Primary By-products Research Articles

Adsorption and biodegradation of butyl xanthate in mine water by Pseudomonas sp. immobilized on yak dung biochar

The butyl xanthate (BX) in mining wastewater poses significant environmental challenges due to its toxicity and persistence. This study aimed to evaluate the effectiveness of Pseudomonas sp. immobilized on yak dung biochar (Ps.@YDBC600) for BX degradation, emphasizing the synergistic effects of biochar adsorption and microbial degradation. BX removal efficiency of free Pseudomonas sp. cells was assessed under various environmental conditions, with optimal degradation observed at 30 °C and an initial pH of 5.0. Yak dung biochar prepared at 600 °C (YDBC600) was selected due to its high surface area, porosity, and favorable adsorption properties, enhancing the immobilization and activity of Pseudomonas sp. The absorption of BX by biochar followed a two-compartment first-order kinetic model and primarily involved hydrogen bonding, hydrophobic interactions, and pore filling. The primary crystalline mineral component of YDBC600 and Ps.@YDBC600 before and after the adsorption and degradation of BX was SiO₂. The Ps.@YDBC600 was shown to significantly enhance BX removal efficiency compared to free Pseudomonas sp. cells or biochar alone. Molecular studies indicated that biochar facilitated BX degradation by providing a stable environment for Pseudomonas sp. and optimizing metabolic resource allocation. The primary by-products, including CS₂, HS–, ROCOS–, ROCSSH and (ROCSS)₂ were effectively minimized (each by-product was reduced more than 80%), reducing secondary pollution. These findings demonstrated the potential of Pseudomonas sp. immobilized on biochar as an effective approach for treating BX-contaminated mining wastewater, offering a sustainable approach to environmental remediation and management.

Photoformation of Environmentally Persistent Free Radicals During Phototransformation of Poly-Cyclic Aromatic Hydrocarbons (PAHs) on Particles in an Aqueous Solution: The Hydrogenation of PAHs and Effect of Co-Existing Water Matrix Factors.

Environmentally persistent free radicals (EPFRs) generated on particles under irradiation in water have attracted particular attention, and their formation mechanisms are not well understood. This study investigated the photoformation of EPFRs on both actual samples collected from an oil production plant in Panjin, Liaoning, China, and simulated Fe(III)-montmorillonite samples in water. The EPFRs detected on actual samples were not easily generated compared with those in the soil or in the air, based on the concentrations of identified PAHs. EPR signals in the range of 1017 to 1018 spin/g were detected on the simulated Fe(III)-montmorillonite samples. Their g factors were smaller than 2.0030, which indicated the generation of carbon-centered EPFRs. The primary byproducts were identified by chromatography-mass spectrometry (GC-MS), and a possible EPFR formation pathway during PAH degradation was proposed. Hydrogenation of PAHs during the photoformation of EPFRs was observed and might be due to the catalysis of the simulated particles and the interaction of the intermediates. Meanwhile, the effects of the typical anions (NO2- and Cl-) and the surfactant (TWEEN® 80 and sodium dodecyl sulfate) were investigated and indicated that the phototransformation process and adsorption process would affect the formation of EPFRs. Overall, our study provided useful information to understand the photoformation of EPFRs in aqueous environments.

Investigation of Acetoin Biosynthesis by Bacillus subtilis ACA-DC 1176 Growing on Crude Glycerol in Flask and Bioreactor Trials

Acetoin biosynthesis by two Bacillus subtilis strains valorising crude glycerol was thoroughly explored within a pre-defined range of culture conditions and systems. B. subtilis ACA-DC 1176 stood out for its higher efficiency in acetoin production, prompting an investigation into the potential for enhanced productivity through the evaluation of diverse culture conditions and media compositions. The primary by-products of the biodiesel and corn industries, namely crude glycerol and corn steep liquor, respectively, were successfully employed as the principal carbon and nitrogen sources of the newly developed low-cost culture medium. Furthermore, the results of the various feeding strategies that were tested indicated that the conversion of 2,3-butanediol (BDO) to acetoin occurred exclusively when the concentration of glycerol was below approximately 5 g/L. This seemed to be necessary for the production of NADH, which is essential for maintaining cellular processes. Following the complete depletion of glycerol, acetic acid increased and became the predominant metabolite, while both acetoin and BDO decreased, presumably resulting in ATP generation. This is likely a mechanism employed by the cell to generate energy in the absence of a carbon source. In the fed-batch bioreactor culture, the kinetics of metabolites differed, as there was no conversion of BDO to acetoin at the final depletion of glycerol. At volumetric mass transfer coefficient (kLa) levels exceeding approximately 70 1/h, the production of acetoin was favoured over that of BDO, with the highest observed acetoin/BDO ratio reaching 4.29 g/g. Conversely, at kLa values below approximately 60 1/h, the titres of acetoin and BDO were found to be nearly equal. The final concentrations of acetoin and BDO reached 36.0 g/L and 25.5 g/L, respectively, resulting in a total yield of both (acetoin + BDO) per glycerol consumption of 0.40 g/g. To the best of our knowledge, this is the first study to focus on acetoin production from crude glycerol fermentative valorisation. The study presents new findings regarding the parameters influencing the level of BDO conversion to acetoin. However, further research is required in order to gain a comprehensive understanding of the underlying phenomena and metabolic pathways involved.

Phototransformation of tetrabromobisphenol A bis (allyl ether) in an aqueous solution: Role of environmentally persistent free radicals

Tetrabromobisphenol A bis (allyl ether) (TBBPA-BAE) represents an extensively used brominated flame retardant (BFRs) in the production of many fields and their phototransformation in natural water is still unclear. The environmentally persistent free radicals (EPFRs) with preserved activities could exist in the environment for a long time and involve in the phototransformation of many organic pollutants. Here, the photodegradation of TBBPA-BAE with the degradation rate constant (k = 0.060 h−1) under simulate sunlight and the promoting effect of EPFRs on TBBPA-BAE photodegradation (k = 0.135 h−1) were investigated. According to the detected photogenerated electrons (e−) and singlet oxygen (1O2) rather than hydroxyl radicals (•OH) by the electron paramagnetic resonance (EPR), the effect mechanism may not be related to the typical •OH induced by EPFRs. The possible transformation pathways of the ether cleavage, hydrolysis and hydroxylation of propenyl bond and the debromination were proposed by the primary byproducts identified by UPLC-Q-Exactive Orbitrap MS. EPFRs caused a further debromination and ether cleavage and probably be due to EPFRs directly providing electrons to TBBPA-BAE which promoted the photodegradation of TBBPA-BAE, and their reaction mechanism needed further attention. Overall, this study provided useful information to understand the role of EPFRs on phototransformation of TBBPA-BAE in water.

Levofloxacin Degradation, Antimicrobial Activity Decrease, and Potential for Water Disinfection Using Peroxydisulfate Activation by Ag/TiO2 under Sunlight

Water quality and usability are global concerns due to microbial and chemical pollution resulting from anthropogenic activities. Therefore, strategies for eliminating contaminants are required. In this context, the removal and decrease in antibiotic activity (AA) associated with levofloxacin (LEV), using TiO2 and Ag/TiO2 catalysts, with and without sunlight and peroxydisulfate, was evaluated. Additionally, the disinfection capacity of catalytic systems was assessed. The catalysts were synthesized and characterized. Moreover, the effect of Ag doping on visible light absorption was determined. Then, the photocatalytic treatment of LEV in water was performed. The materials characterization and EPR analyses revealed that LEV degradation and AA decrease were ascribed to a combined action of solar light, sulfate radical, and photocatalytic activity of the TiO2-based materials. Also, the primary byproducts were elucidated using theoretical analyses (predictions about moieties on LEV more susceptible to being attacked by the degrading species) and experimental techniques (LC-MS), which evidenced transformations on the piperazyl ring, carboxylic acid, and cyclic ether on LEV. Moreover, the AA decrease was linked to the antibiotic transformations. In addition, the combined system (i.e., light/catalyst/peroxydisulfate) was shown to be effective for E. coli inactivation, indicating the versatility of this system for decontamination and disinfection.

Degradation mechanism and decomposition of sulfamethoxazole aqueous solution with persulfate activated by dielectric barrier discharge

ABSTRACT The present study focused on the degradation of sulfamethoxazole (SMX) aqueous solution and the toxicity of processing aqueous by the dielectric barrier discharge (DBD) activated persulfate (PS). The effects of input voltage, input frequency, duty cycle, and PS dosage ratio on the SMX degradation efficiency were measured. Based on the results of the Response Surface Methodology (RSM), SMX degradation efficiency reached 83.21% which is 10.54% higher than that without PS, and the kinetic constant was 0.067 min−1 in 30 min when the input voltage at 204 V (input power at 110.6 W), the input frequency at 186 Hz, the duty cycle at 63%, and the PS dosage ratio at 5.1:1. The addition of PS can produce more active particles reached 1.756 mg/L (O3), 0.118 mg/L (H2O2), 0.154 mmol/L (·OH) in 30 min. Furthermore, the DBD plasma system effectively activated an optimal amount of PS, leading to improved removal efficiency of COD, and TOC to 30.21% and 47.21%, respectively. Subsequently, eight primary by-products were pinpointed, alongside the observation of three distinct pathways of transformation. Predictions from the ECOSAR software indicated that most of the degradation intermediates were less toxic than SMX. The biological toxicity experiments elucidated that the treatment with the DBD/PS system effectively reduced the mortality of zebrafish larvae caused by SMX from 100% to 20.13% and improved the hatching rate from 55.69% to 80.86%. In particular, it is important to note that the degradation intermediates exhibit teratogenic effects on zebrafish larvae.

Comparative Kinetic Analysis of Triclosan Degradation under UV-C and Simulated Solar Irradiation

This research delves deeply into the intricate degradation kinetics of triclosan, employing two distinct methodologies: UV and simulated solar irradiation. Through a comprehensive comparative analysis, the study endeavors to elucidate the efficacy of these techniques, aiming to shed light on their respective methodological strengths and limitations. The study compares the efficacy of UV and simulated solar irradiation techniques for triclosan degradation, revealing that both methods exhibit effectiveness in degrading triclosan, with variations observed in degradation rates and byproduct formation. Through a detailed examination of the kinetics of triclosan degradation, the study reveals the intricate pathways and mechanisms involved in the photodegradation process. Results highlight the influence of irradiance levels and residence times on degradation efficiency. The research identifies optimal conditions for triclosan degradation, emphasizing the importance of residence time and irradiance levels. Results show that a residence time of 4 h and an irradiance level of 450 W m−2 maximize degradation efficiency. Analysis of degradation byproducts provides insights into the transformation pathways of triclosan under UV and simulated solar irradiation, indicating the formation of 2,4-dichlorophenol, quinone, and hydroquinone as primary byproducts.

Recycling Blast Furnace Dust as Raw Material in Iron-Making

A large amount of dust is formed as one of the primary by-products during the blast furnace ironmaking process. Iron and carbon are mainly compositions in the dust. Blast furnace dust (BFD) is cycled to protect the environment and recover valuable components. In this study, BFD is used pelletization process with iron ore concentration for raw materials charging to the iron-making furnace. The mixture of BFD and iron ore (30; 40; 50 by mass %) with 2 % bentonite as a binder was used for making pellets. The produced pellets were tested drop strength and fired at 1200 °C for 30 minutes in the atmosphere environment. Fired pellets were examined compressive strength and reduced at 900; 1000; 1100 °C in 30 minutes. Mechanical, porosity and reduction degree properties of reduced pellets were analysed. The results show that green strength and compressive strength are acceptable values. Good porosity is observed when using a high amount of BFD so that it gives a high degree of reduction. XRD, SEM were used for characterization. Iron whiskers were observed in the sample, which was reduced at 1000 °C. It is clearly shown that the pellets using BFD are appropriated for charging to blast furnace as raw materials.

Biosorption of Ciprofloxacin (CIP) using the Waste of Extraction Process of Microalgae: The Equilibrium Isotherm and Kinetic Study

Scientists are investigating the efficacy of different biosorbents for promoting economic and environmental viability in purifying contaminants. Among the primary by-products of biodiesel production is waste microalgae biomass, which has the potential to be used as a cheap biosorbent for the treatment of pollution. In the present study, the biomass left over after extracting the chlorella vulgaris was used to test the potential biosorption of CIP from simulated aqueous solutions. Bisorbent's ability was characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). Analysis with a Fourier Transform Infrared Spectrometer revealed that CIP biosorption occurred mainly at biomass sites containing carboxyl and amino groups. The equilibrium isotherm data and biosorption kinetics were addressed in the present study. The biosorption data match the Langmuir isotherm model, and the maximal biosorption capacity was determined to be 7.56 mg/g. While The pseudo-second-order model accurately described the biosorption kinetic data. Biosorbent regeneration was also studied using two different sodium hydroxide concentrations, the results showing that after desorption, the biosorption capacity decreased from 5.2 to 3.74 and 1.77 (mg/g) using 0.1NaOH and 0.5NaOH, respectively.

Purification of Galacto-oligosaccharide (GOS) by fermentation with Kluyveromyces lactis and Interaction between GOS and casein under simulated acidic fermentation conditions.

In the enzymatic synthesis of galacto-oligosaccharide (GOS), the primary by-products include glucose, galactose and unreacted lactose. This This study was aimed to provide a method to to purify GOS by yeat fermentation and explore the interaction between GOS and CAS with a view for expanding the prospects of GOS application in the food industry. The crude GOS(25.70g/L) was purified in this study using the fermentation method with Kluyveromyces lactis CICC 1773. Optimal conditions for purification with the yeast were 75g/L of the yeast inoculation rate and 50g/L of the initial crude GOS concentration for 12h of incubation. After removing ethanol produced by yeast by low-temperature distillation, GOS content could reach 90.17%. A study of the interaction between GOS and casein (CAS) in a simulated acidic fermentation system by D-(+)-gluconic acid δ-lactone (GDL) showed that the GOS/CAS complexes with higher GOS concentrations, e.g., 4% and 6% (w/v), was more viscoelastic with higher water-holding capacity, but decreased hardness, elasticity, and cohesiveness at 6% (w/v) of GOS. The addition of GOS to CAS suspension significantly caused (p<0.05) decreased particle sizes of the formed GOS/CAS complexes, and the suspension system became more stable. FT-IR spectra confirmed the existence of different forms of molecular interactions between CAS and GOS, e.g., hydrogen bonding and hydrophobic interaction, and the change of secondary structure after CAS binding to GOS.

Application of liquid chromatography quadrupole time-of-flight mass spectrometry for the elucidation of fenamiphos photodegradation by-products

The degradation of the insecticide fenamiphos was undertaken by using a homogeneous photocatalysis employing iron (III) aqua complex, [Fe(H2O)5(OH)]2+. The irradiation was studied by excitation at 365 nm and the generated primary by-products were elucidated by Liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry in the positive ion mode, that leads to the formation of the protonated forms of the studied compounds, [M + H+]. Collision-induced dissociation tandem mass spectrometry (CID-MS/MS) of the protonated molecules was carried out, and the effect of the collision energy as well as the elemental compositions of the product ions were used in order to propose the chemical structures. The primary processes were then i) hydroxylation on the aromatic ring; ii) the loss of propene from the aminoisopropyl chain and iii) the loss of the methylene at the ethoxy moiety.

A Review of Environmental Impact of Azo Dyes

Green plants are one of nature’s factories, fixing inorganic chemicals into organic compounds through photosynthesis and other reactions. Microbes are one of the nature’s most effective tools, converting organic materials—dead plants and animals—into inorganic forms through decomposition and mineralization. Together, green plants and microbes are responsible for maintaining a balance between the organic and inorganic worlds, but pollutants, such as synthetic dyes, can upset this balance. Compared with synthetic dyes, natural dyes are safer and more environmentally friendly, but they are also costlier and more difficult to apply, so they are not viable in most commercial applications. Azo dyes are low cost and have high intensity and color fastness, so they are the most frequently used class of synthetic dyes. The main threats related to the dumping of untreated azo dyes into the environment come from their primary byproducts––aromatic amines––which result from the cleavage of the central azo bonds, and which have been classified as significant carcinogenic compounds, representing a great risk to humans as well as the environment. To address this threat, the degradation of synthetic azo dyes is showing promise as an approach to treating azo-dye wastewater. In this review, the classification of azo dyes and their color mechanism is presented first, and then an overview of the research on their environmental impacts is provided, including their effects on biochemical and chemical oxygen demand, water ecosystems, plants, and crops. Finally, the legislation and guidelines on azo dyes and their byproducts are discussed. Keywords: azo dyes; climate change; biochemical oxygen demand; chemical oxygen demand; aromatic amines

Electric arc furnace slag as aggregates in semi-dense asphalt

Electric Arc Furnace Slag (EAFS) is one of the primary by-products of the steel recycling industry, which comes out initially as large pieces, that can be further crushed and be used as aggregates in infrastructure materials. While being a waste product, the relatively high strength of the aggregates means that EAFS can provide favorable properties when used correctly. One possible destination for EAFS of higher value is semi-dense asphalt (SDA), a surface course used as low-noise pavement. Due to the relatively high percentage of air voids in SDA (10–18%), the mixture mechanical properties depend on strong interlocking of the aggregates. This study looks at the incorporation of EAFS fractions (2/4 and 0.125/2 mm) into SDA 4 mixtures at replacement of 13% by volume of the aggregates. These mixtures are compared to the control mixture with sandstone aggregates in terms of volumetrics, water sensitivity, stiffness modulus and fatigue by cyclic indirect tensile loading, along with permanent deformation by the cyclic compression test. The water sensitivity, rheological properties and fatigue resistance of the EAFS mixtures did not vary significantly from the control. The life cycles assessment (LCA) shows that compared to the reference SDA, the EAFS-modified SDA reduces the greenhouse gas emissions and ecological scarcity eco-points by 40% and 90%, respectively due to the avoidance of EAFS landfilling. However, the non-renewable cumulative energy demand is not improved by using EAFS in SDA, due to the additional consumption of bitumen.

Solar photoelectro-Fenton-like process with anodically-generated HClO in a flow reactor: Norfloxacin as a pollutant with a particular structure

The degradation and mineralization of the drug norfloxacin (NFX) has been assessed in a model solution, containing 15 mM NaCl +45 mM Na2SO4 at pH 3.0, using a flow plant with an FM01-LC filter-press reactor equipped with a Ti|Ir-Sn-Ru oxides anode to electrogenerate HClO from Cl− oxidation and a stainless-steel cathode. Unexpectedly, anodic oxidation with active chlorine (AO-HClO) outperformed electro-Fenton (EF-HClO), photoelectro-Fenton (PEF-HClO) and solar photoelectro-Fenton (SPEF-HClO) due to: (i) the formation of refractory complexes between iron ions and carboxyl group of NFX, and (ii) the conversion of HClO into less effective •OH upon its Fenton-like reaction with added Fe2+ catalyst. SPEF-HClO was superior among Fenton-based treatments because the •OH concentration was largely increased by the photolysis of Fe(III) species. At an initial NFX concentration in the range 0.103–0.146 mM, the optimum conditions for SPEF-HClO were 0.40 mM Fe2+ and 15 mA cm−2. A BDD anode allowed a higher production of •OH, accelerating the degradation and mineralization, with similar energy requirements as compared to trials with Ti|Ir-Sn-Ru oxides anode. The SPEF-HClO process in urban wastewater was less powerful because of the parallel oxidation of natural organic matter. HClO, Fe2+ and Fetotal were quantified in both water matrices. The initial degradation sequence for NFX, proposed from 10 primary by-products identified by LC-MS/MS, revealed the occurrence of hydroxylation, chlorination and defluorination steps. Additionally, 5 stable by-products were detected by GC–MS.

The photocatalytic degradation of naproxen with g-C3N4 and visible light: Identification of primary by-products and mechanism in tap water and ultrapure water

Differences in the photocatalytic degradation rates of naproxen (a nonsteroidal anti-inflammatory drug) in ultrapure water and tap water were assessed using g-C3N4 nanosheets as photocatalyst and irradiating with natural sunlight and low-power (4 × 10 W) white light LEDs. The graphitic carbon nitride (g-C3N4) photocatalyst was synthesised and characterised. All the photodegradations followed pseudo-first-order kinetics. Liquid chromatography with tandem mass spectrometry (UPLC-QToF-MS) was used to identify the intermediates generated in the degradation of naproxen by accurate mass and MS/MS data. Among the by-products detected, 2-(naphthalene-2-yl)propanal, a compound with structural warning for genotoxic carcinogenicity, has been reported for the first time. This persistent by-product was completely depleted with g-C3N4 and natural sunlight in 50–70 min. According to the kinetics of by-products and spectrometry data a plausible transformation pathway has been proposed. Furthermore, the main active species involved in the photodegradation with g-C3N4 were study to fully understand the process. To accomplish this goal, different scavengers were introduced in the degradation of naproxen to quench possible superoxide radicals (·O2−), photoexcited holes (h+) and hydroxyl radicals (·OH).

Characterization of enoxacin (ENO) during ClO2 disinfection in water distribution system: Kinetics, byproducts, toxicity evaluation and halogenated disinfection byproducts (DBPs) formation potential

Enoxacin (ENO) is widespread in water because it is commonly used as a human and veterinary antibiotic. However, little effort has been dedicated to revealing the transformation mechanisms of ENO destruction using ClO2, especially within a water distribution system (WDS). To address this knowledge gap, the kinetics, byproducts, toxicity, and formation potential of halogenated disinfection byproducts (DBPs) associated with ENO destruction using ClO2 in a pilot-scale PE pipe was explored for the first time. Statistical analyses showed that the destruction efficiency of ENO in the pilot-scale PE pipe was lower than that in deionized water (DI water), and the reactions in DI water followed the second-order kinetic model. Furthermore, pH has a significant effect on the destruction of ENO, and the removal ratio increased at a higher pH. Additionally, increasing the flow rate elevated the ENO removal efficiency; however, the influence of flow velocity was limited to ENO destruction. The ENO removal rates within the diverse pipes exhibited the following order: stainless steel pipe < PE pipe < ductile iron pipe. Nine possible intermediates were identified, and those that were formed by piperazine group cleavage represented the major primary byproducts of the entire destruction process. Additionally, the ENO destruction in a pilot-scale PE pipe had minimal influence on halogenated DBPs and chlorite formation. Finally, the toxicity evaluation illustrated that the presence of ENO increased the potential risk of water quality safety when treated with ClO2.

Effects of protein oxidation induced by rice bran rancidity on the structure and functionality of rice bran glutelin

Rice bran is the primary by-products of rice milling, and presents high nutritional values. However, the unavoidable occurrence of rice bran rancidity will cause protein oxidation, and impact the protein structure and functionality. The aim of this study is to evaluate the changes in oxidation parameters, structure and functionality of rice bran glutelin during rice bran rancidity. The results indicated the prolongation of rice bran storage time caused the formation of carbonyl groups (from 2.31 to 19.50 nmol/mg) and the loss of sulfhydryl groups (free sulfhydryl groups from 7.66 to 2.16 nmol/mg, and total sulfhydryl groups from 54.88 to 38.76 nmol/mg). The increasing storage time also strengthened the aggregation and cross-linking of rice bran glutelin. The FT-IR spectra implied rice bran rancidity led glutelin to form more complex secondary structure. As rice bran was stored for 1 day, the solubility, water holding capacity, emulsion stability and foam stability raised, and then decreased with the storage time further prolonged. The correlation analysis showed the oxidation parameters, the α-helix/β-sheet ratio and surface hydrophobicity were significantly correlated to the functionality of rice bran glutelin.

A benzimidazole-based new fluorogenic differential/sequential chemosensor for Cu2+, Zn2+, CN-, P2O74-, DNA, its live-cell imaging and pyrosequencing applications

A benzimidazole–based chemosensor ( DFB) for Cu 2+ and Zn 2+ was developed, and its sequential anions (CN − and P 2 O 7 4- ) and DNA sensing capability and its live-cell imaging, as well as its PPi detection in PCR-amplified DNA products, has been demonstrated. • A benzimidazole-based chemosensor ( DFB ) shows “ off-on ” responses upon differential detection of Cu 2+ and Zn 2+ . • The DFB derived Cu 2+ & Zn 2+ complexes act as efficient sensors toward CN − , PPi and DNA in an aqueous medium. • DFB acts as a sequential fluorescent probe to detect Cu 2+ , Zn 2+ and PPi in living cancer cells. • DFB-Zn 2 + can detect the PPi in the PCR amplified DNA products. Differential chemosensors have emerged as next-generation systems due to their simplicity and favourable responsive properties to produce different signals upon selective binding of various analytes simultaneously. Nevertheless, given their inadequate fluorescence response and laborious synthetic procedures, only a few differential chemosensors have been developed so far. In this work, we have employed a single pot synthesis strategy to establish a new benzimidazole-based Schiff base type fluorogenic chemosensor ( DFB ) which differentially detects Cu 2+ (detection limit (LOD) = 24.4 ± 0.5 nM) and Zn 2+ (LOD = 2.18 ± 0.1 nM) through fluorescence “ off-on ” manner over the library of other metal cations in an aqueous medium. The DFB -derived ‘ in situ ’ complexes DFB-Cu 2+ and DFB-Zn 2+ showed fluorescence revival “ on-off ” responses toward cyanide (CN − ) and bio-relevant pyrophosphate (P 2 O 7 4- -PPi) ions with a significantly low LOD of 9.43 ± 0.2 and 2.9 ± 0.1 nM, respectively, in water. We have demonstrated the phosphate group-specific binding capability of DFB-Zn 2+ , by testing it with both ssDNA and dsDNA samples which displayed fluorescence “ turn-off ” response (LOD ∼10 -7 M), similar to the PPi binding in an aqueous medium, indicating that it interacts explicitly with the phosphate backbone of DNA. We have also harnessed the DFB as a sequential fluorescent probe to detect Cu 2+ , Zn 2+ , CN − and P 2 O 7 4- ions in human cervical (HeLa) and breast (MCF-7 and MDA-MB-231 (aggressive and invasive)) cancer cell lines. Moreover, we have explored the PPi recognition capability of DFB-Zn 2+ in the polymerase-chain-reaction (PCR) products where PPi is one of the primary by-products during amplification of DNA.

Selective Production of Xylooligosaccharides by Xylan Hydrolysis Using a Novel Recyclable and Separable Furoic Acid.

Xylooligosaccharides (XOS) have gained considerable attention worldwide as prebiotics due to their immune-strengthening activity and beneficial gut bacteria development and can be produced from xylan-rich resources by acid hydrolysis. The present study proved the organic acid hydrolysis to be beneficial for XOS yield. In this study, a recyclable and separable organic acid, i.e., furoic acid, was used for hydrolyzing xylan to produce XOS, and the response surface methodology design was applied to maximize the XOS yield; the results indicated that the quadratic model terms of the interaction between reaction temperature and hydrolysis time showed the most significant impact on XOS yields (P < 0.05). The predicted maximum yield of XOS was 49.0% with 1.2% furoic acid at 167°C for 33 min, being close to the experimental value (49.2%), indicating that the fitted models were in good agreement with the experimental results. Meanwhile, the primary byproducts, including xylose and furfural, were concurrently bio-oxidized into xylonic acid and furoic acid by Gluconobacter oxydans and separated by electrodialysis. Subsequently, the furoic acid with low solubility (<3.7%, 25°C) was recovered by natural crystallization. The above results indicate that the use of multi-steps contributes to sustainable XOS production by furoic acid.

Production of Cyanide Using Thermal Plasma: Thermodynamic Analysis and Process-Specific Energy Consumption

A plasma process for making cyanide from nitrogen and hydrocarbon (methane and propane) has been successfully demonstrated, which can directly fix atmospheric nitrogen into hydrocarbons. Nitrogen serves as both the plasma gas and the primary reactant. The thermodynamic analysis as well as the experimental outcome indicates that it is feasible to achieve very high conversion of hydrocarbons into cyanide by increasing the partial pressure of nitrogen gas within the reaction mixture, but the high conversion comes at a cost of an increase in total energy consumption and was detrimental to process energy efficiency. Hence, the process was optimized based on specific energy consumption (SEC) instead of conversion. The conversion with respect to nitrogen and hydrocarbon ratio follows thermodynamic prediction. The primary byproducts obtained were hydrogen, acetylene, and soot. The laboratory system was stable and could be run for extended periods, achieving a minimal SEC of approximately 15.5 kW h/kg NaCN.