Behaviour in solution of humic acids from lignite in the presence of calcium ions

Humic acids (HA) extracted from Spanish lignite, were studied to discover their Ca-complexing capacity and their coagulation threshold. It was found that the concentration of Ca^{+ +} ions necessary for the complete flocculation increased with the increase of pH and ionic strength (μ) and it was linearly dependent on the concentration of HA. The calcium-complexing capacity of HA increased with the increase of pH and registered lower values as μ was increased. The i.r. spectra of the Ca-humic acid complexes show that the metal is complexed mainly by carboxylic groups from the HA.     

Ozonolysis Of Humic Acid And Its Effect On Decoloration And Biodegradability

The objectives of this research were to investigate the reactivity of humic acid (HA) with ozone and to evaluate its effect on decoloration and biodegradability. Reagent HA was selected as a target compound, and the change in overall water quality parameters, molecular weight distribution, color and biodegradability during ozonation were investigated. Partial oxidation such as decoloration was observed, though the complete destruction represented by TOC removal was not significant. The rate of ozone usage decreased as the reaction proceeded. Degradation to the lower molecular weight fragments was confirmed by ultrafiltration. The close relationship between color and fragmentation was verified. Decoloration was represented by a pseudo-first order reaction. Formic, acetic, oxalic and glyoxylic acids were identified by HPLC and ion chromatography as typical low molecular weight organic acids. The biodegradability of ozonated HA solutions, represented in terms of the ratio of BOD₅ to TOC, was improved.     

Organic fouling of RO membranes: Investigating the correlation of RO and UF fouling resistances for predictive purposes

This study examines the characteristics of deposits from dead-end UF and cross-flow RO filtration of dilute mixtures of sodium alginate (SA) and humic acids (HA), which are representative of common foulants in RO and NF feed waters. The data are interpreted in terms of specific cake resistance, α. The presence of alginates in the mixed fouling layers, even in relatively small percentage, imparts characteristic properties to these deposits; i.e. a gel-like structure which is associated with reduced compressibility and permeability. With SA/HA mixtures, high rejection of organic species and high deposition factors are obtained in UF and RO tests, respectively. The specific resistance of mixed SA and HA deposits tends to increase with increasing SA concentration in solution. The resistances α exhibit fairly strong (power law) dependence on the pressure difference across the cake, ΔΡ_c, for both RO and UF tests. The fairly satisfactory correlation of resistance α versus ΔΡ_c data, obtained from both types of tests (for the mixtures of organic species tested at small salinity) is a significant result of this work. Based on this correlation, an approach is suggested for estimating fouling index I and initial membrane fouling rate of a specific RO process, relying on limited UF tests.     

Ozonation of humic acid in water

BACKGROUND: Humic acids (HAs) are heterogeneous macromolecules widely dispersed in natural waters, which display significant resistance to biodegradation. Removal of HA by ozone and its related reaction mechanisms are investigated. RESULTS: Ozonation of HA showed a significant reduction of UV₂₅₄, Color₄₃₆ and had the capability of mineralizing the TOC to CO₂ and improving the biodegradability. Fourier trandform infrared (FT‐IR) spectra, elemental composition analysis and high performance size exclusion chromatography (HPSEC) revealed that ozonation could not only change the structure characteristics but modify the molecular size distribution of HA. Volatile compounds detected by gas chromatography‐mass spectroscopy (GC‐MS) showed that ozonation brought out 43 different organics, which were identified as mainly: aldehydes, ketones, aromatics, carboxylic acids and alcohols. CONCLUSION: Ozonation of HA could be elucidated by the followed mechanism: ozonation with its direct and indirect pathway hydroxylated the HA in water, and polyhydroxy HA was further oxidized to bond rupture leading to the change of molecular structure and size distribution of HA, trimming out a series of small molecular volatile compounds. The volatile compounds with electron denoting group could be further oxidized to acids and esters, and even totally mineralized to CO₂. Copyright © 2007 Society of Chemical Industry     

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.     

Fatty acid esters from betulinol

Betulinol esters were prepared from stearic-, lauric-, palmitic-, oleic- and tall oil fatty acids via the acid-chloride and direct con-densation routes. The degree of esterification was determined by high pressure liquid chromatography (HPLC), infrared (IR) and acid value measurements. The use of esters for air-dried, polyure-thane and plastisol coatings was evaluated.     

CuO/腐植酸复合材料的制备及其吸附性能

采用水热法合成了CuO-腐植酸（HA）纳米复合材料,研究了其对亚甲基蓝的初始吸附性能及再生吸附性能。运用扫描电镜/能谱仪（SEM/EDS）、傅里叶变换红外光谱仪（FTIR）、X射线粉末衍射仪（XRD）、激光粒度分析仪和比表面积测定仪（BET）对其结构进行了表征。研究了pH、亚甲基蓝初始浓度和反应温度等因素对CuO/HA吸附亚甲基蓝的影响,采用多种模型研究了CuO/HA复合材料对亚甲基蓝的吸附动力学和热力学行为。结果表明：合成的CuO/HA平均粒径约为135.0nm,比表面积为188.15m²/g。CuO/HA对亚甲基蓝（MB）的吸附动力学行为符合拟一级动力学模型,在60min内达到吸附平衡,较好地符合Frendlich吸附模型。在室温下pH=7时,CuO/HA复合材料初始饱和吸附量达172.01mg/g;循环使用8次,可保持初始吸附能力的89.27%,表明有较好的吸附性能,可作为一种有效除去水体中亚甲基蓝污染物的高容量吸附材料。     

腐殖酸聚集体对膜蒸馏过程膜污染的作用机理

膜污染是膜蒸馏过程应用于工业水处理中遇到的主要问题之一。选取水体中具有代表性的有机物（腐殖酸）、微溶无机盐（碳酸钙）作为典型污染物,研究有机腐殖酸聚集体对于膜蒸馏过程膜污染进程的影响规律,探讨天然有机物-无机微溶盐混合水体中腐殖酸聚集体对于无机盐结晶过程的控制机理。结果表明：膜蒸馏通量的衰减大致可分为由滤饼层的形成造成的不可恢复部分以及由浓差极化、膜孔“半润湿”而造成的可部分恢复的通量降低。Ca²⁺通过加速腐殖酸分子的聚集过程,使表面负电性降低的腐殖酸聚集体率先吸附在聚偏氟乙烯中空纤维膜内表面,形成有机基质污染层;碳酸钙在有机腐殖酸聚集体的诱导下在膜内表面异相成核,最终成长为稳定的晶体。腐殖酸聚集体为无机盐晶体在疏水性膜内表面的生长提供了异相成核的基础。可通过控制污染水体中有机物的含量控制微溶碳酸钙在膜内表面成核及生长,实现控制其在膜内表面附着进而诱发疏水膜发生亲水化的过程。     

改性腐植酸新型阻垢缓蚀剂的制备及应用

采用溶液共混技术，制备了腐植酸钠（HA）和丙烯酰胺-烯丙基磺酸钠（SAS）共聚物（P(AM-SAS)的共混物（HA/P（AM-SAS）。与HA和P（AM-SAS）相比，HA/P（AM-SAS）共混物具有更好的阻垢，缓蚀和分散能力。当HA/P（AM-SAS）质量比超过1或2时，HA和P（AM-SAS）的共混对于CaCO3和Ca3(PO4)2的阻垢作用表现出了明显的协同效应。     

聚乙二醇对羟基磷灰石纳米晶粒形成的影响

用聚乙二醇(PEG)对羟基磷灰石(HA)进行不同的表面改性处理,考察PEG对HA纳米晶粒形成的影响。以PEG作为反应物媒介对HA进行物理修饰和在HA合成煮沸后加入PEG进行表面修饰。结果表明:以PEG作反应媒介合成HA得到的浆料在静置12 h后能够保持51%的高度,HA颗粒通过一条或多条链串在一起;合成煮沸后加入PEG改性处理得到的HA浆料保持45%的高度,相对于无改性的HA,晶粒明显地呈现针状,但长度相等。改性后均使PEG吸附在HA表面,低温烧结后晶粒结构趋同。PEG作反应媒介,能够阻止HA晶粒的生长,减少晶粒的大小。而合成煮沸后PEG的加入,不影响HA晶粒的生长发育。     

UF membrane fouling by mixtures of humic acids and sodium alginate: Fouling mechanisms and reversibility

The fouling characteristics of ultrafiltration (UF) hollow fibers are studied in dead-end mode, with and without periodic backwashing, by filtering dilute mixtures of humic acids (HA) and sodium alginate (SA) — a polysaccharide — in the presence and absence of calcium ions. The fouling behaviour of the HA/SA mixtures (regarding reversibility by backwashing and flux recovery) is quite similar to that of polysaccharides alone, even when the SA proportion is relatively small. The organic species rejection in filtration of HA/SA mixtures is greater than that for separate HA or SA filtration, increasing with increased polysaccharides concentration in solution. In the presence of Ca²⁺, the cake filtration mechanism dominates; some deviation, at the start of filtration, especially with HA-rich mixtures, is attributed to membrane pore constriction possibly caused by small molecules, not retained by the developing cake. The specific cake resistances of HA/SA mixtures are relatively high and tend to be much closer to those of SA deposits, than to HA layer resistances. The reversibility of mixed fouling layers and the very high flux recovery by backwashing are attributed to their coherent gel-like structure, which is a typical feature of polysaccharides.     

Sorption of humic acids by a zeolite-feldspar-bearing tuff in batch and fixed-bed column

The sorption of humic acids (HA) on zeolite-feldspar-bearing Phlegraean Yellow Tuff enriched with calcium ions has been investigated at neutral pH both on fixed-bed columns and in batch. A two-step sorption kinetics and a relatively long time to reach the equilibrium were observed in batch. In line with this behaviour, the breakthrough curves and shipping curves from exhaust columns showed distinctive properties that cannot be easily modelled by the common mass balance equations; noteworthy, the breakthrough curves were dependent on the space velocity also for very slow processes and the bed sorption capacity decreased linearly with the space velocity. Moreover, after an initial high-rate burst, HA desorption from exhausted columns proceeded at a very slow rate, particularly so for columns loaded with higher amounts of HA.     

Identification of Oxidation Intermediates in Humic Acid Oxidation

The effects of using ultraviolet irradiation (UV), ozone (O₃) and the combined O₃-UV advanced oxidation process (AOP) on humic acid (HA), which is regarded as the main disinfection by-products (DBPs) precursor, have been evaluated and compared. In particular, aromatic acids, short-chain aldehydes and carboxylic acids were measured. The purpose of this study was to determine the different classes and yields of oxidation intermediates, compare O₃, UV and O₃-UV for HA removal, as well as investigate the effects of O₃, irradiation time, UV intensity on the mineralization of HA. Based on that, the knowledge gap of DBPs generation was made up. The results showed that by UV irradiation and O₃ oxidation, HA broke down into smaller molecules that were more hydrophilic, namely formaldehyde, acetaldehyde, propaldehyde, butyraldehyde, glyoxal, methyl-glyoxal, formic, acetic, fumaric, benzoic, phthalic, protocatechuic and 3-hydroxybenzoic acids. Meanwhile, unsaturated conjugated double bonds in the structure of HA were destroyed, which lead to UV₂₅₄ a slight decrease. Due to the synergistic effect of O₃-UV, DOC and UV₂₅₄ significantly decreased and remained stable after the reaction of 10 min, indicating that O₃-UV system had stronger potential of mineralization and lower nonselectivity. Besides, the kinds and concentration levels of the intermediates were obviously reduced with light intensity increasing. Hydroxyl radical (^.OH) could mineralize some organics that could not be mineralized by O₃.     

Influence of tartaric acid on the electrodeposition of silver from binary water + dioxane AgNO3 solutions

Silver electrodeposits prepared from AgNO₃ solutions never give compact, smooth plates unless an organic additive, such as tartaric acid (H₂A), is used as growth inhibitor. It was shown previously that the relevant chemical entity controlling growth inhibition is the bulk concentration of a neutral associate Ag(HA) formed in the solution between Ag⁺ and tartaric monoanions HA^–. In the present work we extend this investigation to mixed water + dioxane solvent systems where the addition of dioxane, affecting the formation constant of Ag(HA), changes the bulk concentration of this associate. It was found that the associate Ag(HA) also formed in water + dioxane solvent systems is the active component in the solution governing the growth inhibition. On the concentration of this associate most of the structural features of Ag deposits (e.g., the grain size, the superficial roughness and the degree of the preferred orientation <1 1 0>) depend.     

Effects of plasma gas composition on bond strength of hydroxyapatite/titanium composite coatings prepared by rf-plasma spraying

The effects of plasma gas composition on the bond-strength of HA/Ti composite coatings were investigated. HA/Ti composite coatings were deposited on titanium substrates by a radio-frequency (rf) thermal plasma spraying method with input powers of 10–30 kW. The ratio of the HA and Ti powders supplied into the plasma was precisely controlled by two microfeeders so as to change the coating's composition from Ti-rich at the bottom to HA-rich at its upper layer. The bond (tensile) strength of the obtained HA/Ti composite coatings was 40–65 MPa when sprayed with plasma gas containing N₂ (i.e., Ar–N₂). On the other hand, HA/Ti composite coatings prepared with plasma gas containing O₂ (i.e., Ar–O₂) had significantly lower bond strength (under 30 MPa). XRD patterns of Ti coatings without HA showed that titanium nitride and titanium dioxide formed, respectively, on titanium deposits sprayed with Ar–N₂ and Ar–O₂ plasma. Scanning electron microscopic (SEM) observation showed an acicular texture on the Ti deposits prepared with Ar–N₂ plasma. SEM observations implied that, when sprayed with Ar–O₂ plasma, a thin TiO₂ layer formed at the interfaces between the Ti splats in the deposits.     

Purification of biomolecules combining ATPS and membrane chromatography

Upstream processes for production of therapeutic proteins have been innovated and fermentation processes have been adopted for the use of recombinant microorganisms with high expression, but the downstream process is still the bottleneck in the biotechnological manufacturing process. A combined process consisting of aqueous two phase extraction (ATPE) and membrane chromatography is suggested to debottleneck downstream processing. ATPE has a large capacity, but the yield of the target product is from 74% to 97%. For this reason the product of ATPE waste stream is captured by membrane chromatography. In this work the binding capacity for the protein on protein A, ion exchange and hydrophobic exchange membrane chromatography was investigated experimentally with different concentration of polyethylene glycol (PEG), salt and protein. Protein A membrane was loaded with solutions resembling waste streams of ATPE for purifying IgG. For ion exchange and hydrophobic interaction membrane chromatography, the membrane was loaded with bovine serum albumin (BSA). PEG shows no significant effect on stability and capacity of membrane process. Even for small amount of BSA/IgG and high salt concentrations membrane adsorption is applicable. In this work it is demonstrated experimentally that a total product recovery of 99.9% for the purification of monoclonal antibody is possible.     

混凝对垃圾渗滤液中腐殖质的去除特性

通过分别投加混凝剂聚合氯化铝(PAC)、聚合硫酸铁(PFS)和聚合氯化铝铁(PAFC)对垃圾渗滤液进行混凝沉淀处理,考察了3种混凝剂对渗滤液中TOC、CODCr和UV254的去除效果,并且根据单因素试验确定出PAC为最佳混凝剂,最佳投药量为6g/L.对渗滤液腐殖质分离方法进行了简化,并对经3种混凝剂处理后水样内的腐殖酸...     

Humic acids from lignite. 1. Analytical characteristics and thermal degradation

Humic acids (HA) extracted from a lignite with two alkaline reagents have been studied. In contrast to humic acids extracted from soil HA, the lignite acids show no differences in their physical and chemical analyses with the exception of the total carbonyl content. After acid hydrolysis the analytical characteristics do not change, but their behaviour on Sephadex indicates a molecular condensation. The parent material has similar characteristics to those reported in the literature and also shows no analytical differences after acid hydrolysis, but a number of i.r. absorption bands, due to kaolinite, the only clay mineral present, disappear after this treatment. By pyrolysis/gas chromatography both the lignite and the humic acids produce several low-b.p. compounds, the same in the three cases but in different amounts. By methylation it has been proved that a great part of such compounds are produced by radical reactions. Some, which do not increase on methylation, may indicate the presence of some longer chains in lignites.     

水溶性煤基酸对除草剂生物活性的影响

利用室内生物测定的方法研究了三种不同来源的水溶性煤基酸对六种除草剂 ( 2 ,4- D丁酯、草甘膦、巨星、禾大壮、乙草胺和百草枯 )生物活性的影响 .结果表明 :水溶性煤基酸对2 ,4- D丁酯、草甘膦和巨星的生物活性有明显的增效作用 ;加快了禾大壮的作用速度 ;对乙草胺的生物活性影响较小 ;却使百草枯失去了活性 .三种不同来源的水溶性煤基酸对除草剂生物活性的影响程度不同 ,经化学降解制备的水溶性煤基酸略高于从风化煤中直接提取的水溶性煤基酸 .通过水溶性煤基酸对溶液表面活性以及对除草剂渗透性的影响 ,初步探讨了水溶性煤基酸影响除草剂生物活性的机理     

Biofunctionalization of commercially pure titanium with chitosan/hydroxyapatite biocomposite via silanization: evaluation of biological performances

Chitosan (CS) and hydroxyapatite (HA) bioactive molecules have been grafted onto commercially pure titanium surfaces (cpTi) to promote osteoblast adhesion and bone growth. The major challenge of this type of grafting is the attachment of the CS/HA biocomposite to the cpTi surface. In this study cpTi is biofunctionalized with CS/HA biocomposite material via silanization and the coated specimens were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), water contact angle measurement and attenuated total reflectance-Fourier transform infrared (ATR-FTIR). The cpTi specimens were further evaluated for their in vitro bioactivity, hemocompatibility, protein adsorption and cell viability. The SEM micrographs showed uniform coatings adhered on cpTi specimens. The XRD and ATR-FTIR confirmed the presence of CS and HA on the cpTi specimens. The coated specimens showed improved in vitro bioactivity and hemocompatibilty along with enhanced adsorption of specific proteins. The cell viability studies showed non-cytotoxic nature of all the specimens and exhibited greater cell viability in the titanium CS/HA specimens. Hence, the studies showed that functionalized cpTi with covalent coating of CS/HA has significant potential in biomedical device implantation with improved bioactive properties.