An infrared spectroscopy study of lipid adsorption from hexane onto an acid-activated bleaching clay

The mode of adsorption of oleic acid (OA) (0.05 M), triglyceride (TG) (0.05 M) and phosphatidylcholine (PC) (0.5 mM) from hexane solution onto 0.5 g of an acid-activated bleaching clay was investigated using diffuse reflectance Fourier transform infrared spectroscopy. OA was mostly weakly adsorbed by bound water, with some OA adsorbed to silanol sites through carboxyl carbonyl groups. TG was hydrogen- bonded to surface silanol groups through ester carbonyl groups. The CH₂ stretches indicated that TG was oriented perpendicular or at an angle to the surface. PC phosphate groups were bound by the surface moisture with little interaction with silanol groups. The adsorption mechanism of these lipids contrasts with the adsorption of carotenoid and chlorophyll under the same conditions. These pigments are bound by chemisorption, with catalytic modification often occurring before adsorption.     

Lipid adsorption on commercial silica hydrogels from hexane and changes in triglyceride complexes with time

The structures of and lipid complexes with two commercial silica hydrogels (Trisyl and Sorbsil 40), which contain about 60% moisture, were examined by diffuse reflectance Fourier transform infrared spectroscopy. The spectra suggested that Trisyl contained less moisture than Sorbsil 40. However, the silanol groups of Sorbsil 40 were more active in adsorbing oleic acid, triglyceride, and phosphatidylcholine (PC) from hexane than those of Trisyl. Both adsorbents strongly bound PC through the PC carbonyl and phosphate groups. Lipid adsorption from hexane solution by Trisyl depended solely on trapped moisture, while Sorbsil 40 used moisture and silanol groups on the silica surface. Spectra of triglyceride-silica hydrogel complexes, obtained 24 and 72 h after obtaining the initial spectra, showed that Sorbsil 40 adsorption was by Van der Waals forces, but the triglyceride reoriented over time with an increase in hydrogen bonding. In contrast, Trisyl initially adosorbed triglyceride by hydrogen bonding which was stable for at least 72 h.     

Diffuse-reflectance Fourier-transform infrared spectroscopy of vegetable oil triglyceride adsorption on silicic acid

The adsorption of triglyceride by silicic acid from hexane miscellas was observed with diffuse-reflectance Fouriertransform infrared spectroscopy. Triglyceride was adsorbed by hydrogen bonding to silanol groups through the ester carbonyl group. Addition of isopropanol (IPA) to the triglyceride-hexane solution prior to adsorption resulted in unchanged triglyceride adsorption on silicic acid despite IPA's ability to adsorb on silicic acid and hydrogen-bond with triglyceride. Washing the triglyceride, adsorbed on silicic acid, with hexane containing IPA resulted in partial desorption of the triglyceride and a small amount of IPA being adsorbed. Triglyceride desorption into fresh hexane-IPA is due to the establishment of a new equilibrium of lipid and IPA between hexane and silicic acid. The relative strengths of all the possible pairwise interactions among triglyceride, IPA and silicic acid are revealed by the relative amounts of adsorption under various conditions.     

Preparation of molecular dispersed polymer blend composed of polyethylene and poly(vinyl acetate) by in situ polymerization of vinyl acetate using supercritical carbon dioxide

A novel polymer blend comprising polyethylene (PE) and poly(vinyl acetate) (PVAc) with a biocompatible surface was developed for fabricating medical devices. This blend was obtained by a new synthetic method using supercritical carbon dioxide fluid. Further, the acetyl group on the surface of this blend was converted to the hydroxyl group following the phosphorylcholine (PC) group. Surface analysis of the blend with attenuated total reflection Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and dynamic contact angle measurement revealed that the PC groups were located on the surface. Biocompatibility was evaluated by the adsorption of the bovine serum albumin and bovine plasma fibrinogen on the sheet surface. The hydrophilicity of the blend depended on the surface chemical structure introduced by surface reactions. Plasma protein adsorption decreased with the surface hydrophilicity. The PC groups were highly effective in reducing protein adsorption. We conclude that our process is a promising procedure for synthesizing new polymer materials including biomaterials.     

Diffuse reflectance Fourier transform infrared spectroscopy of oleic acid adsorption on silicic acid

Diffuse reflectance Fourier transform infrared spectroscopy was used to observe adsorption complexes of oleic acid and isopropanol (IPA) on silicic acid in hexane. The spectra provide definite evidence of the molecular nature of the surface interaction. In addition, the effect on oleic acid adsorption of modifying the solvent with IPA, which competes for adsorption sites and modifies the solvent polarity, was studied. Oleic acid adsorption was reduced in the presence of an equimolar IPA concentration in hexane, relative to that from hexane alone. This could be explained by a combination of competitive adsorption of IPA and IPA interacting with oleic acid in solution. IPA, in solution, and silica are probably competing for the lipid. This is additional evidence that suggests that lipid adsorption onto silicic acid is influenced by competitive adsorption. The adsorption of oleic acid and IPA, from a mixture of the two in hexane, was controlled by (i) the equilibrium between surface-bound species and molecules in solution and (ii) the polar interaction between oleic acid and IPA in solution. Thus, washing pre-bound oleic acid with hexane removed only a small amount of oleic acid, while washing with a solution of IPA in hexane removed most of the pre-bound oleic acid.     

Adsorptive Behavior of Phosphate onto Activated Carbons Varying Surface Physicochemical Properties

This study demonstrated the modification of commercially available activated carbons (CS and R1) by de-ashing (DA), oxidation (Ox) and outgassing (OG) treatment to possess different surface area, pore volume, and the amount of surface functional groups, and these parameters were related to the efficiency of phosphate removal. The results showed that positively charged carbon surface due to the adsorption of protons to the basic sites resulted in the promotion of phosphate adsorption, that is, the extent of the surface area with the basic sites such as Cπ electrons and/or basic oxygen groups would enable to enhance the efficiency of phosphate adsorption.     

氢氧化锆及其焙烧产物对磷酸根的吸附特性研究

以氢氧化锆作为吸附水溶液中磷酸根的吸附剂,考察了氢氧化锆在不同焙烧温度下的分子式及其对磷酸根吸附效果的影响。通过正交试验确定了最佳实验条件,此条件下氢氧化锆的吸附量为210.9 mg/g。经100、200、300、400、500、600 ℃焙烧后的氢氧化锆对磷酸根的吸附量随温度升高逐渐减小;氢氧化锆经700 ℃焙烧后,焙烧产物氧化锆不具有吸附性。TG、XRD分析表明,随着焙烧温度的升高,氢氧化锆的表面活性基团（-OH）数量逐渐减少。结果表明,吸附剂表面羟基的数量直接影响吸附剂的吸附性。     

Fire‐retardant action of resorcinol bis(diphenyl phosphate) in PC–ABS blend. II. Reactions in the condensed phase

The thermal decomposition of polycarbonate (PC), PC containing resorcinol bis(diphenyl phosphate) (RDP), and PC—acrylonitrile–butadiene–styrene (PC–ABS) blend containing RDP was studied by thermogravimetry. Volatile and solid products of thermal decomposition were collected at different steps of thermal decomposition and characterized either by gas chromatography–mass spectrometry or infrared and chemical analysis. It was found that phosphorus accumulates in the condensed phase. Upon combustion of the fire‐retardant mixture PC–ABS + RDP, accumulation of phosphorus is observed in the charred layer, at the surface of the burning specimens. It is suggested that PC undergoes a Fries‐type rearrangement upon thermal decomposition, and RDP reacts with the formed phenolic groups through a trans‐esterification mechanism. Kinetic analysis of the thermal decomposition of PC containing RDP supports the proposed mechanism. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1863–1872, 1999     

包埋型单宁酸铁制备及吸附催化脱氮性能研究

单宁酸铁(TA-Fe)具有吸附催化脱氮性能,包埋型TA-Fe可解决其固液分离问题。采用海藻酸钠(SA)制备包埋型SA/TA-Fe,并对其特性进行表征,同时评价SA/TA-Fe的吸附催化脱氮性能,以及制备条件对SA/TA-Fe的吸附催化脱氮性能的影响。结果表明,SA/TA-Fe具有明显孔隙结构且TA-Fe存在于孔隙表面,但比表面积明显下降。SA/TA-Fe对NH4⁺-N和NO₂^--N均具有吸附能力,但吸附能力低于TA-Fe,同时对NH4⁺-N的吸附能力大于NO₂^--N。包埋后TA-Fe对吸附NO₂^--N的影响更为显著。SA/TA-Fe对NH4⁺-N和NO₂^--N具有吸附催化能力,可同步提高NH4⁺-N和NO₂^--N的去除量。采用20 g/L的SA溶液,按照TA-Fe和SA质量比为2:1,交联时间为12 h,制得的SA/TA-Fe对NH4⁺-N和NO₂^--N的吸附催化去除效果最佳。     

Interactive transport of guanidinylated poly(propylene imine)-based dendrimers through liposomal and cellular membranes

The ability of guanidinylated poly(propylene imine) dendrimers to translocate across lipid bilayers was assessed by employing either a model phosphate-bearing liposomal membrane system or A549 human lung carcinoma cells. Two dendrimer generations, differing in the number of surface guanidinium groups, were employed, while surface acetylation or the use of spacers affected the binding of the guanidinium group to the phosphate moiety and finally the transport efficiency. Following adhesion of dendrimers with liposomes, fusion or transport occurred. Transport through the liposomal bilayer was observed at low guanidinium/phosphate molar ratios, and was enhanced when the bilayer was in the liquid-crystalline phase. For effective transport through the liposomal membrane, an optimum balance between the binding strength and the degree of hydrophobicity of the guanidinylated dendrimer is required. In experiments performed in vitro with cells, efficient penetration and internalization in subcellular organelles and cytosol was observed.     

Competitive adsorption between superplasticizer and retarder molecules on mineral binder surface

In a self-levelling mortar based on the ternary binder system ordinary Portland cement (OPC), calcium aluminate cement (CAC) and anhydrite, a polycarboxylate-based superplasticizer (PC) showed no plasticizing effect in combination with citrate retarder while good flowability was observed with tartrate. The mechanism behind the incompatibility between PC and citrate was investigated by means of adsorption and zeta potential measurements. Also, anionic charge densities of the admixtures were compared. Adsorption measurements revealed that, in presence of citrate, PC adsorption drops dramatically to less than 10% of dosage added, implying a complete loss of fluidity in the paste. In presence of tartrate, however, PC adsorption remains high enough to still provide good flowability. In contrast, adsorption of casein biopolymer is not much affected by addition and type of retarder. Thus it provides high fluidity with both retarders. Comparison of specific anionic charge density of Ca²⁺ retarder complexes and PC reveals a direct correlation between their adsorption behaviour and anionic charge density. Admixtures with higher anionic charge density show higher affinity to the binder surface and thus adsorb preferredly. When several admixtures are present, molecules with lower anionic charge density will adsorb only if, after adsorption of the admixture with higher anionic charge, a cationic surface charge and enough adsorption area still exists. The incompatibility problem between PC and citrate in the self-levelling mortar formulation was solved by increasing the anionic charge density of the PC molecule. Similar to casein, adsorption of this modified PC is not much influenced by retarder molecules.     

Use of sodium alginate biopolymer as an extracting agent of methylene blue in the polymer-enhanced ultrafiltration technique

In this study, the removal of methylene blue (MB) cationic dye from an aqueous solution was investigated using the polymer-enhanced ultrafiltration (PEUF) technique with sodium alginate (SA) as an extracting soluble polymer, in combination with an ultrafiltration membrane of regenerated cellulose with a 10 kDa molar mass cut-off. SA was characterized via Fourier-transform infrared spectroscopy and thermogravimetric analysis. For ultrafiltration studies, the washing method was used to evaluate various experimental variables, such as the pH, SA dose and initial MB concentration, and adsorption isotherms to identify the optimal adsorption conditions. Finally, the regeneration of the SA polymer was evaluated in five consecutive cycles of adsorption–desorption of MB. In the obtained characterization results, the structural composition of SA and the characteristic thermal stability of the polymer were verified. The PEUF results demonstrated that a retention capacity of 98% of the MB was realized at pH 8.0 using 0.025 g of SA at an initial optimal MB concentration of 50 mg L⁻¹. It is possible to observe that the Freundlich model better explain the interaction between the dye and the polymer surface. According to the results is demonstrated the regeneration capacity of the polymer and its subsequent reuse.     

Quaternized Three-Dimensionally Ordered Macroporous Cross-Linked Polystyrene and its Adsorption Character toward Salicylic Acid in Aqueous Solution

Three-dimensionally ordered macroporous cross-linked polystyrene loaded with quaternary ammonium groups (3DOM CLPS-QA) was prepared for using as a novel adsorbent. The performance of 3DOM adsorbent was evaluated by adsorbing salicylic acid (SA) in aqueous solution. Adsorption isotherm and kinetics were investigated under different temperatures (293 K, 303 K, 313 K). The rising temperature led to a significant increase in the adsorption capacity towards SA, and 3DOM CLPS-QA exhibited a high adsorption capacity (317.86 mg/g when the initial concentration of SA was 500 mg/L at 303 K). Moreover, the effect of solution pH on adsorption indicated that the charge interaction was the dominating driving force for the adsorption of SA onto 3DOM CLPS-QA from the aqueous solution. The 3DOM adsorbent was also reusable and could be regenerated by 0.1 M hydrochloric acid solution. After reusing for six times, the adsorption capacity still maintained about 80% of the original capability.     

The effect of added solvents on soy oil lutein adsorption by silicic acid

It has been reported that addition of isopropanol to a soy oil miscella inhibits the binding of soy lutein to added silicic acid by competitive adsorption. It was suggested that the competition was based on the polarity of the miscella constituents. This investigation studied the effects of a homologous series of lower alcohols to competitively inhibit lutein binding to silicic acid from a soy oil hexane miscella. Lutein binding inhibition by molecules of carbon chains with the same lengths, but with different functional groups, was also examined. Minor differences were found between members of a homologous series of alcohols. A similar result was found with short-chain fatty acids. The ability of various functional groups to displace lutein from silicic acid was dependent on the molecules’ ability to form hydrogen bonds, rather than on polarity.     

ZnAl类水滑石制备温度对吸附剩余污泥脱水液中磷酸根的影响

A group of Zn-Al layered double hydroxides (LDHs) were synthesized at different temperatures from 25–90 °C in order to investigate the influence of synthesis temperature on characteristics of the LDHs and their phosphate adsorption behaviour. The results reveal that an increase in the synthesis temperature generally improves the specific surface area of the sample and the phos-phate adsorption capacity. The significantly enhanced crystallinity of the Zn-Al-30, synthesized at 30 °C, leads to a remarkable de-crease in the specific surface area and consequently a poor phosphate adsorption capacity. It is suggested that the surface adsorption plays an important role in the phosphate uptake by the Zn-Al LDHs. Zn-Al-70 presents a relatively higher crystallinity and a lower specific surface area, compared with Zn-Al-60 and Zn-Al-80, but the highest phosphate adsorption capacity, indicating that surface adsorption is only one of the pathways for phosphate removal. The phosphate adsorption by the Zn-Al follows a pseudo-second-order kinetic equation. The adsorption isotherms fit Langmuir models, and the maximum adsorption capacities of the Zn-Al-25, Zn-Al-50 and Zn-Al-70 are estimated to be 17.82, 21.01 and 27.10 mg•g1 adsorbent, respectively.     

Fabrication of a novel cellulose acetate imprinted membrane assisted with chitosan‐wrapped multi‐walled carbon nanotubes for selective separation of salicylic acid from industrial wastewater

Highly selective cellulose acetate (CA) blend imprinted membranes for salicylic acid (SA) removal were synthesized by phase inversion technique with chitosan as a functional polymer and chitosan‐wrapped multi‐walled carbon nanotubes (CHI‐wrapped MWCNTs) as the additives. The surface and cross‐sectional morphology of membranes were strongly affected by the amount of CHI‐wrapped MWCNTs. As compared to M₁‐MIM, M₂‐MIM, and M₄‐MIM, the M₃‐MIM with 2.0 wt % CHI‐wrapped MWCNTs showed higher membrane flux, faster kinetic, binding capacity and better selectivity for SA. The experimental data of adsorption kinetic were well fitted to the pseudo‐second‐order kinetic model by multiple regression analysis. The M₃‐MIM had the maximum adsorption capacity for SA. The selectivity coefficients of SA to p‐hydroxybenzoic acid (p‐HB) and acetylsalicylic acid (ASA) over M₃‐MIM were 6.3090 and 6.0019, respectively, showing that M₃‐MIM had excellent binding affinity and selectivity for separation of SA from SA‐contained aqueous solution. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42654.     

Computer simulation of proteins adsorption on hydroxyapatite surfaces with calcium phosphate ions

Protein adsorption plays a key role in determining the biological properties of calcium phosphate biomaterials. Calcium (Ca) and phosphate (P) ions are involved in the protein adsorption process and influence the protein adsorption behaviors. In this study, the proteins adsorption on hydroxyapatite (HA) (001), (100), (110), (010) surfaces with Ca, P ions in solution were investigated by Molecular Dynamics (MD) simulation. The results reveal that basic proteins were more favorable to adsorb on HA surface than acidic proteins. HA (110) surface absorbed more acidic proteins than HA (001) and (100). HA (010) surface adsorbed more basic protein. Basic residues play a more important role than acidic residues in the adsorption process, as the basic residues have shown higher absorption energy than acidic residues, and they were more likely to adsorb on HA surfaces than to bind P ions in solution. Most of the active sites of protein, especially for acidic residues, are prefer to interact with HA surface through water molecules. Basic residues are more likely to adsorb onto HA surfaces directly. The presence of Ca, P ions in solution can influence the adsorption behaviors of protein. The formation of Ca, P ion cluster may lead to desorption of proteins. And they can compete with water molecules to bond to HA surfaces, acting as a bridge of protein interacting with HA surfaces instead of water-bridge. This Ca, P ions bridge connection make the adsorption energy of protein weakened. The results of this study provided new information at atomic/molecular level to further interpret the mechanism of protein adsorption on calcium phosphate surfaces with Ca, P ions. It is also helpful for designing new calcium phosphate biomaterials with specific surface properties to adsorb target protein for biomedical applications.     

海藻酸钠/二氧化硅杂化微球结构与吸附性能

利用海藻酸钠（SA）和正硅酸四乙酯（TEOS）为原料,并利用醇解TEOS提供二氧化硅（SiO₂）源与SA分子结构上的羟基（-OH）进行反应,制备一系列不同组分的杂化微球。采用旋转流变仪（DHR）、傅里叶变换红外光谱（FTIR）、X-射线光谱（XRD）、热重分析仪（TG）、扫描电子显微镜（SEM）和氮气吸附-脱附方法（BET）对杂化溶液的流变性能以及杂化微球的化学结构、结晶能力、热分解能力、微球形貌、比表面积和孔径进行分析,并研究了其对亚甲基蓝（MB）和重金属铜（Cu²⁺）的吸附能力。结果表明：SA/SiO₂杂化溶液体系黏度下降,在初始剪切速率25s^-1时杂化溶液黏度比SA黏度低了2.2Pa·s;FTIR图说明SA中羟基与TEOS中的硅氧键反应生成硅氧碳键,TEOS与SA发生化学反应;杂化微球结晶曲线中CA结晶特征峰强度降低,同时出现SiO₂的结晶特征峰;杂化微球分解温度由250℃提升到310℃,热分解温度提高;BET测试得到海藻酸钙（CA）比表面积为7.254m²/g,孔径为19.65nm,CA/SiO₂杂化微球的比表面积为49.151m²/g,孔径为21.75nm,杂化微球比表面积提高,孔径类型为介孔;当MB初始浓度为100mg/L时,SA/SiO₂杂化微球去除率达到87.09%;当Cu²⁺初始浓度为2.5g/L时,SA/SiO₂杂化微球去除率达到86.8%。     

Selective adsorption for indium(III) from industrial wastewater using chemically modified sawdust

Abstract-To selectively adsorb indium(III) in industrial wastewater coexisting with zinc(II), the surface of sawdust was modified into phosphate groups through chemical reaction. Among various manufacturing methods, phosphorylated sawdsust made from using non-grinding sawdust with same ratio (based on volume) of H₃PO₄ and distilled water had a very high selectivity to indium(III), which shows removal efficiency of about 90% with 1.0 g at pH 3.5. Meanwhile, in case of zinc(II), there is almost no adsorption onto phosphorylated sawdust. The surface condition and phosphorus content of phosphorylated sawdust were analyzed by scanning electron microscopy (SEM) photograph and energy dispersive x-ray (EDX) spectrum. Also, the effects of loading of adsorbent and time on selective adsorption characteristics of indium(III) were investigated.     

Synthesis and properties of geminis with two alkyl and two phosphate headgroups

Amphipathic compounds having two phosphate groups and two long‐chain alkyl groups were prepared by a two‐step process: (a) preparation of monoalkyl phosphate from pyrophosphoric acid and dodecanol, (b) preparation of bis‐phosphoric acid from monoalkyl phosphate, (CH₃)₄NOH and 1,6‐dibromo hexane by using acetonitrile as solvent. The experimental results showed that a 5 : 10 : 2.5 molar ratio of reactants (alkyl phosphate/(CH₃)₄NOH/1,6‐dibromo hexane) and 3 h duration was the optimum for the reaction. The structure of the synthesized product was verified by analytical methods, viz. FT‐IR and ¹H‐NMR. The surface‐active and performance properties like foaming, wetting and anionic content of the disodium salt of bis‐phosphoric acid were also evaluated. The synthesized anionic gemini surfactants possessed maximum anionic content, i.e. 73.4%, and showed better water solubility, foaming and wetting ability than conventional monoalkyl phosphates.