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We outline techniques for the control and measurement of the nucleation of crystalline materials. Small angle x-ray scattering/wide angle x-ray scattering x-ray diffraction measurements are presented that demonstrate the impact of low power, continuous, non-cavitational ultrasound on the nucleation and crystallization of a wax—n-eicosane dissolved in a heptane/toluene solvent. A mathematical-physical approach based on the rectification of heat and mass transport by such a low power oscillating pressure field is outlined, and it is suggested that this approach be combined with dissipative particle dynamics computational modeling to develop a predictive method capable of modeling the impact of low power oscillating pressure fields (acoustics and ultrasonics) on a wide range of nucleating systems. Combining the ultrasound pitch and catch speed of sound measurements with low power harmonically oscillating pressure fields to monitor and control nucleation presents the prospect of entirely new industrially significant methods of process control in crystallization. It also offers new insights into nucleation processes in general. However, for the acoustic control technique to be widely applied , further theoretical and modeling work will be necessary since, at present, we are unable to predict the precise effect of low power ultrasound in any given situation.

The main objective of this research is to investigate both the mechanism and the kinetics of solvent-free destabilization of the model caffeine/malonic acid cocrystal (CA/MO 2:1) in the presence of...

Mechanistic understanding of competitive destabilization of carbamazepine:nicotinamide and carbamazepine:saccharin cocrystals under solvent free conditions has been investigated. The crystal phase transformations were monitored using hot stage microscopy, variable-temperature powder X-ray diffraction, and sublimation experiments. The destabilization of the two cocrystals occurs via two distinct mechanisms: vapor and eutectic phase formations. Vapor pressure measurements and thermodynamic calculations using fusion and sublimation enthalpies were in good agreement with experimental findings. The mechanistic understanding is important to maintain the stability of cocrystals during solvent free green manufacturing.

This research aimed to evaluate the alga Scenedesmus obliquus toxicity induced by textile-dyeing effluents (TDE). The toxicity indicator of TDE in alga at the physiological (algal growth), biochemical (chlorophyll-a (Chl-a) synthesis and superoxide dismutase (SOD) activity) and structural (cell membrane integrity) level were investigated. Then we further study the relationship among toxicity indicators at physiological and biochemical level, and supplemented by research on algal biomacromolecules. According to the analysis of various endpoints of the alga, the general sensitivity sequence of toxicity endpoints of Scenedesmus obliquus was: SOD activity > Chl-a synthesis > algal growth. The stimulation rate of SOD activity increased from day 3 (57.25%~83.02%) to day 6 (57.25%~103.81%), and then decreased on day 15 (−4.23%~-32.96%), which indicated that the antioxidant balance system of the algal cells was destroyed. The rate of Chl-a synthesis inhibition increased gradually, reaching 19.70%~79.39% on day 15, while the rate of growth inhibition increased from day 3 (−12.90%~10.16%) to day 15 (−21.27%~72.46%). Moreover, the algal growth inhibition rate was positively correlated with the inhibition rate of SOD activity or Chl-a synthesis, with the correlation coefficients were 0.6713 and 0.5217, respectively. Algal cells would be stimulating to produce excessive reactive oxygen species, which would cause peroxidation in the cells, thereby destroying chloroplasts, inhibiting chlorophyll synthesis and reducing photosynthesis. With increasing exposure time, irreversible damage to algae can lead to death. This study is expected to enhance our understanding of the ecological risks through algal tests caused by TDE.

The influence of Cl

In the oxidation treatment of textile dyeing sludge, the quantitative and transformation laws of organic chlorine are not clear enough. Thus, this study mainly evaluated the treatment of textile dyeing sludge by Fenton and Fenton-like system from the aspects of the influence of Cl

Nitrogenization is an effective method for improving the capacitive deionization (CDI) performance of porous carbon materials. In particular, polymer organic frameworks with heteroatom doping, containing an ordered pore structure and excellent electrochemical stability, are ideal precursors for carbon materials for high-performance CDI. In this study, a nitrogen-enriched micro-mesoporous carbon (NMC) electrode was fabricated by carbonizing a Schiff base network-1 at 500, 600, and 700 °C. Scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, N2 adsorption-desorption, the contact angle of water, cyclic voltammetry, and electrochemical impedance spectroscopy were used to characterize the morphological structure, wettability, Brunauer–Emmett–Teller surface areas, and electrochemical performance of the NMCs. The results showed that the NMC carbonized at 600°C achieved the best specific capacitance (152.33 F/g), as well as a high electrosorption capacity (25.53 mg/g) because of its chemical composition (15.57% N) and surface area (312 m2/g). These findings prove that NMC is viable as an electrode material for desalination by high-performance CDI applications.

The main content of this work is to investigate the removal of polycyclic aromatic hydrocarbons (PAHs: phenanthrene, anthracene, and fluoranthene) from simulated sludge solid phase employing an Fenton/Cl

Chlorophenols (CPs) are toxic contaminants that tend to accumulate in textile dyeing sludge and pose a threat to the environment through the disposal process. To comprehensively evaluate CPs in sludge, the characteristics and risks of CPs from five textile dyeing plants (TDPs) were investigated in this study. The total concentration of 19 CPs (Σ19 CPs) varied from 170.90 to 6290.30 ng g−1 dry weight (dw), among which high-chlorine phenols accounted for the greatest proportion. The ecological screening level (ESL) of CPs was used to judge their pollution levels, while the risk quotient (RQ) value and dioxin conversion rate were used to analyze their potential risk. The results indicated that CPs may pose a moderate to high risk to the environment. The Fenton process was used to condition the hazardous sludge, and a higher content of CPs was found after conditioning. A lower rate of CP increase was achieved with a reagent dose of 180 mmol/L, H2O2:Fe2+ = 1:1, pH of 3–4 and reaction time of 30 min. In summary, the work helps to address the general knowledge gap in the textile dyeing industry and provides a reference for further research.

A novel magnetic SO4/Fe-Al-TiO2 solid acid catalyst was synthesized for biodiesel production via the (trans)esterification of waste cooking oil (WCO). The nanocomposite catalyst was prepared by the sequential functionalisation of commercial rutile/anatase mixed phase TiO2 nanoparticles (NPs) with alumina as a buffer layer, and subsequently hematite to impart magnetic character, prior to sulfation with chlorosulfonic acid to introduce Bronsted acidity. XRD showed that the SO4/Fe-Al-TiO2 catalyst comprised titania (rutile and anatase phases), aluminium sulphate, and hematite nanoparticles, while electron microscopy revealed the layer-by-layer assembly of these components within the SO4/Fe-Al-TiO2 catalyst. FTIR confirmed the presence of surface sulphate groups SO42- and S2O72-/S3O102-, creating a predominantly Bronsted acid catalyst with high acid loading. The catalyst achieved 96 % fatty acid methyl ester (FAME) yield from WCO after 2.5 h of reaction at 90 °C, using 3 wt% of the magnetic catalyst, and a methanol:oil molar ratio of 10:1. SO4/Fe-Al-TiO2 was also effective for feedstocks containing up to 20 wt% of free fatty acid (FFA), and showed excellent stability for WCO (trans)esterification over 10 recycles.

A quantitative kinetics analysis of the solution-mediated phase transformations in aqueous-ethanol between the enantiotropically related alpha and beta polymorphs of p-aminobenzoic acid (PABA) is presented. A new temperature-controlled transmission flow-cell design for use with a laboratory X-ray source which can be utilized for diffraction or scattering experiments is described. This transmission cell in combination with in situ slurry X-ray diffraction is utilized to provide a quantitative analysis of the percentage by mass of respective solid phases in flowing suspensions, coupled with solution concentration as measured with UV–vis spectroscopy. The separate phases are identified through individual fingerprint peaks, the (1 0 3) reflection at 2θ = 15.6° relating to the alpha phase and the (0 2 2) reflection at 2θ = 25.3° for the beta phase. Examination of the conversion of a slurry of beta PABA in a 70:30 water/ethanol solvent mixture to the alpha polymorph, at a temperature range of 24–30 °C reveals the rate of dissolution of the beta phase is consistent with zero order kinetics (rate constant kdβ 6.80 × 10–4 to 8.17 × 10–5 wt % s–1), while the growth of the alpha phase follows first order kinetics (kgα 1.00 × 10–3 to 2.50 × 10–4 wt % s–1). Extrapolation of the growth and dissolution rate constants yields a transformation temperature for the phase interconversion of 22–24 °C. Overall the data are consistent with a fast de-supersaturation of the solution concentration indicating a dissolution-controlled polymorphic transformation process.

The thermal expansion behaviour of the alpha and beta polymorphs of para-aminobenzoic acid are presented and discussed in terms of the bulk crystal chemistry and the associated strengths of the constituent intermolecular synthons for these two materials. Analysis of temperature dependant powder diffraction data over the temperature range 298.15–403.15 K facilitates calculation of the linear thermal expansion coefficients: αa = 8.36 × 10−06 K−1, αb = 94.5 × 10−06 K−1 and αc = 9.91 × 10−06 K−1 for the alpha polymorph and αa = 21.5 × 10−06 K−1, αb = 48.5 × 10−06 K−1 and αc = 2.22 × 10−06 K−1 for the beta polymorph. The exceptionally large increase in the thermal expansion of the b axis for the alpha form reflects the weak dispersive interactions which propagate along this axis. In contrast, the a and c axes contain relatively strong hydrogen bonds which stabilise the lattice and limit thermal expansion. The thermal expansion of the beta form reflects the more isotropic nature of the intermolecular synthons for this polymorph in comparison to the alpha form. The thermal expansion of the b axis of the beta form is larger than that of the a and c axes but to a much lesser extent than that observed for the alpha form. This is rationalised through identification of a hydrogen bonding component which contributes to the stabilisation of the b axis in comparison to the almost fully dispersive nature found in the alpha structure.

A novel, efficient and recyclable mesoporous TiO 2 /PrSO 3 H solid acid nano-catalyst was synthesised by the post-synthetic grafting of propyl sulfonic acid groups onto a mixed phase of a TiO 2 support. The synthesised nano-catalyst was characterised using FTIR, SEM, TEM, XPS, N 2 adsorption–desorption isotherms, XRD, DSC, TGA, and CHNS analysis. The loading percentage of propyl sulfonic acid on the TiO 2 support was calculated using CHNS analysis and TGA. The catalytic performance of TiO 2 /PrSO 3 H on the production of the fatty acid methyl esters (FAME) via simultaneous esterification and transesterification reactions from used cooking oil (UCO) has been studied. The effects of different process parameters showed that 98.3% of FAME can be obtained after 9 h of reaction time with 1:15 molar ratio of oil to methanol, 60 °C reaction temperature and 4.5 wt% catalyst loading. It was also found that the one-pot post-surface functionalisation strategy with hydrophilic functional groups (–SO 3 H) enhanced the acid strengths of the nano-catalyst providing more acid sites for the reactants, and improving the accessibility of methanol to the triglycerides (TG)/free fatty acids (FFAs) by increasing the pore volumes/sizes of the nano-catalyst. The solid acid nano-catalyst was re-used in four consecutive runs without significant loss of catalytic efficiency. Finally, the synthesised biodiesel fuel satisfied ASTM and EN standards.

In order to support the use of integrated ultrasound-Mn(VII) for the removal of anilines, this study investigated for the first time the influence of the sludge characteristics on the reaction kinetics of target anilines including o-toluidine, p-chloroaniline, 2-methoxy-5-methylaniline, and 2,4,5-trimethylaniline. The results indicated that with a KMnO4 dosage of 1 mM and an ultrasound power density of 0.90 W cm−3, 68.85%, 85.53%, and 78.50% of anilines can be removed from textile sludge plant 1, 2, and 3. Higher removal efficiency of anilines was achieved at a lower pH value, smaller particle size, and more negative ζ-potential. The target anilines exhibited substantial reactivity toward Mn(VII) with the maxima of second-order rate constants at a pH value near their pKa values for o-toluidine (0.80 M−1s−1 at pH 4), p-chloroaniline (0.65 M−1s−1 at pH 4), 2-methoxy-5-methylaniline (0.45 M−1s−1 at pH 4), and 2,4,5-trimethylaniline (0.34 M−1s−1 at pH 5). Moreover, the biodegradability of textile-dyeing sludge was greatly enhanced by integrated ultrasound-Mn(VII) treatment. This integrated treatment was proposed as an effective method for the disposal of anilines in textile-dyeing sludge.

Catalytic transesterification of triglycerides and esterification of free fatty acids underpins sustainable biodiesel production, wherein efficient heterogeneous catalysts are sought to replace mineral acids. A robust, magnetic core-shell SO4/Mg-Al-Fe3O4 catalyst was synthesised by stepwise co-precipitation, encapsulation, and surface functionalisation. The resulting magnetically-separable catalyst has a surface area of 123 m2 g-1, uniform 6.5 nm mesopores, and a high total acid site loading of 2.35 mmol g-1. Optimum conditions for the (trans)esterification of waste cooking oil (WCO) over the sulfated solid acid catalyst were 95 °C, a methanol:WCO molar ratio of 9:1, and 300 min reaction to achieve 98.5 % FAME yield. Esterification of oleic acid to methyl oleate resulted in an 88 % yield after 150 min under the same reaction conditions. The magnetic solid acid catalyst exhibited good thermal and chemical stability and enabled facile catalyst separation post-reaction and the production of high quality biodiesel.

A route to the accelerated nucleation of α-para-aminobenzoic acid in ethanol/water (EtOH/H2O) mixed solvent solutions, using antisolvent crystallization, is presented. An isothermal by design approach is adopted, whereby the exothermic enthalpy of mixing associated with antisolvent addition is offset by the control of the temperature of the antisolvent added. Induction times (τ) are found to be reduced by 4 orders of magnitude using this methodology, consistent with the use of this approach as a nucleation acceleration technique. Calculation of the nucleation kinetic parameters for a range of solution concentrations, compositions, and supersaturations (S) reveal that effective interfacial tensions (γeff) vary from 8.4 to 2.3 mJ m–2 from solutions in H2O solvent and EtOH solvent, respectively, in line with the trend in solubility. The critical nucleus radius (r*) decreases from 1.98 to 0.40 nm associated with a decrease in the number of molecules in the critical nucleus (i*) from 196 to 2 molecules. A change in nucleation mechanism from heterogeneous nucleation to homogeneous nucleation is observed to take place at S ≈ 1.5. Limitations, particularly with focus toward larger-scale operation, are highlighted together with potential solutions to overcome such aspects.

The main content of this work is to investigate the removal of polycyclic aromatic hydrocarbons (PAHs: phenanthrene, anthracene, and fluoranthene) from simulated sludge solid phase employing an Fenton/Cl− system under various Cl− contents and pH values. The steady-state concentrations of the hydroxyl, chlorine, and dichloride anion radicals ([·OH]ss, [·Cl]ss, and [Cl2·-]ss) in heterogeneous system were first measured using tert-butanol, nitrobenzene, and benzoic acid. The outcomes exhibited that increasing the Cl− content from 50 to 2000 mg/L (pH = 3.0) or raising the pH from 3.0 to 5.0 (1000 mg/L Cl−) caused [·OH]ss to continuously decrease and [Cl2·-]ss and the concentration of superoxide anions (HO2·/O2·-) to continuously increase. When the pH was 3.0 and the Cl− concentration was 1000 mg/L, [·Cl]ss had a maximum value of 9.27 × 10−14 M. Combining the results of PAH removal, radical quenching, and product analysis, it was found that ·Cl in the Fenton/Cl− system promoted the oxidative degradation of phenanthrene without forming chlorination byproducts. Furthermore, HO2·/O2·- was helpful in removing anthracene and fluoranthene. Under the environment of high Cl− content (≥1000 mg/L), PAHs could be removed more effectively by using HO2·/O2·-. This investigation underpins further study on the regulation of reactive species and the efficient degradation of target organic matter in Fenton/Cl− system, and provides a basis for studying the formation of chlorinated or toxic byproducts in the process of treating textile dyeing sludge by Fenton.

A novel solid acid nano-catalyst [Ti(SO 4 )O] was synthesised and used for the simultaneous esterification and transesterification of free fatty acids in used cooking oil (UCO) to produce biodiesel. The synthesised nano-catalyst was fully characterized by different analytical techniques. The XPS results clearly confirmed that the bidentate sulphate coordinated to the Ti 4+ metal in the nano-catalyst product. Obtained d -spacing values from the experimental data of XRD peaks and the SAED pattern of produced nano-catalyst agreed well with the d -spacing values from the JCPDS-ICDD card numbers 04-011-4951 for titanium sulphate oxide or titanium oxysulfate crystal structures.This confirms the sulphate groups were within the crystalline structure rather than on the surface of titania nanoparticles, which has not been previously reported. It has been demonstrated 97.1% yield for the fatty acid methyl ester can be achieved usign the synthetised catalyst under a reaction time of 3 h, catalyst to UCO ration of 1.5 wt% and methanol to UCO ratio of 9:1 at 75 °C reaction temperature. The nano-catalyst showed a good catalytic activity for the feedstock containing ≤6 wt% free fatty acid. Furthermore, the catalytic activity and re-usability of the Ti(SO 4 )O for the esterification/transesterification of UCO were investigated. XRD results confirmed that the amount of S O 4 2 − species in the solid acid nano-catalyst slowly decreased with re-use after 8 cycles under optimised conditions, which is higher than the reusability of other functionalised titania reported in the literature. Finally, the biodiesel prodcued from this process satisfied the ASTM and European Norm standards.

Daidzein has extremely poor water solubility affecting its bioavailability even with high doses. To achieve the therapeutic effects of Daidzein, the aim of this research project is to design multi-component crystal forms of Daidzein cocrystals with improved solubility and dissolution rate to maximize its therapeutic effect. The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. Daidzein (7,4' -dihydroxyisoflavone, DAI) is an isoflavone found in soybeans and Pueraria. DAI has potential therapeutic benefits on cancer and osteoporosis yet has quite low solubility, limiting its use. Herein a cocrystal screening of DAI with pyridine-derived molecules, i.e., nicotinamide, isonicotinamide, caffeine, d -Proline, l -Proline and 4,4' -Bipyridine was conducted. A new cocrystal of Daidzein and 4,4' -Bipyridine (DAI-BIP) was successfully generated via grinding and solvent methods. DAI-BIP showed an increased solubility and dissolution rate. In comparison to DAI, there was a 2.03-fold increase of the dissolution performance parameter for DAI-BIP where the concentration observed for DAI quickly reached the equi- librium solubility and continued to reach 1.49 times DAI solubility. A parachute effect was also observed during the dissolution of DAI-BIP, indicating that BIP might be able to maintain the supersaturated state of DAI in solution proving DAI’s ability to form cocrystals of higher solubility and enhanced dissolution properties through co-crystallisation

In this study, polycyclic aromatic hydrocarbons (PAHs) at practical concentrations in the simulated sludge treated by the Fe2+/H2O2 and Fe2+/peroxymonosulfate (PMS) systems were evaluated in terms of the PAHs (phenanthrene, anthracene, fluoranthene) removal, element migration, Cl− effect, and chlorination by-product formation. The results indicated that according to the removal rate of PAHs, the optimal dosage of the Fe2+/PMS system (∑PAHs removal rate was 64.66 ± 2.82 %) was 1/30 of that for the Fe2+/H2O2 system (∑PAHs removal rate was 78.63 ± 0.38 %). The elemental contents in the simulated sludge were mainly affected by the extent of advanced oxidation and the amount of generated iron flocs. By studying the PAHs removal, free chlorine formation, total organochlorine content, and PAHs products in Fe2+/H2O2/Cl- and Fe2+/PMS/Cl- systems, it was found that chlorine radicals (·Cl) had high reactivity with phenanthrene and fluoranthene, whereas dichloride anion radicals (Cl2·-) exhibited the opposite behavior. Furthermore, PAHs were oxidized by ·Cl and hydroxyl radical in the Fe2+/H2O2/Cl- system, whereas PAHs and their products were chlorinated by free chlorine and ·Cl in the Fe2+/PMS/Cl- system to six chlorinated by-products such as Cl-PAHs (9-Cl-phenanthrene, 2-Cl-anthracene, 9,10-Cl2-anthracene, 3-Cl-fluoranthene). These results provide some useful suggestions for the safe advanced oxidation process treatment of textile dyeing sludge.

Chlorobenzenes (CBs) present in synthetic dyes are discharged into natural waters during the treatment of textile dyeing wastewater, which may have adverse effects on human and environment. In this study, the existence and removal of 12 CBs in different units of five treatment plants were examined. The ecological risk of CBs in textile dyeing wastewater was assessed by ambient severity (AS) and risk quotients (RQs). The results showed that trichlorobenzene, tetrachlorobenzene, pentachlorobenzene and hexachlorobenzene were ubiquitous in textile dyeing wastewater, and their distribution was similar. In one of the plants, the content of hexachlorobenzene was found to be as high as 9.277 μg/L in the raw water, which was an oil-water mixture. In other plants, there was no significant difference in the content and composition of CBs among influent and effluent suggesting that the conventional wastewater treatment plants cannot improve the existence of them. Monochlorobenzene and dichlorobenzene were not detected, which may have been related to strong volatility, biochemical properties, and weak instrument sensitivity. In the treatment process and effluent, trichlorobenzene is the main pollutant and accounted for 39.51% of all CB. CB removal was found only in the anaerobic system, while the aerobic system did not have the corresponding removal effect on CB and total organic carbon. According to ecological risk assessment, CBs in effluent has not been found the significant potential harm to human health (AS 1), but posed moderate ecological risk to aquatic ecosystem (RQs 0.1).

In this study, the mixing mechanism and phase transition process of different metals during the sintering of tailings bricks with four different metal oxides (CuO, PbO, ZnO, and CdO) at temperatures ranging from 700 to 1100 °C for 2 h were investigated. The properties of the sintered product was characterized and analyzed, and the results showed that the main crystalline phases are quartz, cristobalite, hematite, and mullite while the metal oxides are ascribed to copper ferrite spinel (CuFe2O4), gahnite (ZnAl2O4), zinc ferrite spinel (ZnFe2O4), lead feldspar (PbAl2Si2O8), and cadmium feldspar (CdAl2Si2O8). Further analysis indicates that the heavy metals were transited into spinel or silicate structures with favorable efficiency. This indicates a good heavy-metal fixation effect from the structural change after the sintering process. Finally, the leaching experiments of the sintered samples suggest that the metal leaching decreased to a low and stable value when the sintering temperature was higher than 950 °C, which meets the China standard (GB 5085.3-2007). The above results indicate that the sintering process facilitates the combination of Cu, Zn, Pb and Cd offering an effective and safe method for the application of materials that contain tailings.

The solubility and crystallisability of a range of binary mixtures of n-hexadecane (C16H34) and n-octadecane (C18H38), as the predominant alkanes present in hydrotreated vegetable oil (HVO), from three representative fuel solutions (dodecane, toluene and kerosene) is presented. The dissolution (saturation) and crystallisation (supersaturation) points of the solutions are measured using poly-thermal methods utilising turbidometric detection over four concentrations from (192 g/l to 400 g/l). The data reveals the existence of more soluble, less stable crystal structures that form from the alkane mixtures, when compared to the stable triclinic crystal structures formed from the single solute component solutions. An increased carbon chain length results in lower solubility for all three solvents and the solvent type is not found to have any significant effect on the solid forms produced from the mixtures. van’t Hoff analysis reveals the solvent type to influence the solute solubility with the closest to ideal behaviour being dodecane followed by kerosene and toluene, respectively. This finding is further supported by the calculated dissolution enthalpies and activity coefficients, which are the lowest in dodecane followed by kerosene and toluene. Larger values of activity coefficients are observed for compositions with molar fraction (y) = 0.1, 0.5–0.7 C18H38 which reflect the complex multi-phase formation in the solutions when compared with the more simple binary melt crystallisation system.

Understanding the occurrence states of persistent organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) in textile dyeing sludge is the key to their further treatment and disposal. Here, the effects of inorganic salts (silicate, sulfate, phosphate, hydroxide, and iron salts) that were typically rich in textile dyeing sludge on PAH adsorption by sludge and PAH degradation by an ultrasound (US) combined zero-valent iron/EDTA/Air (ZEA) system were studied in a simulated sludge system. The results showed that the simulated sludge containing inorganic salts had a larger specific surface area, which was beneficial for the adsorption of PAHs. More low-ring PAHs were adsorbed on the surface of the particles in the simulated sludge because of the inorganic salts, which was conducive to low-ring PAHs degradation by US/ZEA. The PAH removal rates were increased by 15.37% and 11.19%, respectively, in the presence of SiO32− and HPO42−. The yield of hydroxyl radicals ( OH) was increased by 42.39% and 66.25% by SiO32− and HPO42−, respectively. The reason was that the oxidation of the ligand ([FeⅡ(EDTA)]) formed by ethylenediaminetetraacetic acid (EDTA) and divalent iron was promoted by SiO32− and HPO42−. The formation of OH in the US/ZEA system was inhibited by the corrosion inhibition of SO42− on zero-valent iron (ZVI), the reaction of ferric salt with EDTA, and the reaction of Mg(OH)2 with the ligand ([FeIII(EDTA)]). This work provides an essential theoretical insight into the role of the inorganic components of sludge in the removal of PAHs by advanced oxidation processes.

Sodium chlorate (NaClO₃) crystals change from a cuboid to a tetrahedron of {1̅1̅1̅} morphology when crystallized in the presence of sodium dithionate (Na₂S₂O₆) impurity. Polarized extended X-ray absorption fine structure at the S K-edge, used to probe the local structure around this impurity with respect to its orientation within the bulk crystal lattice, reveals that the S–S bond of the S₂O₆²‾ ions is closely aligned along the / lattice direction. High resolution diffraction studies using X-ray multiple diffraction reveal growth-induced anisotropy in the doped crystals associated with subtle lattice distortions in the symmetry-independent {1̅1̅1̅} and {111} growth sectors. The data are consistent with a mechanistic model involving the creation of lattice vacancies and the substitution of one of the SO₃ anionic groups of the dopant ion for a host ClO₃ ion when incorporated at the {1̅1̅1̅} growth interface with the other SO₃ group substituting for one or more anionic sites in the succeeding growth layer depending on the degree of impurity concentration within the crystallization solution. This mechanism is also fully consistent with the formation of twinning at higher impurity concentrations previously reported by Lan et al. Cryst. Growth & Des. 2014, 14, 6084–6092.

The aim of this study was to evaluate the influence of three chemically diverse polymers, namely hydroxypropylmethylcellulose acetate succinate (HPMCAS), polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG) on the phase transformation of three carbamazepine (CBZ) cocrystals including carbamazepine–nicotinamide (CBZ–NIC), carbamazepine–saccharin (CBZ–SAC) and carbamazepine–cinnamic acid (CBZ–CIN) in solution and tablet-based formulations. Based on the solubility and powder dissolution studies, it is demonstrated that cocrystals can be easily formulated through a simple solution formulation or powder formulation to generate supersaturated concentrations and faster dissolution rates to overcome those drugs with solubility and/or dissolution limited bioavailability. However, a polymer-based CBZ cocrystal tablet formulation has not shown any advantage of an improved CBZ release rate compared with the formulation of CBZ III or physical mixtures of CBZ III and coformers. This is in contrast to the solution behaviours of CBZ cocrystals in the solubility and powder dissolution tests because crystallization of the stable solid form of CBZ dihydrate (CBZ DH) within the tablet has taken place, leading to a reduced drug release rate and incomplete release. The mechanism of a polymer inhibition effect on drug precipitation in solution has been elucidated through investigating the molecular interactions among CBZ, coformers and polymers in solution using infrared spectroscopy. Finally, a formulation strategy has been proposed to capture the significant advantages of cocrystals.

In order to control the particle size and morphology, zinc carbonate hydroxide Zn 5 (CO 3 ) 2 (OH) 6 nanoparticles have been synthesized using a reverse microemulsion technique. The pseudo-ternary phase diagrams of the two microemulsion systems, prepared using CTAB/1-butanol/n-octane/aqueous phase system with the aqueous phase comprised of either zinc nitrate (Zn(NO 3 ) 2 ) or sodium carbonate (Na 2 CO 3 ), were experimentally constructed. The nanoparticles synthesized by mixing of the two emulsion systems were further characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The nanoparticles were further characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Several important experimental parameters have been investigated for the ability to control particle size and morphology as the function of water/surfactant molar ratio (ω), water/oil molar ratio ( S ) and the initial concentration of reactants in the aqueous phase. Results indicate that ω values have the ability to affect the particle size and levels of aggregation, while S values had no apparent effect. In addition, the initial concentration of reactants in the aqueous phase was considered to be an important parameter as raising its values from 0.1 M to 0.5 M produced an unknown phase of zinc carbonate, exhibiting larger particle size with a unique flake like morphology.

This paper aims to examine the influence of various catalysts on biodiesel production, especially from non-food feedstocks with an ambition to optimize the catalytic biodiesel production. Homogenous acid catalysts are mainly used in biodiesel production, but they cannot be recovered and demand costly fuel purification as being corrosive. Similarly, enzyme catalysts are expensive in industrial-scale production of biodiesel. However, heterogeneous catalysts simplify the easy separation of product and by-products from the catalyst along with catalyst reusability and reduction of waste. Solid acid and base catalysts offer more advantages due to their non-toxicity, high surface area, reusability, higher stability, and the simplicity of purification. Solid base catalysts yield better activity than solid acid catalysts, however, they cannot esterify large amounts of free fatty acids (FFAs) in non-food feedstocks. The solid acid catalysts have the added advantages of being more tolerant to high amounts of FFAs and being able to simultaneously esterify FFAs and transesterify triglycerides in cheap feedstocks like waste cooking oil. Recently, an array of inorganic, organic and polymeric solid acid and nanomaterial-based catalysts have been developed using cheap feedstocks. However, the issues of low reactivity, small pore sizes, low stabilities, long reaction times, and high reaction temperatures still need to be solved. The developments of producing efficient, cheap, durable, and stable solid acid and nanomaterial-based catalysts have been critically reviewed in this study. Furthermore, the challenges and future perspectives of production of biodiesel and its industry growth have also been discussed.

The influence of solvent type on the solution thermodynamics, nucleation-kinetics and crystal growth of alpha para-aminobenzoic acid (PABA) crystallising from supersaturated ethanol, acetonitrile and water solutions, is examined using poly-thermal analysis of the metastable zone width. Application of a recently proposed model for analysis of crystallisation kinetics (J. Cryst. Growth, 2010, 312, 698-704) indicates a solvent and concentration dependence of the nucleation mechanism and key nucleation parameters for the alpha form of PABA. The mechanism of nucleation is found to change from instantaneous to progressive with decreasing concentration and also when changing the solvent from ethanol to acetonitrile to water. The dependence of the nucleation mechanism is correlated to the kinetic component of the nucleation rate through calculated values of instantaneously nucleated crystallites, which increase from 1.40 × 10(9) m(-3) in ethanol to 1.08 × 10(10) m(-3) in acetonitrile to 2.58 × 10(10) m(-3) in water. This in combination with low calculated number concentrations of interfacial tension between 1.13 and 2.71 mJ m(-2), supports the conclusion that the kinetic component of the nucleation rate is more limiting when crystallising PABA from ethanol solutions in comparison to water solutions. This finding is further supported by molecular dynamics simulations of the solvation free energy of PABA, which is found to be greatest in water, -42.4 kJ mol(-1) and lowest in ethanol, -58.5 kJ mol(-1).

Carbon-doped titanium dioxide (TiO2) coating on multiwalled carbon nanotubes (MWCNTs) was prepared by oxidation of titanium carbide (TiC) coated MWCNTs. The structure, morphology and surface chemistry states of the TiO2 coating on MWCNTs were characterized by XRD, SEM, HRTEM and XPS. The results suggest that the TiO2 coated MWCNTs keep the similar morphology and length with the pristine MWCNTs. The TiO2 coating, composed of homogeneous nanosized particles, contacts closely with MWCNTs via chemistry bond and Ti–O–C bonds are found. The visible light photocatalytic activity of the prepared photocatalyst was evaluated by decomposition of methylene blue aqueous solution. A probable mechanism of TiO2 and MWCNTs on the enhancement of visible light performance is proposed. It suggests that MWCNTs play key roles, which may act as a support, absorbent, photo-generated transfer station and carbon-doping source.

Pure hexagonal phase of ZnO nanoparticles have been successfully synthesized via microwave assisted decomposition of zinc acetate precursor in a green solvent, the ionic liquid, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide in a very short time scale. The ZnO nanoparticles were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and selected area electron diffraction.

High resolution X-ray diffraction is applied to study Mn3+ doped potassium dihydrogen phosphate (KDP) single crystals as a function of dopant concentration with quantitative dopant composition within the crystals being assessed using Rutherford backscattering spectroscopy (RBS). Synchrotron radiation high resolution X-ray multiple diffraction studies using both the Renninger scanning and two-dimensional angular mapping techniques are consistent with the Mn3+ ionic complex entering the crystal lattice via a substitutional incorporation mechanism for Mn3+ at a concentration of 0.1 wt %. For a higher Mn concentration of 0.9 wt %, the data indicate incorporation via an interstitial mechanism associated with a decrease in lattice perfection (an increased mosaic spread). This analysis is supported through X-ray powder diffraction studies which reveal lattice contraction for lower dopant levels with lattice dilation for the higher dopant levels. The potential impact of this observation on the associated crystal ...

Crystal structures of two conformational polymorphs (Form A and Form D) of NG-monomethyl-l-arginine hydrochloride, a drug developed to treat septic shock, are presented. Form A is orthorhombic in a tetra-molecular unit cell and Form D is monoclinic in a bimolecular unit cell (space groups P212121 and P21, respectively). The two forms display differences in the conformation of the terminal N-methyl group, which is cis in Form D and trans in Form A. Structural energy calculations demonstrate that Form D has a lower lattice energy compared to Form A (−134.7 and −128.8 kcal/mol, respectively). This is supported by solution stability studies where the potential for solution-mediated phase transformation was investigated and Form D is found to be the more stable polymorphic structure at room temperature. The melting behavior of forms A and D indicates a monotropic phase transformation relationship between the two polymorphic forms albeit their melting points (215.7 and 203.7 °C for forms A and D, respectively) ...

The molecular assembly and subsequent nucleation of para-amino benzoic acid (PABA) from ethanolic solutions is probed using a multi-scale and multi-technique approach. This is applied by examining and interrelating information regarding the molecular, solution-state, cluster, solid-state and surface structures to understand why the alpha form of PABA is crystallised in preference to its low temperature beta form. Calculations suggest that conformational changes within the solute molecule play little or no role in directing the nucleation of either the alpha or beta crystal forms. Combined ab initio and molecular dynamics calculations of the stability of small clusters in solution suggests that the hydrogen-bonded carboxylic acid dimers, present in the alpha structure, are the most stable in solution and play a major role in the self-assembly and polymorphic expression of the alpha form in ethanol in preference to the beta form. These calculations are in good agreement with X-ray small-angle scattering analysis which reveals the presence of PABA clusters in ethanol which are consistent with the size and shape of a carboxylic acid dimer. SAXS studies also reveal the presence of larger cluster structures in a size range 10–40 nm which appear to grow, perhaps reflecting a change in the balance between monomers and dimers within the solution during the nucleation process. The results of crystallisation-kinetics experiments indicate an instantaneous nucleation mechanism where the number of instantaneously nucleated crystallites is calculated to be 1360–660 nuclei per ml and the subsequent growth is found to be only rate limited by diffusion of the growth unit to the crystallite surface. A linear dependence of growth rate with respect to supersaturation is observed for the (0 1 −1) capping face, which is associated with strong π–π stacking interactions. This is consistent with a solid-on-solid mechanism associated with surface roughened growth and concomitant poor lattice-perfection. Conversely, the side (1 0 −1) surface has a growth mechanism consistent with a 2D nucleation birth and spread mechanism. Hence, these mechanisms result in very fast growth along the b-axis and the needle-like morphology that is observed for alpha-PABA.

Zinc carbonate hydroxide Zn5(CO3)2(OH)6 nanoparticles have been successfully synthesised by the hydrothermal treatment of an aqueous solution of zinc acetate dihydrate (Zn(CH3COO)2·2H2O) and urea (NH2CONH2) at 120°C. The as-synthesized nanoparticles were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Thermogravimetric Analysis (TGA). XRD and SEM revealed Zn5(CO3)2(OH)6 nanoparticles produced in 20-40nm size range with spherical morphology. TGA showed the expected one-step decomposition of zinc carbonate hydroxide to zinc oxide (ZnO) between temperatures of 180°C and 350°C. The hydrothermal reaction time (2, 3 and 4hours) studied did not show any significant effect on the particle size and morphology. However, the crystallinity of the synthesised nanoparticles seems to be enhanced at longer hydrothermal reaction time by showing larger XRD diffraction peaks.

The tomographic X-ray technique (TEDDI) has been used to continue investigation into crystallite alignment and polymorphic content inside a model batch crystalliser. Previously, the β-polymorph of glutamic acid was shown to exhibit zoning with a supernatant alignment band under stirring conditions, whereas the α-polymorph has now been shown to demonstrate very different behaviour; in particular, its prismatic crystallites appear to be more buoyant than the β-form platelets and there are no apparent preferred orientation effects. In a mixed phase suspension, the β-form appears to dominate, impeding the rise of the α-form in the vessel. In addition, investigation into the effects of crystallite size reveals that the larger β-form crystallites are more buoyant than smaller crystallites. Higher resolution experiments confirm results seen previously in lower resolution intensity maps.

The polymorphic and morphological forms, and growth rates of different crystal facets are important parameters in pharmaceutical crystallisation processes that call for techniques for their real-time monitoring. In this paper, we describe a method for real-time classification of crystal polymorphic and morphological forms based on on-line imaging and image analysis. The focus of discussion is on deriving quantitative shape descriptors from images obtained on-line in real-time, automatic classification of crystals, the estimation of ratios of different polymorphs and new monitoring charts showing the relative average growth rates of facets of crystals. The work presented is based on experimental results of crystallisation in a batch reactor of ( L )-glutamic acid that has two polymorphs, the prismatic alpha and needle-shaped beta forms.