Nitro-functionalization on MIL-53(Fe) for PCMX degradation: Elevating Fenton-like catalytic propelled by abundant reaction sites and iron cycle.

To address the issue of excessive residues of 4-chloro-3,5-dimethylphenol (PCMX) in the water environment. In a one-step solvothermal process, iron-based metal-organic frameworks (Fe-MOFs) material MIL-53(Fe) undergoes a synthetic modification strategy. 2-Nitroterephthalic acid as an organic ligand reacted with Fe3+ in a solvothermal process lasting 18 h to yield the nitro-functionalized MIL-53(Fe)-NO2(18h). The objective was to augment the abundance of Fe central unsaturated coordination sites (Fe CUCs) and expedite the Fe(III)/Fe(II) redox cycle, thereby enhancing the heterogeneous Fenton-like treatment capability of pollutants. MIL-53(Fe)-NO2(18h) has excellent hydrogen peroxide (H2O2) catalytic activity and PCMX degradation across a broad pH spectrum (4.0∼8.0). Almost complete removal of PCMX was achieved within 30 min, while pseudo-first-order kinetic rate constants (kobs) increased 4.37 times over MIL-53(Fe). The confirmation of increased Fe CUCs abundance in MIL-53(Fe)-NO2(18h) was achieved through Lewis acidity, oxygen vacancies (OVs) signals, and Fe-O coordination characterization results. Density functional theory (DFT) calculations revealed that Fe CUCs in MIL-53(Fe)-NO2(18h) exhibits heightened affinity for H2O2 adsorption, showcasing stronger charge transfer and enhanced H2O2 dissociation ability. The Fe(III)/Fe(II) redox cycle, a driving force of Fenton-like reactions, was notably improved in the nitro-modified materials. These enhancements significantly expedited the Fenton-like process, resulting in the generation of increased amounts of reactive oxygen species (ROSs), with hydroxyl radicals (OH·) being pivotal components in degradation. The MIL-53(Fe)-NO2(18h)/H2O2 system has demonstrated versatility in treating a variety of emerging contaminants, achieving removal efficiencies exceeding 99.7% for other antibiotics and endocrine disruptors within 60 min. Furthermore, MIL-53(Fe)-NO2(18h) demonstrated outstanding reusability and adaptability in actual water environments. This study introduces a straightforward and environmentally friendly strategy for remediating environmental pollution using Fe-MOF-catalysed heterogeneous Fenton-like technology.

Fe2+-NTA synergized UV254 photolytic defluorination of perfluorooctane sulfonate (PFOS): Enhancing through intramolecular electron density perturbation via electron acquisition.

Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant posing a risk in environmental persistence, bioaccumulation and biotoxicity. This study was to reach a comprehensive and deeper understanding of PFOS elimination in a UV254 photolytic treatment with the co-presence of Fe2+ and nitrilotriacetic acid trisodium salt (NTA). PFOS defluorination was noticeably enhanced in the UV/Fe2+-NTA treatment compared with UV/NTA, UV/Fe2+ and our previously studied UV/Fe3+ treatments. UV-vis, FTIR, and UPLC/MS-MS results indicated the formation of PFOS-Fe2+-NTA complex in PFOS, Fe2+ and NTA mixture. The transition energy gap of PFOS-Fe2+-NTA decreased below the excitation energy supplied by UV254 irradiation, corresponding with red shift appearing in UV-vis scanning spectrum. This favored intramolecular electron transfer from Fe2+-NTA to PFOS under UV254 irradiation to form electron-accepting PFOS. Molecular electrostatic potential and atom charge distribution analyses suggested electron density rearrangement and perturbation in the perfluorinated carbon chain of electron-accepting PFOS, leading to the decrease in bond dissociation energies. Intermediate products detection suggested the parallel defluorination pathways of PFOS desulfonation, middle carbon chain scission and direct C-F cleavage. NTA exhibited crucial functions in the UV/Fe2+-NTA treatment by holding Fe2+/Fe3+ in soluble form as a chelant and favoring water activation to generate hydrated electrons (eaq-) under UV irradiation as a photosensitizer. Fe2+ acting as the conduit for electron transfer and the bridge of PFOS anion and NTA was thought functioning best at 200 µM in this study. The degree of UV/Fe2+-NTA -synergized PFOS defluorination also depended on eaq- yield and UV254 photon flux. The structure dependence on the electron transfer process of PFOS and PFOA was explored incorporating molecular structure descriptors. Because of possessing greater potential to acquire electrons or less likeliness to donate its electrons than PFOA, PFOS exhibited faster defluorination kinetics in the published "reduction treatments" than "oxidation" ones. Whereas, PFOA defluorination kinetics were at similar level in both "reduction" and "oxidation" treatments.

Modelling drug degradation of amorphous solid dispersion during twin-screw extrusion.

Twin-screw extrusion is one of the major technologies for solid dispersion in the pharmaceutical industry. However, the thermal exposure to the drug during extrusion can easily trigger and exacerbate drug degradation. A conventional method for investigating drug degradation in extrusion is trial-and-error, which can consume much time and material. We propose to model drug degradation kinetics and combine it with thermal history simulation to predict drug degradation. Ritonavir and copovidone were used as a model system of solid dispersion. Hydantoin aminoalchol was the major degradant of RTV in extrudate. In studying the RTV degradation kinetics, only in nitrogen atmosphere, RTV degradation pathway in TGA or DSC was like the degradation pathway in extrusion. The mixing and solubilization of RTV in copovidone also prevented RTV from degrading to oxazolidine derivative. The degradation samples were collected at various temperatures and at different times. The data was fitted into first-order kinetics model to get degradation rates constant at each temperature. The degradation rate constants were fitted into the Arrhenius equation with an activation energy of 159.3 kJ/mol, and a pre-exponential of 1.23 × 1017. An array of extrusion conditions was developed and analyzed via design of experiment (DOE). Relying on the measured melt temperature and residence time after kneading element and die, we simulated the thermal history in the section between kneading element and die. The RTV degradation kinetics in conjunction with simulated thermal history predicted degradation and achieved a 78% regression.

Fabrication of an in situ-grown TiO2 nanowire thin film and its enhanced photocatalytic activity.

TiO2 is a promising photocatalyst used in practical environmental remediation. TiO2 photocatalysts are usually implemented in two forms: suspended powder and immobilized thin films. A simple technique for fabricating TiO2 thin film photocatalyst was developed in this work. The fabricated TiO2 thin film photocatalyst featured a homogeneous nanowire layer grown in situ on the parent Ti plate. The optimized fabrication protocol was to soak the ultrasonically cleaned and acid-washed Ti plate in 30% H2O2 solution containing 3.2 mM melamine and 0.29 M HNO3 at 80 °C for 72 h and then anneal at 450 °C for 1 h. TiO2 nanowires with uniform diameters were homogeneously arrayed on the Ti plate surface. The thickness of the TiO2 nanowire array layer was 1.5 µm. The pore properties of the TiO2 thin film were close to those of P25. The band gap of the fabricated photocatalyst was 3.14 eV. The photocatalytic activity of the fabricated photocatalyst toward 10 mg/L RhB and 1 mg/L CBZ demonstrated greater than 60% degradation under 2 h UVC irradiation. The RhB and CBZ degradation efficiencies remained at a good level after 5 consecutive cycles. Mechanical wearing, such as 2 min sonication, will not lead to significant suppression of the photocatalytic activity. Photocatalytic RhB and CBZ degradation using the fabricated photocatalyst favored an acidic > alkaline > neutral environment. The presence of Cl- slightly suppressed the photocatalytic degradation kinetics. However, RhB and CBZ photocatalytic degradation kinetics were promoted in the copresence of SO42- or NO3-.

Control for chlorine resistant spore forming bacteria by the coupling of pre-oxidation and coagulation sedimentation, and UV-AOPs enhanced inactivation in drinking water treatment.

Spore forming bacteria (SFB) are strongly chlorine resistant. Their presence in drinking water may cause diseases and pose threat to public health. Three SFB strains, i.e. Bacillus alvei, Bacillus cereus, and Lysinibacillus fusiformis, were isolated and identified from the finished water of a drinking water treatment plant where bacteria colonies occasionally reached the limit value. Due to their chlorine resistance, a SFB control strategy coupling pre-oxidation, coagulation sedimentation, and UV-AOPs inactivation in water treatment process was studied in lab scale. Five minutes pre-oxidation treatment by applying Cl2 and ClO2 induced remarkable spore transformation. Longer pre-oxidation exposure time didn't have apparent improvement. Cl2 and ClO2 dosages of 0.9 mg/L and 0.5 mg/L were suggested, respectively. The formed spores can be efficiently removed by the following coagulation sedimentation treatment. At a suggested dosage combination of 20 mg/L PAC and 0.08 mg/L PAM, spore removal efficiency reached about 3.15-lg. Comparing to applying sole UV irradiation, enhanced UV inactivation by adding 0.1 mM H2O2, or Cl2, or peroxymonosulfate (PMS) substantially improved the inactivation of the most chlorine resistant SFB strain, Lysinibacillus fusiformis. UV-AOPs stably achieved 2-lg inactivation rate at UV dosage of 40 mJ/cm2. UV/H2O2, UV/Cl2 and UV/PMS inactivation kinetically enhanced 1.20 times, 1.36 times and 1.91 times over sole UV irradiation. Intracellular DNA and ATP leakages were detected, and remarkable damages of Lysinibacillus fusiformis cells' surface and ultrastructure were observed. These findings evidenced cell wall and cell membrane destructions, guaranteeing substantial SFB cells inactivation. This study was carried out based on three SFB strains isolated from a finished water, and common engineering practical operations. By providing engineeringly relevant references, the outcomes obtained would be helpful for dealing with SFB outbreak risk in drinking water treatment.

New insights into ferric iron-facilitated UV254 photolytic defluorination of perfluorooctanoic acid (PFOA): Combined experimental and theoretical study.

UV/Fe3+-facilitated PFOA defluorination was often reported and recognized to proceed through a "ligand-to-metal charge transfer (LMCT)" mechanism in the literatures. Sufficient Fe3+ supply is important for sustaining the LMCT reaction pathway. In this study, an interesting "excessive defluorination" was observed, even the continuous Fe3+ supply was cut off, implying a parallel mechanism strengthening PFOA defluorination. Based the results of intermediate products detection, 19F NMR analysis, and exploration of electron density alternation, transition energy evolution, and bonds characteristics, remarkable electron density perturbation in [PFOA-Fe]2+ was revealed. This effect was triggered by the complexation between PFOA anion and Fe3+, diminishing electron shielding on the perfluorinated carbon chain. Hence, the dissociation energy of C-C bonds was reduced by maximally 53% (C4-C5). Once attacked by high-flux UV254 photons, the perfluorinated carbon chain underwent scission, and subsequent defluorination was achieved via hydrolysis reactions. This parallel mechanism cooperated with the LMCT mechanism, leading to the observed "excessive defluorination." The degree of UV/Fe3+-synergized PFOA defluorination depended on UV254 photon flux and Fe3+ dosage. High UV254 intensity guaranteed fast defluorination kinetics. A [Fe3+]/[PFOA] molar ratio near 1 showed the best UV/Fe3+ synergic effect on PFOA defluorination.

Physicochemical changes and chemical degradation of gliclazide during twin-screw melt granulation.

Using a miscible model formulation consisting of 80% gliclazide (GLZ) and 20% hydroxypropyl cellulose, we investigate how the twin-screw melt granulation process affects the chemical stability and process-induced physicochemical changes of the drug. No degradation was observed in the conveying section that leads to kneading element. Approximately 1/3 of the GLZ degradant was generated at the kneading section, while the remaining 2/3 was generated in the conveying section post-kneading and during cooling outside the barrel. A strong correlation was observed between the overall degradation and the temperature of the granules at the barrel exit. In the kneading section, the degradant content correlates best with the specific mechanical energy. With higher specific mechanical energies, the size of the GLZ crystals was reduced further, resulting in more surface defects. In the section post-kneading element, GLZ degradation correlates best with the granule temperature measured at the kneading section. This knowledge of drug degradation during twin-screw melt granulation can be used to develop processing strategies to maintain drug stability during and post processing.

Feasibility study on the electrochemical reductive decomposition of PFOA by a Rh/Ni cathode.

The discharge of widely used per- and poly-fluorinated compounds (PFCs) leads to their environmental prevalence, bioaccumulation and biotoxicity; and attracts researches focusing on their treatment in wastewater. Electrochemical reductive treatment is a promising alternative due to its milder reaction conditions and easy operation. The feasibility of electrochemical reductive decomposition of PFOA using a Rh/Ni cathode was explored. The Rh/Ni cathode was fabricated by coating Rh3+ on Ni foil through electrodeposition. The Rh coating was primarily elemental and in a Rh(111) crystalline form. PFOA decomposition and defluorination were observed when using the Rh/Ni cathode where DMF was the solvent and the cathode potential was -1.25 V. A hydrodefluorination reaction was considered having occurred. Because possessing d electrons and empty d orbitals, the Rh coating enhanced PFOA adsorption onto the cathode surface and facilitated CF bond activation through Rh···F interactions. Moreover, the Rh(111) crystal helped chemisorb the generated H* and supply it participating in PFOA decomposition. With the continuous interaction of cathode-supplied electrons, CF bond would ultimately dissociate and transform to CH bond by H* substitution. Adding FeCp2* as a supporting electrolyte enhanced PFOA decomposition by working as the shuttle facilitating PFOA migration to the cathode surface.

Fe(II) enhances simultaneous phosphorus removal and denitrification in heterotrophic denitrification by chemical precipitation and stimulating denitrifiers activity.

Using Fe(II) salt as the precipitant in heterotrophic denitrification achieves improved TP removal, and enhancement in denitrification was often observed. This study aimed to obtain a better understanding of Fe(II)-enhanced denitrification with sufficient carbon source supply. Laboratory-scale experiments were conducted in SBRs with or without Fe(II) addition. Remarkably improved TP removal was experienced. TP removal efficiency in Fe(II) adding reactor was 85.8 ± 3.4%; whereas, that in the reactor without Fe(II) addition was 31.1 ± 2.8%. Besides improved TP removal, better TN removal efficiency (94.1 ± 1.1%) were recorded when Fe(II) was added, and that in the reactor without Fe(II) addition was 89 ± 0.8%. The specific denitrification rate were observed increase by 12.6% when Fe(II) was added. Further microbial analyses revealed increases in the abundances of typical denitrifiers (i.e. Niastella, Opitutus, Dechloromonas, Ignavibacterium, Anaeromyxobacter, Pedosphaera, and Myxococcus). Their associated denitrifying genes, narG, nirS, norB, and nosZ, were observed had 14.2%, 19.4%, 21.6%, and 9.9% elevation, respectively. Such enhancement in denitrification shall not be due to nitrate-dependent ferrous oxidation, which prevails in organic-deficient environments. In an environment with a continuous supply of Fe(II) and plenty of carbon sources, a cycle of denitrifying enzyme activity enhancement in the presence of Fe(II) facilitating nitrogen substrate utilization, stimulating denitrifier metabolism and growth, elevating denitrifying genes abundance, and increasing denitrifying enzymes expression were thought to be responsible for the Fe(II)-enhanced heterotrophic denitrification. Fe(II) salt is often a less expensive precipitant and has recently become attractive for TP removal in wastewater. The findings of this study solidify previous observation of enhancement of both TP and TN removal by adding Fe(II) in denitrification, and would be helpful for developing cost-effective pollutant removal processes.

A review of twin screw wet granulation mechanisms in relation to granule attributes.

Due to the trend of continuous pharmaceutical manufacturing, twin screw wet granulation (TSWG), a continuous process, has gained increased research interest as a potential substitution of traditional batch granulation processes. Despite the complex nature of TSWG, its mechanisms have been gradually unveiled with the aid of innovative research strategies. This review synthesizes these recent findings to provide a comprehensive and mechanistic understanding of TSWG. We explain the impact of screw profiles (i.e. conveying, kneading, turbine mixing, and screw mixing elements) and process conditions (i.e. screw speed, feed rate, and liquid-to-solid ratio) on TSWG mixing performance and granule growth along the barrel, both of which ultimately affect critical granule attributes such as content uniformity, size distribution, strength, and compaction properties.

How Does the Dissimilarity of Screw Geometry Impact Twin-screw Melt Granulation?

Using a model formulation of 80% gabapentin and 20% hydroxypropyl cellulose (KlucelTM), we investigate how differences in the geometry of mixing elements in the Leistritz Nano-16 and Micro-18 extruders affect granulation mechanisms and the properties of the resulting granules. Two extruders, Leistritz Nano-16 and Micro-18, commonly used in development and manufacturing, respectively, were used. The kneading blocks of the Nano-16 extruder are less efficient in dispersive mixing than the kneading blocks of the Micro-18 due to the thinner discs (2.5 mm wide) of the Nano-16. Therefore, our model formulation could be granulated only under a higher degree of fill (DF) by enhancing the axial compaction and heating of the barrel. In contrast, the thicker (5 mm wide) kneading blocks of the Micro-18 extruder provide efficient dispersive mixing that enables granulation without axial compaction and barrel heating. The higher specific mechanical energy (SME) achieved at higher screw speeds and lower feed rates led to more granulation. Because of the difference in granulation mechanisms between the two extruders, critical processing parameters also differed. Tabletability and degradant content of granules correlated positively with DF for the Nano-16 but with SME for the Micro-18 extruder.

Effect of Hydroxypropyl Cellulose Level on Twin-Screw Melt Granulation of Acetaminophen.

This study investigated the effect of binder level on the physicochemical changes and tabletability of acetaminophen (APAP)-hydroxypropyl cellulose (HPC) granulated using twin-screw melt granulation. Even at 5% HPC level, the tablet tensile strength achieved up to 3.5 MPa. A minimum of 10% HPC was required for the process robustness. However, 20% HPC led to tabletability loss, attributable to the high mechanical strength of APAP granules. The over-granulated APAP granules had thick connected HPC scaffold and low porosity. Consequently, these granules were so strong that they underwent a lower degree of fracture under compression and higher elastic recovery during decompression. HPC was enriched on the surface of APAP extrudates at all HPC levels. Amorphous APAP was also observed on the extrudate surface at 20% HPC level, and it recrystallized within 24 h storage. To achieve a robust process and optimal improvement in APAP tabletability, the preferred HPC level was 10 to 15%.

Twin-screw melt granulation: Current progress and challenges.

Twin-screw melt granulation (TSMG) is a new alternative method for granulation that offers several advantages over wet and dry granulation methods. TSMG has rapidly gained interest over recent years in the pharmaceutical industry. Since it is an inherently continuous process with controlled temperature and shear history, TSMG produces products with more consistent quality than the batch process. Several studies have investigated how various formulation and processing parameters influence granulation behavior and granule properties; however, there are still challenges that require a better mechanistic understanding. This review summarizes the current progress of TSMG while highlighting how various formulation and process parameters affect the physicochemical properties of granules. The challenges related to the process-induced physicochemical changes of drug substances are also discussed.

Sustainable strategy for municipal solid waste disposal in Hong Kong: current practices and future perspectives.

Hong Kong (HK) is confronted by increasing problems of solid waste disposal, as it is an overpopulated city with limited land resources. Currently, solid waste disposal mainly relies on three landfills located in the New Territories. However, the current waste treatment facilities and policies cannot appropriately control and manage increments of solid waste. The primary reason is the increased amount of municipal solid waste (MSW) caused by the growth of the population and the economy, with food waste accounting for the largest proportion of MSW in HK. The secondary reason is that the capacity of existing landfills will be exhausted in the near future as the level of waste generated continues to grow. To deal with these problems, in this paper, we propose five approaches with the aim of identifying the most sustainable strategy for efficient solid waste disposal in HK: a food waste recycling program; an MSW charging scheme; the implementation of incineration plants (i.e., waste to energy); black soldier fly bioconversion and a waste trading scheme; and black soldier fly bioconversion and a hybrid anaerobic digestion system. This is followed by a detailed demonstration of each approach, particularly focusing on the benefits, limitations, and implementation of each in the case of HK. The results of this study may shed light on how to effectively and sustainably manage the increasing amount of solid waste in HK.

Fabrication of hydrolytically stable magnetic core-shell aminosilane nanocomposite for the adsorption of PFOS and PFOA.

Aminosilane materials, with their low cost and ease of modification, have exhibited great potential for the adsorption of perfluorinated compounds (PFCs) from water. However, this kind of material may be facing two drawbacks during its application: low resistance to hydrolysis and difficulties in separation from the water matrix. This work proposed a strategy of grafting N-(2-aminoethyl) aminopropyltrimethoxysilane (AE-APTMS) on the surface of magnetic γ-Fe2O3 nanoparticles by full utilization of the sorption sites provided by the aminosilane and the magnetism by γ-Fe2O3. The FTIR and XRD results verified the formation of the magnetic AE-APTMS nanocomposite. The core-shell nanocomposite showed a superparamagnetic property and an isoelectric point at pH = 8.2. Particularly, compared to the aminopropyltriethoxysilane (APTES) nanocomposite, the AE-APTMS nanocomposite exhibited improved hydrolytic stability with 60% less loss of the amine groups during the 48 h adsorption process, as the longer alkyl chain hindered the aminosilane detachment. The AE-APTMS nanocomposite exhibited a rapid adsorption with the removal efficiency of 78% for perfluorooctane sulfonate (PFOS) and 65% for perfluorooctanoate (PFOA) due to the electrostatic interaction and hydrophobic interaction. The regeneration and reuse of the magnetic AE-APTMS nanocomposite were conveniently realized with the removal efficiency higher than 70% for both PFOS and PFOA even after 15 adsorption-desorption cycles. The stable magnetic aminosilane nanocomposite with the ease of separation may provide a new strategy to achieve the economical and effective removal of typical PFCs from water.

Phosphate removal from industrial wastewater through in-situ Fe2+ oxidation induced homogenous precipitation: Different oxidation approaches at wide-ranged pH.

Phosphate removal through in-situ Fe2+ oxidation induced homogenous phosphate precipitation has shown its advantages in municipal wastewater treatment. Its feasibility and suitability for phosphate removal in industrial wastewater with wide-range pH variation like electro-plating wastewater were investigated in bench scale experiments using synthetic wastewater and continuous experiment using real wastewater. Bench scale experiments showed that different Fe2+ oxidation approaches worked well for phosphate removal at varied pH conditions. Sole dosing Fe2+ salt with aeration achieved sound phosphate removal at alkaline condition (pH ≥ 8). At neutral pH (6 < pH < 8), transition metallic ions catalytic oxidation is a suitable alternative. Cu2+ exhibited superior catalytic Fe2+ oxidization over Mn2+, Zn2+, and Ni2+. At acid pH (3.0 ＜ pH ≤ 6.0), Fenton reaction oxidation (H2O2 = 5 mg/L) showed its efficiency. At their corresponding optimal pH conditions and with Fe2+/P ratio of 1.8, dosing sole Fe2+ salt, Cu2+ catalyzed Fe2+ oxidation, and Fe2+/H2O2 treatments can achieve the TP discharge limit of 0.5 mg/L. In a 30-day continuous experiment using real electro-plating wastewater (pH 4.9-5.5), in both direct Fe2+/H2O2 treatment and Cu2+ catalyzed Fe2+ oxidation treatment after wastewater pH being adjusted to 7 effluent TP met China's discharge requirement 0.5 mg/L.

Theoretical studies of perfluorochemicals (PFCs) adsorption mechanism on the carbonaceous surface.

Understanding the mechanism by which perfluorochemicals (PFCs) adsorbed on carbonaceous surface is eventually important to the design and process optimization of effective PFCs removal technologies. In this study, the possible binding mechanism of six different PFCs onto carbonaceous surface was investigated by means of first principles quantum mechanical methods based on density functional theory (DFT) calculation and wave function analysis. The adsorption process fitted well with pseudo-second-order kinetic indicated that chemical bonding could not be underestimated. The results indicate that there were monolayer adsorption, electrostatic and hydrophobic interactions existed in PFCs adsorption process. DFT results suggested that the adsorption of PFCs on carbonaceous surface was one chemisorption process that accompanied by Van der Waals interactions. As there was different head functional groups in PFOS and PFOA, their adsorption capacity mainly controlled by the availability of active sites that was occupied by PFCs. The variation of chain length of PFBS and PFOS also take a certain responsible for different adsorption paths, due mainly to their hydrophobic effect. The obtained results from wave function and DFT analysis give in-depth understanding of PFCs adsorption on carbonaceous surface and help to their effectively removal.

Rapid and high-capacity adsorption of PFOS and PFOA by regenerable ammoniated magnetic particle.

Adsorption is well accepted as an effective method for perfluorinated compounds' (PFCs) removal from water among various conventional methods. However, development of adsorbents that combine good performance of PFC removal and regenerability has not yet been realized. This work demonstrated the fabrication and application of an ammoniated magnetic adsorbent for efficient and economical PFOS and PFOA removal. Functional ammonium groups and γ-Fe2O3 were effectively incorporated in the particle with the proposed method. These fabricated magnetic particles presented superior adsorption performance for PFOS and PFOA with short equilibrium time of 120 min and high adsorption capacity. The isotherms revealed that the adsorption process belonged to multilayer sorption with their intricate interactions including anion exchange and hydrophobic interaction. The magnetic particle maintained its removal efficacy over a wide pH range of 3-9 or with coexisting substances. Moreover, the regeneration and reuse of the magnetic particle were successfully carried out with PFOS and PFOA removal efficiency sustained higher than 80% in 15 consecutive treatment cycles. Along with the efficient adsorption and easy separation of adsorbents, we expect that this ammoniated magnetic particle can serve as an excellent alternative for PFOS and PFOA removal from water.

Degradation of tetrabromobisphenol A by ferrate(VI) oxidation: Performance, inorganic and organic products, pathway and toxicity control.

This study systematically investigated the degradation of tetrabromobisphenol A (TBBPA) by ferrate (VI) oxidation. The reaction kinetics between ferrate (VI) with TBBPA were studied under pseudo-first-order conditions in the pH range 5.5-10.5. Then, a series of batch experiments were carried out to investigate other factors, including the ferrate (VI) dosage, temperature and interfering ions. Additionally, the generation of inorganic products (bromide ion and bromate) was evaluated. The organic intermediates were identified, and possible pathways were proposed. In addition, the toxicity variation was analyzed with marine luminous bacteria (V. fischeri). Degradation of TBBPA by ferrate (VI) oxidation was confirmed to be an effective and environmentally friendly technique. The reaction was fitted with a second-order rate model. With a ferrate (VI) dosage of 25.25 µmol/L, TBBPA concentration of 1.84 µmol/L, an initial pH of 7.0, and a temperature of 25 °C, a 99.06% TBBPA removal was achieved within 30 min. The evaluation of inorganic products showed that the capacity of ferrate (VI) oxidation to yield bromide ions was relatively strong and could prevent the formation of bromate compared to photocatalytic and mechanochemical techniques. Eleven intermediates were identified, and the proposed degradation pathway indicated that TBBPA might undergo debromination, beta scission, substitution, deprotonation and oxidation. The results of toxicity testing showed that ferrate (VI) could effectively control the toxicity of the treated samples, although the toxicity increased in the initial reaction stage due to the accumulation and destruction of more toxic intermediates.

Synergistic Effect of Polyvinyl Alcohol and Copovidone in Itraconazole Amorphous Solid Dispersions.

PURPOSE: The first objective is to evaluate the feasibility of melt-extruding polyvinyl alcohol-based amorphous solid dispersions for oral drug delivery. The second objective is to investigate the miscibility between polyvinyl alcohol 4-88 and copovidone, and to characterize the properties of ternary itraconazole amorphous solid dispersions comprising both polymers. METHODS: Samples were prepared using a co-rotating, twin-screw extruder. A solution precipitation study was conducted to compare the precipitation inhibition of polyvinyl alcohol against other commonly used polymers for amorphous solid dispersions. Miscibility between polyvinyl alcohol 4-88 and copovidone was determined using DSC and XRD analyses. All extrudates were characterized using DSC, XRD, and non-sink dissolution. RESULTS: Polyvinyl alcohol demonstrated the highest capacity for inhibiting the precipitation of itraconazole. Itraconazole was found to be more soluble in copovidone (>30%) than in polyvinyl alcohol 4-88 (<5%) in binary extrudates. Polyvinyl alcohol and copovidone are miscible when the proportion of polyvinyl alcohol 4-88 does not exceed 30% (w/w). Compared to binary extrudates, the ternary extrudate demonstrated a higher degree of supersaturation and more sustained supersaturation of itraconazole in purified water and phosphate buffer pH 6.8 solution. CONCLUSION: As a surface-active material, polyvinyl alcohol was effective in inhibiting precipitation of itraconazole in aqueous media. Solubility of itraconazole in polyvinyl alcohol in solid state was limited because of the high polarity of the polymer. Ternary systems comprising a mixture of polyvinyl alcohol and copovidone demonstrated better supersaturation in aqueous media than binary systems. Ternary systems benefited from both the high solubilizing capacity of copovidone and high precipitation inhibition capacity of polyvinyl alcohol.