Mixed adsorption of poly(vinylpyrrolidone) and sodium dodecylbenzenesulfonate on kaolinite

The mixed adsorption of the nonionic polymer poly(vinylpyrrolidone) (PVP) and the anionic surfactant sodium dodecylbenzenesulfonate (SDBS) on kaolinite has been studied. Both components adsorb from their mixture onto the clay mineral. The overall adsorption process is sensitive to the pH, the electrolyte concentration, and the amounts of polymer and surfactant. Interpretation of the experimental data addresses also the patchwise heterogeneous nature of the clay surface. In the absence of PVP, SDBS adsorbs on kaolinite by electrostatic and hydrophobic interactions. However, when PVP is present, surfactant adsorption at 10(-2) M NaCl is mainly driven by charge compensation of the edges. The adsorption of PVP from the mixture shows similar behavior under different conditions. Three regions can be distinguished based on the changing charge of polymer-surfactant complexes in solutions with increasing SDBS concentration. At low surfactant content, PVP adsorbs by hydrogen bonding and hydrophobic interactions, whereas electrostatic interactions dominate at higher surfactant concentrations. Over the entire surfactant concentration range, polymer-surfactant aggregates are present at the edges. The composition of these surface complexes differs from that in solution and is controlled by the surface charge.     

Surface properties of poly(N-monoalkylmaleamic acid-alt-styrene) sodium salts: effect of the molecular weight and the side chain length

The surface properties of poly(N-monoalkylmaleamic acid-alt-styrene) sodium salts are studied as a function of the molecular weight and the size of the linear alkyl lateral chain of the polyelectrolyte. The experimental results are well described by the Gibbs-Szyszkowski treatment. Both the surface tension behavior and the standard free energy of adsorption depend on the polyelectrolyte side chain and on the average molecular weight, M(w). An M(w)-dependent contribution to the free energy of adsorption ranging from -1.21 to -1.05 kJ for mole of methylene groups is found. The area covered by monomer units increases with M(w) and the sizes of side chains are similar to those reported in small-molecule systems. The nature of the functional group amide in the side chain has practically no effect on the surface properties as compared with the ester group in this kind of polyelectrolytes.     

Synchronous multilayered adsorption of macrocations and macroanions on colloidal spheres. Influence of foreign salt and basicity or acidity of the macroions

The influence of foreign salt, the basicity or the acidity of macroions and the equivalency of the number of ionic groups of macrocations and macroanions upon alternate multiple adsorption on surfaces of colloidal silica (CS91, 110 nm in diameter) and polystyrene spheres (D1A19, 220 nm) have been studied by electrophoretic light scattering measurements. The macrocations used were poly(4-vinyl-N-n-butyl pyridinium bromide (C4PVP, strongly basic), poly(4-vinyl-N-ethyl pyridinium bromide (C2PVP, strongly basic) and poly(allylamine) (PAL, weakly basic). Sodium poly(styrene sulfonate) (NaPSS, strongly acidic) and sodium polyacrylate (NaPAA, weakly acidic) were used as macroanions. The alternate adsorption disappears even in the presence of a small amount of sodium chloride. The alternate multiple adsorption takes place on the addition of C4PVP first and NaPSS next, PAL first and NaPAA next, NaPAA first and C4PVP next, and NaPAA first and PAL next on the CS91 spheres. The influence of the equivalency of the number of ionic groups of C2PVP and NaPAA has been studied for the adsorption on the D1A19 spheres. The synchronous delicate balancing of the electrostatic interactions among the macrocations, the macroanions and the surfaces of the colloidal spheres is important for the alternate multiple adsorption.     

几种天然矿物脱除高温气体中碱蒸气研究

在实验室条件下用六种天然矿物对高温气体中碱蒸气的脱除进行了研究比较，结果得出高岭土具有最高的碱容量；实验表明吸附剂对碱蒸气的吸附不仅与吸附剂的化学成分有关，还与吸附剂的孔结构有关；同时讨论了反应温度、气体流速以及反应时间对高岭土碱容量的影响，并研究了850 ℃，气体流速为11.0 m/h时高岭土与碱蒸气的反应动力学，得出反应同时受化学反应和产物层的扩散所控制。     

The solution behavior of poly(vinylpyrrolidone): its clouding in salt solution, solvation by water and isopropanol, and interaction with sodium dodecyl sulfate

This article deals with the solution properties of poly(vinylpyrrolidone) (PVP) in salt and surfactant environment. The cloud point (CP) of PVP has been found to be induced by the salts NaCl, KCl, KBr, Na2SO4, MgSO4, and Na3PO4. On the basis of CP values for a salt at different [PVP], the energetics of the clouding process have been estimated. The effect of the surfactant, sodium dodecyl sulfate (SDS), on the salt-induced CP has also been studied, and reduction in CP at low [SDS] and increase in CP at high [SDS] have been observed. The water vapor adsorption of PVP has been determined by isopiestic method. The results display a BET Type III isotherm whose analysis has helped to obtain the monolayer capacity of PVP and formation of multilayer on it. The solvation of PVP in a solution of water and a water-isopropanol mixture has been determined by conductometry from which contribution of the individual components were estimated. The interaction of PVP with SDS in solution led to formation of a complex entity, which has been studied also by conductometry adopting a binding-equilibrium scheme. SDS has been found to undergo two types of binding as monomers in the pre- critical aggregation concentration (CAC) range and as small clusters in the post CAC region. The stoichiometries of binding and binding constant were evaluated.     

表面活性剂和聚乙烯吡咯烷酮在ZrO2上的吸附对其悬浮体稳定性的影响

研究了水溶液中十二烷基苯磺酸钠（ＳＤＢＳ）、溴代十四烷基吡啶（ＴＰＢ）和聚乙烯吡咯烷酮（ＰＶＰ）在ＺｒＯ２上的吸附及对ＺｒＯ２水悬浮体稳定性的影响。结果表明：ｐＨ＝２．４时ＳＤＢＳ在ＺｒＯ２上的吸附等湿线为ＬＳ型，ｐＨ＝７．０时ＴＰＢ的吸附等温线为Ｓ型，吸附等温线与ＺｒＯ２粒子ζ电势变化同线有大体一致的关系。在最大吸附量时ＺｒＯ２粒子ζ电势较大，且吸附的表面活性剂离子形成大部分亲水基朝向水相的表面     

Anionic surfactant adsorption on to asphalt-covered clays

Asphalt adsorption from from water-saturated tolene on Na⁻ kaolinite, Ca²⁻ kaolinite, Na⁻ illite and Ca²⁻ illite clays was investigated. It was found that the kaolinite surface adsorbed more asphalt than illite for both the Na⁻ -and the Ca²⁻ exchanged forms. Adsorption from aqueous solutions of sodium dodecylbenzenesulphonate (SDBS) and sodium dodecyl sulphate (SDS) on various asphalt-covered clays was also studied. The shape of the isotherms depended on the asphalt-clay substrate and showed a much lower adsorption of SDBS beyond the CMC. Desorption of asphalt from various clays with SDBS and SDS surfactants was measured spectrophotometrically. The percentage weight of asphalt desorbed with SDBS was twofold higher than that desorbed with SDS surfactant.     

硫酸铵介质中阴离子型聚丙烯酰胺分散液的制备和表征

以硫酸铵(AS)水溶液为反应介质、聚乙烯吡咯烷酮(PVP)为分散剂进行丙烯酰胺(AM)与丙烯酸(AA)的分散聚合,制备了阴离子型聚丙烯酰胺(APAM).研究了硫酸铵浓度、单体配比、体系pH和分散剂PVP用量等对聚合产物特性黏数、溶解时间、聚合分散液的表观黏度的影响.得到优化条件:w(AS)＝0.26,w(PVP)＝0.04,m(AM)/m(AA)＝4,pH＝6.5.利用傅里叶红外光谱和光学显微镜对所合成的分散液进行了结构表征和形态分析,表明生成的产物是微球表面较光滑的APAM分散液.     

Successive interaction of pairs of soluble organics with nanosilica in aqueous media

Successive interaction of different pairs of water-soluble polymers (poly(ethylene glycol) (PEG), poly(vinyl pyrrolidone) (PVP), poly(vinyl alcohol) (PVA)), proteins (bovine serum albumin (BSA), ovalbumin, gelatin, and ossein), and smaller organics such as lecithin (1-stearoyl-2-oleoyl phosphatidylcholine, SOPC) and Aethonium (1,2-ethylene-bis(N-dimethyl carbodecyl oxymethyl) ammonium dichloride) with nanosilicas A-300 (S(BET)=232 and 297 m(2) g(-1)) and A-50 (S(BET)=52 m(2)g(-1)) was studied using dynamic light scattering, adsorption, and infrared (FTIR) spectroscopy methods. Time-dependent rearrangement of particle size distributions (PSDs) depicts appearance of both smaller and larger aggregates for silica/PEG(I-first adsorbate)/BSA(II-second adsorbate) and silica/PVP(I)/BSA(II) (i.e., BSA adsorbs onto PEG/silica or PVP/silica) than that for silica/organic compound I. However, in the cases of PVA(I)-BSA(II) and PVA(I)-SOPC(II) a similar effect is not observed because only increased aggregation occurs. The successive equilibrium adsorption of similar pairs shows a diminution of the adsorption of the second compound (gelatin, ovalbumin) with increasing amount of the first adsorbed polymer (PEG or PVP).     

Theoretical Study About Effects of H2O and Na+ on Adsorption of CO2 on Kaolinite Surfaces

The density functional theory(DFT) was used to investigate the adsorptions of carbon dioxide(CO₂) on kaolinite surfaces and the influences of Na⁺ and H₂O on the adsorption. Both cluster and periodic models of kaolinite were considered. The calculated results indicate that stable complexes can be formed between adsorbed CO₂ and the surfaces of kaolinite in the presence or absence of sodium cation and water molecule. The Al-O octahedral surface has a larger adsorption affinity for CO₂ than the Si-O tetrahedral surface of kaolinite because the hydroxyl groups of kaolinite Al-O surface present more activity than the basal O atoms of the Si-O tetrahedral surface in the inter-molecular interactions. The existence of exchangeable sodium cations exerts the significant effect on the adsorption of CO₂ with the dramatic increase of the adsorption energy, while the presence of water molecule decreases the adsorption strength insignificantly. The calculated Gibbs free energies of the adsorption reveal that the adsorptions of CO₂ on all the investigated kaolinite surfaces are feasible thermodynamically in the gas phase. Surface free energy was calculated to provide the predictions of the surface stability as a function of temperature.     

Effect of polyvinylpyrrolidone and sodium lauroyl isethionate on kaolinite suspension in an aqueous phase

Suspension of concentrated kaolinite (20 g/30 ml-medium) in the presence of polyvinylpyrrolidone (PVP) and sodium lauroyl isethionate (SLI) was allowed to evaluate its degree of dispersion based on their rheological studies. Flow curves at low shear rate, measured by means of cone-plate method, showed a non-Newtonian flow. Plastic viscosity and Bingham yield value were derived from the flow curves. Relative viscosity, effective volume fraction and void fraction of secondary particle were also obtained. Results of dispersity and fluidity of the suspension were explained. PVP acted as a flocculant at a concentration lower than 0.1% but as a dispersant at a higher concentration. The presence of SLI could decrease both the Bingham yield value and suspension viscosity. Cooperative and competitive effects of PVP and SLI were found. Results indicated that SLI enhanced the degree of dispersion of kaolinite when PVP was less than 0.1%. The suspension, however, showed a maximum flocculation (i.e., aggregation) at 4 mM SLI when the concentration of PVP was higher than 0.1%.     

Adsorption of cadmium(II) onto goethite and kaolinite in the presence of benzene carboxylic acids

The effect of benzene carboxylic acids on the adsorption of Cd(II) (5×10⁻⁵ M) by goethite and kaolinite has been studied in 0.005 M NaNO₃ at 25°C. The concentrations of phthalic (benzene-1,2-dicarboxylic acid), hemimellitic (1,2,3), trimellitic (1,2,4), trimesic (1,3,5), pyromellitic (1,2,4,5) and mellitic (1,2,3,4,5,6) acids varied from 2.5×10⁻⁵ to 1×10⁻³ M. Mellitic acid complexes Cd(II) strongly above about pH 3, but the other acids only at higher pH, phthalic acid forming the weakest complexes. Phthalic, trimesic and mellitic acids adsorbed strongly to goethite at pH 3, but adsorption decreased at higher pH; however, mellitic acid was still about 50% adsorbed at pH 9, by which the other two were almost entirely in solution. At 10⁻³ M all the acids enhanced the adsorption of Cd(II) to goethite, the higher members of the series being the most effective. The higher members of the series suppressed Cd(II) adsorption onto kaolinite, but phthalic and trimesic acids caused slight enhancement. The effects of mellitic acid on Cd(II) adsorption depended strongly on its concentration. The maximum enhancement of Cd(II) adsorption onto goethite was at 10⁻⁴ M. The greatest suppression of Cd(II) adsorption onto kaolinite was at 10⁻³ M, and at 2.5×10⁻⁵ M mellitic acid enhanced Cd(II) adsorption onto kaolinite at intermediate pH. The results are interpreted in terms of complexation between metal and ligand (acid), metal and substrate, ligand and substrate, and the formation of ternary surface complexes in which the ligand acts as a bridge between the metal and the surface.     

Surfactant--polymer aggregates formed by sodium dodecyl sulfate, poly(N-vinyl-2-pyrrolidone), and poly(ethylene glycol)

The interaction of sodium dodecyl sulfate (SDS) in aqueous solution with poly(N-vinyl-2-pyrrolidone) (M(w) = 55,000 g/mol) in the presence of poly(ethylene glycol) (M(w) = 8000 g/mol) is investigated by electrical conductivity, zeta potential measurements, viscosity measurements, fluorescence spectroscopy, and small-angle X-ray scattering (SAXS). The results indicate that SDS-polymer interaction occurs at low surfactant concentration, and its critical aggregation concentration is fairly dependent on polymer composition. The polymer-supported micelles have average aggregation numbers dependent on surfactant concentration, are highly dissociated when compared with aqueous SDS micelles, and have zeta potentials that increase linearly with the fraction of PVP at constant SDS concentration. The analysis of the SAXS measurements indicated that the PVP/PEG/SDS system forms surface-charged aggregates of a cylindrical shape with an anisometry (length to cross-section dimension ratio) of about 3.0.     

"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。     

Interaction of radium with freshwater sediments and their mineral components

Radiotracer method has been used for investigation of the adsorption and desorption of traces of radium on kaolinite and montmorillonite under conditions similar to those prevailing in waste and surface waters. It has been found that adsorption depends on the pH and ionic strength of the solution, and the character of these dependences is different for kaolinite and montmorillonite. Sulfates at concentration 60 mg·l^–1 have negligible effect on the adsorption. Montmorillonite represents better adsorbent for radium than kaolinite, but both minerals may significantly affect the form and migration of radium in surface waters, if present as (major) components of freshwater sediments. Radium can be quantitatively desorbed by 1M HCl from kaolinite but not from montmorillonite. The desorption by 0.1M NaCl is generally lower and depends on the pH during the preliminary adsorption. Mechanisms of radium adsorption on both minerals and the character of the adsorption sites are discussed.     

Preferential adsorption of extracellular polymeric substances from bacteria on clay minerals and iron oxide

The adsorption of extracellular polymeric substances (EPS) from Bacillus subtilis on montmorillonite, kaolinite and goethite was investigated as a function of pH and ionic strength using batch studies coupled with Fourier transform infrared (FTIR) spectroscopy. The adsorption isotherms of EPS on minerals conformed to the Langmuir equation. The amount of EPS-C and -N adsorbed followed the sequence of montmorillonite>goethite>kaolinite. However, EPS-P adsorption was in the order of goethite>montmorillonite>kaolinite. A marked decrease in the mass fraction of EPS adsorption on minerals was observed with the increase of final pH from 3.1 to 8.3. Calcium ion was more efficient than sodium ion in promoting EPS adsorption on minerals. At various pH values and ionic strength, the mass fraction of EPS-N was higher than those of EPS-C and -P on montmorillonite and kaolinite, while the mass fraction of EPS-P was the highest on goethite. These results suggest that proteinaceous constituents were adsorbed preferentially on montmorillonite and kaolinite, and phosphorylated macromolecules were absorbed preferentially on goethite. Adsorption of EPS on clay minerals resulted in obvious shifts of infrared absorption bands of adsorbed water molecules, showing the importance of hydrogen bonding in EPS adsorption. The highest K values in equilibrium adsorption and FTIR are consistent with ligand exchange of EPS phosphate groups for goethite surface. The information obtained is of fundamental significance for understanding interfacial reactions between microorganisms and minerals.     

In situ FTIR spectroscopic study of the effect of CO2 sorption on H-bonding in PEG-PVP mixtures

A study of the H-bonding between poly(ethylene glycol) (PEG) and polyvinylpyrrolidone (PVP) in the presence of supercritical carbon dioxide at various temperatures, pressures, different M(w) of PEG and PVP and different PEG/PVP ratios is presented. In situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was used to investigate H-bonding by examining changes in the relative intensities and positions of peak maxima of the 2nd derivative ν(C=O) bands associated with 'free' and H-bonded C=O groups. In general, relative intensities of bands associated with H-bonded CO groups decreased upon CO(2) sorption and was accompanied by an increase in intensity of bands associated with 'free' C=O groups. At the same time, these bands were shifted to higher wavenumbers. These shifts were attributed to the shielding effect of CO(2) molecules on H-bonding interactions between PEG and PVP. The magnitude of the effects of CO(2) shielding generally increased with decreasing polymer M(w) and increasing CO(2) content. However, upon CO(2) venting the extent of the H-bonding between PEG and PVP reappeared. The extent of H-bonding recovery was greatest for blends with low M(w) PEG (M(w): 4×10(2)) and PVP (M(w): 9×10(3)) and PEG content ≥0.54 wt% under mild conditions of pressure (80 bar) and temperature (35°C). For the same low M(w) blends, increasing pressure to 150 bar, or temperature to 50°C, showed poor H-bond recovery upon CO(2) venting. Overall, it was shown that supercritical CO(2)-induced shielding of H-bonding interactions in polymer blends is reversible upon CO(2) venting, and the magnitude of both was influenced by processing conditions and blend composition.     

Protein adsorption characteristics of calcium hydroxyapatites modified with pyrophosphoric acids

Protein adsorption characteristics of calcium hydroxyapatite (Hap) modified with pyrophosphoric acids (PP(a)) were examined. The PP(a) modified Hap particles (abbreviated as PP-Hap) possessed anchored polyphosphate (PP: P-{O-PO(OH)}(n)-OH) branches on their surfaces. The proteins of bovine serum albumin (BSA: isoelectric point (iep)=4.7, molecular mass (M(s))=67,200 Da, acidic protein), myoglobin (MGB: iep=7.0, M(s)=17,800 Da, neutral protein), and lysozyme (LSZ: iep=11.1, M(s)=14,600 Da, basic protein) were examined. The zeta potential (zp) of PP-Hap particles as a function of pH overlapped; zp-pH curves were independent of the concentration of pyrophosphoric acids (abbreviated as [PP(a)]) used for modifying Hap surface. The saturated amounts of adsorbed BSA (Delta n(ads)(BSA)) were increased three-fold by the surface modification with PP(a) though they were independent of the [PP(a)]. Furthermore, the fraction of BSA desorption was independent of the [PP(a)]. This enhancement of BSA adsorption onto the PP-Hap is due to the hydrogen bonding between oxygen and OH groups of the PP-branches and functional groups of BSA molecules. In the case of LSZ, a more higher adsorption enhancement was observed; the saturated amount of adsorbed LSZ (Delta n(ads)(LSZ)) for Hap modified at [PP(a)]=6 mmol/dm(3) was nine-fold than that for Hap unmodified. This remarkable adsorption enhancement was explained by a three-dimensional binding mechanism; LSZ molecules were trapped inside of the PP-branches. Hence, a fraction of LSZ desorption was decreased with an increase in the [PP(a)]; as more PP-branches are presented on the surface the higher retardation of LSZ desorption was induced. It was expected from their small size that MGB adsorb between the PP-branches as well as LSZ. However, the amounts of adsorbed MGB (Delta n(ads)(MGB)) did not vary and were independent of the [PP(a)] due to the small numbers of functional groups of MGB. In addition, no dependence of the fraction of MGB desorption on the [PP(a)] was observed. The results of zp for all the protein systems supported the mode of protein adsorption discussed. The anchored structure of the PP-branches developed on the Hap surface to provide three-dimensional protein adsorption spaces was proved by a comparative experiment that was elucidating the effect of pyrophosphate ions for BSA adsorption onto Hap.     

水蒸气对高岭土高温吸附铅的影响

使用沉降炉开展了水蒸气对高岭土高温吸附铅影响的实验研究，其中铅的形态为PbO和PbCl₂两种。首先研究了0-20%水蒸气对高岭土吸附PbO（1100-1300 ℃）和PbCl₂（800-1300 ℃）的影响规律，然后基于XRD、SEM和残余羟基率等分析，掌握了水蒸气影响高岭土高温吸附的机理。结果表明，水蒸气可以减少高岭土表面羟基的高温脱落，从而阻碍了PbO吸附、促进了PbCl₂吸附。综合高温下惰性莫来石的出现和高岭土孔隙结构的坍塌等因素，PbO和PbCl₂的最佳吸附温度分别为1200和1000 ℃。     

Partial specific adsorption of organic molecules in binary mixtures of adsorbents: 2,2'-bipyridine on kaolinite and hematite and 1,10-phenanthroline on montmorillonite and hydroxy-Al montmorillonite

The adsorption of 2,2'-bipyridyl in binary mixtures of sodium kaolinite and hematite at pH 6.6 and of 1,10-phenanthroline in binary mixtures of sodium montmorillonite and hydroxy-Al montmorillonite at pH 7.5 was studied as a function of the equilibrium concentration and composition of the mixture. A model is presented for determining the partial specific adsorption of two adsorbents by each component of the mixture, based on the graphic method for determining partial quantities. The partial specific adsorption values obtained for binary mixtures of Na-kaolinite with hematite and Na-montmorillonite with hydroxy-Al montmorillonite are strongly influenced by the concentration of adsorbates and adsorbents in the mixtures.