Search

Periodate (PI) has recently been studied as an excellent oxidant in advanced oxidation processes, and its reported mechanism is mainly the formation of reactive oxygen species (ROS). This work presents an efficient approach using N-doped iron-based porous carbon (Fe@N-C) to activate periodate for the degradation of sulfisoxazole (SIZ). Characterization results indicated the catalyst has high catalytic activity, stable structure, and high electron transfer activity. In terms of degradation mechanism, it is pointed out that the non-radical pathway is the dominant mechanism. In order to prove this mechanism, we have carried out scavenging experiments, electron paramagnetic resonance (EPR) analysis, salt bridge experiments and electrochemical experiments, which demonstrate the occurrence of mediated electron transfer mechanism. Fe@N-C could mediate the electron transfer from organic contaminant molecules to PI, thus improving the efficiency of PI utilization, rather than simply inducing the activation of PI through Fe@N-C. The overall results of this study provided a new understanding into the application of Fe@N-C activated PI in wastewater treatment. [Display omitted] • The activation of PI was successfully promoted with Fe@N-C. • The reaction mechanism of Fe@N-C/PI system is electron transfer mechanism. • The degradation pathway of pollutants in Fe@N-C/PI system was proposed. • No iodate and other harmful byproducts were produced during the reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • 100% CIP degradation was achieved within 10 min in the CCN/PI/Vis system. • Efficient CIP removal activity is achieved in a wide range of pH, anions and organic matter, and natural water environments. • 1O 2 was the major pathway for CIP degradation, followed by IO 3 •. • CCN/PI/Vis system exhibited a much higher degradation rate than PCN/PI/Vis system. • CCN acted as an electron shuttle to facilitate electron transfer from CIP to PI. The development of suitable and efficient periodate activation methods is currently a hot research topic. In this study, a novel efficient photocatalytic activation strategy using crystalline carbon nitride (CCN) and visible light (Vis) to activate PI for pollutant degradation was proposed. In the CCN/PI/Vis system, 100% ciprofloxacin hydrochloride (CIP) degradation was achieved within 10 min which was much higher than polymerized carbon nitride (PCN)/PI/Vis system. Besides, CCN/PI/Vis system demonstrated outstanding CIP removal activity in a wide range of pH, anions and organic matter, and natural water environments. Mechanistic studies demonstrated that the CCN/PI/Vis system decomposed CIP via nonradical/radical mixing processes dominated by 1O 2 and electron transfer. The excellent degradation ability depends on the establishment of an electron cycle among CCN, PI, and CIP. In which, CCN generated photogenerated electrons, CIP acted as an electron donor, and PI served as an electron acceptor. Due to the extended in-plane periodicity and reduced interlayer distance and the formation of ordered electron transport channels caused by the increase of crystallinity, CCN had stronger light absorption and more efficient charge carriers separation and mobility than PCN, resulting in more durable and efficient photogenerated electron and thus much enhanced synergetic photocatalytic and PI activation ability of CCN. [ABSTRACT FROM AUTHOR]

• The addition of PI greatly promoted the degradation of organic pollutants by In 2 O 3 /Vis-LED process. • • OH was formed through the reaction of holes with H 2 O and played a major role. • PI received electrons from the conduction band of the In 2 O 3 and eventually changed to iodate. • The species variation of PI with pH did not affect its ability to accept electrons. Periodate (PI) as an oxidant has been extensively studied for organic foulants removal in advanced oxidation processes. Here PI was introduced into In 2 O 3 /Vis-LED process to enhance the formation of ·OH for promoting the degradation of organic foulants. Results showed that the addition of PI would significantly promote the removal of sulfamethoxazole (SMX) in the In 2 O 3 /Vis-LED process (from 9.26% to 100%), and ·OH was proved to be the dominant species in the system. Besides, the process exhibited non-selectivity in the removal of different organic foulants. Comparatively, various oxidants (e.g., peroxymonosulfate, peroxydisulfate, and hydrogen peroxide) did not markedly promote the removal of SMX in the In 2 O 3 /Vis-LED process. Electrochemical analyses demonstrated that PI could effectively receive photoelectrons, thus inhibiting the recombination of photogenerated electron-hole (e −/ h +) pairs. The holes then oxidized the adsorbed H 2 O to generate ·OH, and the PI converted to iodate at the same time. Additionally, the removal rate of SMX reduced from 100% to 17.2% as Vis-LED wavelengths increased from 440 to 560 nm, because of the low energy of photons produced at longer wavelengths. Notably, the species of PI do not affect its ability to accept electrons, resulting in the degradation efficiency of SMX irrespective of pH (4.0–10.0). The coexistence of inorganic cations and anions (such as Cl−, CO 3 2−/HCO 3 −, SO 4 2−, Ca2+, and Mg2+) also had an insignificant effect on SMX degradation. Furthermore, the process also showed excellent degradation potential in real water. The proposed strategy provides a new insight for visible light-catalyzed activation of PI and guidance to explore green catalytic processes for high-efficiency removal of various organic foulants. [Display omitted] [ABSTRACT FROM AUTHOR]

• An efficient selective elimination of sulfonamide antibiotics was developed. • The pathway of periodate oxidized catechol to ortho -benzoquinone was confirmed. • The ortho -benzoquinone dominates the degradation process via michael addition. • Several catechol derivatives have similarly synergistic effects and imply potential applications. Natural organic matter, specifically ortho -quinones organics among them, was considered can participate in the transformation of sulfonamide antibiotics (SAs). Herein, based on targeted oxidizing for ortho -dihydroxyl structures (catechol as the model) upon periodate, an efficient approach for SAs elimination was introduced. Results first indicated the generation of ortho -benzoquinone (o -BQ) within periodate/catechol system progresses readily (the energy barriers for 9.6854 kcal/mol). The near-complete eliminations were observed towards sulfamethoxazole (SMX) in periodate/catechol system (with the rate of 0.4229 min−1) as well as other SAs and exhibited unprecedented resistance to operating parameters. Besides, periodate converts little into toxic low-valent iodate species during the reaction process, and both the cytotoxicity and acute toxicity assays revealed a significant decline in antibiotics bioactivity. Mechanistic insight revealed that o -BQ dominated the degradation process, comprehensive analysis further confirmed Michael addition reaction was the first degradation stage, in which electrons flow from o -BQ to SMX and form covalent bonds upon aniline. Furthermore, several catechol derivatives were used to verify the universality of the mechanism, and their wide distribution in both subsurface and wastewater implies the potential applications. Overall, the mechanisms elucidated behind this research proposed an efficient strategy for eliminating trace SAs in aqueous environments and selectively removing SAs from complex wastewater matrices. [Display omitted] [ABSTRACT FROM AUTHOR]

• Mn(II)-nitrilotriacetic acid activated periodate realizes fast removal of organics. • Mn(IV)-oxo species instead of free radicals or Mn(V) is the primary active species. • The NTA drives Mn(IV)-oxo to form permanganate in the absence of organic pollutants. • Carbamazepine undergoes a series of degradation courses and produces 12 products. • Iodate is the only reduction product of periodate but not undesired iodine species. Periodate-based (PI, IO 4 −) oxidation processes for pollutant elimination have gained increased attention in recent years. This study shows that nitrilotriacetic acid (NTA) can assist trace Mn(II) in activating PI for fast and long-lasting degradation of carbamazepine (CBZ) (100% degradation in 2 min). PI can oxidize Mn(II) to permanganate(MnO 4 − , Mn(VII)) in the presence of NTA, which indicates the important role of transient manganese-oxo species. 18O isotope labeling experiments using methyl phenyl sulfoxide (PMSO) as a probe further confirmed the formation of manganese-oxo species. The chemical stoichiometric relationship (PI consumption: PMSO 2 generation) and theoretical calculation suggested that Mn(IV)-oxo-NTA species were the main reactive species. The NTA-chelated manganese facilitated direct oxygen transfer from PI to Mn(II)-NTA and prevented hydrolysis and agglomeration of transient manganese-oxo species. PI was transformed completely to stable and nontoxic iodate but not lower-valent toxic iodine species (i.e., HOI, I 2 , and I−). The degradation pathways and mechanisms of CBZ were investigated using mass spectrometry and density functional theory (DFT) calculation. This study provided a steady and highly efficient choice for the quick degradation of organic micropollutants and broadened the perspective on the evolution mechanism of manganese intermediates in the Mn(II)/NTA/PI system. [Display omitted] [ABSTRACT FROM AUTHOR]

A spectrophotometric flow-injection method has been devised for the determination of nanomole quantities of some oxidants i.e. iodate, periodate, permanganate and hydrogen peroxide. The method is based on the oxidation of iron(II) to iron(III) and the measurement of the absorbance of the red iron(III)–thiocyanate complex at 485 nm. The optimal oxidation pH and the linearity ranges of the calibration curves have been investigated. The analytical aspects of the method including the statistical evaluation of the results are discussed. The analysis of some authentic samples showed an average percentage recovery of 99%.

In this study, Ru(III) ions were utilized to activate periodate (PI) for oxidation of trace organic pollutants (TOPs, e.g., carbamazepine (CBZ)). The Ru(III)/PI system can significantly promote the oxidation of CBZ in a wide initial pH range (3.0-11.0) at 1 μM Ru(III), showing much higher performance than transition metal ions (i.e., Fe(II), Co(II), Zn(II), Fe(III), Cu(II), Ni(II), Mn(II), and Ce(III)) and noble metal ion (i.e., Ag(I), Pd(II), Pt(II), and Ir(III)) activated PI systems. Probe experiments, UV-vis spectra, and X-ray absorption near-edge structure (XANES) spectra confirmed high-valent Ru-oxo species (Ru(V)=O) as the dominant oxidant in the process. Because of the dominant role of Ru(V)=O, the Ru(III)/PI process exhibited a remarkable selectivity and strong anti-interference in the oxidation of TOPs in complex water matrices. The Ru(V)=O species can undertake 1-e - and 2-e - transfer reactions via the catalytic cycles of Ru(V)=O → Ru(IV) → Ru(III) and Ru(V)=O → Ru(III), respectively. The utilization efficiency of PI in the Ru(III)/PI process for the oxidation of TOPs can approach 100% under optimal conditions. PI stoichiometrically transformed into IO 3 - without production of undesired iodine species (e.g., HOI and I 2 ). This study developed an efficient and environmentally benign advanced oxidation process for rapid removal of TOPs and enriched understandings on reactivity of Ru(V)=O and Ru catalytic cycles.

Abstract α-amylase from isolated bacterial strain (Bacillus acidocaldarius) was chemically modified by covalent coupling to several periodate oxidized polysaccharides. Conjugated enzyme with oxidized dextran (MW 84 kDa) retained the highest activity (77.4%) and the highest specific activity (3948.4 U/mg protein). Compared to the native enzyme, the dextran conjugated α-amylase exhibited higher optimum temperature, higher K m (Michaelis constant), lower V max (maximal reaction rate), lower V max / K m (catalytic efficiency), lower E a (activation energy), lower deactivation constant rate (k d), higher half-life time (t 1/2), and higher decimal reduction time values (D). Covalent attachment of α- amylase to oxidized dextran brought about significant enhancement of thermal stability, stability at extreme pHs, and resistance against the inhibitors. In the presence of the substrate, the conjugated enzyme retained 68.2% of its original activity after incubation at 70 °C for 30 min which was 1.4-fold higher than that retained by the native enzyme (50.3%) under the same conditions. The K d value at 80 °C for the dextran conjugated α-amylase was 2.5-fold lower than that of the native enzyme. Dextran conjugated α-amylase was more resistance against the inhibitors than the native enzyme, and retained 70.6% of its activity in presence of 10 mM CuSO 4 , while the native form retained only 34.1%. Graphical abstract fx1 Highlights • Production of α-amylase from isolated bacterial strain. • Activation of polysaccharides by sodium periodate oxidation. • Chemical modification of α-amylase by conjugation to oxidized polysaccharides. • Characterizations of dextran conjugated α-amylase and compared with the native form. • Chemical modification enhanced enzyme properties (catalytic, kinetics and stability). [ABSTRACT FROM AUTHOR]

Abstract: Nanocellulose with a morphology ranging from long flexible to rod-like fibrils were produced via periodate oxidation route followed by reductive treatment with NaBH4 of never-dried eucalyptus pulp. The effect of the aldehyde content on the size and morphology of the resulting nanocellulose was studied by preparing three samples with 450, 830 and 1480 µmol g−1 aldehyde content. The change in particle size after the oxidation and reduction was monitored by dynamic light scattering and the morphology of the nanocellulose was characterized by transmission electron microscopy. It was shown that the length of the cellulose fibrils significantly decreased with increasing oxidation. Depending on the aldehyde content, elementary nanofibrils or bundles of nanofibrils with a length from 100 nm up to several µm were obtained after the reduction process. The reinforcing potential of the nanocellulose was also investigated by dynamic thermomechanical analysis of nanocomposite films with different nanocellulose contents.Graphical Abstract: [ABSTRACT FROM AUTHOR]

A series of water‐insoluble iron(III) and manganese(III) porphyrins, FeT(2‐CH3)PPCl, FeT(4‐OCH3)PPCl, FeT(2‐Cl)PPCl, FeTPPCl, MnT(2‐CH3)PPOAc, MnT(4‐OCH3)PPOAc, MnT(2‐Cl)PPOAc and MnTPPOAc, in the presence of imidazole (ImH), F−, Cl−, Br− and acetate were used as catalysts for the aqueous‐phase heterogeneous oxidation of styrenes to the corresponding epoxides and aldehydes with sodium periodate. Also, the effect of various reaction parameters such as reaction time, molar ratio of catalyst to axial base, type of axial base, molar ratio of olefin to oxidant and nature of metal centre on the activity and oxidative stability of the catalysts and the product selectivity was investigated. Higher catalytic activities were found for the iron complexes. Interestingly, the selectivity towards the formation of epoxide and aldehyde (or acetophenone) was significantly influenced by the type of axial base. Furthermore, Br− and ImH were found to be the most efficient co‐catalysts for the oxidation of olefins performed in the presence of the manganese and iron porphyrins, respectively. The optimized molar ratio of catalyst to axial base was different for various axial bases. Also, the order of co‐catalyst activity of the axial bases obtained in aqueous medium was different from that reported for organic solvents. The use of a convenient axial base under optimum reaction catalyst to co‐catalyst molar ratio in the presence of the manganese porphyrin gave the oxidative products with a conversion of ca 100% in a reaction time of less than 3 h. However, the catalytic activity of the iron porphyrins could not be effectively improved by increasing the catalyst to co‐catalyst molar ratio. [ABSTRACT FROM AUTHOR]

The silk dyeing utilising chemical oxidation of (+)-catechin was attempted in order to establish the deep dyeing at low temperature in a short time for inventing novel human- and eco-friendly dyeing. In the study, the dyeability of the new oxidation technique was compared with the mordanting method. The compounds giving Al3+, Cu2+, Fe2+, or Fe3+ ion in aqueous solution were used as mordants for the mordanting dyeing. The oxidation by the use of O2, H2O2 or NaIO4 was tried for the oxidation dyeing. The two-step treatment was performed as the oxidation dyeing, in which the first treatment is adsorption of (+)-catechin onto the silk fabric and the second one is oxidation of the adsorbed (+)-catechin by the oxidant. The results show that O2 and H2O2 are not available as oxidants for the oxidation dyeing. The silk fibre is dyed brown colours by the mordanting dyeing and deep reddish brown by the oxidation dyeing with NaIO4 at 30 °C and pH = 7.0 of for 80 min of total treatment time. The dyeability of the oxidation dyeing with NaIO4 is much higher than that of mordanting dyeing. Colour fastness obtained by the oxidation dyeing to washing is high enough in practical use. [ABSTRACT FROM AUTHOR]

Aqueous solutions of quinoline (Qu) were treated with photo-activated potassium periodate (UV/KPI) process. A low consumption, cylindrical photo-reactor was employed for this purpose. Either KPI oxidant or UV irradiation alone had little effect in Qu degradation; however, the combined UV/KPI process leads to significant degradation and mineralization. Experiments were conducted based on central composite design (CCD) methodology. The established optimized conditions for treatment of 40 mg L−1 of the substrate were [KPI] = 695.5 mg L−1, pH = 4.3 and T = 35.6 °C. Under these conditions, 96.5% degradation and 71.5% mineralization were obtained after 70 min operations. A quadratic equation predicts the variation of degradation efficiency as a function of the influencing parameters. To investigate about the involved species, tert-butyl alcohol was used as radical scavenger and it was found that the contribution of hydroxyl radical was about 73.1%. Kinetic study revealed that Qu degradation was a pseudo first-order reaction and the corresponding activation energy was determined. Meanwhile, the required irradiation energy for one order of magnitude degradation was estimated as 3.13 kWh m−3. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1621-1627, 2017 [ABSTRACT FROM AUTHOR]

Periodate (PI)-photoactivated advanced oxidation process (AOP) has recently received increasing attention for the removal of micropollutants from water. However, periodate is mainly driven by high-energy ultraviolet light (UV) in most cases, and few studies have extended it to the visible range. Herein, we proposed a new PI visible light activation system employing α-Fe 2 O 3 as catalyst. It is completely different from traditional PI-AOP based on hydroxyl radicals (•OH) and iodine radical (•IO 3). The vis-α-Fe 2 O 3 /PI system can selectively degrade the phenolic compounds via non-radical pathway under the visible range. Notably, the designed system not only shows a well pH tolerance and environmental stability, but also exhibits a strong substrate-dependent reactivity. Both quenching experiments and electron paramagnetic resonance (EPR) experiments demonstrate that photogenerated holes are the main active species in this system. Moreover, a series of photoelectrochemical experiments reveal that PI can effectively inhibit the carrier recombination on the α-Fe 2 O 3 surface, thereby improving the utilization of photogenerated charges and increasing the number of photogenerated holes, which effectively reacts with 4-CP through electron transfer way. In a word, this work proposes a cost-effective, green and mild mean to activate PI, and provides a facile way to solve the fatal shortcomings (i.e., inappropriate band edge position, rapid charge recombination and short hole diffusion length) of traditional iron oxide semiconductor photocatalysts. [Display omitted] • This is the first time to realize the activation of PI with visible irradiation on Fe-based materials. • The vis-α-Fe 2 O 3 /PI system demonstrates a substrate-dependent reactivity. • Photogenerated holes instead of •OH and •IO 3 are mainly responsible for 4-CP degradation. • This novel AOPs tolerates inorganic ions, DOM and pH change well. [ABSTRACT FROM AUTHOR]

At present, the potential mechanism of manganese oxide (MnO 2) activation of PI and the key active sites of PI activation are still unclear and controversial. To this end, three different crystal forms of MnO 2 were prepared in this study and used to activate PI to degrade pollutants. The results showed that different crystal types of MnO 2 showed different catalytic abilities, and the order was γ-MnO 2 > α-MnO 2 > β-MnO 2. Through quenching experiments, EPR tests, Raman experiments and in situ electrochemical experiments, it has been confirmed that electron transfer-mediated non-free radical process is the main mechanism of pollutant degradation, in which the active substance is the highly active metastable intermediate complex (MnO 2 /PI*). Hydroxyl radical (HO•), superoxide radical (O 2 •−), singlet oxygen (1O 2) and iodine radical (IO 3 •) did not participate in pollutant degradation. The quantitative structure-activity relationship analysis confirmed that the catalytic performance of MnO 2 was highly positively correlated with the surface Mn(IV) content, which indicated that the surface Mn(IV) site was the main active site. Overall, this study will be of great help to the design and application of manganese dioxide activation for periodate degradation of pollutants. [Display omitted] • α-MnO 2 , β-MnO 2 and γ-MnO 2 could all effectively activate PI. • The α-MnO 2 /PI, β-MnO 2 /PI and γ-MnO 2 /PI systems were non-radical processes dominated by electron transfer. • The high activity of metastable intermediate complex (MnO 2 /PI*) was the main factor for organic pollutants removal. • The catalytic activities of MnO 2 were positively correlated with the content of Mn (IV) on the catalyst surface. [ABSTRACT FROM AUTHOR]

• Electrochemical activation using graphite electrodes can successfulliy activate periodate (PI) for water decontamination. • 1O 2 as the primary reactive species is produced in the E-GP/PI system through the combination of O 2 •−. • A dual descriptor model is proposed to reveal the selective oxidation behavior of 1O 2. • The E-GP/PI system shows strong pH tolerance, long-lasting performance, and high resistance to aqueous matrices. • BPA degradation mechanism is proposed based on experimental results and DFT calculations. Advanced oxidation technologies based on periodate (PI, IO 4 −) have garnered significant attention in water decontamination. In this work, we found that electrochemical activation using graphite electrodes (E-GP) can significantly accelerate the degradation of micropollutants by PI. The E-GP/PI system achieved almost complete removal of bisphenol A (BPA) within 15 min, exhibited unprecedented pH tolerance ranging from pH 3.0 to 9.0, and showed more than 90% BPA depletion after 20 h of continuous operation. Additionally, the E-GP/PI system can realize the stoichiometric transformation of PI into iodate, dramatically decreasing the formation of iodinated disinfection by-products. Mechanistic studies confirmed that singlet oxygen (1O 2) is the primary reactive oxygen species in the E-GP/PI system. A comprehensive evaluation of the oxidation kinetics of 1O 2 with 15 phenolic compounds revealed a dual descriptor model based on quantitative structure−activity relationship (QSAR) analysis. The model corroborates that pollutants exhibiting strong electron-donating capabilities and high p K a values are more susceptible to attack by 1O 2 through a proton transfer mechanism. The unique selectivity induced by 1O 2 in the E-GP/PI system allows it to exhibit strong resistance to aqueous matrices. Thus, this study demonstrates a green system for the sustainable and effective elimination of pollutants, while providing mechanistic insights into the selective oxidation behaviour of 1O 2. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The efficient activation of periodate was achieved by pinewood biochar-CuO. • Contributing radicals were IO 3 ·, IO 4 ·, ·OH, and O(3P) at neutral pH. • The presence of O(3P) only at highly alkaline pH indicates the important role of pH. • The degradation products and pathways of MB are identified and discussed. The degradation kinetics and mechanisms of various types of recalcitrant organic pollutants (ROPs) by a novel biochar-CuO (B-CuO)/periodate (PI) system have been deeply investigated in the present study. More precisely, the study aimed to explore the significant effects of pH on the formation of various oxidative species using this treatment system. According to the results achieved, iodate (IO 3 ∙) and periodate radicals (IO 4 ∙), ∙OH and O(3P) were mostly generated at pH ≈ 7, resulting in the efficient removal of methylene blue (MB) (90% after 30 min, k obs = 0.09 min−1), while the system favoured the formation of O(3P) under highly alkaline pH values (pH = 11), leading to lower degradation kinetics of the pollutant (51% after 30 min, k obs = 0.028 min−1). Additionally, no oxidative species were found at highly acidic pH values (pH = 3), and no significant MB removal was observed (21% after 30 min, k obs = 0.0081 min−1). Elevating the temperature (from 25 °C to 80 °C) and bubbling with nitrogen or oxygen gas also did not have any significant effects on the degradation of ROPs. Additionally, the system maintained its efficiency in various water matrices, including real wastewater, confirming the applicability of the biochar-CuO/PI system for real water treatment processes. The system also exhibited a high degradation efficiency for other types of ROPs, such as ciprofloxacin. Experiments using ultra-high performance liquid chromatography in combination with quadrupole time-of-flight mass spectrometry were performed to identify the degradation products and pathways of MB, revealing the contribution of two different degradation pathways and the formation of five degradation products in the B-CuO/PI system. The ECOSAR program was employed to evaluate the predicted toxicity of the degradation products. The results showed that the system could efficiently detoxify MB. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ball milling loading of Mn 2 O 3 improved the degree of defects in the sludge biochar. • The loading of Mn 2 O 3 markedly improved the electron transfer capacity of catalyst. • Non-radical pathway of electron transfer was predominant. • The leaching of Mn decreased from 0.0224 mg L−1 to 0.0027 mg L−1 after ball milling. In this study, a one-step solvent-free method using the ball milling technique was employed to prepare Mn 2 O 3 -loaded sludge biochar (BM-SBC/Mn 2 O 3), and it was applied to the efficient activation of periodate (IO 4 −) to achieve rapid removal of sulfamethoxazole from the water column. A nearly two-fold improvement in the degradation rate of sulfamethoxazole (pseudo-first-order constants from 0.049 to 0.09 min−1) was achieved with only a small loading of Mn 2 O 3 (the mass ratio of Mn 2 O 3 and SBC was 1:6). The BM-SBC/Mn 2 O 3 possessed excellent IO 4 − activation ability and achieved 95.3% removal efficiency of sulfamethoxazole within 30 min. The removal efficiency of sulfamethoxazole was maximized at an initial pH of 3 and was almost unaffected by the coexisting inorganic anions and humic acid. Mechanistic studies suggested that free radical (•OH) and non-radical pathways were collectively responsible for the removal of sulfamethoxazole, while the non-radical pathway of electron transfer was predominant. Ball milling loading of Mn 2 O 3 improved the degree of defects in the catalyst and enhanced the electron transfer efficiency. This study advances the fundamental understanding of the underlying mechanisms involved in the process of IO 4 − activation catalyzed by ball milling loaded metal oxides onto sludge biochar. [ABSTRACT FROM AUTHOR]

The structure of the title compound, trilead(II) bis[dihydroxidotetraoxidoiodate(VII)], was determined from a crystal twinned by non-merohedry with two twin domains present [twin fraction 0.73 (1):0.27 (1)]. It contains three Pb2+ cations and two IO4(OH)23− anions in the asymmetric unit. Each of the Pb2+ cations is surrounded by eight O atoms (cut-off value = 3.1 Å) in the form of a distorted polyhedron. The octahedral IO4(OH)23− anions are arranged in rows extending parallel to [021], forming a distorted hexagonal rod packing. The cations and anions are linked into a framework structure. Although H-atom positions could not be located, O...O distances suggest medium-strength hydrogen-bonding interactions between the IO4(OH)2 octahedra, further consolidating the crystal packing.

In this research, scanometry was used as a new, simple, fast and inexpensive method for a colorimetric determination of Mn2+ ion in water samples and thermocouple wire through the use of periodate reagent in an acidic medium. The results showed the oxidization of colorless Mn2+ ion by periodate and the formation of a purplish MnO4- ion. The system had a linear range of 1.0 to 70.0 µg mL-1 Mn2+ ion with a detection limit of 0.314 µg mL-1 and a relative standard deviation of 2.77% for G color value. This method has the capability to determine low levels of Mn2+ ion in thermocouple wire and water samples.

Immobilization of horse radish peroxidase (HRP) within alginate beads was improved by chemical modification of the enzyme and polysaccharide chains. HRP and alginate were oxidized by periodate and subsequently modified with ethylenediamine. Highest specific activity of 0.43 U/ml of gel and 81 % of bound enzyme activity was obtained using aminated HRP and alginate oxidized by periodate. Immobilized enzyme retained 75 % of original activity after 2 days of incubation in 80 % (v/v) dioxane and had increased activity at basic pH values compared to native enzyme. During repeated use in batch reactor for pyrogallol oxidation immobilized peroxidase retained 75 % of original activity. [Projekat Ministarstva nauke Republike Srbije, br. ON173017 i br. ON172049]

Hemoglobin-stabilized gold nanoclusters (Hb-AuNCs) were prepared by using hemoglobin as both reducing and stabilizing agents. The Hb-AuNCs display a strong catalytic effect on the chemiluminescence (CL) reaction of luminol with NaIO. The CL mechanism is discussed and the experimental variables are examined. It is found that dopamine strongly inhibits CL. This finding is exploited in a CL-based dopamine assay that works in the range between 0.3 and 9.0 nM and has a 0.1 nM detection limit. The relative standard deviation is 3.1% at a 5 nM dopamine level (for n = 11). The method was applied to the determination of dopamine in spiked human plasma with satisfactory results. [ABSTRACT FROM AUTHOR]

In this study, iodine-doped granular activated carbon (I-GAC) was prepared and subsequently applied to activate periodate (IO 4 − ) to degrade organic contaminants at ambient temperature. The physicochemical properties of GAC and I-GAC were examined using scanning electron microscopy, N 2 adsorption/desorption, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. No significant difference was observed between the two except for the existence of triiodide (I 3 − ) and pentaiodide (I 5 − ) on I-GAC. The catalytic activity of I-GAC towards IO 4 − was evaluated by the degradation of acid orange 7 (AO7), and superior catalytic performance was achieved compared with GAC. The effects of some influential parameters (preparation conditions, initial solution pH, and coexisting anions) on the catalytic ability were also investigated. Based on radical scavenging experiments, it appeared that IO 3 was the predominant reactive species in the I-GAC/IO 4 − system. The mechanism underlying the enhanced catalytic performance of I-GAC could be explained by the introduction of negatively charged I 3 − and I 5 − into I-GAC, which induced positive charge density on the surface of I-GAC. This accelerated the interaction between I-GAC and IO 4 − , and subsequently mediated the increasing generation of iodyl radicals (IO 3 ). Furthermore, a possible degradation pathway of AO7 was proposed according to the intermediate products identified by gas chromatography-mass spectrometry. [ABSTRACT FROM AUTHOR]

Post-synthesis modification of hydrogels is frequently used for chemical functionalization, immobilization of molecules or optimization of mechanical properties. In this work, novel gels were developed using a divinyl compound (+) N , N′ -diallyltartramide (DAT) as a crosslinking agent. DAT possesses a vicinal diol and it was found that can be selectively cleaved by reaction with periodate, obtaining aldehydes as products. The treatment of the gels crosslinked only with DAT leads to complete digestion of the material, obtaining a liquid as a product. The cleavage reaction in gels crosslinked with two agents, one reactive with periodate and another inert, allows modification of the crosslinking degree, maintaining the state of the gel. The change in the mechanical properties of the gels due to periodate reaction was followed by rheological studies. Furthermore, the reaction of periodate with DAT, the aldehyde obtained as a product and its reactivity with adipic acid dihydrazide (ADH) was studied by nuclear magnetic resonance (NMR) spectroscopy. [ABSTRACT FROM AUTHOR]

Periodate salts are being developed as potential replacements for perchlorate due to potential health hazards associated with exposure to perchlorate. The aim of this study was to investigate acute and subacute effects of periodate salts in rats. Acute oral toxicity of potassium and sodium periodate was determined using the Sequential Stage-Wise Probit method. The LD 50 for potassium periodate was 732 (95% CI = 539–838, slope = 13.4) and 685 mg/kg (95% CI = 580–809, slope = 10.6) for females and males, respectively. The LD 50 for sodium periodate was 318 (95% CI = 292–347, slope = 24.3) and 741 mg/kg (95% CI = 704–779, slope = 31.2) for females and males, respectively. In the subacute study, rats were administered sodium periodate at five doses (1/16 LD 50 up to LD 50 ) or distilled water for 14-days via oral gavage. Female rats in the 318 mg/kg-day group and male rats in the 185, 370, and 741 mg/kg-day groups exhibited moribundity, kidney toxicity, uremia, and a stress response. BMDL 10 s of 17.2 and 33.7 mg/kg-day were derived for females and males, respectively. Comparison with the NOAEL for perchlorate-induced thyroid toxicity in rats (0.009 mg/kg-day) suggests sodium periodate is less toxic than perchlorate on a subacute basis. [ABSTRACT FROM AUTHOR]