Organo-LDH synthesized via tricalcium aluminate hydration in the present of Na-dodecylbenzenesulfate aqueous solution and subsequent investigated by near-infrared and mid-infrared

Na-dodecylbenzenesulfate (SDBS), a natural anionic surfactant, has been successfully intercalated into a Ca based LDH host structure during tricalcium aluminate hydration in the presence of SDBS aqueous solution (CaAl-SDBS-LDH). The resulting product was characterized by powder X-ray diffraction (XRD), mid-infrared (MIR) spectroscopy combined with near-infrared (NIR) spectroscopy technique, thermal analysis (TG–DTA) and scan electron microscopy (SEM). The XRD results revealed that the interlayer distance of resultant product was expanded to 30.46 Å. MIR combined with NIR spectra offered an effective method to illustrate this intercalation. The NIR spectra (6000–5500 cm−1) displayed prominent bands to expound SDBS intercalated into hydration product of C3A. And the bands around 8300 cm−1 were assigned to the second overtone of the first fundamental of CH stretching vibrations of SDBS. In addition, thermal analysis showed that the dehydration and dehydroxylation took place at ca. 220 °C and 348 °C, respectively. The SEM results appeared approximately hexagonal platy crystallites morphology for CaAl-SDBS-LDH, with particle size smaller and thinner.

A new approach to prepare ZVI and its application in removal of Cr(VI) from aqueous solution

Zero valent iron (ZVI) was prepared by reducing natural goethite (NG-ZVI) and synthetic goethite (SG-ZVI) in hydrogen at 550 °C. XRD, TEM, FESEM/EDS and specific surface area (SSA) and pore analyser were used to characterize goethites and reduced goethites. Both NG-ZVI and SG-ZVI with a size of nanoscale to several hundreds of nanometers were obtained by reducing goethites at 550 °C. The reductive capacity of the ZVIs was assessed by removal of Cr(VI) at ambient temperature in comparison with that of commercial iron powder (CIP). The effect of contact time, initial concentration and reaction temperature on Cr(VI) removal was investigated. Furthermore, the uptake mechanism was discussed according to isotherms, thermodynamic analysis and the results of XPS. The results showed that SG-ZVI had the best reductive capacity to Cr(VI) and reduced Cr(VI) to Cr(III). The results suggest that hydrogen reduction is a good approach to prepare ZVI and this type of ZVI is potentially useful in remediating heavy metals as a material of permeable reaction barrier.

A natural oil-based emulsion containing allantoin versus aqueous cream for managing radiation-induced skin reactions in patients with cancer : a phase III double-blind randomised controlled trial

Purpose To investigate the effects of a natural oil-based emulsion containing allantoin versus aqueous cream for preventing and managing radiation induced skin reactions (RISR). Methods and Materials A total of 174 patients were randomised and participated in the study. Patients either received Cream 1 (the natural oil-based emulsion containing allantoin) or Cream 2 (aqueous cream). Skin toxicity, pain, itching and skin-related quality of life scores were collected for up to four weeks after radiation treatment. Results Patients who received Cream 1 had a significantly lower average level of Common Toxicity Criteria at week 3 (p<0.05), but had statistically higher average levels of skin toxicity at weeks 7, 8 and 9 (all p<0.001). Similar results were observed when skin toxicity was analysed by grades. With regards to pain, patients in the Cream 2 group had a significantly higher average level of worst pain (p<0.05) and itching (p=0.046) compared to the Cream 1 group at week 3, however these differences were not observed at other weeks. In addition, there was a strong trend for Cream 2 to reduce the incidence of grade 2 or more skin toxicity in comparison to Cream 1 (p=0.056). Overall, more participants in the Cream 1 group were required to use another topical treatment at weeks 8 (p=0.049) and 9 (p=0.01). Conclusion The natural oil-based emulsion containing allantoin appears to have similar effects for managing skin toxicity compared to aqueous cream up to week 5, however, it becomes significantly less effective at later weeks into the radiation treatment and beyond treatment completion (week 6 and beyond). There were no major differences in pain, itching and skin-related quality of life. In light of these results, clinicians and patients can base their decision on costs and preferences. Overall, aqueous cream appears to be a more preferred option.

Hydrolysis of triasulfuron, metsulfuron-methyl and chlorsulfuron in alkaline soil and aqueous solutions

The hydrolysis of triasulfuron, metsulfuron-methyl and chlorsulfuron in aqueous buffer solutions and in soil suspensions at pH values ranging from 5.2 to 11.2 was investigated. Hydrolysis of all three compounds in both aqueous buffer and soil suspensions was highly pH-sensitive. The rate of hydrolysis was much faster in the acidic pH range (5.2-6.2) than under neutral and moderately alkaline conditions (8.2-9.4), but it increased rapidly as the pH exceeded 10.2. All three compounds degraded faster at pH 5.2 than at pH 11.2. Hydrolysis rates of all three compounds could be described well with pseudo-first-order kinetics. There were no significant differences (P =0.05) in the rate constants (k, day-1) of the three compounds in soil suspensions from those in buffer solutions within the pH ranges studied. A functional relationship based on the propensity of nonionic and anionic species of the herbicides to hydrolyse was used to describe the dependence of the 'rate constant' on pH. The hydrolysis involving attack by neutral water was at least 100-fold faster when the sulfonylurea herbicides were undissociated (acidic conditions) than when they were present as the anion at near neutral pH. In aqueous buffer solution at pH > 11, a prominent degradation pathway involved O-demethylation of metsulfuron-methyl to yield a highly polar degradate, and hydrolytic opening of the triazine ring. It is concluded that these herbicides are not likely to degrade substantially through hydrolysis in most agricultural (C) 2000 Society of Chemical Industry.

Removal of methyl orange from aqueous solutions through adsorption by calcium aluminate hydrates

Methyl orange (MO) is a kind of anionic dye and widely used in industry. In this study, tricalcium aluminate hydrates (Ca-Al-LDHs) are used as an adsorbent to remove methyl orange (MO) from aqueous solutions. The resulting products were studied by X-ray diffraction (XRD), infrared spectroscopy (MIR), thermal analysis (TG-DTA) and scanning electron microscope (SEM). The XRD results indicated that the MO molecules were successfully intercalated into the tricalcium aluminate hydrates, with the basal spacing of Ca-Al-LDH expanding to 2.48 nm. The MIR spectrum for CaAl-MO-LDH shows obvious bands assigned to the N@N, N@H stretching vibrations and S@O, SO_ 3 group respectively, which are considered as marks to assess MO_ ion intercalation into the interlayers of LDH. The overall morphology of CaAl-MOLDH displayed a ‘‘honey-comb’’ like structure, with the adjacent layers expanded.

Reduction and adsorption of Pb2+ in aqueous solution by nano zero-valent iron : a SEM, TEM and XPS study

This study reports the synthesis, characterization and application of nano zero-valent iron (nZVI). The nZVI was produced by a reduction method and compared with commercial available ZVI powder for Pb2+ removal from aqueous phase. Comparing with commercial ZVI, the laboratory made nZVI powder has a much higher specific surface area. XRD patterns have revealed zero valent iron phases in two ZVI materials. Different morphologies have been observed using SEM and TEM techniques. EDX spectrums revealed even distribution of Pb on surface after reaction. The XPS analysis has confirmed that immobilized lead was present in its zero-valent and bivalent forms. ‘Core-shell’ structure of prepared ZVI was revealed based on combination of XRD and XPS characterizations. In addition, comparing with Fluka ZVI, this lab made nZVI has much higher reactivity towards Pb2+ and within just 15 mins 99.9% removal can be reached. This synthesized nano ZVI material has shown great potential for heavy metal immobilization from waste water.

A non-aqueous solution synthesis of boron carbide by control of in-situ carbon

Synthesis of high quality boron carbide (B4C) powder is achieved by carbothermal reduction of boron oxide (B2O3) from a condensed boric acid (H3BO3) / polyvinyl acetate (PVAc) product. Precursor solutions are prepared via polymerisation of vinyl acetate (VA) in methanol in the presence of dissolved H3BO3. With excess VA monomer being removed during evaporation of the solvent, the polymerisation time is then used to manage availability of carbon for reaction.

Degradation of hydroxycinnamic acid mixtures in aqueous sucrose solutions by the Fenton process

The degradation efficiencies and behaviors of caffeic acid (CaA), p-coumaric acid (pCoA) and ferulic acid (FeA) in aqueous sucrose solutions containing the mixture of these hydroxycinnamic acids (HCAs) mixtures were studied by the Fenton oxidation process. Central composite design and multi-response surface methodology were used to evaluate and optimize the interactive effects of process parameters. Four quadratic polynomial models were developed for the degradation of each individual acid in the mixture and the total HCAs degraded. Sucrose was the most influential parameter that significantly affected the total amount of HCA degraded. Under the conditions studied there was < 0.01% loss of sucrose in all reactions. The optimal values of the process parameters for a 200 mg/L HCA mixture in water (pH 4.73, 25.15 °C) and sucrose solution (13 mass%, pH 5.39, 35.98 °C) were 77% and 57% respectively. Regression analysis showed goodness of fit between the experimental results and the predicted values. The degradation behavior of CaA differed from those of pCoA and FeA, where further CaA degradation is observed at increasing sucrose and decreasing solution pH. The differences (established using UV/Vis and ATR-FTIR spectroscopy) were because, unlike the other acids, CaA formed a complex with Fe(III) or with Fe(III) hydrogen-bonded to sucrose, and coprecipitated with lepidocrocite, an iron oxyhydroxide.

Removal of herbicides from aqueous solutions by modified forms of montmorillonite

This investigation for the removal of agricultural pollutants, imazaquin and atrazine was conducted using montmorillonite (MMT) exchanged with organic cations through ion exchange. The study found that the adsorption of the herbicides was affected by the degree of organic cation saturations, the size of organic cations and the different natures of the herbicides. The modified clays intercalated with the larger surfactant molecules at the higher concentrations tended to enhance the adsorption of imazaquin and atrazine. In particular, the organoclays were highly efficient for the removal of imazaquin while the adsorption of atrazine was minimal due to the different hydrophobicities. Both imazaquin and atrazine were influenced by the changes of pH. The amphoteric imazaquin exists as an anion at the pH 5–7 and the anionic imazaquin was protonated to a neutral and further a cationic form when the pH is lower. The weak base, atrazine was also protonated at lower pH values. The anionic imazaquin had a strong affinity to the organoclays on the external surface as well as in the interlayer space of the MMT through electrostatic and hydrophobic interactions. In this study, the electrostatic interaction can be the primary mechanism involved during the adsorption process. This study also investigated a comparative adsorption for the imazaquin and atrazine and the lower adsorption of atrazine was enhanced and this phenomenon was due to the synergetic effect. This work highlights a potential mechanism for the removal of specific persistence herbicides from the environment.

Abatement of aqueous anionic contaminants by thermo-responsive nanocomposites: (Poly(N-isopropylacrylamide))-co-silylanized Magnesium/Aluminun layered double hydroxides

A series of novel thermo-responsive composite sorbents, were prepared by free-radical co-polymerization of N-isopropylacrylamide (NIPAm) and the silylanized Mg/Al layered double hydroxides (SiLDHs), named as PNIPAm-co-SiLDHs. For keeping the high affinity of Mg/Al layered double hydroxides towards anions, the layered structure of LDHs was assumed to be reserved in PNIPAm-co-SiLDHs by the silanization of the wet LDH plates as evidenced by the X-ray powder diffraction. The sorption capacity of PNIPAm-co-SiLDH (13.5 mg/g) for Orange-II from water was found to be seven times higher than that of PNIPAm (2.0 mg/g), and the sorption capacities of arsenate onto PNIPAm-co-SiLDH are also greater than that onto PNIPAm, for both As(III) and As(V). These sorption results suggest that reserved LDH structure played a significant role in enhancing the sorption capacities. NO3− intercalated LDHs composite showed the stronger sorption capacity for Orange-II than that of CO32−. After sorption, the PNIPAm-co-SiLDH may be removed from water because of its gel-like nature, and may be easily regenerated contributing to the accelerated desorption of anionic contaminants from PNIPAm-co-SiLDHs by the unique phase-transfer feature through slightly heating (to 40 °C). These recyclable and regeneratable properties of thermo-responsive nanocomposites facilitate its potential application in the in-situ remediation of organic and inorganic anions from contaminated water.

Effective removal of zinc (II) from aqueous solutions by tricalcium aluminate (C3A)

Recently, studies have identified high zinc levels in various environmental resources, and excessive intake of zinc has long been considered to be harmful to human health. The aim of this research was to investigate the effectiveness of tricalcium aluminate (C3A) as a removal agent of zinc from aqueous solution. Inductively coupled plasma-atomic emission spectrometer (ICP-AES), X-ray diffraction (XRD) and scanning electron microscopy (SEM) have been used to characterize such removal behavior. The effects of various factors such as pH influence, temperature and contact time were investigated. The adsorption capacity of C3A for Zn2+ was computed to be up to 13.73 mmol g−1, and the highest zinc removal capacity was obtained when the initial pH of Zn(NO3)2 solution was between 6.0 and 7.0, with temperature around 308 K. The XRD analysis showed that the resultant products were ZnAl-LDHs. Combined with the analysis of solution component, it was proved the existence of both precipitation and cation exchange in the removal process. From the experimental results, it was clear that C3A could be potentially used as a cost-effective material for the removal of zinc in aqueous environment.

Rapid detection of TNT in aqueous media by selective label free surface enhanced Raman spectroscopy

We report rapid and ultra-sensitive detection system for 2,4,6-trinitrotoluene (TNT) using unmodified gold nanoparticles and surface-enhanced Raman spectroscopy (SERS). First, Meisenheimer complex has been formed in aqueous solution between TNT and cysteamine in less than 15 min of mixing. The complex formation is confirmed by the development of a pink colour and a new UV–vis absorption band around 520 nm. Second, the developed Meisenheimer complex is spontaneously self-assembled onto unmodified gold nanoparticles through a stable Au–S bond between the cysteamine moiety and the gold surface. The developed mono layer of cysteamine-TNT is then screened by SERS to detect and quantify TNT. Our experimental results demonstrate that the SERS-based assay provide an ultra-sensitive approach for the detection of TNT down to 22.7 ng/L. The unambiguous fingerprint identification of TNT by SERS represents a key advantage for our proposed method. The new method provides high selectivity towards TNT over 2,4 DNT and picric acid. Therefore it satisfies the practical requirements for the rapid screening of TNT in real life samples where the interim 24-h average allowable concentration of TNT in waste water is 0.04 mg/L.

In-situ carbon control in the preparation of precursors to boron carbide by a non-aqueous solution technique

Synthesis of high quality boron carbide (B4C) powders is achieved by carbothermal reduction of boron oxide (B2O3) from a condensed boric acid (H3BO3)/polyvinyl acetate (PVAc) product. Precursor solutions are prepared via free radical polymerisation of vinyl acetate (VA) monomer in methanol in the presence of dissolved H3BO3. A condensed product is then formed by flash evaporation under vacuum. As excess VA monomer is removed at the evaporation step, the polymerisation time is used to manage availability of carbon for reaction. This control of carbon facilitates dispersion of H3BO3 in solution due to the presence of residual VA monomer. B4C powders with very low residual carbon are formed at temperatures as low as 1,250 °C with a 4 hour residence time.

Solubility of ibuprofen in aqueous ethanol at low ethanol contents

The solubility of ibuprofen was measured in water (W) - ethanol (E) mixtures from 0 to 50% w/w ethanol at 10, 25 and 40 °C by the dissolution method using UV spectrophotometry to determine the ibuprofen concentrations. The UV calibration for ibuprofen in different water - ethanol mixtures showed Beer - Lambert linearity, however the slopes differed, which indicated the structure of the drug is influenced by the solvent system i.e. the water - ethanol ratio. The ibuprofen solubility in water (zero ethanol) is low (~ 50 ppm) but increases near exponentially with increasing ethanol content. At 40 °C, there is phase separation between 34% and 63% w/w E/(E+W). The solubility data will be used to select precipitation crystallizer conditions to directly produce free flowing ibuprofen particles (<5 m) for developing a dry powder inhaler (DPI) formulation for lung delivery.