A ratiometric fluorescent probe based on UiO-66-TCPP for selective and visual detection of quercetin in food.

Quercetin (QCT) is a flavonoid with significant health benefits, necessitating sensitive detection methods for food safety and quality control. This study presents a novel UiO-66-TCPP ratiometric fluorescent probe for the quantitative and visual detection of QCT. Under optimal conditions, the fluorescence intensity of UiO-66-TCPP decreased linearly with increasing QCT concentration, with a detection limit of 26 nM. The probe demonstrated high specificity, showing no significant interference from various substances and QCT analogues. Practical applicability was confirmed by testing artificially contaminated juice samples, achieving recovery rates between 98.0% and 104.8%. Furthermore, a paper-based sensor was developed by incorporating UiO-66-TCPP onto Whatman#1 chromatography paper. This sensor exhibited stable fluorescence and a reliable, sensitive visual response to QCT concentrations, detectable via a smartphone-based color recognizer application. The UiO-66-TCPP ratiometric fluorescent probe provides a sensitive, specific, and practical method for detecting QCT in food matrices, offering significant potential for both laboratory and on-site applications.

Sustainable chitosan-based materials as heterogeneous catalyst for application in wastewater treatment and water purification: An up-to-date review.

Water pollution is one of serious environmental issues due to the rapid development of industrial and agricultural sectors, and clean water resources have been receiving increasing attention. Recently, more and more studies have witnessed significant development of catalysts (metal oxides, metal sulfides, metal-organic frameworks, zero-valent metal, etc.) for wastewater treatment and water purification. Sustainable and clean catalysts immobilized into chitosan-based materials (Cat@CSbMs) are considered one of the most appealing subclasses of functional materials due to their high catalytic activity, high adsorption capacities, non-toxicity and relative stability. This review provides a summary of various upgrading renewable Cat@CSbMs (such as cocatalyst, photocatalyst, and Fenton-like reagent, etc.). As for engineering applications, further researches of Cat@CSbMs should focus on treating complex wastewater containing both heavy metals and organic pollutants, as well as developing continuous flow treatment methods for industrial wastewater using Cat@CSbMs. In conclusion, this review abridges the gap between different approaches for upgrading renewable and clean Cat@CSbMs and their future applications. This will contribute to the development of cleaner and sustainable Cat@CSbMs for wastewater treatment and water purification.

A review on chitosan/metal oxide nanocomposites for applications in environmental remediation.

A cleaner and safer environment is one of the most important requirements in the future. It has become increasingly urgent and important to fabricate novel environmentally-friendly materials to remove various hazardous pollutants. Compared with traditional materials, chitosan is a more environmentally friendly material due to its abundance, biocompatibility, biodegradability, film-forming ability and hydrophilicity. As an abundant of -NH2 and -OH groups on chitosan molecular chain could chelate with all kinds of metal ions efficiently, chitosan-based materials hold great potential as a versatile supporting matrix for metal oxide nanomaterials (MONMs) (TiO2, ZnO, SnO2, Fe3O4, etc.). Recently, many chitosan/metal oxide nanomaterials (CS/MONMs) have been reported as adsorbents, photocatalysts, heterogeneous Fenton-like agents, and sensors for potential and practical applications in environmental remediation and monitoring. This review analyzed and summarized the recent advances in CS/MONMs composites, which will provide plentiful and meaningful information on the preparation and application of CS/MONMs composites for wastewater treatment and help researchers to better understand the potential of CS/MONMs composites for environmental remediation and monitoring. In addition, the challenges of CS/MONM have been proposed.

Microplastics in terrestrial insects, long-horned beetles (Coleoptera: Cerambycidae), from China.

Despite studies have proposed that microplastics (MPs) could exert adverse effects on terrestrial ecosystems and biota, the occurrence of MPs in wild terrestrial insects has been rarely investigated. This study examined MPs in 261 long-horned beetle (Coleoptera: Cerambycidae) samples collected from four different Chinese cities. Detection frequency of MPs in long-horned beetles from different cities was 68-88 %. Long-horned beetles from Hangzhou (4.0 items/individual) had the highest mean abundance of MPs, followed by that from Wuhan (2.9 items/individual), Kunming (2.5 items/individual), and Chengdu (2.3 items/individual). The mean size of MPs in long-horned beetles from four Chinese cities was 381-690 µm. Fiber consistently represented the major shape of MPs in long-horned beetles from different Chinese cities, contributing 60, 54, 50, and 49 % of total items of MPs in Kunming, Chengdu, Hangzhou, and Wuhan, respectively. Polypropylene was the major polymer composition of MPs in long-horned beetles from Chengdu (68 % of total items of MPs) and Kunming (40 %). However, polyethylene and polyester were the major types of polymer compositions of MPs in long-horned beetles from Wuhan (39 % of total MP items) and Hangzhou (56 %), respectively. To our knowledge, this is the first study investigating the occurrence of MPs in wild terrestrial insects. These data are important for evaluating the risks of exposure to MPs for long-horned beetles.

Adsorptive removal of anionic azo dye by Al3+-modified magnetic biochar obtained from low pyrolysis temperatures of chitosan.

Magnetic γ-Fe2O3/Al3+@chitosan-derived biochar (m-Fe2O3/Al3+@CB) was prepared by introducing magnetic maghemite (γ-Fe2O3) nanoparticles and aluminum sulfate [Al2(SO4)3] into chitosan-derived biochar (CB) obtained at low pyrolysis temperatures. m-Fe2O3/Al3+@CB was used to remove typical anionic azo dye (Congo red, CR). Effects of initial CR concentration, contact time, initial pH value, background electrolytes, and temperature on CR adsorption by m-Fe2O3/Al3+@CB were studied. Compared with magnetic chitosan-derived biochar (m-Fe2O3@CB), m-Fe2O3/Al3+@CB exhibited excellent performance for a wider range of pH values (pH 1-7) and in the presence of background electrolyte. The introduction of Al3+ is an effective method for improving the properties of magnetic chitosan-derived biochar. High CR adsorption capacity (636.94 mg g-1) of m-Fe2O3/Al3+@CB could result from collaborative effect of flocculation/coagulation and electrostatic attraction. These results demonstrated that m-Fe2O3/Al3+@CB is a potential adsorbent for effective removal of organic dyes from aqueous solution due to its high adsorption capacity and convenient magnetic recovery and stronger anti-interference ability against coexisting anions in wastewater.

Magnetic Fe3O4 embedded chitosan-crosslinked-polyacrylamide composites with enhanced removal of food dye: Characterization, adsorption and mechanism.

The water solubility in acid solution, relative low adsorption capacities and unsatisfactory separation performance limit application of traditional chitosan-based adsorbents in wastewater treatment. To break the limitation, a hydrophilic magnetic Fe3O4 embedded chitosan-crosslinked-polyacrylamide composites (abbreviated as m-CS-c-PAM) were prepared by a two-step method. The m-CS-c-PAM composites were systematically characterized using SEM, XRD, FTIR, VSM, TGA and BET. Sunset yellow (SY) was selected as model food dye to investigate adsorption kinetics and thermodynamic parameters of food dye adsorption onto m-CS-c-PAM. Compared with magnetic Fe3O4/chitosan, m-CS-c-PAM can adapt to a wider range of pH (2-10) and resist the presence of inorganic salts. m-CS-c-PAM was proved to have high adsorption capacity (359.71 mg g-1) for SY dye at 298 K, much higher than magnetic Fe3O4/chitosan and many reported adsorbents. Moreover, m-CS-c-PAM could be rapidly and efficiently separated from treated solution within 15 s by an external magnet and regenerated by NaOH solution. With its excellent adsorption capacity, pH-independent adsorption capability for food dye, easy and convenient separation ability, satisfactory reusability, m-CS-c-PAM can be a promising material for food wastewater treatment.

Enhanced Antimicrobial Cellulose/Chitosan/ZnO Biodegradable Composite Membrane.

In this study, chitosan and sugarcane cellulose were used as film-forming materials, while the inorganic agent zinc oxide (ZnO) and natural compound phenyllactic acid (PA) were used as the main bacteriostatic components to fabricate biodegradable antimicrobial composite membranes. The water absorption and antimicrobial properties were investigated by adjusting the concentration of PA. The scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) results demonstrated that the components of the composite membrane were successfully integrated. The addition of ZnO improved the mechanical and antimicrobial properties of the composite membrane, while the addition of PA with high crystallinity significantly reduced the water absorption and swelling. Moreover, the addition of 0.5% PA greatly improved the water absorption of the composite membrane. The results of antimicrobial experiments showed that PA improved the antimicrobial activity of the composite membrane against Staphylococcus aureus, Escherichia coli, Aspergillus niger and Penicillium rubens. Among them, 0.3% PA had the best antimicrobial effect against S. aureus, E. coli and A. niger, while 0.7% PA had the best antimicrobial effect against P. rubens.

Colloidal CdS sensitized nano-ZnO/chitosan hydrogel with fast and efficient photocatalytic removal of congo red under solar light irradiation.

Colloidal CdS sensitized nano-ZnO/chitosan (CdS@n-ZnO/CS) hydrogel was prepared and characterized extensively by XRD, SEM-EDS, TEM, UV-Vis DRS, FT-IR and TGA. The photocatalytic activity of CdS@n-ZnO/CS was evaluated with the photodegradation of congo red (CR) as an organic pollutant under solar light irradiation. The influences of initial dye concentration, catalyst dosage, recycling runs, and radical scavenger on decolorization of CR by CdS@n-ZnO/CS were investigated. 95% of CR was removed in just 1 min for 5.0 mg L-1 and 94.34% of CR was removed in 30 min for 100 mg L-1. CdS@n-ZnO/CS exhibited an excellent and ultra-fast performance toward CR removal under solar light due to the synergistic effect of adsorption by chitosan and photocatalysis by ZnO and CdS in CdS@n-ZnO/CS hydrogel. Radical trapping control experiments indicated that h+ and O2- played the major role for CR decolorization. The high performance of CdS@n-ZnO/CS hydrogel was also demonstrated under natural solar light irradiation, suggesting that CdS@n-ZnO/CS hydrogel could be used in practical wastewater treatment.

Magnetic NiFe2O4/MWCNTs functionalized cellulose bioadsorbent with enhanced adsorption property and rapid separation.

Magnetic NiFe2O4 nanoparticles and multi-walled carbon nanotubes functionalized cellulose composite (m-NiFe2O4/MWCNTs@cellulose) as a magnetic bioadsorbent was prepared and used for effectively removing Congo Red (CR) from aqueous solution. The chemical and physical properties of the prepared m-NiFe2O4/MWCNTs@cellulose were characterized by XRD, TGA, FT-IR, VSM, SEM and TEM. Batch experiments were carried out to investigate the adsorption capacity and mechanisms. Effects of different adsorption parameters such as initial CR concentration, adsorbent dosage and temperature were studied. Results demonstrated that m-NiFe2O4/MWCNTs@cellulose had high adsorption capacity for CR from aqueous solution. The obtained experimental data fitted well with the pseudo-second-order equation and followed the Langmuir isotherm model with a maximum adsorption capacity of 95.70 mg g-1 for CR. The m-NiFe2O4/MWCNTs@cellulose with rapid magnetic separation and high adsorption capacity can be a promising and recyclable engineering biomaterials for purification and treatment of practical wastewater.

An optimized fed-batch culture strategy integrated with a one-step fermentation improves L-lactic acid production by Rhizopus oryzae.

In previous work, we proposed a novel modified one-step fermentation fed-batch strategy to efficiently generate L-lactic acid (L-LA) using Rhizopus oryzae. In this study, to further enhance efficiency of L-LA production through one-step fermentation in fed-batch cultures, we systematically investigated the initial peptone- and glucose-feeding approaches, including different initial peptone and glucose concentrations and maintained residual glucose levels. Based on the results of this study, culturing R. oryzae with initial peptone and glucose concentrations of 3.0 and 50.0 g/l, respectively, using a fed-batch strategy is an effective approach of producing L-LA through one-step fermentation. Changing the residual glucose had no obvious effect on the generation of L-LA. We determined the maximum LA production and productivity to be 162 g/l and 6.23 g/(l·h), respectively, during the acid production stage. Compared to our previous work, there was almost no change in L-LA production or yield; however, the productivity of L-LA increased by 14.3%.

Migration of nitrate, nitrite, and ammonia through the municipal solid waste incinerator bottom ash layer in the simulated landfill.

Simulated landfill was operated for 508 days to investigate the effect of municipal solid waste incinerator (MSWI) bottom ash layer on the migration of nitrate, nitrite, and ammonia when it was used as the intermediate layer in the landfill. The result suggested that the MSWI bottom ash layer could capture the nitrate, nitrite, and ammonia from the leachate. The adsorption of the nitrate, nitrite, and ammonia on the MSWI bottom ash layer was saturated at the days 396, 34, and 97, respectively. Afterwards, the nitrogen species were desorbed from the MSWI bottom ash layer. Finally, the adsorption and desorption could reach the equilibrium. The amounts of adsorbed nitrate and nitrite on the MSWI bottom ash layer were 1685.09 and 7.48 mg, respectively, and the amount of the adsorbed and transformed ammonia was 13,773.19 mg, which was much higher than the desorbed. The water leaching test and synthetic precipitation leaching procedure (SPLP) results showed that the leachable nitrate, nitrite, and ammonia in the MSWI bottom ash were greatly increased after the landfill operation, suggesting that the adsorbed nitrogen could be finally leached out. Besides, the results also showed that MSWI bottom ash layer could affect the release of nitrate and ammonia at the initial stage of the landfill. However, it had little effect on the release of nitrite.

High-efficiency l-lactic acid production by Rhizopus oryzae using a novel modified one-step fermentation strategy.

In this study, lactic acid fermentation by Rhizopus oryzae was investigated using the two different fermentation strategies of one-step fermentation (OSF) and conventional fermentation (CF). Compared to CF, OSF reduced the demurrage of the production process and increased the production of lactic acid. However, the qp was significantly lower than during CF. Based on analysis of µ, qs and qp, a novel modified OSF strategy was proposed. This strategy aimed to achieve a high final concentration of lactic acid, and a high qp by R. oryzae. In this strategy, the maximum lactic acid concentration and productivity of the lactic acid production stage reached 158g/l and 5.45g/(lh), which were 177% and 366% higher, respectively, than the best results from CF. Importantly, the qp and yield did not decrease. This strategy is a convenient and economical method for l-lactic acid fermentation by R. oryzae.

Effects of the addition of iron and aluminum salt on phosphorus adsorption in wetland sediment.

Adsorption and removal of phosphorus (P) in wetland sediment from aqueous solutions were investigated by using four kinds of iron (Fe) and aluminum (Al) salt (FeCl3, AlCl3, poly FeCl3, and poly AlCl3). Under optimal temperature of 25 °C, P concentration of 50 mg/L, and mole concentration ratio of 4:1 (Fe(3+)/PO4 (3-) or Al(3+)/PO4 (3-)), the P sorption capacities of wetland sediments by FeCl3, poly FeCl3, AlCl3, and poly AlCl3treatments were 296.03, 371.41, 276.3, and 357.85 µg/g, respectively, and were enhanced by 83.36, 158.74, 63.63, and 145.18 µg/g, respectively. The P sorption capacities based on different additives were in the order of poly FeCl3 > poly AlCl3 > FeCl3 > AlCl3. The EPC0 values, K values, and maximum adsorption capacities indicated that poly FeCl3 was good reagent to restore P pollution in aqueous solution by wetland sediment in the consideration of both P treatment efficiency and potential environmental impact. These findings, obviously, are useful basis to develop new effective methods for P removal in waters.

Retention and leaching of nitrite by municipal solid waste incinerator bottom ash under the landfill circumstance.

The retention and leaching of nitrite by municipal solid waste incinerator (MSWI) bottom ash could affect its migration in the landfill. In this study, the effect of the dosage of MSWI bottom ash as well as the variation of the landfill environmental parameters including pH, anions and organic matter on the nitrite retention and leaching behavior was investigated by batch experiments. The highest removal percentage (73.0%) of nitrite was observed when the dosage of MSWI bottom ash was 10 g L(-1) in 2 mg L(-1) nitrite solution. Further increase of the dosage would retard the retention, as the nitrite leaching from MSWI bottom ash was enhanced. The optimum retention of nitrite was observed when the pH was 5.0, while the leaching of nitrite showed a consistent reduction with the increase of pH. Besides, the presence of Cl(-), SO4(2)(-) and acetic acid could enhance the leaching of nitrite and mitigate the retention process. However, the retention of nitrite was enhanced by PO4(3)(-), which was probably due to the formation of the apatite, an active material for the adsorption of the nitrite. These results suggested that MSWI bottom ash could affect the migration of nitrite in the landfill, which was related to the variation of the landfill circumstance.

Effects of pellet characteristics on L-lactic acid fermentation by R. oryzae: pellet morphology, diameter, density, and interior structure.

The effects of pellet morphology, diameter, density, and interior structure on L-lactic acid fermentation by Rhizopus oryzae were characterized for different inoculum sizes and concentrations of peptone and CaCO3. Inoculum size was the most important factor determining pellet formation and diameter. The diameter decreased with increasing inoculum size, and larger pellets were observed for lower inoculum sizes. Peptone concentration had the greatest effect on pellet density, which increased with increasing peptone concentration. L-lactic acid production depended heavily on pellet density but not on pellet diameter. Low-density pellets formed easily under conditions of low peptone concentration and often had a relatively hollow structure, with a thin condensed layer surrounding the pellet and an extraordinarily loose biomass or hollow center. As expected, this structure greatly decreased production. The production of L-lactic acid increased until the density reached a certain level (50-60 kg/m(3)), in which the compact part was distributed homogeneously in the thick outer layer of the pellet and loose in the central layer. Homogeneously structured, denser pellets had limited mass transfer, causing a lower overall turnover rate. However, the interior structure remained nearly constant throughout all fermentation phases for pellets with the same density. CaCO3 concentration only had a slight influence on pellet diameter and density, probably because it increases spore germination and filamentous hypha extension. This work also provides a new analysis method to quantify the interior structure of pellets, thus giving insight into pellet structure and its relationship with productivity.

A novel magnetically separable gamma-Fe2O3/crosslinked chitosan adsorbent: preparation, characterization and adsorption application for removal of hazardous azo dye.

A novel magnetically separable adsorbent, namely magnetic gamma-Fe(2)O(3)/crosslinked chitosan composites (Mgamma-Fe(2)O(3)/CSCs), was prepared by microemulsion process and characterized by XRD, FT-IR, TGA, DSC, SEM and VSM. Adsorption of methyl orange (MO), used as a model pollutant, from aqueous solution on Mgamma-Fe(2)O(3)/CSCs was investigated. Characterization results indicated that magnetic gamma-Fe(2)O(3) nanoparticles have been introduced in Mgamma-Fe(2)O(3)/CSCs and kept intrinsic magnetic properties. The saturated magnetization (sigma(s)) of Mgamma-Fe(2)O(3)/CSCs can be expediently adjusted by changing additive dosage of gamma-Fe(2)O(3). Adsorption results showed that both nanocomposite adsorbents with weight ratio of gamma-Fe(2)O(3) to chitosan of 1:10 and 2:5 exhibited higher adsorption capacities and attained adsorption equilibria in shorter time compared with crosslinked chitosan. After adsorption, Mgamma-Fe(2)O(3)/CSCs were effectively separated from reaction solution in 10s by applying an adscititious magnetic field. Adsorption kinetics of MO on 1:10 Mgamma-Fe(2)O(3)/CSCs followed the pseudo-second-order kinetic model. Effects of both initial pH and adsorbent dosage on the adsorption of MO were remarkable in experimental conditions.

Photocatalytic decolorization and degradation of Congo Red on innovative crosslinked chitosan/nano-CdS composite catalyst under visible light irradiation.

The crosslinked chitosan/nano-CdS (CS/n-CdS) composite catalyst prepared by simulating bio-mineralization process was extensively characterized by FT-IR spectra, XRD, SEM, TEM and TGA. An azo dye, Congo Red (CR), was used as model pollutant to study its photocatalytic activity under visible light irradiation. The influences of catalyst amount, initial CR concentrations, pH of the reaction solution and different anions on CR decolorization and degradation reaction kinetics were investigated. Results of characterization indicated the successful formation of hexagonal phase of CdS on raw chitosan under mild conditions. The photocatalytic degradation was found to follow a pseudo-first-order kinetics according to Langmuir-Hinshelwood (L-H) model. The dye could be decolorized more efficiently in acidic media than alkaline media. The presence of NO(3)(-) accelerated evidently the degradation of CR, while the other chosen anions (Br(-), SO(4)(2-) and Cl(-)) had an inhibitory effect on the decolorization of CR, of which the inhibitory effect of Cl(-) was the most pronounced. UV-vis spectra were analyzed to indicate that degradation of CR in the solution was the break up of the NN bonds and degradation of aromatic fragment in this reaction system. The recycling experiments confirmed the relative stability of the catalyst.