氢氧化镁改性硅藻土对阴离子染料的吸附性能研究

对硅藻土进行氢氧化镁改性以提高它对印染废水中染料的吸附性能.采用原位沉淀法由MgCl2及NaOH在硅藻土上制备了氢氧化镁,并用SEM、XRD对改性材料进行了表征;用分光光度法研究了它对阴离子染料的吸附性能.结果显示:改性硅藻土的染料吸附能力比原硅藻土及氢氧化镁都高;染料的吸附等温线采用Langmuir及Freundlich模型拟合,结果表明改性硅藻土对染料的吸附更符合Freundlich模型.     

活性炭及硅藻土对染料的吸附特性研究

采用活性炭、硅藻土、氢氧化镁改性硅藻土对1种阳离子染料和2种阴离子染料进行了吸附研究.BET液氮吸附法测定结果显示硅藻土改性后的比表面积增大而平均孔径降低;染料吸附结果表明:硅藻土改性后对天龙红(TR)及雷马素金黄(RGY)两种阴离子染料的吸附性能提高,而对阳离子染料亚甲基蓝的吸附性能降低;改性硅藻土对天龙红的吸附容量大于活性炭,而对雷马寨金黄及亚甲基蓝的吸附容量低于活性炭;采用准一级、准二级两种吸附动力学模型对染料的吸附动力学数据进行了拟合,结果显示改性硅藻土及活性炭的染料吸附过程更符合准二级动力学模型.     

Fluorine sorption by aluminosilicate-modified diatomite from highly concentrated fluorine solutions: 1. Adsorption equilibrium

The adsorption capacity of natural (D1) and chemically structure-modified diatomite (DMA) in the removal of fluorine ions from highly concentrated fluorine solutions (up to 0.3 mol/L) under static conditions at room temperature is studied. The effect of different parameters—solution pH, initial fluorine concentration, sorbent weight, and particle surface charge density—is examined to determine the adsorption properties of DMA under different process conditions. It is shown that the solution pH plays a crucial role in the removal of fluorine from solutions. An efficient removal of fluorine occurs at a pH of 4.5–5.5. Under equilibrium conditions, upon the saturation of the DMA surface with fluorine ions, the adsorption capacity of DMA achieves 58 mmol/g of sorbent; this value is 5.5 times higher than that of unmodified D1. Fluorine adsorption isotherms for DMA samples are derived; equilibrium adsorption data are modeled using a twostage Langmuir model; it is shown that the experimental and calculated data on fluorine adsorption are in good agreement: correlation coefficient R² for the D1 and DMA samples is 0.9952 and 0.9687, respectively. The fluorine adsorption mechanism is studied. X-ray diffraction and chemical analyses, FTIR spectroscopy, potentiometric titration, and adsorption–desorption experiments reveal that the diatomite–NaF–H₂O system is characterized by the occurrence not only of physical adsorption and ion exchange but also of the chemical bonding of the fluorine ions with the active sites of the sorbent surface, i.e., the formation of weakly soluble fluorine compounds with Al on DMA and with Ca on D1 (AlF₃, Na₃AlF₆, СаF₂).     

硅藻土的分离及其负载氧化铁后光催化抗菌性能研究

采用饱和蔗糖溶液为溶剂,通过低速离心,可去除硅藻土中的杂质和破碎小颗粒,对其进行纯化分离。同时研究了不同煅烧温度对硅藻土比表面积和表面化学性质的影响。结果表明,600℃以下煅烧对硅藻土的比表面积影响甚小,800℃以上温度煅烧不仅明显降低其比表面积,而且可除去硅藻土表面羟基。当硅藻土表面负载上一定浓度的Fe2O3纳米颗粒后,其在可见光下的光催化抑菌率可达到96.2%。     

Physicochemical and adsorption-structural properties of diatomite modified with aluminum compounds

A selective sorbent based on the diatomite of local origin modified with aluminum compounds has been studied by the methods of powder X-ray diffraction; FTIR; and differential thermal, adsorption-structural (BET), and chemical analyses. The surface modification of diatomite is carried out by heating it in an NaOH solution and its subsequent treatment with a solution of aluminum salt and ammonia. The amorphous surface silica partially dissolves during the treatment with NaOH and forms an aluminosilicate compound at the addition of an aluminum salt. The obtained material is deposited both on the surface of the diatomite and on the inner surface of the macro- and larger mesopores, which leads to the development of the specific surface area of 81.8 m²/g, which is 2.5 times larger than the corresponding value in the initial diatomite (37.5 m²/g). The precipitated aluminosilicate compound with the concentration equal to 0.34 g of Al/g of aluminosilicate contributes to the development of a porous structure in the treated diatomite, so the volume of the mesopores increases from 0.029 to 0.079 cm³/g and that of the micropores from 0.012 to 0.027 cm³/g. The qualitative changes in the composition of the obtained sorbent are confirmed by the emergence of new lines in the X-ray diffraction patterns, which are characteristic for aluminosilicates, and additional peaks in the infrared spectra corresponding to the stretching vibrations of Si-O-Al. The selectivity of the obtained adsorbent with respect to fluoride ions increases significantly, specifically, its adsorption capacity increases from 8.9 to 57.6 mg of F/g at the initial fluorine concentration equal to 0.15 mol/L.     

聚丙烯酰胺/硅藻土复合材料处理染料废水

通过自制阴离子聚丙烯酰胺HPAM对硅藻土矿物改性制备一种有机无机复合吸附剂材料,采用SEM及FTIR技术对复合材料进行表征,并对3种模拟染料废水及2种真实印染污水进行脱色性能研究。结果显示,改性时较佳的HPAM用量在0.8%(质量分数)左右,复合后HPMA高聚物在硅藻土表面大孔内壁形成牙状絮体;通过与未改性硅藻土及颗粒活性炭对上述几种染料废水的处理效果对比,HPMA改性硅藻土复合材料对阳离子染料废水和真实印染废水均具有较高的脱色率。     

片状硅藻土表面化学镀银工艺及介电性能

以片状硅藻土为模板,利用化学镀法在其表面包覆银来制备核壳式复合功能微粒.研究化学镀工艺对硅藻土表面银含量和微观形貌的影响,并对镀银硅藻土微粒的介电性能进行分析.结果表明,随着施镀时间和装载量的增大,硅藻土表面银含量随之升高;在银含量为34.65％时,镀层均匀、连续、致密,且硅藻土表面微孔被镀层完全覆盖;镀银硅藻土微粒的介电性能与其表面银含量、镀层质量及体积添加比有关,此外所有样品的介电常数虚部均低于其实部,表明未出现渗漏现象.     

Removal of enrofloxacin from aqueous solutions using illite and synthetic zeolite X

Enrofloxacin uptake and removal from aqueous solutions using illite and synthetic zeolite X prepared from illite, were studied in batch experiments under varying pH, contact time, and initial enrofloxacin concentrations. The X-ray diffraction and Fourier transform infrared spectroscopy caracterization were used to analyse the enrofloxacin adsorption in order to elucidate the adsorption mechanisms. It was found that enrofloxacin could be efficiently removed at pH 7 and pH 8 for clay and zeolite X, respectively. In addition, the second order model of kinetics is more adopted for the two samples. The isotherms of adsorption of enrofloxacin by illite and zeolite X show that the latter has the twice higher adsorption capacity of the clay. Equilibrium data fit well with the Langmuir and Freundlich isotherms. Moreover, the cation exchange, the electrostatic interaction, the cation bridging and the formation of bidentate ligands were the possible mechanisms of the enrofloxacin retention.     

硅藻土涂料在热模法离心铸造球铁管中的应用

采用硅藻土为骨料配制的悬浊液作为涂料涂覆于管模内壁生产球铁管,论述了涂料原材料选择、涂料配制、性能及合适的施涂方式。试验表明,膨润土浆持续搅拌2h,再静止10h后配制涂料;硅藻土是涂料热模法中最合适的骨料;对于小管径的管模涂料,膨润土含量高一些,硅藻土与膨润土的质量比为(8～15):1;对于大口径管模涂料,膨润土含量稍低,硅藻土与膨润土质量比为(12～20):1,另外,有气喷涂是最佳的喷涂方式。     

金属型离心铸铁管硅藻土水基涂料的研制

介绍了金属型离心铸铁管硅藻土水基涂料中材料的选用及作用,并通过正交试验方法最终确定了符合生产要求的硅藻土水基涂料配方。     

Preparation,characterization, and adsorption-photocatalytic activity of nano TiO_2 embedded in diatomite synthesis materials

Nano TiO_2 embedded in diatomite(NTED)synthesis materials were prepared by a sol-gel method in absolute ethyl alcohol suspension. NTED synthesis materials have a higher specific surface area and larger pore volume using micromeritics ASAP 2020. The result of characterization was measured by X-ray diffraction(XRD),Fourier transform infrared(FT-IR) spectroscopy, scanning electron microscope(SEM), and energy dispersive spectroscopy(EDS). The cyanide wastewater was employed to evaluate the adsorption capacity and photocatalytic activity of prepared NTED synthesis materials. The better photocatalytic activity and adsorption capacity of NTED synthesis materials are attributed to their high surface area and higher UV absorption intensity for the cyanide wastewater.     

Interactions between whey proteins and kaolinite surfaces

The nature of the interactions between whey proteins and kaolinite surfaces was investigated by adsorption–desorption experiments at room temperature, performed at the isoelectric point (IEP) of the proteins and at pH 7. It was found that kaolinite is a strong adsorbent for proteins, reaching the maximum adsorption capacity at the IEP of each protein. At pH 7.0, the retention capacity decreased considerably. The adsorption isotherms showed typical Langmuir characteristics. X-ray diffraction data for the protein–kaolinite complexes showed that protein molecules were not intercalated in the mineral structure, but immobilized at the external surfaces and the edges of the kaolinite. Fourier transform IR results indicate the absence of hydrogen bonding between kaolinite surfaces and the polypeptide chain. The adsorption patterns appear to be related to electrostatic interactions, although steric effects should be also considered.     

Adsorption of copper ions on porous ceramsite prepared by diatomite and tungsten residue

In order to realize resource utilization of industrial tungsten residue and treatment of heavy metal wastewater in mining and metallurgical area of south China, a novel ceramsite was prepared with the main raw materials of diatomite and tungsten residue. The adsorption behavior of copper ions in solution on the ceramsite was investigated. Results indicated that the surface of the newly-developed ceramsite was rough and porous. There were lots of pores across the ceramsite from inner to outside. MnFe₂O₄ was one of the main components of the ceramsite. The Cu²⁺ adsorption capacity by the ceramsite reached 9.421 mg/g with copper removal efficiency of 94.21% at 303 K, initial Cu²⁺ concentration of 100 mg/L and dosage of 0.5 g after 300 min adsorption. With increase of ceramsite dosage, the total adsorption amount of Cu²⁺ increased, but the adsorption capacity decreased. The adsorption capacity increased with the increase of solution pH. The isothermal adsorption of Cu²⁺ by the ceramsite fitted the Freundlich model better. The adsorption mainly occurred on a heterogeneous surface, and was a favorable process. The adsorption process closely followed the pseudo-second kinetic equation. In initial stage of wastewater treatment, the adsorption process should be controlled mainly by diffusion, and the removal of Cu²⁺ can be improved by enhancing agitation.     

硅藻土/三聚磷酸铝溶胶-凝胶法合成及其应用

在以偏铝酸钠(NaAlO2)和磷酸(H3PO4)为反应原料,NP-5为表面活性剂、正丁醇为助表面活性剂、正辛烷为油相和去离子水为水相的微乳体系中,溶胶-凝胶法制备防锈包覆颜料三聚磷酸铝/硅藻土。确定了反应时间和反应温度,并讨论了不同原料比和R值对产物形貌的影响。通过XRD、FESEM及对照实验进行性能测试并分析,得出当H3PO4与NaAlO2的摩尔比为4:1、R=10时合成的三聚磷酸铝包覆颜料粒径较小,尺寸分布较均匀。并对其防锈性能、防锈机理分别进行实验和探讨。     

Removal and recovery of titanium (IV) from leach liquor of high-sulfur bauxite using calcium alginate microspheres impregnated with di-(2-ethylhexyl) phosphoric acid

In the leaching solution of high-sulfur bauxite roasted by sulfuric acid, a high concentration of aluminum presented along with titanium and iron. The present work was to remove Ti(IV) from the leach liquor by calcium alginate microsphere sorbent material (CA-P204) based on natural alginate impregnated with di-(2-ethylhexyl) phosphoric acid (D2EHPA) to purify leaching solution. Cation exchange and chelation make major contributions to the adsorption mechanism according to Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis. The results showed that Ti(IV) was successfully removed by the CA-P204 adsorbent from the Ti(IV)?Al(III)?Fe(III) ternary system with a dynamic column experiment. The removal rate of titanium was nearly 95% under optimal conditions and the maximum adsorption capacity was 66.79 mg/g at pH 1.0. Reusability of CA-P204 was evaluated over three consecutive adsorption/desorption cycles. The adsorption process was simple, low-cost, and had no waste discharge, suggesting that the CA-P204 was promising, efficient, and economical for removing Ti(IV) from high-sulfur bauxite leaching solution.     

Synthesis and Characterization of Novel Sulfur-Functionalized Silica Gels as Mercury Adsorbents

This paper describes the synthesis, functionalization, and characterization of silica gels as mercury adsorbents. The synthesis was carried out according to the modified Stöber method using tetraethyl orthosilicate [TEOS], 3-mercaptopropyl trimethoxysilane [MPTMS] and bis(triethoxysilylpropyl) tetrasulfide [BTEPST] as precursors. The functionalization was carried out via co-condensation and impregnation methods using MPTMS, BTESPT, elemental sulfur [ES], and carbon disulfide [CS₂] as sulfur ligands. The choice of the sulfur ligands as precursors and functionalization agents was due to the existence of sulfur active groups in their molecular structures which were expected to have high affinity toward Hg(II) ions. The synthesized adsorbents were characterized by using scanning electron microscope, fourier transform infrared spectrophotometer, nitrogen adsorption/desorption, and energy dispersive X-ray diffractometer. The batch Hg(II) adsorption experiments were employed to evaluate the Hg(II) adsorption performances of the synthesized adsorbents under different pH values. The results revealed that the highest Hg(II) adsorption capacity was obtained for the SG-MPTMS(10) which was 47.83 mg/g at pH 8.5. In general, the existence of sulfur functional groups, especially MPTMS in the silica matrices, gave a significant enhancement of Hg(II) adsorption capacity and the sulfur functionalization via co-condensation method, which is potential as a superior approach in the mercury adsorbent synthesis.     

离心铸铁管硅藻土水基涂料组分的选择

介绍了金属型离心铸铁管所用硅藻土水基涂料的组分选取时所做的一些研究工作,强调了在涂料组分的选取时,不同产地的同一种材料在性能上存在较大差异,需要进行严格筛选。     

Adsorption of anion and cation dyes onto pillared montmorillonite

Al₂O₃- and Al(Ce)₂O₃-pillared montmorillonite materials were synthesized using the intercalation of large-sized polyhydroxocomplexes of aluminum and aluminum/cerium in order to obtain adsorbents for removing the water-soluble anionic (acid red, AR) and cationic (methylene blue, MB) dyes. It was shown that the adsorption of dyes heavily depended upon the pH of the medium reaching a maximal adsorption capacity for AR at low pH and for MB at high pH. The distinction between the adsorption efficiencies for dyes observed in the materials with a different pillar structure was interpreted in the light of both the charge states (the ζ-potential) of tactoids in suspensions and texture properties of adsorbents investigated by small-angle X-ray diffraction and porosimetry. We used the classic models to describe adsorption: the kinetic pseudo-first-order and pseudo-second-order models and the equilibrium Langmuir and Freundlich equations.     

MgCl_2改性柑橘皮对水溶液中重金属离子的吸附性能

以柑橘皮(OP)为原料,通过MgCl2进行改性制备新型柑橘皮生物吸附剂MgOP。考察溶液pH值、温度、固液比、吸附时间和金属离子浓度对MgOP从单组分溶液中吸附Cu2+、Cd2+、Pb2+、Zn2+和Ni2+的吸附性能的影响。结果表明,pH值和固液比对吸附率的影响较明显;温度对吸附率的影响较小;所有吸附过程可在20 min内达到吸附平衡,对5种金属离子的吸附动力学均符合准二级动力学方程;与原始柑橘皮相比,MgOP对5种金属离子的最大吸附量显著提高;MgOP可重复使用10次以上;共存金属离子对吸附率影响很小。     

Corrosion inhibition and adsorption behavior of <Emphasis Type="Italic">Murraya koenigii</Emphasis> extract for corrosion control of aluminum in hydrochloric acid medium

The corrosion behavior of aluminum in the hydrochloric acid medium of pH 3 was studied using Tafel polarization and electrochemical impedance spectroscopy techniques in the presence or the absence of the Murraya koenigii (commonly known as curry) leaves extract at 303 K to 323 K. The concentration of the inhibitor used was in a range of 0.05–0.4 gL^?1. The inhibition efficiency was found to increase with increasing the inhibitor concentration and decreasing temperature. Polarization data showed that the curry leaves extract (CLE) acted as anodic type of inhibitor at lower concentrations of the inhibitor and as mixed type at higher concentrations of the inhibitor. The maximal inhibition efficiency of 91.79% was obtained with the CLE at its optimum concentration of 0.4 gL^?1. Adsorption of the CLE was found to obey the Langmuir adsorption isotherm and underwent both physisorption and chemisorption process. The kinetic and thermodynamic parameters were calculated and discussed in detail. The results obtained by both methods were in good agreement with each other. The protective film formed on the surface of aluminum by the adsorption of inhibitor molecules present in the CLE in the hydrochloric acid medium of pH 3 was confirmed by the scanning electron microscopy and energy-dispersive X-ray spectroscopy. So, the CLE emerged as a potential, cost-effective and eco-friendly natural inhibitor for the corrosion control of aluminum in the hydrochloric acid medium.