改性NaY分子筛吸附模拟油中噻吩的研究

用静态吸附方法研究了CuY分子筛、CeY分子筛和CeCuY分子筛对3种含噻吩的模拟油的吸附。实验结果表明,在相同条件下,以上3种分子筛对模拟油A、B的脱硫率为95%左右,对含环己烯的模拟油C的脱硫率均低于63%。运用BET对分子筛孔结构进行表征和运用IR对吸附模拟油后的分子筛情况进行考察,分析结果表明,Cu和Ce离子交换后的分子筛,BET比表面积下降,微孔比表面积下降,由此影响对模拟油A、B中噻吩的吸附。IR谱图表明,以上3种分子筛都会吸附环己烯,是导致其对模拟油C脱硫率下降的主要原因。     

粉煤灰合成Na-P1沸石去除饮用水中氟的研究

采用水热法合成了Na-P1型粉煤灰沸石,改性后用于去除饮用水中的氟离子。研究了吸附时间、沸石用量、氟离子浓度对除氟率的影响,探讨了沸石除氟的吸附机理。研究表明,将粉煤灰沸石用1.0%的NaOH溶液浸泡12 h,然后用2.0%的硫酸铝钾溶液浸泡36 h活化,能够明显提高其吸附除氟能力。在考察的范围内,除氟率随吸附时间的延长和沸石用量增多而增加。吸附等温线拟合结果表明,吸附除氟过程符合Langmuir吸附等温式。     

NaY分子筛的改性及吸附脱氮性能

采用离子交换法用NH⁺₄、Zn²⁺、Cu²⁺、Cr³⁺阳离子改性NaY分子筛,并利用XRD、FT-IR和低温N₂吸附-脱附等方法对改性的分子筛进行了表征。XRD 和FT-IR表征结果表明,改性后的分子筛骨架完好。Cr改性Y分子筛(CrY)的比表面积、孔体积及平均孔径均较小,但存在部分介孔。研究了改性分子筛对含喹啉模拟燃料的吸附脱氮,喹啉分子尺寸的模拟结果为0.711 6 nm×0.500 2 nm,说明其并不易进入Y型分子筛0.74 nm的微孔。吸附脱氮结果表明,CrY的脱氮效果最好,CuY和ZnY次之,NH₄Y效果最差,改性分子筛的吸附脱氮性能与金属离子的价态有关,同价金属离子改性后的分子筛,吸附时间对其影响趋势相同,且金属离子价态越高,改性分子筛的吸附脱氮性能越好。吸附温度对CrY和NH₄Y分子筛吸附脱除喹啉的影响不大,可在室温下使用,但高温有利于CuY和ZnY吸附脱氮。XRD表征结果表明,焙烧后CrY分子筛骨架已完全塌陷失去了绝大部分吸附脱氮性能。     

改性聚酰胺负载丁二肟吸附富集原子吸收光谱法测定水中镍

研究了负载丁二肟的改性聚酰胺对镍的吸附和富集行为,确立了负载丁二肟的改性聚酰胺对镍的吸附洗脱条件,建立了负载丁二肟改性聚酰胺对镍富集、分离原子吸收光谱测定的分析方法。结果表明,在pH10的碱性条件下,负载丁二肟的改性聚酰胺对镍有较好的吸附行为,其吸附容量为0．5mg／g;用5mL0．6mol／L的硝酸作为洗脱液,洗脱率可达到100％;负载丁二肟的改性聚酰胺可重复使用三次,吸附率仍可高达到95％以上;方法的富集倍率为80倍;通过对地表水的测定结果令人满意。     

CMC-Na/DETA-B62型蛇笼树脂对金属离子的吸附性能

本文研究了自合成的蛇笼型螯合树脂-二乙烯三胺交联甘油环氧树脂/羰甲基纤维素体系对Cd^2 ,Pb^2 ,Fe^2 的吸附量，吸附动力学，等温吸附过程等静态吸附性能，同时研究了pH值等因素对吸附性能的影响。实验结果表明，该树脂对Cd^2 具有较强的吸附选择性，能在Cd^2 ,Pb^2 ,Fe^2 3种离子共存时选择吸附Cd^2 ，其选择性系数分别为Kcd^2 /pb^2 =3.77,Kcd^2 /Fe^2 =9.61。该树脂对上述3种离子的吸附量可分别达4.00,1.06,0.42mmol/g。该类树脂可用于含重金属离子污水的处理和金属离子的分离等方面。     

Cr~(3+)改性NaY分子筛的吸附脱氮性能

对Cr~(3+)离子改性NaY分子筛的实验条件进行了研究,通过XRD、FT-IR、N_2吸附-脱附等方法对改性后的CrY分子筛进行表征,确定最佳改性条件为温度40℃,Cr~(3+)浓度0.5 mol/L,改性两次。FT-IR谱图表明,CrY分子筛波数1 147 cm~(-1)处峰明显消失,且波数1 024 cm~(-1)峰与标准的NaY分子筛相比发生了蓝移现象,可以判定Cr~(3+)交换到分子筛骨架上。考察了吸附时间和温度对CrY分子筛吸附脱除模拟燃料中喹啉的影响。结果表明,吸附温度对吸附影响不大,可在室温下进行。CrY对喹啉的吸附主要为化学吸附,且吸附类型为配位吸附和π络合吸附,最佳吸附时间为30 min,吸附等温线线性回归表明,CrY分子筛对喹啉吸附动力学模型为L型和F型混合吸附。     

Na_2CO_3溶液处理对Ni-Mo/HZSM-5分子筛硫醚化催化性能的影响

采用Na2CO3溶液对ZSM-5分子筛进行碱处理,考察了处理温度和处理时间对ZSM-5分子筛结构特征和物化性能的影响。利用XRD、N2吸附-脱附、XRF、SEM及NH3-TPD表征对处理前后样品进行分析。以正丁硫醇和异戊二烯组成的模型化合物为原料,对碱处理后含微-介孔HZSM-5分子筛制得的Ni-Mo/HZSM-5催化剂进行硫醚化活性评价。结果表明,Na2CO3溶液处理没有破坏原分子筛晶体形貌,保持微孔结构的同时,适当的提高处理温度和延长处理时间有利于ZSM-5分子筛比表面积、外比表面积、介孔孔容和平均孔径的增大,并调节了酸性质。但过长的处理时间并不利于介孔的生成和酸性的调变。经90℃的Na2CO3溶液处理5 h得到催化剂表现较高硫醚化活性,正丁硫醇和异戊二烯转化率分别可达92.36%和97.33%。由此,Na2CO3溶液处理可提高催化剂硫醚化活性,且改性过程温和可控。     

改性高分子除氟吸附材料的研究进展

饮用水中氟离子超标对人体造成严重危害。吸附法是目前氟污染水体处理方法中较经济理想的分离技术,开发经济、高效、易再生的新型吸附材料是目前水体除氟重点研究的方向。其中,高分子吸附材料是最受研究者关注的除氟吸附剂种类之一。结合近年来的研究工作,本文综述了导电高分子类、生物高分子类以及树脂类高分子吸附剂的合成和改性方法,及不同改性高分子对水中氟离子的吸附性能和除氟机理,并对今后高分子类除氟吸附材料的发展提出展望。     

螯合树脂研究：ⅩⅩⅡ.用螯合树脂吸附和分离铂和铼

研究了三种含硫氯的凝胶型螯合树脂对铂和铼的吸附和解吸性能。树脂对铂铼的吸附容量随树脂氮含量的增加而增加;随溶液中铂铼浓度的增大而增大;随溶液酸度的增大而下降。含铂和铼的溶液通过树脂柱,两种金属离子可全部被吸附,其饱和吸附容量可达353mgRe/g树脂和319mgPt/g树脂。吸附在树脂上的铂和铼可用解吸能力较弱的洗脱剂先洗脱铼,然后用解吸能力较强的洗脱剂洗脱铂。两者可在洗脱过程中达到有效的分离。洗脱率均在98％以上,树脂可再生重复使用。     

CuCl改性Y型分子筛的CO吸附性能研究

利用自发单层分散原理,讨论了在NaY,NH4Y,CuY分子筛上CuCl分散改性情况,并对所得到的改性分子筛进行了CO吸附性能研究。实验结果表明,在低CuCl担载量时,CuCl可在这三种载体表面达到原子水平分散,其分散容量分别为0.58g/gNaY,0.68g/gNH4Y和0.41g/gCuY。由于CO与Cu^+可生配位化合物,经CuCl改性的Y型分子筛对CO显示出较高吸附性能。其中,0.6gCuCl/gNH4Y分子筛表现出最高的CO吸附容量,在室温、常压下可达123mL/gNH4Y.     

Adsorption equilibrium modeling and solution chemistry dependence of fluoride removal from water by trivalent-cation-exchanged zeolite F-9

Fluoride in drinking water above permissible levels is responsible for human dental and skeletal fluorosis. In this study, therefore, the large internal surface area of zeolite was utilized to create active sites for fluoride sorption by exchanging Na+-bound zeolite with Al3+ or La3+ ions. Fluoride removal from water using Al3+- and La3+-exchanged zeolite F-9 particles was subsequently investigated to evaluate the fluoride sorption characteristics of the sorbents. Equilibrium isotherms such as the two-site Langmuir (L), Freundlich (F), Langmuir-Freundlich (LF), Redlich-Peterson (RP), Toth (T), and Dubinin-Radushkevitch (DR) were successfully used to model the experimental data. Modeling results showed that the isotherm parameters weakly depended on the solution temperature. From the DR isotherm parameters, it was considered that the uptake of fluoride by Al3+-exchanged zeolite proceeded by an ion-exchange mechanism (E = 11.32-12.13 kJ/mol), while fluoride-La3+-exchanged zeolite interaction proceeded by physical adsorption (E = 7.41-7.72 kJ/mol). Factors from the solution chemistry that affected fluoride removal from water were the solution pH and bicarbonate content. The latter factor buffered the system pH at higher values and thus diminished the affinity of the active sites for fluoride. Natural groundwater samples from two Kenyan tube wells were tested and results are discussed in relation to solution chemistry. In overall, Al3+-exchanged zeolite was found to be superior to La3+-exchanged zeolite in fluoride uptake within the tested concentration range.     

磁性4A沸石制备及其对水中氯乙酸吸附

以工业级水玻璃、NaAlO2、NaOH和去离子水为原料,采用水热法先合成4A分子筛,然后在二价和三价铁离子混合溶液中用氨水调节负载铁的氧化物及真空干燥等步骤,制得了一系列磁化率不同的磁性分子筛,并对其进行了XRD、SEM、IR及TG等表征分析.结果表明,合成磁性4A沸石晶形完整,表面负载的四氧化三铁分布均匀,磁化率随所负载四氧化三铁量的增加而增大,粒度比纯4A沸石大.磁性4A沸石对钙、镁、铅和氯乙酸的吸附性能与纯4A沸石相当,利用磁性4A沸石可以方便地用磁场分离的特性,其粉末状产品不用成型就可以直接在溶剂或溶液中使用.     

氟氯有机化合物对HZSM-5分子筛改性过程中氟和氯的作用

利用ＸＲＤ，ＭＡＳ，ＮＭＲ，ＩＲ和ＸＰＳ等手段研究了ＣＦ４－ｎＣｌｎ改性的ＨＺＳＭ－５分子筛的体相和表面结构的变化。结果表明，改性过程中Ｆ和Ｃｌ均能使ＨＺＳＭ－５脱铝和脱硅。Ｃｌ可以使沸石骨架ＳｉＯ２／Ａｌ２Ｏ３升高，而Ｆ除使沸石骨架脱铝外，还会极化其晶格。Ｆ比Ｃｌ更容易在沸石表面富集。Ｆ和Ｃｌ是通过取代Ｏ或ＯＨ与沸石表面Ｓｉ或Ａｌ作用的。改性后的沸石表面有数种含氟表面物种存在。     

Fluoride sorption and associated aluminum release in variable charge soils

Fluoride sorption and related aluminum (Al) release are evaluated in two iron-oxide-rich soils as a function of soil depth, composition, and physical-chemical properties and potential mechanisms of fluoride-surface interaction are suggested. Measured Al concentrations at equilibrium fluoride sorption, reflective of the net balance between Al dissolution and sequestration of the released Al by the solid phase, suggest net fluoride-assisted dissolution of Al-bearing amorphous and crystalline soil minerals. Strikingly, soils of similar depth and horizonation from the same soil order but of distinct soil series exhibited markedly different susceptibility to Al loss in the presence of fluoride, possibly a combined result of differences in the mechanism of fluoride sorption, soil mineralogy, reactivity of the surficial Al and Fe, and soil solution chemistry. Fluoride sorption is strongly correlated with soil Al and Fe present as high-surface-area amorphous and crystalline oxide phases. Fluoride complexation to surficial Al and Fe ions via ligand exchange with surficial OH groups and water molecules appears to be the dominant sorption mechanism. At high dissolved fluoride concentrations (>7 mM), other mechanisms of fluoride retention including adsorption of AlF solution complexes, entrapment in the interparticle pore fluid, and precipitation into solution and/or onto the soil surface are also likely.     

Fe-Beta分子筛催化剂在选择催化还原氮氧化物反应中的活性:Fe含量的影响

NOx是主要的大气污染物之一,对环境和人体健康具有极大的危害.其主要来源之一是柴油机尾气排放,V2O5-WO3/TiO2催化剂是现阶段大规模商用的SCR催化剂,但V2O5-WO3/TiO2催化剂相对较窄的温度窗口和V2O5的生物毒性使得迫切需要新型的环境友好的高效SCR催化剂,其中分子筛因其特殊的孔道结构和催化性能受到广泛的关注.用于SCR过程的分子筛主要包括ZSM-5,Beta,MOR,SAPO-34和SSZ-13等,通常采用Cu,Fe,Mn和Co等过渡金属对其进行改性,通过调变分子筛的表面酸性和氧化还原性能,提高催化剂的SCR活性.Beta分子筛具有三维12元环孔道结构,相对其它分子筛具有较好的水热稳定性,而且制备工艺成熟,价格低廉,因此该类分子筛催化剂在SCR过程中具有很好的应用前景.我们采用离子交换法制备了系列Fe-Beta催化剂,发现将相同质量硝酸铁溶解在不同体积去离子水中,配制成不同浓度的硝酸铁溶液后与分子筛进行离子交换反应,制备得到的Fe-Beta催化剂中Fe的含量和NH3-SCR催化活性均存在显著差别.在此基础上,我们固定硝酸铁溶液浓度(0.02mol/L),通过增加溶液的体积,分别制备了Fe含量为(2.6,6.3和9)wt%的Fe-Beta分子筛.结果表明,Fe负载量为6.3 wt%时,Fe-Beta催化剂表现出最好的催化活性,NOx转化率大于80%的温度窗口为202-616℃.虽然三个催化剂在比表面积,孔径和Fe的价态上没有明显的差别,但Fe含量为6.3 wt%的催化剂在保持相对较高的Fe负载量的同时具有更多的孤立Fe3+物种,同时具有较好的NH3和NO吸附性能以及NO氧化能力,这些特性使得该催化剂相对于其它两个催化剂表现出更高的NH3-SCR催化活性.当Fe含量增加到9 wt%时,催化剂中FexOy纳米颗粒的含量大幅增加,使得NH3非选择性氧化能力加强,从而导致高温NH3-SCR反应活性大幅下降.     

Influence of steric confinement within zeolite Y on photoinduced energy transfer between [Ru(bpy)3]2+ and iron polypyridyl complexes

The spectroscopic and photophysical properties of zeolite-Y-entrapped [Ru(bpy)3]2+ co-doped with either [Fe(bpy)3]2+ or [Fe(tpy)2]2+ over a range of iron complex loadings are presented. In solution, [Ru(bpy)3]2+ undergoes efficient bimolecular energy transfer to [Fe(bpy)3]2+, whereas only radiative or trivial energy transfer occurs between [Ru(bpy)3]2+ and [Fe(tpy)2]2+. In sharp contrast, within zeolite Y, both [Fe(bpy)3]2+ and [Fe(tpy)2]2+ were found to effectively quench the donor emission. Fitting the Perrin model to the photophysical data yields an effective quenching radius of 32 and 27 A, respectively, for [Fe(bpy)3]2+ and [Fe(tpy)2]2+. The long-range nature of the quenching suggests F?rster energy transfer. Detailed spectroscopic investigations indicate that [Fe(tpy)2]2+ bound within zeolite Y undergoes significant distortion from octahedral geometry. This distortion results in increased oscillator strength and enhanced spectral overlap, between the [Ru(bpy)3]2+ (3)d pi-pi* donor emission and the co-incident acceptor (1)T2-(1)A1 ligand field absorption compared with solution. This turns on an efficient energy transfer to [Fe(tpy)2]2+ within the confinement of the zeolite Y supercage. Overall, this is an interesting example of the ability of the zeolite environment to provoke new photophysical processes not possible in solution.     

Removal of Safranine from Aqueous Solution by Using Adsorptive Bubble Separation Techniques

Safranine, a cationic dye, was removed from synthetic wastewater by ion flotation. Over 98% of safranine was removed from the solution in 10 min. A stoichiometric amount of surfactant (1 mol of surfactant to 1 mol of dye) was found to be most effective for safranine removal. The separation efficiency of safranine decreased with increasing concentration of NaNO3. Safranine was also removed by adsorbing colloid flotation technique using Fe(OH)3 as the coagulant. Sodium lauryl sulfate was used as the collector, and over 97% of safranine was removed in 5 min. The separation efficiency decreased with increasing ionic strength of the solution. The deleterious effect of neutral salt was compensated somewhat with the aid of Al^3 as the activator. Both ion flotation and adsorbing colloid flotation may be applicable in the removal of safranine from wastewater.     

超声波合成磁性4A沸石分子筛

为了解决微细粉末状沸石产品应用中与所处理溶液难以分离的问题, 在传统水热合成法合成4A沸石的晶化原料液中, 加入磁性Fe3O4微粒, 经过70 ℃, 功率为100 W的超声波晶化6 h, 合成了一系列Fe3O4含量不同的磁性4A沸石,并对其进行了XRD、SEM、IR、TG/DTA、EDX、磁化率及吸附性能等表征测试. 结果表明, 磁性4A沸石具有良好的磁稳定性, 其磁化率随Fe3O4含量的增加而增大; 磁性4A沸石对水中氟离子和六价铬的吸附与纯4A沸石性能相同, 其吸附速率可以用拟二级动力学方程来描述.     

Simultaneous removal of ammonium and phosphate by zeolite synthesized from fly ash as influenced by salt treatment

To develop an effective technique for enhancing the removal efficiency of ammonium and phosphate at low concentrations without losing potential removal capacity, Na-ZFA (zeolite synthesized from fly ash) was converted into Ca-, Mg-, Al-, and Fe-ZFA by salt treatment and the simultaneous removal of ammonium and phosphate by ZFA saturated with different cations was investigated. It was shown that Al3+-ZFA had the highest removal efficiencies (80-98%) for ammonium, followed by Mg2+ (43-58%), Ca2+ (40-54%), Na+ (<20%), and Fe3+ (<1%). Both alkaline pH values (in the cases of Na+, Ca2+, Mg2+) and acidic pH value (in the case of Fe3+) inhibited the sequestration of ammonium. At low initial phosphate concentrations, the efficiency of phosphate removal by Al3+- and Fe3+-ZFA approached 100%, followed by Ca2+ (60-85%), Na+ (<25%), and Mg2+ (<5%). The difference in phosphate removal efficiency was explained by the adsorption mechanisms. It was concluded that ZFA could be used in simultaneous removal of NH4+ and phosphate at low concentrations with presaturation by an appropriate cation such as Al3+ through salt treatment.