钙蒙脱土吸附镧的影响因素及其应用

以钙基蒙脱土(Ca-MMT)为载体,研究其对镧(La)的吸附。 采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和元素mapping分析、傅里叶红外光谱(FT-IR)、BET、X射线荧光光谱分析(XRF)对其晶型结构、表面形态、比表面积、化学结构进行表征,考察了La的初始浓度、pH值、温度对Ca-MMT吸附镧性能的影响,考察了载镧钙基蒙脱土(Ca-MMT@La)的除磷效果。 结果表明:Ca-MMT投入量为10 g/L时,Ca-MMT的平衡吸附量随镧的初始浓度增加而增大,最大吸附量为49.62 mg/g;随着pH值增大,吸附能力增强,pH=6时为最佳pH吸附镧条件,吸附量为38.36 mg/g;随温度的升高,其吸附量先下降再上升,20 ℃吸附能力最大,吸附量为41.23 mg/g。 Langmuir等温吸附方程推断其吸附属于单分子层吸附。 Ca-MMT不具有吸附磷效果,而Ca-MMT@La对磷酸根有很强的吸附能力,吸附量为7.24 mg/g,除磷率为72.41%,其除磷率随含镧量增大而增大。     

功能化介孔硅分子筛吸附剂除磷性能的研究

分别在甲基二甲氧基硅烷改性介孔分子筛MCM41上锚定Al和Fe离子,成功制备了功能化的介孔硅分子筛有机/无机杂化吸附剂Al-NN-MCM41和Fe-NN-MCM41。详细考察了磷溶液初始浓度、吸附时间,溶液pH值和共存离子等对吸附剂磷吸附性能的影响。实验结果表明:Langmiur等温方程比Freundlich等温方程能更好地描述磷酸根离子在两种吸附剂上的吸附,两种吸附剂的吸附动力学过程更适合动力学准二级方程(r20.99)。磷溶液的pH值对吸附剂的磷吸附容量有显著影响。此外,同时添加NO33-、Cl-、SO42-、CO32-四种共存离子对吸附剂磷吸附效率没有显著影响。     

锆、铁水合氧化物对磷酸根的吸附

将氯氧化锆、三氯化铁分别与双氧水和氨水反应,生成锆、铁水合金属氧化物。用这两种氧化物作为吸附剂对水中的磷进行吸附。讨论了吸附过程对吸附容量的影响因素(温度、pH、时间)及除磷机理。实验结果表明,在低的pH值下,吸附容量最大;该吸附过程主要是以离子交换反应进行的吸热过程;可以用Freundlich方程表示静态吸附的吸附等温线;吸附动力学符合一级反应方程。     

多壁碳纳米管对稀土元素的吸附性能

研究了改性多壁碳纳米管(MWCNTs)对稀土元素的吸附。 采用硝酸、次氯酸钠、过氧化氢、高锰酸钾4种方法对MWCNTs进行改性,考察了改性MWCNTs对稀土元素的吸附能力。 采用紫外-可见分光光度法测定稀土元素的浓度,比较了未处理和不同方法处理的MWCNTs对稀土元素的吸附能力。实验结果表明,NaClO改性的MWCNTs对稀土元素的吸附能力最强。以稀土元素钐(Sm)、钆(Gd)、镱(Yb)为代表,研究了NaClO改性MWCNTs对稀土元素的吸附性能。 考察了溶液pH值、离子强度、吸附剂用量、温度等因素对吸附性能的影响。当溶液pH值在2~7范围内,NaClO改性的MWCNTs对Sm、Gd、Yb的吸附随pH值增大而增强。 当离子强度和MWCNTs的用量增大时,对稀土元素的吸附能力降低。3种元素在NaClO改性的MWCNTs上的吸附均为放热过程,其反应焓变ΔH分别为：-6.44、-5.63和8.31 kJ/mol。吸附等温线符合Langmuir和Freundlich等温吸附方程。     

活性炭的改性研究及对四环素的吸附

研究了改性对活性炭的物理化学性质及其对四环素吸附性能的影响。结果发现,硝酸氧化改性可增加活性炭表面的酸性基团,提高比表面亲水性,降低pHPZC值,同时也改变了活性炭的表面微观形貌。低温、低浓度硝酸氧化改性,增加了活性炭的比表面积,对四环素的吸附以物理吸附为主。高温氧化改性使得比表面积降低,酸性基团增加,且吸附容量与活性炭比表面积、表面总酸度呈一定的线性关系。     

顺丁烯二酸酐改性凹凸棒石及对苯胺的吸附性能研究

利用硅烷化试剂KH-792和顺丁烯二酸酐(MA)对凹凸棒石(ATP)进行改性,通过热分析、红外光谱(FT-IR)、X射线衍射(XRD)、高分辨率透射电镜(TEM)等对改性前后的凹凸棒石进行了表征;研究了溶液的pH值、温度和时间等因素对苯胺吸附特性的影响,并对苯胺的吸附过程进行了热力学和动力学分析。研究表明,在温度为30℃、pH值为6.5、时间为120min的条件下,吸附效果最好;苯胺的吸附平衡数据的拟和结果较符合Langmuir方程,吸附过程是一个自发的放热的熵增过程,以物理吸附为主,吸附动力学数据符合准一级动力学速率方程。     

钽掺杂六方相氧化钨对Sr~(2+)的吸附:Zeta电位的测量及吸附机理的研究（英文）

研究Ta掺杂六方相氧化钨(hex-WO_3)材料在吸附Sr~(~(2+))过程中其表面zeta电位的变化情况,并进一步探讨了吸附过程的热力学及吸附机理。结果表明:(1)在实验pH值范围内,Ta掺杂hex-WO_3悬浮液的zeta电位值随溶液中电解质的价态增大而增大;(2)且zeta电位随体系中离子强度的增加而增大;(3)Ta掺杂hexWO_3对Sr~(2+)的吸附容量随着温度降低而增大,随着离子强度的增加而减少;(4)吸附过程的吸附焓为-47 k J?mol~(-1),且Sr~(2+)离子与材料表面之间主要为化学相互作用;(5)Ta掺杂hex-WO_3对Sr~(2+)吸附过程主要为材料表面吸附及材料孔道内离子交换共同作用。     

响应面法优化硅藻土负载纳米零价铁去除水中Cr(Ⅵ)

近年来,纳米零价铁(Nanoscale zerovalent iron, NZVI)因高还原性、高比表面积等优点被广泛应用于去除水中Cr(Ⅵ)的研究。本文采用壳聚糖改性后的硅藻土(CDt)对NZVI进行负载制备了硅藻土负载型纳米零价铁(NZVI-CDt),并对其去除水中Cr(Ⅵ)的条件进行了响应面法优化。以负载比(CDt与NZVI的质量比)、温度、反应时间以及反应溶液pH值为4个响应因素,以水中Cr(Ⅵ)的去除率为响应值进行了四因素三水平的响应面实验设计(Box-Behnken Design, BBD),建立了响应面模型。分析结果表明：模型在整个回归区域内拟合度好,4个因素对Cr(Ⅵ)去除率的影响是显著的(F值为146.83),影响顺序为溶液p H值>负载比>反应时间>温度。通过模型优化得到最佳去除条件为：负载比3∶1,温度30℃,反应时间35 min,pH=4,且预测的Cr(Ⅵ)最高去除率为97.81%。通过3组平行实验对模型的预测结果进行验证,得到预测值高于实际值且绝对误差为1.93%,说明预测值与实际值的拟合度较好。通过该研究优化了NZVI-CDt去除水中Cr(...     

载Fe活性炭纤维除As(Ⅴ)的动力学及机理

研究了铁改性活性炭纤维(Fe-ACF)吸附地表水中砷离子的吸附特性。通过扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、比表面积和孔径变化等探讨了Fe-ACF表面物质形貌、组成和吸附机理,考察了不同pH值和吸附剂投加量对As(Ⅴ)去除效果的影响,讨论了303K、313K、323K等条件下的吸附动力学及热力学。实验结果表明,Fe-ACF表面生成的氧化物为Fe2O3和Fe3O4,改性前后比表面积和孔容显著减小,吸附机理为Fe(OH)3(s)絮凝除As(Ⅴ)和活性炭纤维吸附除As(Ⅴ)。当pH=7,吸附剂投加量为2.0g/L时,出水As(Ⅴ)浓度可以达到国家地表水环境质量标准(<0.05mg/L)。Fe-ACF对As(Ⅴ)的吸附动力学及等温吸附的实验结果与准二级动力学模型及Langmuir等温吸附模型相吻合;吸附速率及吸附容量都随着温度的增加而增加;吸附速率k2从0.0372g/mg min增加到0.0434g/mg min,由Langmuir等温吸附拟合得到的吸附容量从11.31mg/g增加到18.34mg/g。根据标准吉布斯自由能变ΔG0<0、标准反应焓变ΔH0>0判断,Fe-ACF对As(Ⅴ)的吸附为自发的吸热过程。     

改性埃洛石材料的制备及其对亚甲基蓝吸附行为的研究

使用硅烷偶联剂KH550改性埃洛石纳米管获得改性材料HNTs-APTS,并对其吸附亚甲基蓝的行为进行研究。利用傅立叶变换红外光谱仪(FTIR)、X-衍射仪(XRD)对改性前后的埃洛石进行表征。考察了吸附时间和温度对吸附过程的影响,并采用Lagrange准二级动力学方程、Langmuir等温线方程及Freundlich等温线方程对实验数据进行拟合。结果表明,KH550成功负载到埃洛石表面;改性后材料的吸附能力大大提高。改性埃洛石对亚甲基蓝的吸附约在60 min达平衡,最大吸附容量为21.66 mg/g。其吸附过程符合准二级动力学方程,热力学较好地符合Langmuir等温线方程,且吸附过程为自发吸热,升高温度有利于吸附的进行。改性材料可重复再生6次,具有良好的再生性能,可在工业处理亚甲基蓝废水中使用。     

国产硅藻土吸附尿激酶机理的研究

在常温下, 尿激酶在浙江土和吉林土表面的吸附等温线分别为V型和II型; 焙烧后两者皆转为III型。吸附等温线类型与硅藻土表面结构、孔结构、表面ζ电位有关。在400℃焙烧的硅藻土等电点值最低, 吸附量最大; 改性后, 吸附量也发生改变。本文还测定了尿激酶在硅藻土表面的吸附形态, 其吸附等温线方程符合0/(1-0)=(Kc)^1/β, 并讨论了平衡常数K和尿激酶吸附功能链段数β随温度的变化。     

Interaction of radionickel with diatomite as a function of pH, ionic strength and temperature

Sequestration of Ni(II) on diatomite as a function of reaction time, pH, ionic strength, foreign ions and temperature were investigated by batch sorption technique. The results indicated that the sorption of Ni(II) on diatomite was quickly in the first contact time of 2 h and then slowly with increasing contact time. The interaction of Ni(II) with diatomite was strongly pH- and ionic strength-dependent at low pH values (i.e., which was dominated by ion exchange or outer-sphere surface complexation), while the pH-dependent and ionic strength-independent sorption at high pH suggested that inner-sphere or multinuclear surface complexation was the main sorption mechanism. With increasing temperature, the sorption of Ni(II) on diatomite increased and the experimental data were well fitted by Langmuir model. The sorption samples at pH 6.8 and 10.0 were also characterized by XPS spectroscopy, and the results suggested that Si atoms also participated in Ni(II) sorption on diatomite. The results are important to evaluate the physicochemical behavior of Ni(II) and other similar radionuclides and heavy metal ions in the environment.     

Phosphorus removal from wastewater using a lanthanum oxide-loaded ceramic adsorbent

Phosphorus removal is significant to prevent the eutrophication of water bodies. Adsorption is a promising method with many attractive advantages. An adsorbent is essential to the adsorption method. To investigate the absorption efficiency of lanthanum oxide-loaded ceramic granules, this study loaded lanthanum oxide onto ceramic granules in two different approaches and obtained two adsorbents called G1 and G2. The effects of the initial concentration of phosphorus, pH, temperature, and interfering anions on the phosphorus adsorption of G1 and G2 were investigated in laboratory experiments. When pH ranged from 3.0 to 8.0, the two adsorbents achieved the optimum phosphorus removal efficiency. At pH 4.0, the removal efficiencies of G1 and G2 were 98.1 and 99.8 %, respectively. Temperature fluctuation had an insignificant effect on removal efficiency. The effect of the presence of interfering anions on the adsorption efficiency was limited, i.e., <10 %. Comprehensive comparison showed that G1 exhibited better performance than G2. The Brunauer–Emmett–Teller specific surface area and total pore volume expanded after modification by 40 and ×6, respectively. The X-ray fluorescence results showed a 42 % (percentage by mass) lanthanum content in the modified adsorbents, some of which existed in the endoporus, whereas others were loaded onto the surface of the ceramic granules. The results of the Fourier Transform infrared spectrometry noted combinations between ceramic granulars and lanthanum oxide, and G1 adsorbed PO₄ ^3? from an aqueous solution.     

Flocculation of diatomite by methylated egg albumin

A common and inexpensive protein, egg albumin, was applied to the solid-liquid separation or flocculation of diatomite. Egg albumin was methylated in a 0.05 M HCl methyl alcohol solution at room temperature. About 90% of the carboxylic groups of egg albumin could be methylated within 24 h. The adsorption of egg albumin onto diatomite at pH 6.8 was remarkably enhanced by methylation. The adsorption constant of methylated egg albumin to diatomite at 30 degrees C was about 100-fold larger than that of native egg albumin; however, the adsorption constant of methylated egg albumin decreased to about 1/100 with temperature decreasing from 30 to 6 degrees C. The saturated adsorption amount of egg albumin was also increased by the methylation. The flocculating ability of methylated egg albumin was examined with a diatomite suspension at 6 and 30 degrees C in the pH range from pH 2 to 11. The diatomite suspension was effectively flocculated by the addition of small amounts of methylated egg albumin (only 0.5-1 wt% against diatomite) over a wide pH range from pH 3 to 10.     

巯基/羧基修饰硅藻土及其对Pb(Ⅱ)、Cd(Ⅱ)的吸附性能

以3-巯基丙基三甲氧基硅烷(MPTS)、3-氨基丙基三乙氧基硅烷(APTES)、柠檬酸(CA)为原料,采用水浴法、水浴/低温水热法,分别制备了巯基(—SH)、氨基/羧基(—NH2/—COOH)表面修饰的硅藻土。采用傅里叶变换红外光谱、扫描电子显微镜、氮气吸附-脱附测试、热重/差示扫描量热法、X射线光电子能谱等技术对样品进行了表征,并探讨分析了样品制备机理。当重金属离子溶液pH=7,吸附时间为4 h时,以MPTS制备的巯基修饰硅藻土吸附剂对Pb(Ⅱ)、Cd(Ⅱ)的最大吸附容量分别为396、365 mg·g^-1;以APTES、CA制备的氨基/羧基缩合修饰硅藻土吸附剂对Pb(Ⅱ)、Cd(Ⅱ)最大吸附容量分别为485、462 mg·g^-1。     

Adsorption of Malachite Green by Diatomite: Equilibrium Isotherms and Kinetic Studies

The utilization of diatomite as potential adsorbent to remove malachite green (MG) from aqueous solution was developed. The characterization of the diatomite was evaluated by scanning electron microscope (SEM) and Brurauer Emmerr Teller (BET). The operating variables of pH, diatomite mass, initial MG concentration, and adsorption reaction time were studied. The equilibrium, kinetics, and thermodynamic parameters were investigated as well. It was found that the diatomite was composed of integral and almost circle sieve tray with lots of small pores on it, which afforded the diatomite high specific surface area of 46.09 m² g^?1. The optimum pH and reaction time were 7 and 90 minutes, respectively. The MG removal increased accordingly as the diatomite mass increased. The isotherm results showed that the equilibrium data were fitted to Langmuir model better, indicating the MG adsorption was better characterized by mono-layer. The maximum mono-layer capacity obtained from Langmuir was 23.64 mg g^?1 at 25°C. The kinetic studies indicated that experiment data followed pseudo-second-order model better. It also revealed that intraparticle diffusion was not the only rate-controlling step. The thermodynamic results concluded that the adsorption process was endothermic and more favorable at high temperature. Researches confirmed the applicability of diatomite as an efficient adsorbent and low-cost process to remove hazardous materials.     

Utilization of industrial waste as a novel adsorbent: Mono/competitive adsorption of chromium(VI) and nickel(II) using diatomite waste modified by EDTA

The adsorption of Cr(VI) and Ni(II) using ethylenediaminetetraacetic acid‐modified diatomite waste (EDTA‐DW) as an adsorbent in single and binary systems was investigated. The EDTA‐DW was characterized using various analytical techniques, including Fourier transform infrared spectroscopy, thermogravimetric analysis, Brunauer–Emmett–Teller measurements, X‐ray diffraction, scanning electron microscopy and energy‐dispersive spectrometry. The adsorption experiment was conducted by varying pH, adsorbent dosage, initial concentration and temperature. In the single system, the sorption data for Cr(VI) fitted the Langmuir isotherm, but the Ni(II) adsorption data fitted well the Freundlich isotherm. The maximum sorption capacity of Cr(VI) and Ni(II) was 2.9 mg g^?1 at pH = 3 and 3.64 mg g^?1 at pH = 8, respectively. The kinetic data for both Cr(VI) and Ni(II) followed well the pseudo‐second‐order kinetic model in single and binary systems. Meanwhile, the extended Langmuir and extended Freundlich multicomponent isotherm models were found to fit the competitive adsorption data for Cr(VI) and Ni(II). In addition, in the binary system, the existence of Ni(II) hindered the adsorption of Cr(VI), but the presence of Cr(VI) enhanced the removal of Ni(II). This study provides some realistic and valid data about the usage of modified diatomite waste for the removal of metal ions.     

Adsorption of cyanuric acid on activated carbon from aqueous solution: effect of carbon surface modification and thermodynamic characteristics

The performance of a conventional and two surface-modified activated carbon samples was investigated for the sorption of cyanuric acid from aqueous solution by varying the process parameters such as initial concentration, pH, temperature, dose of adsorbents, and agitation time. The modified carbon samples obtained by acid and ammonia treatment of the conventional sample had a higher BET surface area (989 and 1010 m2 g-1, respectively) and higher specific mesopore surface area (27.36 and 33.21 m2 g-1, respectively) compared to the untreated material (820 and 18.25 m2 g-1). The solute removal was found to be favored at lower solute concentration, increased agitation time, increased adsorbent dose, and lower temperature. The modified adsorbents outperformed the conventional activated carbon for sorption of cyanuric acid especially at higher pH (>7.5) and with increasing temperature. The Freundlich model appears to fit the isotherm data better than the Langmuir model. The thermodynamic parameters (DeltaG degrees ads, DeltaH degrees, and DeltaS degrees) were evaluated showing that the sorption process was thermodynamically favorable, spontaneous, and exothermic. The findings can be used for predictive modeling for analysis and design adsorption systems for removal of cyanuric acid and other polar atrazine degradation products from environmental aqueous samples.     

Enhanced Dye Adsorption by Microemulsion-Modified Calcined Diatomite (μE-CD)

This study attempted to improve the adsorption performance of calcined diatomite for the removal of colour from wastewaters through modification with microemulsions. The surface area, pH_ZPC, Fourier transform infrared (FTIR) of calcined diatomite and μE-CD were studied. It is found that an increase in the BET surface area, pH_ZPC and total pore volume after modification was obtained. A decrease in average pore volume was observed after modification. This suggests that the pore opening deceased to be in the micro- and meso-pore region hence the adsorption capacity for the modified adsorbent will be enhanced by reducing the escaping of dye molecules. The influence of concentration, pH and particle size on the adsorption capacities of methylene blue (MB), hydrolysed reactive black (RB) and hydrolysed reactive yellow (RY) was investigated. It was concluded from FTIR and pH analysis that the predominant mechanism of RY molecules onto μE-CD is by an electrostatic attraction between the carboxylate anion and the dye. In the case of MB and RB, the adsorption mechanism could be a combination of different mechanisms such as electrostatic attraction, capturing by microemulsion micelles in the pores of the calcined diatomite or the hydrophobic attraction. The adsorption capacities were higher than unmodified calcined diatomite. In the case of adsorption of MB molecules, a high adsorption capacity onto μE-CD was obtained.