Chelating Agent EDTA Research Articles

Comprehensive evaluation and Mechanistic comparison of Cr-Catalyzed homogeneous Fenton-Like reactions for coexisting organics degradation

Chromium, as a widely utilized transition metal, presents wastewater with high toxicity and challenging treatment. To date, there has been limited exploration regarding the application of chromium in homogeneous Fenton-like reactions. This study aims to explore the potential of Cr(VI) and Cr(III) to activate hydrogen peroxide (H2O2) and permonosulfate (PMS) for degrading coexisting pollutants in homogeneous solutions. The Cr(VI)/PMS system was found to be the most effective, with a 95.58 % removal efficiency for the azo dye Acid Red 73 (AR73). The Cr(VI)/H2O2 system followed with 72.35 %, while the Cr(III)/H2O2 and Cr(III)/PMS systems showed lower efficiencies at 25.65 % and 16.95 %, respectively. Various techniques were employed to delve into the mechanisms underlying chromium activation. The results indicate that both Cr(VI) and Cr(III) can activate H2O2 to generate hydroxyl radical (HO•). Moreover, Cr(VI) can activate PMS in the pH range of 3 ∼ 11, producing HO•, sulfate radical (SO4•-), and singlet oxygen (1O2), while Cr(III) engages in chelation with PMS, causing the reaction to cease. Additionally, this study reveals that the chelating agent EDTA, upon complexing with Cr(III), efficiently activates PMS to generate 1O2, and the mechanism behind EDTA-Cr(III) activation of PMS was elucidated through DFT calculations. An integrated evaluation of Cr performance in the Fenton-like reaction provides new research directions for the removal of pollutants from chromium-containing wastewater.

Degradation of dioxins in chelated municipal solid waste incineration fly ash by low-temperature pyrolysis

In this study, low-temperature pyrolysis is applied to raw and chelated municipal solid waste incinerator fly ash to degrade and remove PCDD/F (polychlorinated dibenzo-p-dioxins, and dibenzofurans) and corresponding I-TEQs (international toxic equivalents), respectively. Additionally, PCDD/F degradation pathways are identified based on PCDD/F signatures. From the analysis of the average signal intensity of dioxin isomers in thermally treated fly ashes, the PCDD/F degradation rate was between 89.97 and 99.80 %, and the I-TEQs removal rate was 98.96 and 99.90% across all samples compared to untreated raw fly ash. The chelating agent EDTA enhanced the thermal degradation of PCDD/F, but the addition of Na2HPO4 in chelated fly ash as an inhibitor promoted PCDD/F regeneration. Further, there is a variable output of dioxins and corresponding I-TEQs under different temperatures and reaction times; however, longer reaction duration and higher temperatures proved highly effective. The overall toxicity of all thermally tested fly ashes was lesser than the permissible value of 50 ng I-TEQ/kg for resource utilization and observed in the range of 1.84 ± 0.15 to 19.45 ± 0.89 ng I-TEQ/kg. The investigation of the PCDD and PCDF signatures suggests that thermal destruction was a major pathway of degradation by breakage of the C-O bond, compared to dechlorination as observed by a high percentage contribution of HpCDD/F and OCDD/F congeners in thermally treated fly ashes. Low-temperature pyrolysis is an auspicious disposal technology that requires additional studies for large-scale applications.

A sustainable bioremediation of vanadium from marine environment and value-addition using potential thraustochytrids

Rising concerns about global environmental degradation underscore the pressing need for effective solutions to combat heavy metal pollution. Industries such as semiconductor and steel production discharge vanadium into marine ecosystems, posing significant risks to both marine life and human health. The current study investigates efficacy of utilizing marine thraustochytrid for efficient vanadium removal outcompeting other microbial sources. By optimizing pH and temperature conditions during harvesting, achieved a remarkable 50.80 % enhancement in vanadium removal efficiency, from 19.31 to 29.12 mg/L. Furthermore, chelating agents EDTA and citric acid supplementation demonstrated promising enhancements, reaching up to 31.21 and 32.59 mg/L, respectively. Notably, vanadium-treated biomass supplemented with citric acid exhibited maximum enhancement in lipid content, from 58.47 to 75.34 %, indicating thraustochytrid’s potential for biofuel production. This study presents a sustainable approach for industrial-scale vanadium bioremediation, aligning with Sustainable Development Goals focused on dual benefits of environmental protection and renewable energy.

Evaluating chemi-mechanical pulping processes of agricultural residues: High-yield pulps from wheat straw for fiber-based bioproducts

This work evaluates the feasibility of APMP (alkaline peroxide mechanical pulping) and CTMP (chemi-thermomechanical pulping) of wheat straw as small-scale, low-capital expenditure pulping process to produce high-yield pulps for fiber-based bioproducts. APMP and CTMP wheat straw pulps were characterized in terms of pulping yield, freeness, ISO brightness, and fiber morphology. Additionally, both pulps were evaluated for tissue paper applications and benchmarked against BEK (bleached eucalyptus kraft) market pulp. APMP wheat straw pulps presented higher yield (75.2 – 79.8 %) compared to CTMP (69.1 – 80.6 %), depending on cooking chemicals and chemical charge during the chemical impregnation stage. The final brightness of APMP pulps varied from 36.4 % to 37.8 % ISO when sodium hydroxide and hydrogen peroxide were used as pulping agents without additional chemical additives. However, the brightness of APMP pulps can be increased up to 49.7 % ISO by using additional chemical additives such as EDTA (chelating agent), sodium silicate (peroxide stabilizer), or by employing a multi-stage chemical impregnation strategy. Both pulps produced fibers with similar morphological properties. A comparison of tissue-making properties showed that APMP pulps produced bulkier handsheets with higher water absorption capacity and better softness than CTMP pulps. However, CTMP pulps exhibited a higher tensile index than APMP pulps for a given pulp freeness. The results indicate that non-wood fibers, such as those derived from wheat straw, could be a promising alternative for use in fiber-based bioproducts such as hygiene tissue.

Protein purification via consecutive histidine-polyphosphate interaction.

While nickel-nitrilotriacetic acid (Ni-NTA) has greatly advanced recombinant protein purification, its limitations, including nonspecific binding and partial purification for certain proteins, highlight the necessity for additional purification such as size exclusion and ion exchange chromatography. However, specialized equipment such as FPLC is typically needed but not often available in many laboratories. Here, we show a novel method utilizing polyphosphate (polyP) for purifying proteins with histidine repeats via non-covalent interactions. Our study demonstrates that immobilized polyP efficiently binds to histidine-tagged proteins across a pH range of 5.5-7.5, maintaining binding efficacy even in the presence of reducing agent DTT and chelating agent EDTA. We carried out experiments of purifying various proteins from cell lysates and fractions post-Ni-NTA. Our results demonstrate that polyP resin is capable of further purification post-Ni-NTA without the need for specialized equipment and without compromising protein activity. This cost-effective and convenient method offers a viable approach as a complementary approach to Ni-NTA.

Enhanced heavy metal leaching from volcanic muds: Synergistic effects of citric acid and EDTA composite system

The soil leaching technology is a well-established technique commonly employed for the remediation of soils contaminated with heavy metals. Volcanic muds share similar properties to those of soil. This study utilizes soil leaching technology to tackle the presence of heavy metals in volcanic muds. It examines the leaching removal effect of the synergistic system of organic acid citric acid (CA) and chelating agent EDTA on heavy metals Pb, Cd, Cr, and Ni in volcanic muds. The leaching conditions were initially selected and subsequently optimized through the application of response surface methodology (RSM). The priority of leaching conditions can be ranked as follows: leaching duration is found to be more crucial than leaching agent concentration, which is noted to be more pivotal than the solid-liquid ratio. Following an in-depth evaluation of model predictions and experimental validation, it has been established that the optimal leaching concentration of EDTA is 0.15 mol·L−1, the optimal leaching duration is 9 h, and the optimal solid-liquid ratio is 1:10. For the compound CA, the most effective leaching concentration is 0.3 mol·L−1, the optimal leaching duration is 8 h, and the optimal ratio of solid to liquid is 1:10. The significance of the leaching conditions was further explored in conjunction with RSM. Furthermore, the integration of both leaching methods, namely combined leaching and stepwise leaching, has been demonstrated to amplify the removal efficiency of heavy metals, with stepwise leaching showing the highest removal rate. The experimental findings suggest that the leaching technique involving CA and EDTA composite system is an effective approach for the remediation of heavy metals such as Pb, Cd, Cr, and Ni in volcanic muds. This study provides theoretical rationale for the adoption of soil leaching technology in the remediation of heavy metals in volcanic muds. Additionally, the heavy metal content of the remediated volcanic muds substantially meets with the standards for cosmetic raw materials.

The importance of ammonium and potassium ions under hydrothermal preparation conditions on the structure and corrosion properties of CaP coatings

CaP coatings were hydrothermally deposited on the AZ31 magnesium alloy in rection mixture containing ammonium or potassium ions. CaP coatings were deposited on AZ31 alloy in reaction mixture at pH 5 and 7 with and without EDTA chelating agent. It was found that the ammonium ions present have a negative effect on the quality of the CaP coating deposited from mixture at pH 7 and their presence at neutral environment results in the formation of structural defects in the coatings. At the same time, the presence of ammonium ions suppresses hydrolysis and crystallization of OCP and HAp. However, pH and the presence of EDTA have a more pronounced effect on the structure and phase composition. The coatings deposited in the reaction mixture, containing potassium-based precursors and EDTA, at pH 7 showed the best thermal stability due to the majority of HAp phase. The uniform CaP coating deposited in the reaction mixture containing EDTA and K+ ions at pH 7 also achieved the best corrosion properties due to the absence of structural defects and dense structure.

Kinetic mechanisms of organophosphine compounds on calcium carbonate crystal growth: Cruising effect and Spatial matching

Calcium carbonate (CaCO3) is a common mineral in industrial water systems. Organophosphate is a widely used scale inhibitor with 100% inhibition of thousands of mg/L of calcium (Ca2+) ions at concentrations below 10 mg/L. However, chelating agent EDTA is hundreds of times more effective in achieving the same inhibitory effect. Our study explored the significant difference in CaCO3 growth inhibition by these compounds. Through experiments combining molecular dynamics simulations and quantum chemical calculations, we have found that organophosphines dynamically capture and release Ca2+ ions, enhancing the solubility of Ca2+ ions and impeding CaCO3 growth through a mechanism known as the “cruising effect”. Simultaneously, the lattice distortion induced by “spatial matching” was employed to inhibit the growth of CaCO3. On the other hand, chelating agents exhibited robust coordination forces, particularly with ligand atoms (O and N), showcasing superior chemometric characteristics. These findings illuminated the distinct mechanisms of CaCO3 growth inhibition.

Label-free electrochemiluminescence sensor based on magnetic nanoparticles modified with G-quadruplex DNA for detecting lead ions

Developing rapid and renewable sensors to detect heavy metal lead ions is a crucial and promising area of research. Herein, we constructed a label-free electrochemiluminescence (ECL) sensor for detecting Pb2+ using magnetic nanoparticles that were modified with a G-quadruplex probe. The aptamer probe was created by immobilizing a double-stranded DNA (dsDNA) onto the surface of Fe3O4@Au magnetic nanoparticles, with Ru(phen)32+ being intercalated into the dsDNA structure. Upon introduction of Pb2+, the dsDNA structure opened up to form the Fe3O4@Au-G-quadruplex-Pb2+ structure, resulting in the dissociation of single-stranded DNA (ssDNA) and Ru(phen)32+. The dissociated Ru(phen)32+ acted as an ECL probe, allowing for the construction of a highly sensitive sensing system that quantitatively relates Pb2+ concentrations to ECL signals. In the presence of the strong chelating agent EDTA, the hybridization of the two ssDNA strands back into the dsDNA structure allowed for the re-insertion of Ru(phen)32+ into the dsDNA structure, endowing the sensor with excellent renewability. The adapter sensor was characterized using cyclic voltammetry, electrochemiluminescence, and fluorescence spectroscopy. Over the range of 50 pM to 9 nM, the Pb2+ concentration exhibited a linear relationship with its corresponding ECL signal, with a detection limit of 1.2 pM. In addition, the biosensor demonstrated outstanding selectivity, stability, reproducibility, and potential for use in real-world sample applications.

Dual action of a distinctive colloidal 3-(Benzimidazole-2-yl)-2-hydroxybenzaldehyde grafted chitosan support for the continual detection ability for Hg (II) in aqueous environ and inherent emission-induced live cell imaging

In this research work, an interesting sugar based fluorescent materials has been successfully developed to detect metal ions (Hg2+) in aqueous solution. The prepared colloid, 3-(benzimidazole-2-yl)-2-hydroxy benzaldehyde/chitosan (ChI) has significant characteristics as greener and eco-friendly material. ChI has found for switching of proton transfer between enol-imine and keto-enamine forms of ChI through excited-state intramolecular proton transfer (ESIPT) mechanism. The internal chemical-bonding and functionality of ChI are confirmed through FTIR, UV–Vis, fluorescence, SEM, TEM, DLS etc. ChI shows its fluorescence-quenching, selectivity, scavenging and chelating capabilities for Hg2+ ions in the presence of other cations in aqueous solution. Spectral and XRD analysis have established the remarkable continual and consistent detection of Hg2+ in aqueous system with a limit of detection of 0.204 nM. The strong chelating agent EDTA is used to regain of fluorescence of ChI in support of labile chelation ability of ChI and to show reversibility for continual detection of Hg2+ due to the strong EDTA/Hg2+ complexation. Scavenging ability is investigated using Na2S solution followed by the XRD analysis of precipitate appeared. Also, ChI shows its efficiency for the fluorescence cell imaging in live HADF cells with negligible cytotoxicity. Convincingly, ChI has processed as materials with very significant addition and advancement for its multimodal and eco-friendly behavior in current material development research.

Facile synthesis of Ag-Co bimetallic nanoparticles decorated Fe3O4@EDTA nanocomposites and their enhanced catalytic activity

In this study, firstly, bimetallic Ag-Co nanoparticles with rich catalytic sites decorated on Fe3O4 magnetic carriers through metal ion chelating agent EDTA (Ag-Co@EDTA@Fe3O4 NPs) were fabricated by co-reducing agent in-situ deposition method for the first time. The synthesized nanocomposites were characterized by various techniques, including UV–vis, XRD, TEM, EDX, XPS and VSM. Secondly, the catalytic reduction performance of Ag-Co@EDTA@Fe3O4 NPs was analyzed for 2-nitrophenol in the presence of NaBH4 at 25 ℃. Results showed that the k of Ag-Co@EDTA@Fe3O4 NPs was 10.9 and 2.7 times higher than that of Co@EDTA@Fe3O4 and Ag@EDTA@Fe3O4 NPs, respectively, which considered to obey the first-order kinetics equation, proving the strong synergistic effect between Ag and Co nanoparticles. Furthermore, the significantly enhanced catalytic activity of Ag-Co@EDTA@Fe3O4 NPs was discussed. Plenty of Ag NPs were successfully anchored on Fe3O4@EDTA supports maybe the crucial factor, and the doped Co provided much more active sites in the catalytic process. Finally, the degradation efficiency of Ag-Co@EDTA@Fe3O4 NPs still remained above 95% after 5 cycles. Importantly, there was no significant difference between the fresh catalyst and after cycling for 5 times, observed by TEM and SEM. Meanwhile, the change of hydrodynamic diameter of the used Ag-Co@EDTA@Fe3O4 NPs over cycle number was measured around 230 nm which increased unobviously, making it a promising candidate for wastewater treatment in industries.

Synthesis and investigation of bis(phenyl)fluorene and carbazole appended dipodal Schiff base for fluorescence sensing towards Sn(II) ion and its regioselective polymerization

One-pot condensation reaction between 9,9-Bis(4-aminophenyl)fluorene and 9-Ethyl-9H-carbazole-3-carbaldehyde afforded a chemosensor ((N,N′)-4,4′-(9H-fluorene-9,9-diyl)bis(N-((9-ethyl-9H-carbazol-2-yl)methylene)aniline, SB) having Schiff base skeleton. The further step was the synthesis of the polymer (P-SB) via oxidative polycondesation reaction of SB. FT-IR, 1H NMR and 13C NMR instruments were used to characterize the functional groups on the monomer and polymer. Thermal stability and electrochemical features of SB and P-SB were characterized by thermogravimetric analysis-differential thermal analyses (TG-DTA) and cyclic voltammetry (CV), respectively. The glass transition and surface image of P-SB were determined from DSC and SEM measurements, respectively. UV–vis and photoluminescence spectroscopy (PL) allowed to determine the optical properties of SB and P-SB. The obtained polymer, which had the weight average molecular weight of 8400 Da identified by gel permeation chromatography (GPC), exhibited fluorescence property. The synthesized turn-on fluorogenic chemosensor SB showed high selectivity and sensitivity towards Sn2+ among the cations of Ag+, K+, Hg2+, Mn2+, Cd2+, Sn2+, Ca2+, Pb2+, Zn2+, Co2+, Ni2+, Cu2+, Fe3+, Al3+, Cr3+ and Cr6+. The fluorescence turn-on recognition process for the detection of Sn2+ was related to the restriction of CN isomerization, followed by inhibiting intramolecular charge transfer (ICT), with consequent chelation-enhanced fluorescence (CHEF) mechanism. The stoichiometry ratio of the analyte-sensor adduct in the solution was found to be 1:1 by Job's plot method concomitant with a dramatic increase in fluorescent signal at 471 nm and a marked color change from colorless to turquoise blue upon addition of Sn2+ ions. Limit of detection value for the formation of SB-Sn2+ chelation was calculated as 3.37 nM. No change in PL intensity of SB-Sn2+ chelation was observed in the company of other metal ions. Reversibility of the chemosensor in its binding towards Sn2+ was demonstrated in the presence of chelating agent EDTA. The synthesized SB could effectively detect Sn2+ ion as a fluorescent sensor.

Cataracts and copper: A spectroscopic perspective of copper-induced aggregation of betaB2-crystallin.

Cataracts disease is the principal cause of visual impairment worldwide. It is caused by damage, unfolding and subsequent non-amyloid aggregation of the highly soluble lens proteins: the crystallins. It has been demonstrated that essential metal ions, such as copper and zinc, can induce the aggregation of human gamma-crystallins. Here, we report the effect of metal ions one the aggregation of betaB2-crystallin: Pb(II), Hg(II), Cu(II) and Zn(II) ions can induce the non amyloid aggregation of this protein and the chelating agent EDTA can partially revert this effect. Furthermore, SDS-PAGE analysis of Cu(II)-induced protein aggregates reveal disulfide-bridged oligomerization. Spectroscopic studies of the Cu(II)-betaB2-crystallin interaction by electron paramagnetic resonance (EPR), circular dichroism (CD) and X-Ray absorption spectroscopy (XAS) show the presence of at least three metal binding sites. Surprisingly, one of them resembles that of Cu(II) bound to an amino-terminal copper and nickel binding motif (ATCUN), which is found in proteins and peptides that bind copper with high affinity and are involved in copper cellular trafficking. On the other hand, copper-induced formation of sulfur oxidized oligomers of betaB2-crystallin and a decreased EPR Cu(II) spin quantitation suggests the reduction of Cu(II) ions to Cu(I), as confirmed by XAS. Overall, these results suggests that copper-induced aggregation of betaB2-crystallin involves several mechanisms, including the formation of metal-bridged and disulfide-bridged species, and a very interesting copper-dependent redox process. This study expands the bioinorganic facet of cataract disease.

Insight into electrochemically boosted trace Co(II)-PMS catalytic process: Sustainable Co(IV)/Co(III)/Co(II) cycling and side reaction blocking

A novel homogeneous electrocatalytic system was constructed by current-assisted trace Co(II) activating PMS (ECP) to remove reactive blue 19 (RB19). More than 93 % of RB19 was rapidly removed with only a trace dose, and the PMS was 98.35 % utilized during the reaction. By exploring the active species and analyzing the PMS consumption, it was found that current strongly accelerated the Co(III)/Co(II) redox cycle by providing electrons to Co(III), and inhibited the side reaction thus improving the PMS utilization. Electric energy per order was very low, only 0.26 kWh·m3. Radicals (SO4•-) and non-radicals (Co(III), Co(IV) and 1O2) participated in ECP system, in which SO4•- was dominant. By excluding the other three precursors (PMS, •OH and O2•-), the side reaction product SO5•- was identified as the source of 1O2 in ECP system. Combining chelating agent EDTA and chemical probe PMSO, Co(IV) was considered formed by single and double charge transfer. Five degradation pathways of RB19 were proposed using mass spectrometry and DFT calculation. The ecotoxicity and mutagenicity of RB19 and its transformation products were predicted using software simulation. These studies provided an interesting insights into the synergistic Co(II)-PMS systems and offered a new strategy for electrochemical processes.

'AIE + ESIPT' Active 2-hydroxy-naphthalene Hydrazone for the Fluorescence Turn-on Sensing of Al3.

The aggregation-induced emission (AIE) behaviour of an easy-to-prepare Schiff base 2-hydroxy-naphthalene hydrazone (L) was explored in mixed DMSO/HEPES medium by selecting DMSO as a good solvent, whereas HEPES buffer (H2O, 10mM, pH 7.4) as a poor solvent. The weakly fluorescent L in pure DMSO showed a fluorescence enhancement at 532nm upon increasing the fraction of HEPES above 70% because of the self-aggregation of L and excited state intramolecular proton transfer (ESIPT) process. The AIE luminogen (AIEgen) L was applied for the sensing of metal ions in HEPES buffer (5% DMSO, 10mM, pH 7.4). Among the fourteen different metal ions (Cu2+, Co2+, Ni2+, Mn2+, Mg2+, Fe3+, Fe2+, Zn2+, Cd2+, Hg2+, Pb2+, Al3+, Cr3+), AIEgen L showed a selective fluorescence enhancement at 435nm in the presence of Al3+ without disturbing the fluorescence intensity at 532nm due to the chelation-enhanced fluorescence effect (CHEF). The detection limit of 20nM was estimated by performing the fluorescence titration of AIEgen L with Al3+. The reversibility of the Al3+ selective AIEgen L was demonstrated by adding a strong chelating agent EDTA. Finally, the practical utility of AIEgen L was validated by quantifying Al3+ in river and tap water samples.

Pyridoxal derived red-emitting aggregates for the ratiometric sensing of pH and copper(II)

The research on aggregation-induced emission (AIE) continue to gain a bourgeoning interest for their extensive applications in different field including sensing and biosensing. In this study, the red-emitting rod-type aggregates L (λex = 375 nm, λem = 597 nm) was prepared facilely in two steps, i.e., the vitamin B6 cofactor pyridoxal was first condensed with the p-phenylenediamine followed by the DMSO solution of the orange precipitate formed was allowed to self-aggregate by adding poor solvent. Upon self-aggregation of L, the restriction of intramolecular motion and the ESIPT phenomenon play the key role in emitting red fluorescence at 597 nm. The pH dependent emission study of the aggregates L revealed three distinct pH windows: red-emitting between pH 5.4 to 9.1, green emitting above pH 9.9 and non-fluorescent in acidic pH. The aggregates L in HEPES buffer (5% DMSO, 10 mM, pH = 7.4) showed a selective turn-off response towards Cu2+ with a good linearity between 4.8 and 14.7 μM and a detection limit of 2.7 μM. The quenching was occurred due to the non-fluorescent complex formed between L and Cu2+ in the ground state. Addition of strong chelating agent EDTA reversed the quenched fluorescence of L. To improve the practical utility, the turn-off sensor L was converted into a ratiometric sensor for Cu2+ by adding an optimized amount of fluorescein (Fl) dye. The dual emitting L@Fl showed fluorescence quenching at 597 nm whereas concomitant enhancement at 515 nm because of the energy transfer mechanism. The developed ratiometric sensor showed improved detection limit of 0.72 μM. Finally, the practical utility of both L as turn-off sensor and L@Fl as ratiometric sensor was examined by quantifying Cu2+ concentration in different real samples.

Salicylic acid doped silica nanoparticles as a fluorescent nanosensor for the detection of Fe3+ in aqueous solution.

A novel organic-inorganic hybrid nanosensor (SASP) was prepared by a one-step sol-gel method and characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, N2 adsorption-desorption, fluorescence spectroscopy, etc. The nanosensor showed almost 3-fold fluorescence emission quenching upon excitation with a 293 nm wavelength in the presence of 20 μM Fe3+ ions. The presence of 18 other metal ions had no observable effect on the sensitivity and selectivity of the nanosensor. A fluorescence analysis method based on the SASP for the selective detection of Fe3+ was established under optimal conditions. The results showed that there was a linear relationship between the log luminescence value and the concentration of Fe3+ over the range of 2.0 × 10-7-9.0 × 10-5 mol L-1 with a detection limit (3σ) of 2.5 × 10-8 mol L-1. Furthermore, the proposed method was successfully applied for the determination of trace Fe3+ in fetal bovine serum without the interference of other molecules and ions. Good recovery (96.5-104.5%) and a relative standard deviation of less than 8.6% were obtained from serum samples spiked with four levels of Fe3+. Additionally, the nanosensor showed a good reversibility; the fluorescence could be switched "off" and "on" in two ways, by adjusting the pH of the solution and adding metal chelating agent EDTA.

Chelators to assist the high dispersion of Ni2P particles over mesoporous silica nanospheres for hydrogenating reaction

Ni2P supported catalysts exhibit high catalytic activities in hydrogenation reaction, of which the particle sizes of Ni2P active phases are the key influential factor. This research focus on the effect of chelators on the size of Ni2P particles over wrinkle silica nanoparticles (WSNs) by introducing chelating agents EDTA and NTA during impregnation process. The characterization results show that chelators modified catalysts possess smaller size of Ni2P particles than the unmodified Ni2P catalysts. Among all the synthesized catalysts, the EDTA modified Ni2PE(1.5)/WSNs catalyst possesses smallest average particle size of Ni2P, only 2.6 nm. Moreover, the Ni2P catalysts with the assistance of EDTA exhibits better catalytic activity than that of NTA under high reaction temperature, which can be ascribed to the strong bonding between EDTA and Ni. And the EDTA modified Ni2PE(1.5)/WSNs catalyst shows highest hydrogenation ability, almost reaching 100% decalin selectivity.

Surface defect-induced electronic structures of lead-free Cs2AgBiBr6 double-perovskite for efficiently solar-driven photocatalytic performance

Lead-free Cs2AgBiBr6 double-perovskite has triggered appealing interest in various solar energy-related applications including solar devices and photocatalysis. Nevertheless, further development of the perovskite materials is restricted due to their low redox capacity of the energy band, which is determined by the intrinsic electronic structure. Herein, we demonstrate surface defect-induced electronic structures of the Cs2AgBiBr6 for achieving efficient photocatalytic performance by simply controlling the nucleation and growth processes of the lead-free double-perovskite. During the synthesis process, the strong interaction between the chelating agent EDTA and Cs+ ion leads to the generation of Cs vacancies of Cs2AgBiBr6, which promotes the formation of surface defects to control the electronic structure of double perovskite. The optimized Cs2AgBiBr6 has the strongest reduction capacity with the conduction band potential of −1.53 V (vs NHE at pH = 7) so far, which can greatly promote the production of superoxide radicals (O2–), improving the photocatalytic efficiency of the Cs2AgBiBr6. Under one simulated sunlight irradiation, the photodegradation efficiency of tetracycline (TC) for the as-obtained Cs2AgBiBr6 with surface defect is up to 81.8 % within 90 min. Environmental ImplicationEnvironmental pollution resulting from various factitious and industrial activities is primarily composed of organic compounds such as pesticides, dyes, antibiotic and so on. Antibiotic, difficult to decompose, can only be decomposed slowly by chemical or biological methods owing to their strong stability. Photocatalysis is emerging as a promising technology for environmental remediation because of its strong oxidation ability and fast reaction rate. The eco-friendly Cs2AgBiBr6 perovskite with a suitable bandgap (1.83 eV ∼ 2.19 eV) has recently emerged as a promising photocatalyst for application in pollutant degradation.

Diversity and activity of amylase-producing bacteria isolated from mangrove soil in Thailand

Abstract. Klinfoong R, Thummakasorn C, Ungwiwatkul S, Boontanom P, Chantarasiri A. 2022. Diversity and activity of amylase-producing bacteria isolated from mangrove soil in Thailand. Biodiversitas 23: 5519-5531. Mangrove forests are a potential ecosystem for the isolation of various economic enzymes derived from mangrove-associated bacteria. The knowledge of amylase-producing bacteria isolated from mangrove forests in the Southeast Asian region has been scarce. This study aimed to investigate the isolation, genetic identification, and activity characterization of amylase-producing bacteria from mangrove soils in Thailand. The amylase-producing bacteria isolated from mangrove soils in the present were genetically belong to the genera Bacillus, Desulfurella, Peribacillus, Priestia, and Pseudomonas. Several amylase-producing bacteria such as Bacillus proteolyticus, Desulfurella, Pseudomonas entomophila, and Pseudomonas putida found in this study have hardly ever been reported. The Bacillus paralicheniformis strain DNP0507 was the most active amylolytic bacterium with 2.395 ± 0.133 U/mg of amylase activity. The optimum temperature and pH for amylolytic activity were determined to be 50°C at a pH of 7.0 with a thermal stability range of 20-60°C at a neutral pH of 7.0-8.0. The enzyme activity was significantly enhanced by Cu2+, Co2+, and Pb2+ and was inhibited considerably by a chelating agent EDTA. Finally, the most active amylolytic B. paralicheniformis strain DNP0507 could be applied in baking industries, food industries, and starchy waste valorization.