorption of sulphate, hydrogenchromate and dihydrogenphosphate anions on surfactant-modified clinoptilolite

The adsorption of sulphate, hydrogenchromate and dihydrogenphosphate anions on surfactant-modified clinoptilolite (SMC) was investigated. The SMCs were prepared by the adsorption of cis-1-aminoctadecen-9 (oleylamine) on both modified and unmodified natural clinoptilolite tuff. The properties of the modified clinoptilolite samples, such as cation type, structure of the zeolite framework and ECEC value, determined the mechanism of oleylamine adsorption, and consequently anion adsorption on the external clinoptilolite surface. According to the strength of the anion adsorption, two groups of SMCs could be distinguished: strong and weak anion adsorbents. Strong anion adsorbents were obtained by oleylamine adsorption on H⁺-clinoptilolites by protonation of the –NH₂ groups. This mechanism of oleylamine adsorption resulted in the surface precipitation mechanism of anion adsorption being the dominant mechanism. The oleylamine derivatives of Ca- and Na-clinoptilolite were weak anion adsorbents. Oleylamine is adsorbed on Ca- and Na-clinoptilolite by hydrogen bonding, thus yielding insufficient adsorption sites for anions. Hydrogenchromate and dihydrogenphosphate anions were nevertheless adsorbed on these SMCs by interaction with oleylamine. The experiments of anion adsorption on various oleylamine loaded SMCs confirmed the existence of two types of anion adsorption sites and showed that excess oleylamine did not significantly influence the anion adsorption in the investigated concentration range. The kinetic results showed that SO₄²⁻ and H₂PO₄⁻ adsorptions were slow processes while HCrO₄⁻ adsorption was completed in a few minutes.     

铵型斜发沸石脱除Pb~(2+)离子的热力学研究

通过实验测定铵型天然斜发沸石对铅离子全交换容量为80.07mmol/100g沸石.用Langmuir吸附等温方程和Freundlich吸附等温方程拟合了吸附等温数据,绘制NH4--pb2+离_子交换等温线以及Kielland图.依据热力学平衡原理,计算出该过程的焓、吉布斯自由能和熵变化.研究表明天然斜发沸石NH4--pb2+离子交换过程可自发进行,且为吸热反应,高温有利于铅离子的交换.     

Effect of pH and temperature on the ion‐exchange isotherm of Cd(II) and Pb(II) on clinoptilolite

The ion‐exchange equilibrium of Pb(II) and Cd(II) on clinoptilolite from different deposits was studied in this work. The Langmuir isotherm fitted the ion‐exchange equilibrium data of both ions better than the Freundlich isotherm. The capacity of the natural zeolite to exchange Cd(II) and Pb(II) increased, augmenting the solution pH. This behaviour was attributed to the interactions between the ions in solution and the surface charge of the zeolite. Moreover, the capacity of the natural zeolite to exchange Cd(II) and Pb(II) was increased when the temperature was raised from 15 to 35 °C. This tendency was explained by assuming that the ion exchange was an endothermic reaction. The selectivity of the zeolite for the metal cations decreased in the following order: Pb(II) > Cd(II). This order was not modified while reducing the solution pH, but the zeolite selectivity was increased. At pH 2 the selectivity of the zeolite for Pb(II) was nearly three times larger than at pH 4. Copyright © 2006 Society of Chemical Industry