Unique photochemical behavior of novel tetracationic pyrene derivative on the clay surface

Novel tetracationic pyrene derivative (1,3,6,8-tetrakis(N-methylpyridinium-4-yl)pyrene, Py⁴⁺) was synthesized. Photochemical properties such as fluorescence quantum yield and fluorescence lifetime were observed for Py⁴⁺ and Py⁴⁺/clay complexes. Judging from Lambert-Beer plot analysis, Py⁴⁺ molecules adsorb on the clay surface without aggregation up to 69% versus cation exchange capacity of the clay. Py⁴⁺ molecule emits strong fluorescence from an excited state of monomer, while the emission from excimer was not detected, in spite of high density adsorption condition on the solid surface. It is supposed that strong interaction between host and guest by the ‘Size-Matching Effect’ inhibits the formation of excimer on the clay surface.     

Switching of energy transfer reaction by the control of orientation factor between porphyrin derivatives on the clay surface

Photochemical energy transfer was examined on the flat clay surface. By the change of surrounding atmosphere, the molecular adsorption orientation angle of dyes can be modulated. It is turned out that the energy transfer efficiency between dyes can be controlled by the relative orientation change between dyes. The change of orientation factor and spectral overlap factor was the main factor to affect the energy transfer efficiency. This technique would be useful to construct the photo-functional materials such as chromic and light harvesting system.     

Adsorption behavior and corrosion inhibitive potential of xanthene on mild steel/sulphuric acid interface

The inhibition of xanthene (XEN) on the corrosion of mild steel in 0.5 M H₂SO₄ was studied by gravimetric and UV–visible spectrophotometric methods at 303–333 K. Results obtained show that XEN act as inhibitor for mild steel in H₂SO₄ solution. The inhibition efficiency was found to increase with increase in XEN concentration but decreased with temperature. Activation parameters and Gibbs free energy for the adsorption process using Statistical Physics were calculated and discussed. The corrosion process in 0.5 M H₂SO₄ in the absence and presence of XEN follows zero-order kinetics. The UV–visible absorption spectra of the solution containing the inhibitor after the immersion of mild steel specimen indicate the formation of a XEN–Fe complex. Quantum chemical calculations using DFT were used to calculate some electronic properties of the molecule in order to ascertain any correlation between the inhibitive effect and molecular structure of xanthene.     

Active species transfer-type artificial light harvesting system in the nanosheet – Dye complexes: Utilization of longer wavelength region of sunlight

A novel light harvesting system that captures long-wavelength light of sunlight by the use of hole transfer was newly investigated. Ga phthalocyanine(Ga^IIITMAPc⁴⁺(D)) and Ru porphyrin(Ru^IIDMPyMP²⁺(A)) co-adsorbed reaction system on the synthetic nanosheet was examined as an artificial light harvesting system. By irradiating 660?nm light, where Ga^IIITMAPc⁴⁺(D) absorbs, to the system under a presence of PtCl₆^2? as an electron acceptor, cation radical of Ru^IIDMPyMP²⁺(A) was produced despite that Ru porphyrin adsorbs only 413 and 533?nm light. The efficient hole transfer reaction from Ga^IIITMAPc⁴⁺(D)⁺, that is generated from its excited state, to Ru^IIDMPyMP²⁺(A) takes place on the nanosheet.     

Development of xanthene dyes containing arylacetylenes: The role of acetylene linker and substituents on the aryl group

Fluorescent dyes possessing a variety of arylacetylenes at the 9-position of a xanthene skeleton were synthesized and their optical properties were investigated. The π system effectively expanded over the xanthene skeleton and the aryl group through the triple bond. Starting from the emission wavelength (λ_em) of 9-methyl xanthene 20 in basic DMSO solution at 536?nm, the emission wavelengths gradually shifted to the red region for methylacetylene 17 (λ_em?=?600?nm), phenylacetylene 5 (λ_em?=?636?nm), and p-CF₃-phenylacetylene 11 (λ_em?=?660?nm). On the basis of these data, we estimated the substituent effects for the red shift on the emission wavelength and rationally explained the results by DFT calculations. Furthermore, potential applicability of these fluorescent dyes to cell staining was exemplified.     

Adsorption studies of cationic starch onto quartz surface through an electrode-separated piezoelectric sensor

In the construction of an electrode-separated piezoelectric sensor (ESPS), the quartz surface is in direct contact with the liquid phase. The negatively charged quartz crystal surface can adsorb cationic starch. This adsorption process was in situ monitored from the frequency shift of the ESPS. It was shown that the adsorption of cationic starch onto the quartz surface is reversible with respect the dilution of the bulk phase. The adsorption behavior can be described by Langmuir model. The adsorption density and kinetics parameters were estimated from the frequency responses of the ESPS. The influence of pH and ionic strength on adsorption parameters was investigated. It was shown that the influence of pH on the adsorption rate was slight. With increasing ionic strength, the rate constants for adsorption and desorption increase, but the adsorption equilibrium constant and saturation adsorption density decrease. The adsorption equilibrium constant and adsorption density reach a maximum in buffer of pH 10.     

选择性萃取对沉积物非残渣态、粘土矿物结构及吸附特性的影响

用NH2OH·HCl, (NH4)2C2O4和H2O2对表层沉积物中非残渣态的Mn氧化物、Fe/Mn氧化物和有机质进行选择性化学萃取, 同时提取粘土矿物, 并对提取前后的表层沉积物样品进行了比表面积、FTIR、ESEM和XRD等分析. 结果表明, 萃取后沉积物的比表面积显著增大, 沉积物颗粒的分散度随之增大, 晶体边缘逐渐清晰, 棱角逐渐分明, 但沉积物的XRD和FTIR谱图变化不大, 原因在于XRD和FTIR谱图中的特征峰主要是由矿物组分产生的. 萃取后随着沉积物分散度的增大, 晶体颗粒表面粗糙度减弱, 沉积物的吸附能力降低, 表明颗粒表面特征对重金属的吸附起到一定作用; 而沉积物的比表面积与沉积物吸附能力之间的反比关系说明沉积物主要吸附组分对其吸附的贡献远远大于沉积物表面与孔隙结构的贡献.     

"中性"粘土矿物对非水溶液中有机碱的吸附

理想品格中无同晶转换，因而不带层电行的中性粘土矿物（即：1：1型的高岭石，板状蛇纹石和2：1型的叶蜡石，滑石）对非极性有机溶剂中有机碱（偶氮苯化合物，pKa＝1.5-5.0）的吸附等温线均属于Langmuir型，且吸附在矿物表面的有机碱均由其碱型变为酸型.偶氮苯化合物的pKa越大，被吸附的量越多在溶剂为正己烷和二硫化碳时粘土的吸附能力比溶剂为苯时高.这些结果说明不带层电行的粘土矿物表面存在着酸位.蒙脱石的酸位数量明显地储存于阳离子种类，但在Na＋、Ca2＋、Mg2＋饱和的条件下高岭石的改位数量几乎相同.随着相对湿度的增加;两矿物对甲基黄的吸附量均减少，但减少的方式明显不同、因此1：1型高岭石和2：1型叶蜡石一样，也具有与蒙脱石不同的表面酸性起源。     

Adsorption of Pseudomonas putida on clay minerals and iron oxide

Adsorption of Pseudomonas putida on minerals including montmorillonite, kaolinite and goethite was studied. The adsorption isotherms of P. putida on the examined minerals conformed to the Langmuir equation. The amount of P. putida adsorbed followed the order: goethite > kaolinite > montmorillonite. A greater extent of P. putida adsorption on minerals was observed in the range of temperature from 15 to 35 °C. The adsorption of P. putida on minerals decreased with the increase of pH from 3.0 to 10.0. Magnesium ion was more efficient than sodium ion in promoting P. putida adsorption on minerals. The results suggest that electrostatic interactions play a vital role in P. putida adsorption by soil colloidal factions. The information obtained in this study is of fundamental significance for the understanding of the survival and transport of bacteria in soil systems.     

[Et3NH][HSO4]-mediated efficient synthesis of novel xanthene derivatives and their biological evaluation

A series of novel 2-chloro quinoline incorporated xanthene derivatives were synthesized by using various 2-chloro 3-formyl quinoline, dimedone and triethylammonium hydrogen sulfate [Et₃NH][HSO₄] as a catalyst as well solvent to give good to excellent yields. All the xanthene compounds were investigated for their in vitro antimycobacterial activity against M. tuberculosis H37Ra (MTB) and M. bovis BCG strains. Among the synthesized compounds 3a, 3c, 3d, 3e, 3g, 3h and 3k were highly potent against both the strains. Most of the active compounds were non-cytotoxic against THP-1, HCT-116, A549 and MCF-7 cell lines. Most active compounds were having higher selectively index which suggested that these compound were highly potent.     

Effect of clay surface on aldehyde-diol equilibrium

The effect of clay surface on the equilibrium between aldehyde and diol was examined by using 4-formyl-1-methylpyridin-1-ium chloride (MPy⁺) as a substrate. MPy⁺ exists as diol (DHMPy⁺) and aldehyde (FMPy⁺) in water and acetonitrile, respectively. It was turned out that FMPy⁺ was clearly observed in the presence of clay nanosheet even in water. This indicates that clay nanosheet surface acts as unique chemical reaction field, affecting the potential energy surface between FMPy⁺ and DHMPy⁺.     

饱和锌的粘土矿物吸附半胱氨酸的机理

用红外光谱、X射线衍射（XRD）和热分析研究了饱和过渡金属锌的粘土矿物吸附半胱氨酸的机理；XRD结果显示吸附了半胱氨酸后的粘土矿物的d(001)方向的距离明显增大，说明被吸附的半胱氨酸进入了粘土的层状结构之中；饱和了锌的粘土矿物吸附半胱氨酸有两种方式，其一为弱相互作用，另一种强相互作用；后一种方式吸附的半胱氨酸与粘土的过渡金属之间形成了配合结构，结合力比较强，在热作用下，它们一直到395℃左右才分解；强相互作用吸附的半胱氨酸主要是以去质子的两性离子和阴离子形式存在于粘土矿物上，与过渡金属形成螯合的六元环结构。     

Synthesis,characterization and evaluation of long-acting hyperbranched cationic polymer clay stabilizer used in water flooding

In the process of waterflooding development, it is of great importance to prevent the clay from hydration swelling and migration dispersion for protecting the formation and improving the water flooding efficiency. For those reasons, we successfully synthesized a cationic clay stabilizer (HBP-QAT) through melting polycondensation and cationic modification with maleic anhydride, diethanolamine, epichlorohydrin, triethylamine, and trimethylolpropane as monomers and p-toluene sulfonic acid as a catalyst. The chemical structure, cation degree, and molecular weight of HBP-QAT were studied by using FTIR, ¹H NMR, sodium tetraphenylborate (STBP) back titration, and gel permeation chromatography (GPC). The obtained results showed that HBP-QAT was a hyperbranched unsaturated polyester amide with a low molecular weight and a high cation degree, with corresponding values of 28400, and 44.2%, respectively. The clay stability and durability of HBP-QAT were evaluated by linear anti-swelling, water flushing, and cutting rolling recovery tests. The obtained results showed that HBP-QAT has an excellent anti-washing capacity and a long-term inhibition effect. The initial anti-swelling rate of 1.0 wt% HBP-QAT reached 92.37%, and the anti-swelling rate of 1.0 wt% HBP-QAT also remained at 85% after flushing 10 times with water. Besides, the two cutting rolling recoveries exceed 72%. Most importantly, the inhibition mechanism of HBP-QAT was studied by zeta potential, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and contact angles analyses, and thus we proposed an inhibition mechanism, presenting as follows. HBP-QAT inhibited the clay hydration swelling by neutralizing negative charges on the surface of the clay particles to compress the electric double layer, strongly adsorbing on the surface of the clay particles, and forming a waterproof polymer membranes, restraining water of intrusion into the clay interlayer.     

Effect of Phosphate on the Adsorption of Glyphosate on Soils,Clay Minerals and Oxides

The effect of phosphate (ortho-phosphate) on the adsorption of the widely used glyphosate herbicide was evaluated with three typical Danish agricultural soils as well as pure oxides (goethite, FeOOH and gibbsite, Al(OH) 3 ) and silicates (illite and montmorillonite), which are considered the most important glyphosate and phosphate adsorbents in soils. Batch experiments where made in order to find out how phosphate affects adsorption of glyphosate and how glyphosate affects adsorbed phosphate. Solution glyphosate was quantified by liquid scintillation counting of 14 C-taggered herbicide and the concentration of phosphate by the molybdenum blue method. All experiments showed competition between phosphate and glyphosate for adsorption sites but the various adsorbents exhibited great variation in affinity for glyphosate and phosphate. Thus, gibbsite and, in particular goethite strongly prefer phosphate, whereas the competition on the silicates is more equal. The current studies showed that the competition in soils is almost equal, but still phosphate affects the sorption of glyphosate in soil. The amount of glyphosate and phosphate adsorbed by the various kinds of adsorbents was found to decrease in the order: oxides > silicates > soils. For the soils tested aluminium oxides, and to a lesser extent iron oxides seem the most important components in determining a soil's ability to adsorb phosphate and glyphosate, whereas the clay content and clay type seem of minor or little importance for adsorption of these species.     

Removal of Cu(II) and Zn(II) from industrial wastewater by acid-activated montmorillonite-illite type of clay

An acid-activated montmorillonite-illite type of clay collected from the Gulbarga region of Karnataka, India was examined for removing copper and zinc ions from industrial wastewater containing Cu(II), Zn(II) and minor amounts of Pb(II). Langmuir, Freundlich, Brunauer-Emmett-Teller (BET), and competitive Langmuir (two competing ions) isotherms were fitted to experimental data and the goodness of their fit for adsorption was compared. The shapes of isotherms obtained indicated multilayer adsorption of Cu(II) and monolayer adsorption of Zn(II) on the acid-activated clay. Competitive adsorption was found to be significant due to the presence of Cu(II) in the wastewater.     

Adsorption of nitrobenzene andn-pentanol from aqueous solution on hydrophilic and hydrophobic clay minerals

The sorption of nitrobenzene andn-pentanol from dilute aqueous solution on swelling clay minerals and their organophilized derivatives (organo clays) was studied. Adsorption excess isotherms were obtained by the immersion method. The basal spacings of the clay minerals were determined by X-ray diffraction measurements. By combining these two independent methods, composition and structure of the interlamellar space could be calculated. On the hydrophilic surface of montmorillonite negative adsorption of the organic component was observed at low molar fractions of nitrobenzene or pentanol, i.e., water was preferentially adsorbed. On organophilized montmorillonite and vermiculite adsorption of nitrobenzene and pentanol was positive over the whole range of liquid composition. The amount of interlamellar alkyl chains which is determined by the surface charge of clay mineral inversely affected the adsorption of both solutes.     

Adsorption of non-ionic and cationic polymers on silica from their mixed aqueous solutions

The adsorption of polyvinylpyrrolidone (PVP) and poly(dimethyldiallylammonium chloride) (PDC) on silica from their mixed aqueous solutions has been investigated as a function of PVP concentration in the presence of PDC. The adsorption of PVP is almost unchanged with the feed concentration of PVP, while the adsorption of PDC decreases with increasing PVP concentration, especially at high concentrations of PDC. The conformation of PVP in the adsorbed layer on silica is relatively flat at low concentrations of PDC, but is extended in solution at high concentrations of PDC. The stability of the silica dispersion is low and the ζ potential is relatively small at low concentrations of PDC, whereas a stable dispersion is obtained at high concentrations of PDC and the ζ potential is large. Thus the stability of the dispersion is well correlated with the electrostatic repulsion and steric repulsion forces operating at the particles.     

Synthesis of a novel antimicrobial-modified starch and its adsorption on cellulose fibers: part II––adsorption behaviors of cationic starch on cellulose fibers

The adsorption of guanidine polymer modified starches on cellulose fibers was investigated along with the systematic studies on various influencing factors including temperature, pH, ionic strength and charge density of the starches. The AFM results revealed the relationship between the adhesion force and adsorption capacity. The adsorption capacity is not necessarily proportional to the adhesion force. The conditions for achieving the maximum adsorption were: temperature, 40 °C; pH, 6; C_NaCl, 0 mM and charge density, 0.4 meq/g. The corresponding the normalized adhesion force is approximate 1 mN/m. In terms of the surface roughness determined by AFM, it has been proved that adsorbed starches of high charge density tend to form train structure, whereas those of low charge density tend to form tails and loops. Due the comb molecular structure, the adsorption capacity of the novel cationic starch reaches 124.3 mg/g, which is much greater than those reported previously.     

铅-邻苯三酚红络合物吸附波的研究及应用

作者对在0.02mol/l柠檬酸三钠底液中、pH=6.1、Pb-PR络合物吸附波进行了研究,并测定其线性范围,应用于微量铅的测定,其方法回收率在95～104%。