Adsorptive removal of phenol from aqueous phase by using a porous acrylic ester polymer

The removal of phenol from aqueous solution was examined by using a porous acrylic ester polymer (Amberlite XAD-7) as an adsorbent. Favorable phenol adsorption was observed at acidic solution pH and further increase of solution pH results in a marked decrease of adsorption capacity, and the coexisting inorganic salt NaCl exerts positive effect on the adsorption process. Adsorption isotherms of phenol were linearly correlated and found to be well represented by either the Langmuir or Freundlich isotherm model. Thermodynamic parameters such as changes in the enthalpy (DeltaH), entropy (DeltaS) and free energy (DeltaG) indicate that phenol adsorption onto XAD-7 is an exothermic and spontaneous process in nature, and lower ambient temperature results in more favorable adsorption. Kinetic experiments at different initial solute concentrations were investigated and the pseudo-second-order kinetic model was successfully represented the kinetic data. Additionally, the column adsorption result showed that a complete removal of phenol from aqueous phase can be achieved by XAD-7 beads and the exhausted adsorbent was amenable to an entire regeneration by using ethanol as the regenerant. More interestingly, relatively more volume of hot water in place of ethanol can also achieve a similar result for repeated use of the adsorbent.     

Adsorptive removal of methylene blue by tea waste

The potentiality of tea waste for the adsorptive removal of methylene blue, a cationic dye, from aqueous solution was studied. Batch kinetics and isotherm studies were carried out under varying experimental conditions of contact time, initial methylene blue concentration, adsorbent dosage and pH. The nature of the possible adsorbent and methylene blue interactions was examined by the FTIR technique. The pH(pzc) of the adsorbent was estimated by titration method and a value of 4.3+/-0.2 was obtained. An adsorption-desorption study was carried out resulting the mechanism of adsorption was reversible and ion-exchange. Adsorption equilibrium of tea waste reached within 5h for methylene blue concentrations of 20-50mg/L. The sorption was analyzed using pseudo-first-order and pseudo-second order kinetic models and the sorption kinetics was found to follow a pseudo-second order kinetic model. The extent of the dye removal increased with increasing initial dye concentration. The equilibrium data in aqueous solutions were well represented by the Langmuir isotherm model. The adsorption capacity of methylene blue onto tea waste was found to be as high as 85.16mg/g, which is several folds higher than the adsorption capacity of a number of recently studied in the literature potential adsorbents. Tea waste appears as a very prospective adsorbent for the removal of methylene blue from aqueous solution.     

层柱材料的超分子插层组装

首次合成了(脯氨酸-N-甲基膦酸-磷酸氢)锆(α-ZPMPP)层状晶体,以正丁胺为客体分子首次合成了α-ZPMPP-正丁胺超分子插层复合物.研究了α-ZPMPP在常温下对正丁胺的插层性能,用元素分析、红外光谱、X射线衍射、TG-DSC热分析对α-ZPMPP及其插层复合物进行了表征.研究表明,正丁胺的插入使层间距增大从1.52nm增加到1.97nm,插入的正丁胺在150～250℃可被脱除,正丁胺客体分子在主体底物中形成单分子层.     

Permeation of solvents through disk type rice husk silica membrane modified with alkyl silylation reagents

Rice husk silica (RHS) which was obtained with thermal treatment of rice husk has the size of approximately 10 micrometer with 4-5 nm pore. RHS can be mold to a disk type membrane. The membrane may have submicron pore originated from the space among the particles, and the nano pores of the rice husk silica (RHS pore). Even it is difficult to adjust the size of the pores, we can suggest that the membrane shows different permeability for the organic/inorganic solvents if the affinity between the surface of the pores and the permeating molecule is changed. In this study, we investigated the permeation of the typical solvents such as water, ethanol and toluene to the RHS membranes sintered at 1100 degrees C, 1150 degrees C and 1200 degrees C and modified with triethoxymethyl silane (CH3)Si(C2H5O)3, diethoxydiemethyl silane (CH3)2Si(C2H5O)2 and ethoxytriemethyl silane (CH3)3Si (C2H5O). The result showed that permeability of original membranes for water (e.g., 1100 degrees C, 2.87 x 10(-3) mol/m2 s Pa) was larger than ethanol (1100 degrees C, 5.51 x 10(-4) mol/m2 s Pa) and toluene (1100 degrees C, 3.09 x 10(-4) mol/m2 s Pa) at the sintering temperatures. For the silane modified membranes, the permeability for water decreased drastically while those for ethanol and toluene increased.     

Adsorptive removal of water poisons from contaminated water by adsorbents

Adsorptive removal of water poisons such as Pb(II), Cu(II), Mn(II), Hg(II), CN(-), microbes, nerve and blister agents (concentration range from 100 to 1000 mg/L) were studied by using adsorbents such as active carbon, impregnated carbon and bentonite loaded fabric strip. Removal of water poisons (99.5%) could be achieved with an optimum stirring time of 5-15 min and weight of adsorbent of 0.8-8.0 g/100mL contaminated water, respectively. However, 85% bentonite loading was found to be most effective for Pb(II) removal. Effect of contaminants concentration was also studied.     

Adsorptive removal of 2-chlorophenol by low-cost coir pith carbon

Adsorption of 2-chlorophenol (2-CP) by coir pith carbon was carried out by varying the parameters such as agitation time, 2-CP concentration, adsorbent dose, pH and temperature. Adsorption equilibrium reached at 40, 60, 80 and 100 min for 2-CP concentration of 10, 20, 30 and 40 mg/l, respectively. Adsorption followed second-order kinetics. The adsorption equilibrium data obeyed Freundlich isotherm. Acidic pH was favorable for the adsorption of 2-CP. Desorption studies showed that chemisorption plays a major role in the adsorption process.     

Adsorptive removal of phenol from aqueous solutions on activated carbon prepared from tobacco residues: equilibrium, kinetics and thermodynamics

This study consists of producing high surface area activated carbon from tobacco residues by chemical activation and its behavior of phenol removal from aqueous solutions. K(2)CO(3) and KOH were used as chemical activation agents and three impregnation ratios (50, 75 and 100 wt.%) were applied on biomass. Maximum BET surface areas of activated carbons were obtained from impregnation with 75 wt.% of K(2)CO(3) and 75 wt.% of KOH as 1635 and 1474 m(2)/g, respectively. Optimum adsorption conditions were determined as a function of pH, adsorbent dosage, initial phenol concentration, contact time and temperature of solution for phenol removal. To describe the equilibrium isotherms the experimental data were analyzed by the Langmuir, Freundlich, Dubinin-Radushkevich (D-R) and Temkin isotherm models. Pseudo-first order, pseudo-second order and intraparticle diffusion kinetic models were used to find out the kinetic parameters and mechanism of adsorption process. The thermodynamic parameters such as ΔG°, ΔH° and ΔS° were calculated for predicting the nature of adsorption. According to the experimental results, activated carbon prepared from tobacco residue seems to be an effective, low-cost and alternative adsorbent precursor for the removal of phenol from aqueous solutions.     

Control of hydration rate of polymer modified cements by the addition of organically modified montmorillonites

The addition of polyvinyl alcohol (PVA) in concrete causes a delay in the hydration rate of Portland cement paste. Three different montmorillonites (MMTs) (Cloisite Na, 30B, and Nanofil) were previously mixed with PVA in order to control this delay. A comparison between the hydration rate of Portland cement paste and Portland cement paste modified with PVA and the different MMTs was made by means of semi-adiabatic calorimetry, thermal gravimetric analysis and contact angle measurements. Different rates of hydration were obtained with each MMT. The paste with PVA and Nanofil behaves almost the same as the unmodified cement paste. Mechanical properties were also studied. An increase in the flexural strength and a decrease in the compression strength were found, which is expected for a Portland cement paste modified with PVA. The addition of MMT to the cement paste with PVA hardly affects the mechanical properties.     

Selective adsorption of tannin from flavonoids by organically modified attapulgite clay

In this study, selective adsorption of tannin on organically modified attapulgite clay was investigated. Tannin was selectively removed from model tannin/flavonoids mixtures in the solution. In adsorption isotherm experiments of tannin, obtained data fitted well to the Freundlich model. The surface sites of the octodecyl trimethyl ammonium chloride (OTMAC)-attapulgite were heterogeneous. The effect of pH on tannin adsorption was also investigated and the results showed that the adsorbed amount of tannin was highest at pH 6.0. The enthalpy values of adsorption of tannin on OTMAC-attapulgite at pH 4.0, 6.0 and 8.0 were −49.80, −74.31 and −38.62 kJ/mol, respectively. At 2–5.3 and 7.4–10, the driving forces for the adsorption may be the hydrophobic force and hydrogen bonding. And at pH 5.3–7.4 the electrostatic force may be the most important one. These facts implied that the selective adsorption of tannin on OTMAC-attapulgite was driven by the collaboration of hydrogen bonding, electrostatic force and hydrophobic interactions of tannin molecular with adsorbent. The low adsorption of isoflavones of soybean and the puerarin was ascribed to less phenolic hydroxyls of them than those of tannin, which made the low electrostatic interactions and hydrogen bonding interactions between the tannin and OTMAC-attapulgite adsorbent.     

乳状液膜法脱酚的进一步研究

对模拟的含酚废水,采用乳状液膜法脱酚进行了进一步的探讨．实验研究了对所采用的制乳设备——撞击流-旋转填料床对制乳率,提取设备——旋转填料床对脱酚率和破乳设备——无机微孔膜外压内抽式膜法破乳的重要参数如透过压方式、膜孔径等对膜通量和破乳率的影响．并且讨论了破乳后的油相回用情况．实验结果表明:撞击流-旋转填料床对制乳率、脱酚率都很高,且瞬间完成．亲水性无机微孔膜外压内抽方式破乳,是一种更有效的膜法破乳新方法,此过程受透过压方式和膜孔径的影响较大．膜孔径越小,破乳率越高,膜通量越小;外压内抽方式的破乳效果优于单外压方式的破乳效果．并由实验数据得到:撞击流-旋转填料床的制乳效率可达99．90％以上,脱酚率可达99％左右,对于粒径为5-25μm乳液,用膜孔径为2．0μm的SiC微孔膜,在外压为60 kPa、内负压为30 kPa的外压内抽破乳方式下破乳,破乳率可达96．4％,膜通量可达900 L／(m2·h)．     

层状K-Fe-Ti氧化物的剥离及光催化性能

采用软化学法制备了具有层状结构的K-Fe-Ti氧化物K2.3 Fe2.3Ti5.7O16,并用1mol/L稀硝酸对样品进行剥离.通过XRD、TEM等测试技术对剥离前后的样品进行表征,并研究了剥离后样品对甲基橙降解的光催化活性.结果表明,K2.3Fe2.3Ti57O16经过稀硝酸剥离后得到锯齿状或者梳子状的薄片结构,这种薄片结构在pH值小于2时对甲基橙的降解有较高的光催化活性,在太阳光照射100min后甲基橙降解率超过40%.     

Synthesizing layered material of FePS3 and its intercalation with pyridinum

Synthesising and characterizing of the FePS₃ layered compound and its intercalation with pyridinium ion (pyH⁺) were studied. Well-crystallized material of FePS₃ was formed. Full insertion of pyH⁺ was assured by X-ray diffraction (XRD) measurements. Two phases were produced due to intercalation, phase A (d = 12.1 Å) and phase B (d = 9.7 Å). There is a phase transformation of phase A to phase B. As a result of intercalation, there was a change in symmetry of the host lattice from C2/m to R-3m. The intercalated compounds, phase A and phase B, could be described by a trigonal unit cell and the lattice parameters a = b = 3.5026 Å, and different values of the cell parameter c, which is lengthened due to increasing of the d-spacing (the interlayer space increases by 5.7 and 3.3 Å of phase A and phase B, respectively), and γ = 120°. Infrared spectra (IR) showed the presence of the strong peak of FePS₃ at 570 cm⁻¹, which was splitted due to complete intercalation to two or three peaks. As a result of elemental analysis, there is a loss of Fe²⁺ cations due to the intercalation process, and so the intercalated guest species must be mainly present as pyH⁺ to balance electrical charge (i.e. the intercalation of FePS₃ with pyH⁺ is a non-redox intercalation).     

Adsorptive removal of Auramine-O: kinetic and equilibrium study

Present study deals with the adsorption of Auramine-O (AO) dye by bagasse fly ash (BFA) and activated carbon-commercial grade (ACC) and laboratory grade (ACL). BFA is a solid waste obtained from the particulate collection equipment attached to the flue gas line of the bagasse fired boilers of cane sugar mills. Batch studies were performed to evaluate the influences of various experimental parameters like initial pH (pH(0)), contact time, adsorbent dose and initial concentration (C(0)) for the removal of AO. Optimum conditions for AO removal were found to be pH(0) approximately 7.0 and equilibrium time approximately 30 min for BFA and approximately 120 min for activated carbons. Optimum BFA, ACC and ACL dosages were found to be 1, 20 and 2g/l, respectively. Adsorption of AO followed pseudo-second order kinetics with the initial sorption rate for adsorption on BFA being the highest followed by those on ACL and ACC. The sorption process was found to be controlled by both film and pore diffusion with film diffusion at the earlier stages followed by pore diffusion at the later stages. Equilibrium isotherms for the adsorption of AO on BFA, ACC and ACL were analyzed by Freundlich, Langmuir, Dubinin-Radushkevich, and Temkin isotherm equations using linear correlation coefficient. Langmuir isotherm gave the best correlation of adsorption for all the adsorbents studied. Thermodynamic study showed that adsorption of AO on ACC (with a more negative Gibbs free energy value) is more favoured. BFA which was used without any pretreatment showed high surface area, pore volume and pore size exhibiting its potential to be used as an adsorbent for the removal of AO.     

Preparation and mechanism of polystyrene-molybdenum disulfide intercalation materials by a modified two-step route

Polystyrene/molybdenum disulfide nanocomposites were prepared by means of a modified two-step in-situ anion polymerization of the intercalated styrene monomers. The nanocomposites were characterized by means of powder X-ray diffraction, Fourier transform infrared spectroscopy, gel permeation chromatography, and scanning electron microscopy. Thus, the target nanocomposites were prepared at a greatly reduced reaction time using the modified synthetic route. This was characterized by a clean and straightforward intercalation of the interesting polymer monomers into the molybdenum disulfide host. The mechanism of the intercalation method was investigated and compared with the traditional exfoliation-restacked method as well.     

Single-molecule studies of diffusion by oligomer-bound dyes in organically modified sol-gel-derived silicate films

Single-molecule fluorescence spectroscopy is used to study dye diffusion within organically modified silicate (ORMOSIL) films. ORMOSIL films are prepared from sols containing tetraethoxysilane and isobutyltrimethoxysilane in 2:1 and 1:9 molar ratios. Nile red and a new silanized form of nile red that can be covalently attached to the silicate matrix are used as fluorescent probe molecules. The number and rate of single molecules diffusing through these films increases dramatically with increasing film organic content. Autocorrelation of the fluorescence images yields a quantitative measure of the relative populations of fixed and diffusing species. Surprisingly, both "free" and silicate-bound nile red exhibit relatively facile translational motions. Single-molecule/single-point fluorescence correlation spectroscopy (FCS) is used to measure the dye diffusion coefficients in submicrometer-scale film regions. The most common diffusion coefficients for "free" and silicate-bound nile red molecules in the 1:9 films are 3.9 x 10(-10) and 1.6 x 10(-10) cm(2)/s, respectively. The unexpectedly rapid diffusion of silicate-bound nile red is attributed to the presence of liquidlike silicate oligomers in the films. A lower bound for the molecular weight of the oligomers is estimated at 2900. Bulk solution-phase FCS experiments performed on "free" and silicate-bound nile red species extracted into chloroform solutions provide valuable support for these conclusions. Comparison of the results derived from experimental and simulated time transients indicates film heterogeneity occurs on sub-100-nm-length scales and likely results from the presence of inorganic- and organic-rich domains.     

Preparation and characterization of ionic liquid intercalation compounds into layered zirconium phosphates

In this work, immobilizing a series of ionic liquids (ILs) 1-alkyl-3-methylimidazolium chloride [C _n mim]Cl (n = 2, 4, 6, 8) on the layered zirconium phosphates were investigated. [C₄mim]Cl was used to explore in detail the factors affecting intercalation. By comparing several starting materials including α-zirconium phosphate (α-ZrP), γ-zirconium phosphate (γ-ZrP) and the corresponding alkylamine preintercalated composites, it was found that the α-ZrP · 2BA (i.e., preintercalated BA were arranged in a bilayer mode at the galleries of α-ZrP) was a suitable host for intercalating ILs. Intercalation was verified with X-ray diffraction (XRD), Raman, UV–Vis and other instrumental approaches. pH effect on immobilization was investigated. Other ionic liquids including [C _n mim]Cl (n = 2, 6, 8) intercalation compounds were prepared. Based on XRD data, the interlayer distances of the studied intercalation compounds were similar, suggesting that the ionic liquids were arranged in an approximately planar manner, as confirmed by molecular modeling.     

Preparation of rutile TiO2 nanofibers by TiO2 sol intercalation of ultrafine layered titanate

To prepare TiO₂ intercalated tetratitanate, TiO₂ solution and ultrafine layered titanate K₂Ti₄O₉ obtained via solid-state reaction by using nanometer-sized TiO₂ as raw material were used as guest and host materials respectively. The structure and morphology of the resulting samples were characterized by XRD and TEM experiments. It was found that during the intercalation process, the interlayer distance was expanded step-by-step and the interlayer structure of titanate might be destroyed and degraded to slits by prolonging the solution intercalation time. Rutile TiO₂ nanofibers with the average size of 5 × 50 nm were obtained at room temperature while the duration time was prolonged to 72 h.     

脲醛树脂-钠基蒙脱土改性杨木的结构与表征

以脲醛树脂-钠基蒙脱土(UF-Na-MMT)为浸渍液,通过减压-加压方式浸渍改性速生杨木,并采用X-射线衍射仪(XRD)、扫描电镜(SEM)和傅立叶红外光谱(FIRT)等对改性杨木进行检测与分析.SEM的观察显示:大量的UF树脂和有机Na-MMT进入到了杨木的导管中,部分与木材纤维和细胞壁紧密结合;XRD和IRFT的研...     

晶态层状N,N-二乙酸亚氨基亚甲基膦酸-磷酸氢锆的制备及插层研究

采用氢氟酸络合法合成了结晶度高的N,N 二乙酸亚氨基亚甲基膦酸 磷酸氢锆 (α ZPPMIDA) 层状晶体,层间距为 1. 477nm。研究了正丁胺对α ZP PMIDA的插层反应, 用 IR、XRD、TG DSC热分析和元素分析对该插层复合物进行了表征。结果表明正丁胺在主体底物中呈双分子层,层间距增大了0.847nm。