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The increasing global production and utilization of zirconium (Zr) compounds, including zirconium chloride (ZrCl4) and zirconium oxide nanoparticles (NPs-ZrO2), raises concerns about their potential environmental impact. This study investigated the toxicity mechanisms of ZrCl4 and NPs-ZrO2 on the aquatic plant Lemna minor. The physicochemical properties of NPs-ZrO2 in the test medium were characterized, revealing concentration-dependent changes in the hydrodynamic diameter, zeta potential, and solubility over time. The analysis of Zr speciation showed the predominance of Zr(OH)4(aq) species from ZrCl4. Plants of L. minor exposed to ZrCl4 and NPs-ZrO2 exhibited differential Zr bioaccumulation, growth inhibition, oxidative stress, and antioxidant responses. ZrCl4 induced a higher toxicity than NPs-ZrO2, with bioaccumulation strongly correlating with adverse effects. The differential toxicity impact between these two Zr-compounds was also determined by the lowest observed-effect doses for growth and biochemical parameters. The scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy confirmed internalization of NPs-ZrO2 and Zr uptake in the L. minor plant. Therefore, these findings highlighted the importance of chemical speciation, environmental transformations, and biological responses in assessing the ecological impact of Zr-compounds for effective risk assessment and management strategies for protecting aquatic ecosystems. [ABSTRACT FROM AUTHOR]

To valorize crustacean shells, an aquatic organism‐derived food waste, this study was conducted to synthesize 5‐hydroxymethylfurfural (5‐HMF) and levulinic acid (LA) from d‐glucosamine (GlcN) and N‐acetyl‐d‐glucosamine (GlcNAc) using a Lewis acid (ZrCl4) as a catalyst. The Box–Behnken statistical approach was used to optimize the reaction conditions and to analyze the reciprocal relationships between reaction parameters. In the GlcN conversion, the highest LA yield of 38.4% was obtained under a condition with 200 °C for 25 min with 0.35 M GlcN and 25 mol% catalyst/substrate. However, in GlcNAc conversion, the highest 5‐HMF yield of 9.75% was obtained at 175 °C for 20 min with 0.2 mol L−1 GlcNAc and 15 mol% catalyst/substrate. Under the same reaction conditions, a higher yield of LA was obtained from GlcN compared with GlcNAc. It seems that GlcN can be transformed into 5‐HMF and then further rehydrated to LA more readily than GlcNAc. These findings suggest that GlcN and GlcNAc derived from crustacean shells may be an accessible feedstock for the synthesis of valuable chemical compounds. [ABSTRACT FROM AUTHOR]

Peroxidase enzymes are crucial in analytical chemistry owing to significant peroxide analytes and their key role in hydrogen peroxide (H2O2) detection. Therefore, exploiting appropriate catalysts for the peroxidase like reactions has become crucial for achieving desired analytical performance. Zirconium (Zr) has attracted growing interest, as a safe and stable potential eco-friendly catalyst for various organic transformations that address increasing environmental challenges. Hence, aiming at fast, sensitive and selective optical detection of H2O2, a colorimetric platform is presented here, based on the excellent peroxidase enzyme-like activity of Zr decorated on graphene oxide (GO). The synergistic effect achieved due to intimate contact between an enzyme like Zr and the high surface area 0f GO ensures efficient electron transfer that increases the chemical and catalytic activity of the composite and advances the decomposition of H2O2 into hydroxyl radicals. The designed probe, thus, efficiently catalyzes the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB), via hydroxyl radicals, thereby transforming the colorless TMB into blue oxidized TMB within 2 min. The catalytic mechanism of the Zr-GO enzyme mimic is proposed herein and verified using a fluorescent probe terephthalic acid (TA) and other scavenger experiments. The multifunctional optical probe allows sensitive and highly selective recognition of H2O2 in a linear range from 100 to 1000 µM with a low detection limit of 0.57 µM. Essentially, the direct accessibility of Zr prevents having to use the complicated preparation and purification procedures mostly practiced for conventional biozymes and nanozymes. The devised method offers several gains, including being green and an inexpensive catalyst, having lower LOD, being fast, cost-effective and sensitive, and having selective work-up procedures. [ABSTRACT FROM AUTHOR]

The oligomerization of ethylene in aliphatic and aromatic solvents on complex zirconium carboxylate catalytic systems obtained from naphthenic acid fractions isolated from Baku oils is studied for the first time. Comparative studies are performed using complex zirconium carboxylate catalytic systems obtained from individual carboxylic acids CH3(CH2)2COOH and CH3(CH2)8COOH. It is found that the activity of a catalyst and the molecular weight distribution (MWD) of oligomeric products depend mainly on the solvent and the composition of the zirconium complex. It is shown that the rate of ethylene oligomerization when using zirconium carboxylate catalytic systems in aliphatic solvents is 2–3 times lower than in aromatic solvents. The resulting product has a narrow MWD and consists mainly of C4–C10 fractions. The oligomeric products obtained in aromatic solvents have wide MWDs and consist mainly of C4–C18 in the presence of zirconium carboxylates and of C12–C18 and C20 fractions with zirconium naphthenates. [ABSTRACT FROM AUTHOR]

Highlights • Platelet SBA-15 was synthesized with zirconyl oxychloride or zirconium chloride salt. • SBA-15 has monodispersed pores (200 nm × 6.4‒6.8 nm) with surface area of 435‒752 m2/g. • Amine loadings on platelet SBA-16 ranged 93.7‒148 mg/g. • Diffusivity of reactant in platelet SBA-15 is noted 4.8 times to tubular counterpart. • Platelet SBA-15 favorably chemisorb tannic acid at maximum capacity of 769 mg/g. Abstract Mesoporous silica materials are designed to accommodate reactants of large molecular sizes in various applications. The tubular or platelet Santa Barbara amorphous-15 and SBA-15 were synthesized in this study at 90 °C or 120 °C with zirconyl oxychloride or zirconium chloride added for regulating the pore geometry. The tubular SBA-15 has monodispersed pores of length 800 nm and diameter of 5.7‒7.5 nm, yielding a surface area of 685‒737 m2/g. The platelet SBA-15 has monodispersed pores of length 200 nm and diameter of 6.4‒6.8 nm, producing surface area of 435‒752 m2/g. Amine modification reduces the pore diameter and surface area. The loadings of amine on 24 h amine-modified tubular SBA-15 ranged 116.7‒121.0 mg/g, while those on platelet SBA-15 ranged 93.7‒148 mg/g. The zirconium chloride induced platelet SBA-15 has higher amine loading than the zirconyl oxychloride induced ones. Based on kinetic data of amine modification, the effective diffusivity of (3-aminopropyl)triethoxysilane in toluene in platelet SBA-15 is estimated 4.8 times to the tubular counterparts. The so-synthesized platelet SBA-15 can favorably adsorb tannic acid at maximum capacity of 769 mg/g. Graphical abstract Synthesis of platelet SBA-15 and its use in tannic acid adsorption. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The removal of a commercial humic acid (HA) and changes in its chemical composition were examined for coagulation/flocculation (C/F) processes based on jar tests using two different coagulants at a wide range of pH. ZrCl 4 showed a better performance in eliminating HA than Al 2 SO 4 with the same removal rates at lower dosages. The highest removal rates were found at a neutral pH range (5.0–6.5). The HA was further decomposed into three different humic-like components (C1, C2, and C3) by excitation emission matrix coupled with parallel factor analysis (EEM-PARAFAC). Although the removal rates of all three components generally followed those of dissolved organic carbon, the relative removals of the individual components depended on the coagulant's doses and the solution pH. The fluorescent components of five ultrafiltered size fractions of the HA revealed that the peak with a longer emission wavelength could be associated with larger sized molecules. The C1/C3 ratios of the size fractions exhibited a significant linear relationship with the logarithmic values of the average molecular weight (MW) measured by size exclusion chromatography, which made it possible to predict the HA MW value changes upon the C/F using EEM-PARAFAC alone. Irrespective of the coagulant types and the pH, larger sized HA molecules were removed to a greater extent than smaller sized fractions. The preferential removal was more pronounced for ZrCl 4 versus Al 2 SO 4 and at a neutral pH range. Our study suggests a great potential of EEM-PARAFAC in fast tracking the MW of humic substances in conventional C/F processes. [ABSTRACT FROM AUTHOR]

A chemical vapour deposition process using radio frequency induction heating operating at atmospheric pressure was developed for the deposition of ZrC coatings. The precursors utilised in this process were zirconium tetrachloride and methane as zirconium and carbon sources respectively, in an excess of hydrogen. Additionally, a stream of argon was used to, first, remove oxygen from the reactor and then to sweep the vapourised ZrCl 4 at 300 °C to the reaction chamber. The ZrC coatings were deposited on graphite substrates at substrate temperatures in the range of 1200 °C–1600 °C. The molar ratio of CH 4 /ZrCl 4 was varied from 6.04 to 24.44. Before the start of the deposition process, thermodynamic feasibility analysis for the growth of ZrC at atmospheric pressure was also carried out. Response surface methodology was applied to optimise the process parameters for the deposition of ZrC coatings. A central composite design was used to investigate the effects of temperature and molar ratio of CH 4 /ZrCl 4 on the growth rate, atomic ratio of C/Zr and crystallite size of ZrC coatings. Quadratic statistical models for growth rate and crystallite size were established. The atomic ratio of C/Zr followed a linear trend. It was found that an increase in substrate temperature and CH 4 /ZrCl 4 ratio resulted in increased growth rate of ZrC coatings. The carbon content (and concomitantly the atomic ratio of C/Zr) in the deposited coatings increased with temperature and molar ratio of CH 4 /ZrCl 4 . The substrate temperature of 1353.3 °C and the CH 4 /ZrCl 4 molar ratio of 10.41 were determined as the optimal condition for growing near-stoichiometry ZrC coatings. The values were 1.03, 6.05 μm/h and 29.8 nm for C/Zr atomic percentage ratio, growth rate and average crystallite size respectively. [ABSTRACT FROM AUTHOR]

• Post-treatment of the electron transport layer with ZrCl 4 in planar PSCs leads to enhanced short-circuit current. • Enhanced stabilized PCE is observed probably due to reduced charge accumulation at the interface. • UPS/XPS measurements reveal that energy band alignment between perovskite and transport layer is achieved and electrical experiments prove that charge extraction is facilitated. Planar lead halide perovskite solar cells (PSCs) with a n-i-p superstrate structure are now attaining certified efficiencies of over 25%, rivaling those of single crystal silicon photovoltaics. Nanoparticulate films of SnO 2 or compact layers of TiO 2 are usually adopted as the electron transporting layers (ETLs) due to their hole-blocking ability, simultaneously acting as a substrate to control perovskite film crystallization. Despite these advantages, non-radiative recombination, non-ideal band alignment and inefficient electron extraction dominate the interface between the perovskite and ETL, limiting the stabilized output power of the devices. To tackle these issues, in this work, the TiO 2 compact layer was post-treated with ZrCl 4. Optical, morphological and electronic properties of the ETL and the perovskite films were evaluated and the corresponding photovoltaic devices were electrically characterized. The obtained results indicate that ZrCl 4 does not measurably affect the perovskite crystallization but favors energy band alignment at the interface, facilitating electron extraction. Consequently, a stabilized efficiency of 18.6% was attained by the modified devices, increased by ∼18% compared to the reference solar cells. Additionally, the long-term stability against thermal and humidity was improved. These results pave the way for the use of metal chlorides as efficient agents for interface engineering in perovskite-based optoelectronic devices. [Display omitted] [ABSTRACT FROM AUTHOR]

Two sensitive, selective, accurate spectrofluorimetric and spectrophotometric methods have been developed for the determination of gemifloxacin (GMFX) in bulk and tablets. The first method (A) was based on a reaction between gemifloxacin with zirconium (IV) in presence of acetate buffer of pH 6.0 to give highly fluorescent derivatives. The reaction was monitored spectrofluorimetrically by measuring the emission of the reaction product at 397 nm and excitation maxima at 265 nm. Various factors affecting the relative fluorescence intensity of the resulting chelate were studied and optimized. Beer's law was obeyed in the concentration range 0.5-4.0 μg/mL with a correlation coefficient of 0.9997. The second method (B) was based on formation of ternary complex between palladium (II), eosin and GMFX in the presence of methyl cellulose as surfactant and acetate-HCl buffer pH of 4.0. Spectrophotometrically, under the optimum conditions, the ternary complex showed absorption maximum at 530 nm. Beer's law was obeyed in the concentration range 2.0-22 μg/mL with a correlation coefficient of 0.9995. The composition of the complex, studied by the limiting logarithmic method shows that the molar ratio GMFX: Pd (II): eosin is 1:1:1. The detection and quantification limits were also calculated. The proposed methods were successfully applied for the determination of gemifloxacin in its pharmaceutical product with mean percentage recoveries of 98.9%. [ABSTRACT FROM AUTHOR]

Abstract: Microwave-assisted direct conversion of cellulose into HMF in ionic liquids catalyzed by ZrCl4 has been investigated in search of an efficient and environment-friendly process. Firstly, some representative metal chlorides were used to catalyze the conversion of glucose into HMF, and it was demonstrated that ZrCl4 was superior to other catalysts. Then direct conversion of cellulose into HMF was catalyzed by ZrCl4 under microwave irradiation (MI). Under optimal conditions, a high HMF yield up to 51.4% was obtained from cellulose in 3.5min under MI at 400W. Controllable experiments indicated that both ionic liquids, MI and ZrCl4 showed synergetic effects on the efficient conversion of cellulose into HMF. This work provides a meaningful method for the conversion of carbohydrates into fine chemicals. [Copyright &y& Elsevier]

Abstract: ZrB2 platelets were prepared by mechanochemical processing a zirconium (IV) chloride–boron mixture with subsequent annealing from 800°C to 1200°C. The phases present were identified by X-ray diffraction. The size and morphology of the synthesized ZrB2 powders were characterized by scanning electron and transmission electron microscopy. At 800°C, ZrO2 was detected in absence of ZrB2. At or above 1000°C, ZrCl4–B converted to ZrB2. Moreover, at 1200°C, ZrCl4–B completely converted to ZrB2 without trace quantities of residual ZrO2. The synthesized ZrB2 consisted of platelets with a diameter of 0.1–2.1μm and a thickness of 40–200nm. [Copyright &y& Elsevier]

Abstract: A straightforward synthesis of substituted pyrroles using zirconium chloride-catalyzed modified Paal–Knorr method has been accomplished under ultrasound irradiation. Compared to known methods, this new method provides as easy access to various substituted pyrroles in good to excellent yields with short reaction times. [Copyright &y& Elsevier]

Abstract: Zirconium chloride efficiently catalyzes the one-pot, three-component reaction of an aryl aldehyde, cyclic or acyclic enolizable ketones, and thiols under solvent-free conditions at room temperature to afford the corresponding β-aryl-β-mercaptoketones via aldol-Michael addition reactions. This methodology affords a large number of β-aryl-β-mercapto ketone derivatives in high yields and in short reaction times. [Copyright &y& Elsevier]

Abstract: Zirconium chloride has been found to be a new and highly efficient catalyst for the aldol condensation of aldehyde and ketone under solvent free conditions, at room temperature. The reaction is very fast, clean and environmentally benign for the synthesis of variety of 1,3-diaryl-2-propenones. Zirconium chloride also found to be compatible with various solvents and gave the aldol product in acceptable yield (56–70%) but the excellent yield was obtained in solvent free condition. The higher mol% of the catalyst (zirconium chloride) yielded the 1,4-Michael adduct along with the aldol product. [Copyright &y& Elsevier]

Zirconia powders are prepared by reaction of a zirconium precursor with an alkali metal nitrate. The major part of the reactions takes place before the melting points and then the reactions go slowly to completion at 450°C in the molten salts. The roles of the precursor and the alkali metal ion are discussed considering the reaction between two precursors, octahydrated zirconium oxychloride and zirconium tetrachloride, and two nitrates, LiNO3 and NaNO3, and some resulting physico-chemical differences. The obtained zirconia powders contain very small amounts of alkali metal ions which act as stabilizing agent. Their effect on the balance tetragonal–monoclinic ZrO2 depends upon the homogeneity of their distribution which is related to their ability to diffuse inside the bulk of particles and their polarizing power when located mainly on the surface. [Copyright &y& Elsevier]