O_2分子在F掺杂锐钛矿型TiO_2(001)面上吸附影响的研究

利用DFT+U方法研究了氟离子掺杂对锐钛矿型TiO_2(001)面对O_2分析吸附的影响。共研究了由F离子分别取代表面上的2配位或3配位O离子,或表面上5配位Ti离子下的3配位O离子所形成的3种F离子杂质(分别记为FⅠ、FⅡ和FⅢ)的影响。F掺杂的表面与分子的作用结果表明,FⅠ杂质能够提高表面的稳定性,而FⅢ能提高表面的活性;由掺入FⅡ离子的表面与未掺杂的表面的活性相当。结果表明,3种形式F离子掺杂能显著提高的TiO_2表面对O_2分子的吸附能力。电子结构分析显示,F掺杂所形成的Ti 3+在增强表面对分子的吸附能力中起着重要的作用。     

有机与无机改性蒙脱石对鲑鱼精DNA吸附特征研究

利用聚羟基Fe/Al制备出无机柱撑蒙脱石,以阳离子表面活性剂HDTMA、阴离子型的表面活性剂SDS作为有机改性剂制备出有机改性蒙脱石,并且通过XRD、FT-IR、BET和zeta电位等表征手段对柱撑粘土进行表征,首次研究了具有不同层间结构的改性蒙脱石对鲑鱼精DNA的吸附特征。DNA吸附量大小顺序为HTDM-MMT>MMT>SDS-MMT-Fe/Al-MMT。HTDMA改性促进了蒙脱石的吸附,吸附量达61.04μg/mg。而SDS覆盖其表面后,吸附量减至26.88μg/mg。在pH值为5.0～9.0范围内,有机改性蒙脱石对DNA的吸附量随pH值下降幅度远小于原土。吸附动力学研究表明,控制改性蒙脱石吸附DNA的主要步骤是化学吸附。用NaOAc和NaH2PO4解吸DNA时,有机与无机蒙脱石解吸规律有明显差异。实验结果表明,结构、电负性及表面性质是影响不同改性蒙脱石吸附DNA分子的关键因素。     

土酸溶液中六次甲基四胺对碳钢的缓蚀作用及吸附热力学研究

采用失重法研究了土酸溶液中六次甲基四胺在不同温度和浓度下对碳钢的缓蚀作用,发现六次甲基四胺能较好地抑制碳钢的腐蚀。六次甲基四胺在碳钢表面上的吸附是产生缓蚀作用的重要原因,且吸附规律服从Langmuir吸附等温式。用Sekine方法处理实验数据,获得了吸附过程相关的重要热力学参数,吸附过程是吸热过程,熵值增大,吉布斯自由能减小;随温度升高,吉布斯自由能变增加,熵变减少,缓蚀率降低。     

载铜蒙脱石对嗜水气单胞菌的吸附研究

以钙基蒙脱石、钠基蒙脱石、酸活化蒙脱石为原料制备了载铜蒙脱石并研究它们对嗜水气单胞菌的吸附性能. 蒙脱石和嗜水气单胞菌的Zeta电位随pH值升高而降低; 载铜蒙脱石的Zeta电位随pH值升高而增大, 当pH=4～6时Zeta电位从负值转变为正值. 酸活化蒙脱石、钠基蒙脱石和钙基蒙脱石对细菌的平衡吸附率分别为36.5％、20.1％和14.3％, 其相应的载铜蒙脱石对细菌的平衡吸附率分别为99.6％、93.1％和87.4％. 蒙脱石对细菌的吸附率随着pH的增加而减小, 载铜蒙脱石对细菌的吸附率先随pH值的增大而减小, 到pH=5.0后随pH值的增大而增大. 载铜蒙脱石Cu²⁺脱附实验表明, 经过脱附后的沉淀物基本保持着原来的吸附活性, 而经过脱附后的上清液对细菌的吸附率很低. 载铜蒙脱石的抗菌作用是静电吸附细菌与铜离子抗菌的综合作用.     

矿物浮选吸附平衡模型构建与应用：精准解析矿物表面离子/药剂特征吸附

矿物浮选吸附平衡模型是准确描述矿物浮选过程中所涉及的矿物表面离子/药剂吸附平衡的数学模型，首次实现了矿物表面位点与浮选药剂吸附作用亲和性的量化解析。传统浮选理论对矿物表面作用位点缺乏科学描述，难以阐明浮选药剂的吸附作用能力及平衡状态，新浮选药剂体系开发多以“试错法”“复配法”等经验性方法为主。药剂选择性吸附作为浮选作业的核心机制，若不能准确预测其在各矿物表面的吸附行为，将严重限制浮选工艺智能化控制的发展。本文详细论述了矿物浮选吸附平衡模型的构建原理，以赤铁矿-石英和一水硬铝石-高岭石两个浮选体系为例，通过对少量实验数据的拟合计算，解析出矿物表面活性位点密度Ns、加/去质子反应常数Kt1/Kt2、药剂吸附常数Kf等矿物浮选特征常数。将解析的矿物浮选特征常数代入到平衡模型中，预测出各条件下矿物表面电性、离子及浮选药剂的吸附量，通过零电点、实验及测试等方法验证了可靠性，形成了矿物浮选过程预测系统的内核算法。该算法对各条件下每种矿物药剂吸附的初步准确预测，可在一定程度上反映其可浮性趋势，有助于缩短浮选工艺开发周期，对矿物表面药剂吸附机理研究、浮选药剂分子设计、浮选工艺流程优化及智能控制等具有重...     

端羟基超支化聚(胺-酯)非共价改性氧化石墨烯

采用改进的Hummer方法制备了氧化石墨烯(GO),并利用端羟基超支化聚(胺-酯)对其非共价功能化。采用傅里叶变换红外光谱(FT-IR)、拉曼光谱(Raman)、X射线衍射(XRD)、扫描电镜(SEM)和热重分析(TG)及紫外可见分光光度等方法对氧化石墨烯表面改性的性能进行了分析。FT-IR,Raman,XRD和TG分析结果表明,超支化聚(胺-酯)分子成功改性了氧化石墨烯;XRD分析表明,随着超支化聚(胺-酯)含量的增加,石墨烯片层层间距增大,这说明超支化分子能够渗透插入到氧化石墨烯片层之间;Raman分析表明,吸附在氧化石墨烯表面的超支化聚(胺-酯)提高了氧化石墨烯表面的无序化程度和石墨烯结构的不完善程度。SEM形貌分析表明超支化聚(胺-酯)大分子覆盖在氧化石墨烯的表面上,且通过对改性前后氧化石墨烯在乙醇和正己烷中透光率的对比,表明改性后的氧化石墨烯分散性能得到了明显提高。     

烷基铵在低层电荷蒙脱石上的等温吸附

蒙脱石/烷基铵复合物是一种高附加值的矿物复合材料,复合物中烷基铵的吸附量与其凝胶性能密切相关。以山东某低层电荷的膨润土为原料,在提纯、钠化的基础上,系统研究了80℃恒温条件下十八烷基三甲基铵(OTC)、十六烷基三甲基铵(CTAC)及十四烷基三甲基铵(TTAC)在蒙脱石上的等温吸附特性。研究结果表明,在80℃恒温交换体系中,当烷基铵的用量较高时,3种烷基铵在蒙脱石上均呈现超量吸附,且饱和吸附量都随着碳链长度的增加而增加。3种烷基铵在蒙脱石上的等温吸附特性均与Modified Lang-muir模型拟合较好,吸附数据曲线与Modified Lang-muir模型拟合度分别为0.992、0.986和0.979,相应的蒙脱石对烷基铵饱和吸附量分别是2.101、2.042和1.760mmol/g,与实验数据吻合较好。     

壳聚糖脱乙酰度对海藻酸钠/壳聚糖微胶囊的表面性质及蛋白吸附的影响

采用流动电势技术、 接触角技术及表面轮廓技术分别考察了由不同脱乙酰度壳聚糖制备的海藻酸钠/壳聚糖(ACA)膜的表面电荷分布、 表面亲疏水性、 表面粗糙度, 并以纤维蛋白原为模型, 采用静态吸附实验技术考察了表面性质对蛋白在ACA微胶囊表面的吸附量及吸附构象的影响。结果表明, ACA微胶囊表面净电荷为负, 表面正电荷随脱乙酰度的降低而减少。由脱乙酰度60%~90%壳聚糖制备的ACA膜的表面接触角均为70°左右, 且无显著性差异。ACA微胶囊表面呈颗粒状结构, 表面粗糙度随壳聚糖脱乙酰度的降低而减小。蛋白吸附分析表明, "棒状"的纤维蛋白原分子以"侧向"和"直立" 2种形式吸附于ACA微胶囊表面。当壳聚糖脱乙酰度较低时, 蛋白吸附量较小, 且此时蛋白多以"直立"形式吸附。以上结果表明, 由壳聚糖脱乙酰度带来的ACA微胶囊表面性质差异不仅影响了蛋白吸附量, 而且影响了蛋白吸附方式。      

聚丙烯无纺布双亲改性及对壬基酚吸附性能的研究

以甲基丙烯酸缩水甘油酯(GMA)和正辛胺(OA)为单体,聚丙烯非织造布(PP)为基体,采用一步开环法制备了一种新型的两亲性吸附剂(PP-g-GMA-OA)。采用傅里叶变换红外光谱(FT-IR)、扫描电子显微镜(SEM)和接触角测量仪对改性前后PP非织造布的表面化学组成、表面形貌及润湿性能进行分析。采用批量实验法研究其对壬基酚(NP)的吸附行为,主要考察了pH、离子强度及温度对NP吸附效果的影响,并探讨了PP-g-GMA-OA的解吸和再生性能。结果表明,当溶液pH值为9,氯化钠浓度为0.04mol/L,温度为15℃时,PP-g-GMA-OA对NP的吸附效果达到最好,最大吸附量183.2mg/g,且在5次吸附-解吸循环后,吸附效率仍能达到原吸附量的93%。     

离子交换可逆调控棉纤织物表面超疏油性能

采用自组装聚电解质多层膜和离子交换法调控基体表面的疏油性能。在光滑的玻璃表面上可以控制十六烷的接触角在69°和4°之间变化。在棉纤织物上,当聚电解质多层膜吸附全氟辛酸根离子时,织物表面是超疏水和超疏油的,与水的接触角达到154°,与十六烷的接触角高达150°。当全氟辛酸根离子被十二烷基硫酸根离子替代后,水的接触角没有明显的变化,在152°左右,而十六烷却能完全浸润表面,接触角为0°。通过全氟辛酸根离子和十二烷基硫酸根离子的交换,织物表面可以在超疏油和超亲油之间可逆转换,这对于拓展超疏油表面的应用都具有重要的意义。     

Interaction of caffeine with montmorillonite

In this study, caffeine was adsorbed onto montmorillonite and the surface of the montmorillonite was observed before and after the adsorption. Observations were performed by X-ray diffractometry (XRD), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and scanning probe microscopy (SPM). Measurement of the interlayer distance by XRD revealed that it narrowed to 1.09?nm after caffeine adsorption. Adsorption of a small amount of caffeine causes a broadening of d₀₀₁ peaks. This suggested that caffeine molecules were adsorbed into the interlayer space in part, resulting in an irregular layer stacking. The results of SPM observations of caffeine-adsorbed montmorillonite showed the existence of protrusions that are different from minerals on the surface of montmorillonite and suggested a possibility that the protrusions were caffeine molecules adsorbed onto the surface of montmorillonite. DRIFTS demonstrated that the intensity of peaks assigned to Si–OH and siloxane decreased with the increase in the amount of caffeine adsorbed. These results suggested that caffeine molecules were adsorbed both into the interlayer space and onto the surface and interacted with Si–OH and siloxane, in particular. These findings will help us to select ions to be held in the interlayer space and organic compounds to improve the amount of adsorption when montmorillonite is used in the manufacture of caffeine-free drinks and foods.     

Rapid modification of montmorillonite with novel cationic Gemini surfactants and its adsorption for methyl orange

A rapid method was developed to prepare organic montmorillonite (organo-MMT) using three novel Gemini surfactants by microwave irradiation of 1 h, which was more effective than conventional heating method of 8–48 h. The structure and morphology of organo-MMTs were characterized by XRD, FT-IR, TEM and SEM. The adsorption amount of Gemini surfactants on MMT and the thermal stability of organo-MMTs were investigated by thermogravimetric analysis (TGA). The results indicated that Gemini surfactants were more efficient than cetyltrimethyl ammonium bromide in the modification of MMT, the organoclays obtained by microwave irradiation method had larger layer spacing than those from traditional heating method. And with the increase of the dosage and chain length of Gemini surfactants, the amount of the intercalary or adsorbed surfactant on the organoclay gradually increased, whereas the thermal stability weakened appropriately. Besides, the adsorption results for methyl orange indicated that all organo-MMTs displayed more excellent adsorption capacities than unmodified MMT. The amount of methyl orange adsorbed onto the organo-MMTs increased proportionately with the increase of the amount or the chain length of Gemini surfactants. This study affords a rapid and efficient method to obtain the organoclay with large interlayer distance and strong adsorption capacity.     

Electric-Field-Controlled Adsorption of Microcapsules under Fabrication of Planar Structures

It is found that an electric field applied parallel to a substrate surface influences the adsorption of positively charged core–shell microcapsules on glass substrates. As a result, the amount of microcapsules adsorbed near negative contact is up to 2 times larger than the one absorbed near positive contact. It is also found that small concentration (less than 0.2 M) of salt in microcapsule suspension decreases this effect, while an increase in the concentration to 0.45 M results in enhancement of the effect.     

Electrodeposition of amine-terminatedpoly(ethylene glycol) to titanium surface

The immobilization of poly(ethylene glycol), PEG, to a solid surface is useful to functionalize the surface, e.g., to prevent the adsorption of proteins. No successful one-stage technique for the immobilization of PEG to base metals has ever been developed. In this study, PEG in which both terminals or one terminal had been modified with amine bases was immobilized onto a titanium surface using electrodeposition. PEG was dissolved in a NaCl solution, and electrodeposition was carried out at 310 K with − 5 V for 300 min. The thickness of the deposited PEG layer was evaluated using ellipsometry, and the bonding manner of PEG to the titanium surface was characterized using X-ray photoelectron spectroscopy after electrodeposition. The results indicated that a certain amount of PEG was adsorbed on titanium through both electrodeposition and immersion when PEG was terminated by amine. However, terminated amines existed at the surface of titanium and were combined with titanium oxide as N–HO by electrodeposition, while amines randomly existed in the molecule and showed an ionic bond with titanium oxide by immersion. The electrodeposition of PEG was effective for the inhibition of albumin adsorption. This process is useful for materials that have electroconductivity and a complex morphology.     

A comparative study of DFT and XPS with reference to the adsorption of caesium ions in smectites

Chemical states of Cs ion adsorbed on dioctahedral smectites were studied using X-ray photoelectron spectroscopy (XPS) and molecular orbital calculations based on the density functional theory (DFT). Smectites investigated were montmorillonite, montmorillonite–beidellite, Fe–montmorillonite, and nontronite. It was found that montmorillonite samples kept approximately 50% of adsorbed Cs ions after a treatment by BaCl₂ aqueous solution, which were the highest values among the smectite samples. Cs(4d) binding energy was slightly shifted towards a lower energy by 0.2–0.8 eV after a BaCl₂ treatment, which suggests that plural adsorption sites exist on the smectite surface. Stable Cs adsorption sites and the adsorption energies were determined by DFT calculations. As a result, Cs ion is adsorbed strongly on a basal oxygen hexagonal hole. The chemical shift of the calculated Cs(4d) peak gave the same tendency as shown in the XPS measurements.     

Dispersing Characteristics of Graphite Suspension by Surface Modification with ABDM

The stability of dispersions of graphite in aqueous solution with ABDM (alkyl benzyl dimethyle ammonium chloride) as a surfactant was investigated. The adsorbed structures of the ABDM molecules on graphite particles were examined in relation to zeta potential and critical micelle concentration. It was found that the zeta potential seems to be strongly correlated with both ABDM monolayer and bilayer formations on the particle surfaces. The total potential energies resulting from the interaction of the ABDM adsorbed graphite particles in suspension were estimated using the DLVO theory, and highly dispersed systems were obtained at 20 kT and higher. The adsorption amount of ABDM, zeta potential, graphite powder contact angle, and particle sedimentation rate were measured to determine the dispersion stability. It was found that the high dispersible graphite suspension with settling time T 1/2 of 44.5 h at pH 10 and zeta potential of 22.5 mV was produced.

graphite dispersion adsorption surface modification zeta potential     

Monitoring particle adsorption by use of laser reflectometry near the critical angle

We investigate the use of laser reflectometry near the critical angle to monitor particle adsorption onto a flat glass surface. Experimental results show that positive particles are adsorbed onto the glass surface and that their adsorption kinetics depend strongly on the volume fraction occupied by the particles in suspension but not appreciably on the particle size. The reflectance near the critical angle is dominated by the particles on the surface, with the contribution of the particles in suspension being very low. We compare the reflectance change near the critical angle with the change in reflectance near the Brewster angle when particles are adsorbed onto the glass surface. We find that reflectometry near the critical angle is 3000 times more sensitive than it is near the Brewster angle. Some optical images are presented to validate our results.     

Bioavailability of methyl parathion adsorbed on clay minerals and iron oxide

Adsorption, desorption and degradation by Pseudomonas putida of methyl parathion (O,O-dimethyl O-p-nitrophenyl phosphorothioate) on montmorillonite, kaolinite and goethite were studied. Metabolic activities of methyl parathion-degrading bacteria P. putida in the presence of minerals were also monitored by microcalorimetry to determine the degradation mechanism of methyl parathion. Montmorillonite presented higher adsorption capacity and affinity for methyl parathion than kaolinite and goethite. The percentage of degradation of methyl parathion adsorbed on minerals by P. putida was in the order of montmorillonite>kaolinite>goethite. The presence of minerals inhibited the exponential growth and the metabolic activity of P. putida. Among the examined minerals, goethite exhibited the greatest inhibitory effect on bacterial activity, while montmorillonite was the least depressing. The biodegradation of adsorbed methyl parathion by P. putida is apparently not controlled by the adsorption affinity of methyl parathion on minerals and may be mainly governed by the activity of the methyl parathion-degrading bacteria. The information obtained in this study is of fundamental significance for the understanding of the behavior of methyl parathion in soil environments.     

Investigation of the stability of an alumina suspension in the presence of ionic polyacrylamide

The influence of solution pH on the adsorption mechanism of polyacrylamide (PAM) on the alumina surface and stability of its suspension in the presence of polymer were investigated. The structure of polymer adsorption layer was determined from the spectrophotometric, viscosity, surface charge and zeta potential measurements which enable determination of adsorbed amount of polymer, thickness of the polymer adsorption layer, surface charge density and zeta potential of Al₂O₃ particles in the absence and presence of PAM. The measurements of stability of alumina suspension without and with adsorbed polyacrylamide were also carried out using two methods: spectrophotometry and turbidimetry. The obtained results indicate that solution pH influences the structure of PAM adsorption layer (decrease of adsorbed amounts of polymer and increase of its adsorption layer thickness with the increasing pH). These conformational changes of polyacrylamide molecules with the rising pH have an impact on stability of the alumina suspension. The most pronounced effect of polymer on the stabilization properties of investigated systems is observed for PAM addition at pH 6 resulting in a great destabilization of the alumina particles by bridging flocculation.     

Removal of soluble organics from water by a hybrid process of clay adsorption and membrane filtration

The removal of phenol and o-cresol from water by a hybrid process of clay adsorption and ultrafiltration (clay-UF) was studied. Batch adsorption equilibrium experiments showed that the amount of adsorption for phenol and o-cresol decreased in the order kaolin>montmorillonite at an equilibrium pH (pH(e)) of 9.1. The clay-UF experiments were performed as a function of clay dose, solution pH, and transmembrane pressure. The role of pH in clay-UF process mainly depended on the acid-base nature of phenols and clays, and the charge of UF membrane. The rejection of phenol increased with increasing pH, and had a maximum at pH(e)=8.2 with kaolin but at pH(e)=9.1 with montmorillonite. The rejection of o-cresol also increased with increasing pH, and had a maximum at pH(e)=9.2 with kaolin but at pH(e)=10.2 with montmorillonite. Such differences between solute rejections depended on the pK(a) of the solutes, zeta potential of the clays, and surface charge of the membrane. The amount of soluble organics adsorbed onto the surface of membrane was negligible and the flux slightly decreased with increasing transmembrane pressure.