Synthesis of mesoporous TiO2/BMMs via hydrothermal method and its potential application toward adsorption and photocatalytic degradation of crystal violet from aqueous solution

The novel mesoporous TiO₂/BMMs nanocomposites using bimodal mesoporous silica (BMMs) as support and rutile-anatase mixed phase as active species were successfully synthesized via hydrothermal and subsequent calcination method. Their structural and physiochemical properties were characterized by X-ray diffraction, scanning/transmission electron microscopy, BET-isotherms, inductive coupled plasma optical emission spectroscopy, zeta potential, Fourier transform infrared and UV–visible spectroscopy. The results demonstrated that the photocatalytic degradation activity of the synthesized catalysts were extensively enhanced as compare to bare TiO₂, due to the highly uniform dispersion of mixed phases (Anatase and Rutile) TiO₂ on the bimodal mesoporous surfaces. Particularly, the catalytic efficiency became increased as increasing the calcination temperature, showing the highest (98%) overall removal of CV dye using TBH5d as catalyst calcinated at 800 °C. Its most interesting finding is that the % adsorption of TBH5d was 46 %, more than that (26%) of TBH5c calcinated at 600 ℃, however, its % degradation was 21 %, lower than that (39 %) of TBH5c for dye concentration of 20 ppm in 50 min. Meanwhile, the kinetic adsorption and degradation performances were followed the pseudo second and first order models, respectively, further proving the high degradation efficiency of TBH5c with high rate constant than that of TBH5d. Thermodynamic parameters (ΔG_ads, ΔH_ads, and ΔS_ads) were calculated, suggesting the spontaneous and exothermic procedure with high entropy, while the adsorption equilibrium data was fitted to Dubinin-Radushkevich model. Both TBH5c and TBH5d showed an excellent stability and reactivity 71.2 and 61 %, respectively, even after 5th cycles. Thus, these results suggested that that TBH5c may be one of the suitable candidates in wastewater treatments.     

Adsorption of crystal violet dye from aqueous solution using mesoporous materials synthesized at room temperature

In this work, batch adsorption experiments are carried out for crystal violet dye using mesoporous MCM-41 synthesized at room temperature and sulfate modified MCM-41 prepared by impregnation method using H₂SO₄ as sulfatising agent. The surface characteristics, pore structure, bonding behavior and thermal degradation of both the MCM-41 samples are characterized by nitrogen adsorption/desorption isotherms, X-ray diffraction (XRD) patterns, Fourier transform infrared (FT-IR) spectroscopy and thermo gravimetric analysis (TGA). The adsorption isotherm, kinetics and thermodynamic parameters are investigated for crystal violet (CV) dye using the calcined and sulfated MCM-41. Results are analysed using Langmuir, Freundlich and Redlich-Peterson isotherm models. It is found that the Freundlich model is an appropriate model to explain the adsorption isotherm. The highest adsorption capacity achieved is found to be 3.4×10⁻⁴ mol g⁻¹ for the sulfated MCM-41. The percentage removal of crystal violet dye increases with increase in the pH for both the MCM-41 adsorbents. Kinetics of adsorption is found to follow the second-order rate equation. From the thermodynamic investigation, it is evident that the adsorption is exothermic in nature.     

浊点萃取-分光光度法测定水样中痕量结晶紫

提出了浊点萃取-分光光度法测定水样中结晶紫的新方法,研究了非离子表面活性剂Triton X-114浊点萃取的最佳条件,如pH、试剂用量、平衡时间和温度等。结晶紫的最大吸收波长为579 nm,标准曲线的线性范围是32～700 ng/mL,检出限是9.8 ng/mL,富集倍率为20。结晶紫的浓度在0.2和0.5μg/mL时的相对标准偏差分别为2.5%和1.7%(n=8)。应用本方法测定水样中的痕量结晶紫,平均回收率95.2%～98.1%。     

Enthalpies of adsorption of methylene blue and crystal violet to montmorillonite

Calorimetric measurements of the enthalpy of adsorption on montmorillonite indicate different patterns for methylene blue (MB) and crystal violet (CV). The enthalpy of adsorption of MB is endothermic up to 73% of the cation exchange capacity (CEC) (i.e., about 0.6 mmol g^-1 clay), whereas at higher adsorption ratios the adsorption reaction becomes exothermic. The enthalpy of adsorption of CV is exothermic for all amounts adsorbed. These results were confirmed with adsorption experiments that prove that adsorption of MB increase with temperature, whereas CV adsorption decreases. This behavior indicates changes in the equilibrium coefficient according to Van't Hoff's equation. This revised version was published online in July 2006 with corrections to the Cover Date.     

用结晶紫为荧光指示剂筛选G-四链体的小分子配体

基于结晶紫(CV)与G-四链体的特异性结合以及结晶紫和端粒DNA(G-DNA)、G-四链体作用后荧光强度的差异,以天然抗肿瘤中药槲皮素为研究对象,建立了一种简单、快速、无标记筛选G-四链体配体的方法。研究了槲皮素与G-DNA的相互作用,并考察了G-DNA在K+存在下形成G-四链体后与槲皮素的作用情况。该方法已用于筛选G-四链体的小分子配体。     

Controlled crystal phase and particle size of loaded-TiO2 using clinoptilolite as support via hydrothermal method for degradation of crystal violet dye in aqueous solution

TiO₂-supported clinoptilolites (TiO₂/clinoptilolites) were successfully synthesized with controlled crystal phase and particle size via hydrothermal method to enhance photocatalytic performance of TiO₂. The effects of various parameters including temperature, acidity and concentration of Ti-containing solutions on the particle size, crystal phase and agglomeration of TiO₂ supported on clinoptilolite were investigated thoroughly by characterizations of X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), BET isotherm, UV–visible (UV–vis) spectrophotometer and Malvern zetasizer. The results demonstrate that increasing temperature and strengthen acidity are beneficial to enhance the crystallinity and particle size of supported TiO₂. Increase in acidity also leads to more uniform distribution of TiO₂ on the surface of clinoptilolite. The TiO₂ nano-crystals deposited on the surface of clinoptilolite, exhibit rutile or anatase phase, strongly depending on the preparation procedure. The resultant TiO₂/clinoptilolites could be used as photo-catalysts for the degradation of crystal violet (CV) dye in aqueous solution, showing a higher photo-catalytic activity with 89% degradation within 100 min. The effect of operational parameters, such as pH values of reaction media, dose of used catalyst, and concentration of CV dye on the CV degradation performance were investigated, in which the kinetics of CV dye degradation was found to follow the pseudo-first order kinetic model.     

Catalytic action of CTAB/KBr/C9OH micellar media on the basic hydrolysis of crystal violet

The kinetics of basic hydrolysis of crystal violet (CV) in CTAB/KBr/C₉OH micellar media was investigated under pseudo-first-order conditions. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of CV at 590?nm. It was observed that the pseudo-first-order rate constant increases with increase in C₀. The enhancement of reaction rate with C₀ is explained on the basis of dependence of reaction rate on micellar morphology. Further, the viscosity and DLS analysis supports nonanol-induced morphological transitions. Fluorescence spectroscopy has been used to understand dye–micelles interactions. The enhancement of fluorescence intensity of CV with C₀ suggests an increase in dye–micelles interaction with C_0. The concentration of surfactant and salt had a marked effect on reaction rate. The inhibition of reaction rate at high concentration of surfactant and salt is due to the ionic competition of OH^? and Br^? ions for the reaction center. The influence of [OH^?] on CV hydrolysis was also investigated. The results show that the pseudo-first-order rate constant, k’, increases linearly with hydroxide ion concentration, indicating first-order dependence on [OH^?].     

Study of the concentration and separation of cadmium with microcrystalline phenolphthalein modified by crystal violet

A new method for cadmium separation and concentration with microcrystalline phenolphthalein modified by crystal violet (CV) was developed in the paper. In the presence of potassium iodide (KI) and CV, cadmium are quantitatively absorbed on microcrystalline phenolphthalein in the pH range 1.0-6.0 as the forms of water-insoluble ion-associated complexes (CdI₃⁻)·(CV⁺) and (CdI₄²⁻)·(CV⁺)₂. Effect of different parameters such as phenolphthalein amount, stirring time, the concentration of CV and KI, various salts and metal ions was studied in detail. During the present study, a significant enhancement of the extraction of cadmium was observed. Cd(II) can be completely separated from Zn(II), Fe(II), Co(II), Ni(II), Mn(II), Cr(III) and Al(III) in this microcrystalline system and well concentrated without the interference of these metal ions at high level. The possible reactive mechanism of cadmium concentration has been discussed. Analytical results obtained by this new method were very gratifying.     

结晶紫探针瑞利光散射技术测定安乃近

在弱碱性条件下,结晶紫与安乃近相互作用后,导致瑞利光散射增强,建立了一种简便、快速、灵敏及选择性好的测定安乃近的分析方法。在390 nm处的ΔIRLS最大,增强的瑞利散射光与0.06~0.40 mg·L-1范围的安乃近呈良好的线性关系,方法的检出限(3Sb/S)为0.017mg·L-1。该法用于市售安乃近药物中安乃近含量的测定,结果满意。     

Synthesis and properties of oil-soluble butyl crystal violet lactone

A novel compound of butyl crystal violet lactone (BCVL) has been prepared by oxidizing leuco butyl crystal violet lactone (LBCVL), which was obtained by the mixture of N,N-dibutylaniline, p-(dibutylamino) benzaldehyde and methyl-m-(dibutylamino) benzoate. The structure of BCVL was characterized by ¹H-nuclear magnetic resonance (NMR), infrared (IR), and mass spectrometry (MS). The color of BCVL can change reversibly in some acid or alkali solvents. The result of the dissolution experiment showed that solubility of BCVL in organic solvent was improved compared with crystal violet lactone (CVL). Translated from Journal of Fudan University (Natural Science), 2006, 45(3): 375–379 [译自: 复旦学报(自然科学版)]     

A surface-enhanced Raman scattering method for detection of trace glutathione on the basis of immobilized silver nanoparticles and crystal violet probe

Unsatisfactory sensitivity and stability for molecules with low polarizability is still a problem limiting the practical applications of surface-enhanced Raman scattering (SERS) technique. By preparing immobilized silver nanoparticles (Fe₃O₄/Ag) through depositing silver on the surface of magnetite particles, a highly sensitive and selective SERS method for the detection of trace glutathione (GSH) was proposed on the basis of a system of Fe₃O₄/Ag nanoparticles and crystal violet (CV), in which the target GSH competed with the CV probe for the adsorption on the Fe₃O₄/Ag nanoparticles. Raman insensitive GSH replaced the highly Raman sensitive CV adsorbed on the surface of Fe₃O₄/Ag particles. This replacement led to a strong decrease of the CV SERS signal, which was used to determine the concentration of GSH. Under optimal conditions, a linear response was established between the intensity decrease of the CV SERS signal and the GSH concentration in the range of 50–700 nmol L⁻¹ with a detection limit of 40 nmol L⁻¹. The use of a Fe₃O₄/Ag substrate provided not only a great SERS enhancement but also a good stability, which guarantees the reproducibility of the proposed method. Its use for the determination of GSH in practical blood samples and cell extract yielded satisfactory results.     

The ultratrace detection of crystal violet using surface enhanced Raman scattering on colloidal Ag nanoparticles prepared by electrolysis

Highly active,stable and affordable surface enhanced Raman scattering(SERS) substrates were obtained by electrolyzing a mixture of AgNO_3(4×10~(-4) mol/L) and Na_3C_6H_5O_7·H_2O(6×10~(-5) mol/L) for 1,2,3 and 4h at 7V.With crystal violet(CV) as a test molecule,a portable Raman spectrometer with 785 nm laser excitation was employed to carry out the SERS detection.Colloidal Ag nanoparticles prepared by electrolyzing for 3 h with the particle size of(65±17) nm is a perfect SERS substrate for the ultratrace ...     

Application of ionic liquid‐based microwave‐assisted extraction of malachite green and crystal violet from water samples

A simple, environment friendly and efficient technique, ionic liquid‐based microwave‐assisted extraction was first used to determine malachite green and crystal violet (CV) from water samples coupled to HPLC. The key parameters influencing extraction efficiency were investigated, such as the type of ionic liquids, the volume of ionic liquid, extraction time, and so on. Under the optimum conditions, good reproducibility of the extraction performance was obtained (RSD, 1.0% for malachite green (MG) and 5.9% for CV, n = 5). Good linearity (0.10–25 μg L^?1) was observed with correlation coefficients between 0.9991 and 0.9964. The detection limits of MG and CV were 0.080 and 0.030 μg L^?1, respectively. The proposed method had been successfully applied to determine MG and CV in real water samples with recoveries ranging from 95.4 to 102.8%. Compared with the previous technologies, the proposed method required less extraction time (2 min), and provided lower detection limits and higher enrichment factors. Moreover, there were no volatile and hazardous organic solvents released. Based on these simple, environment friendly, rapid, and highly efficient results, the proposed approach provides a new and promising alternative for simultaneously extracting trace amounts of MG and CV from water.     

Oxidation of crystal violet and malachite green in aqueous solutions — a kinetic spectrophotometric study

The reactions of two triphenyl methane (TPM) dyes—crystal violet (CV⁺) and malachite green (MG⁺)—with N₃^• and OH^• radicals were studied by pulse radiolytic kinetic spectrophotometry. The rate constants for the reaction of the cationic dyes (D⁺) with N₃^• are (9.0±0.6)×10⁹ and (3.0±0.2)×10⁹ dm³ mol⁻¹ s⁻¹ respectively and those for the reaction with OH^• are obtained as (8.0±0.6)×10⁹ and (1.1±0.1)×10⁹ dm³ mol⁻¹ s⁻¹ respectively. The transient spectra resulting from the oxidation of the dyes were characterized. The time-resolved spectra indicate that the reaction with OH^• radicals initially generates an adduct which subsequently dissociates to form the radical dication D^•2+. The D^•2+ species decay by further reaction with the parent dye.     

Preparation and spectroscopic characterization of visible light sensitized N doped TiO2 (rutile)

Nitrogen doped TiO₂ represents one of the most promising material for photocatalitic degradation of environmental pollutants with visible light. However, at present, a great deal of activity is devoted to the anatase polymorph while few data about rutile are available. In the present paper we report an experimental characterization of N doped polycrystalline rutile TiO₂ prepared via sol-gel synthesis. Nitrogen doping does not affect the valence band to conduction band separation but, generates intra band gap localized states which are responsible of the on set of visible light absorption. The intra band gap states correspond to a nitrogen containing defect similar but not coincident with that recently reported for N doped anatase.     

The significance of the difference in the point of zero charge between rutile and anatase

The points of zero charge (PZC) of titanium dioxide reported in the literature range from 2 to 8.9. A set of 138 PZC of titanium dioxide was used to explore the effect of the crystalline structure on the PZC. The average and median PZC at pH 5.6 and 5.8, respectively, was found when the entire data set was taken into account. The PZC of anatase (31 entries, average and median 5.9 and 6, respectively) is slightly higher than that of rutile (49 entries, average and median 5.4 and 5.5, respectively), and the difference between the polymorphs corresponds to half of a standard deviation in each set of PZC.     

Photoinduced electron transfer in crystal violet (CV)–bovine serum albumin (BSA) system: evaluation of reaction paths and radical intermediates

Photoinduced electron transfer (PET) from excited probes attached to proteins is of considerable current interest. Photochemical processes following 532 nm excitation of triphenyl methane dye, crystal violet (CV⁺) bound to a protein, bovine serum albumin (BSA), have been investigated in picosecond (ps) to microseconds (μs) time scales by flash photolysis technique. The excited singlet state lifetime of CV⁺ is found to be increased to 130 ps as compared to 1–5 ps for the unbound dye in low viscosity solvents. From flash photolysis studies in microsecond region, transient absorption in the region 650 nm is observed which is attributed to the dication radical CV√²⁺ formed by electron transfer from ³CV^+* to BSA, contrary to electron transfer from BSA to the excited dye as proposed in a recent report. Supporting spectral evidence for the electron transfer from ³CV^+* to BSA is obtained from pulse radiolysis studies.     

Microsolvation effects on the optical properties of crystal violet

We present a joint experimental and theoretical study of the photoabsorption and photodissociation behavior of crystal violet, that is, the tris[p-(dimethylamino)phenyl]methyl cation. The photodissociation spectra of isolated and microsolvated crystal violet have been measured. A single band is observed for the bare cation. This is in good agreement with the calculated vibronic absorption spectrum based on time-dependent density functional theory calculations. The interaction of crystal violet with a single water molecule shifts and broadens the photodissociation spectrum, so that it approaches the spectrum obtained in solution. Theoretical calculations of the structure of the complex suggest that the shift in the absorption spectrum originates from a water molecule bonding with the central carbon atom of crystal violet.     

Determination of crystal violet in seawater and seafood samples through off‐line molecularly imprinted SPE followed by HPLC with diode‐array detection

A highly selective sample cleanup procedure combined with molecularly imprinted SPE was developed for the isolation of crystal violet from seawater and seafood samples. The molecularly imprinted polymer was prepared using crystal violet as the template molecule, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross‐linker. The crystal violet‐imprinted polymer was used as the selective sorbent for the SPE of crystal violet. An off‐line molecularly imprinted SPE method followed by HPLC with diode‐array detection for the analysis of crystal violet was also established. Good linearity on the molecularly imprinted SPE columns was obtained from 0 to 200 μg/L (R² > 0.99). The result demonstrated that the proposed method can be used for the direct determination of crystal violet in seawater and seafood samples. Finally, five samples were analyzed and the following crystal violet concentrations were obtained: 0.92 and 0.52 μg/L in two seawater samples, as well as 0.36 and 0.27 μg/kg in two seafood samples. There is no crystal violet detected in the third seawater sample.     

结晶紫-苯唑西林的共振瑞利散射光谱及应用

在pH 8.71的Tris-HCI缓冲介质中,结晶紫(CV)与苯唑西林(OXA)结合,使体系的共振瑞利散射(RRS)急剧增强并出现新的RRS光谱,最大共振瑞利散射峰位于380nm处,苯唑西林的浓度在0.08～0.8μg·mL-1范围内与散射强度(△1RRS)成良好的线性关系,据此建立了测定苯唑西林的共振瑞利散射法,检出...