High Alkaline Research Articles

Biochemical characterization of a recombinant laccase from Halalkalibacterium halodurans C-125 and its application in the biotransformation of organic compounds.

This study aimed to produce an engineered recombinant laccase from extremophilic Halalkalibacterium halodurans C-125 (Lac-HhC-125) with higher protein yield, into a more active conformation and with properties that meet the fundamental needs of biotechnological application. The rLac-HhC125 was partially purified by size exclusion chromatography and concentrated by ultrafiltration (10kDa) with a yield of 57.6%. Oxidation reactions showed that adding 2mM CuSO4 to the assay solution led to activating the laccase. To increase its initial activity, the rLac-HhC125 was treated at 50°C for 20min before the assays, improving its performance by fourfold using the syringaldazine as a substrate. When treated with EDTA, methanol, ethanol, and DMSO, the rLac-HhC125 maintained more than 80% of its original activity. Interestingly, the acetonitrile induced a twofold activity of the rLac-HhC125. The putative rLac-HhC125 demonstrated a capability of efficient transformation of different organic compounds at pH 6, known as dye precursors, into coloured molecules. The rLac-HhC125 was active at high temperatures and alkaline pH, exhibited tolerance to organic solvents, and efficiently transformed different hydroxy derivatives into coloured compounds, which indicates that it can be used in various biotechnological processes.

Chemical Constituents from the Whole Plants of Limonium sinense and Their in vitro Anti-inflammatory Activity.

The Yellow River Delta possesses lots of characteristic medicinal plants due to its high salinity and high alkaline environment and Limonium sinense is an iconic plant. However, there are very few studies on L. sinense and its chemical constituents have not been investigated in recent ten years. In the present study, the chemical constituents and bioactivities of L. sinense were fully studied for the first time. UPLC-MS/MS method combined with database comparison identified 109 compounds mainly including flavonoids, alkaloids and polyphenols. In addition, the potential bioactivities of L. sinense were considerated as anti-inflammatory, anti-oxidative, anti-tumor, hepatoprotective and hpyerglycemic activities based on these identified compounds and their related literature. Furthermore, four derivatives of 12-oxo-phytodienoic acid and butenolide including two new ones (1 and 2) were isolated from the whole plants of L. sinense. Their structures, including the absolute configurations, were determined by the analysis of comprehensive spectroscopic data. All isolates were evaluated for their anti-inflammatory activity. Compound 1 exhibited moderate anti-inflammatory activity with IC50 value of 37.5±1.2 μM on NO production level.

Release Behavior of Pb(II) Ions on the Galena Surface: Dissolution Experiment, DFT Calculation, and MD Simulation

In this study, the release behavior of Pb(II) ions from the galena surface and their occurrence forms in the migration process under acid and alkaline conditions were investigated by dissolution experiment, the density functional theory (DFT) calculation, and molecular dynamics (MD) simulation. The dissolution experiments indicated that acidic and high alkaline conditions are more beneficial for the release of Pb(II) rather than neutral and weak alkaline conditions. The quantum chemical calculations indicated that under acidic conditions, H+ can destroy the surface structure of galena, leading to the dissolution of Pb2+ from the mineral surface into the liquid phase. OH− can also damage the galena surface to a certain extent under alkaline conditions. Additionally, MD simulations were further utilized to study the occurrence forms of Pb(II) ions in alkaline solutions. The results suggested that with a certain concentration of OH−, Pb2+ ions will form lead hydroxide aggregates, while excessive OH− could lead to the dispersion and dissolution of the lead hydroxo complexes. The surface morphological observation by SEM can well support the calculation and simulation results.

Nanobubble Formation and Coverage during High Current Density Alkaline Water Electrolysis.

Gas bubbles are a necessary byproduct of water electrolysis whereby hydrogen and oxygen are produced from water. These attached gases reduce the electrode's active area, which necessitates a deep understanding of the bubble life cycle starting from nanobubbles. Synchronized with the electrochemistry, the time evolution of the surface nanobubble size and coverage is resolved using grazing incidence small-angle X-ray scattering (GISAXS) and correlated with optical microscopy and theoretical calculations to show that a significant portion of the surface is covered in nanobubbles after larger micron-sized bubbles are observed. These nanobubbles increase in number and decrease in size, toward 2 nm diameter, with the charge passed. The trend in size and number is consistent with an increase in supersaturation, which reduces the nascent bubble size. Altogether, this study suggests a significant portion of the surface contains nanobubbles and that strategies to reduce the dissolved hydrogen would be effective at reducing the nanobubble surface coverage.

Hyperbranched anionic surfactant with superwettability and high alkaline resistance from isobutene upgrading

Isobutene, a byproduct of the crude oil catalytic cracking process, is recognized as an attractive feedstock for producing value-added chemicals. Surfactants, conventionally composed of a hydrophobic tail and a hydrophilic head, constitute an indispensable class of versatile consumer chemicals. To date, there have been no effective pathways for upgrading of isobutene to valuable surfactants. In this contribution, we firstly reported a novel hyperbranched anionic surfactant, IB4SO3Na, which not only showed superwettability on various solid surfaces (contact angle < 30°), but also rapidly penetrated textile surfaces (< 0.6 s) and exhibited superior alkaline resistance (aqueous solutions at > 30 g∙L−1 NaOH), outperforming the commercial rapid penetration agent Aerosol-OT (AOT). The hedgehog-like hydrophobic tail, teraisobutylene (IB4), generated from the dimerization of diisobutylene (IB2), endowed the surfactant with superior defoaming properties. Remarkably, fine-tuning the reaction temperature permitted the synthesis of pure IB4 with excellent selectivity (up to 99 %) at − 40 °C, the proportion of which bearing terminal olefin moieties amounted to 61.0 %. In situ Raman spectroscopy revealed that cracking of IB4 can be effectively inhibited at low temperatures. This study provides a universal design strategy for the development of potential highly alkali-resistant penetrants produced from low-cost feedstocks.

Co-culture of rice and aquatic animals enhances soil organic carbon: A meta-analysis

Co-culture of rice (Oryza sativa) and aquatic animals (CRAAs) is an efficient eco-agricultural model and has been widely implemented in many Asia countries. However, its impact on soil organic carbon (SOC) content has not been synthesized and the relative effects of different CRAAs practices on SOC have not been assessed. Our meta-analysis aims to synthesize the effect of diverse CRAAs regimes on SOC content based on results from 200 field experiments. Our results showed that overall, CRAAs significantly increased SOC content by 11.6 % (P < 0.05). The highest relative effect on SOC content was found under the rice and amphibian coculture (P < 0.05). Also, CRAAs increased SOC content more significantly in temperate regions (19.1 %) than in subtropical (9.7 %) and tropical (12.1 %) regions (P < 0.05). In addition, CRAAs were more effective in enhancing SOC content in paddy soils with high nitrogen content (total nitrogen [TN] >1.2 g·N kg−1 soil) or alkaline soils. Further, SOC increased more in the CRAAs with japonica than indica rice, increasing 17.8 % and 6.1 % as compared to their respective rice-monoculture controls. Random forest analysis revealed that animal type was the most important factor influencing SOC under CRAAs. Together, these results indicate that CRAAs can significantly enhance SOC, particularly in low-N, alkaline paddy soils. Our findings suggest that CRAAs with appropriate rice and animal varieties can provide unique opportunities for soil C sequestration, while enhancing farmers' profitability.

An all solid waste CO2 sequestration material consist of multiple calcium silicate clinkers by carbide slag, copper tailing and red mud: Clinker crystal transformation and carbonation hardening properties

In this study, a CO2 sequestration material was obtained by all components solid wastes, i.e., carbide slag and copper tailing based on red mud (RM) as crystal regulator after a sintering and carbonation process. With the increasing dosage of RM, the mineral compositions of generated RM-modified clinkers were mainly γ-C2S (i.e., around 80 %) at low dosage RM (i.e., 3.0 %), and was gradually increased content of β-C2S (β-dicalcium silicate), C3S (tricalcium silicate) and C2AS (gehlenite) at high dosage RM (i.e., from 3.0 % to 10.0 %). Moreover, the compressive strength of various carbonated compacts made by RM-modified clinkers after CO2 curing were shows firstly increased and then decreased with a RM dosage inflection of 5.0 %. This compressive strength results should be attributed to their carbonation activity, i.e., higher carbonation activity, higher compressive strength. The obvious carbonation activity difference of various RM-modified clinkers were not simply depends on their only γ-C2S content, only β-C2S content, only C3S content or the sum of calcium silicate minerals, but more closely relate to their combined effect. This work provides a new utilization strategy of RM as crystal regulator according to its high alkaline and high Fe content composition characteristic for obtaining a CO2 sequestration materials. And also laid a new insight for a synergistic CO2 sequestration by multiple calcium silicate clinkers in the future.

High Efficiency Alkaline Iodine Batteries with Multi‐Electron Transfer Enabled by Bi/Bi2O3 Redox Mediator

The multi‐electron transfer I‐/IO3‐ redox couple is attractive for high energy aqueous batteries. Shifting from an acidic to an alkaline electrolyte significantly enhances the IO3‐ formation kinetics due to the spontaneous disproportionation reaction, while the alkaline environment also offers more favorable Zn anode compatibility. However, sluggish kinetics during the reduction of IO3‐ persists in both acidic and alkaline electrolytes, compromising the energy efficiency of this glorious redox couple. Here, we establish the fundamental redox mechanism of the I‐/IO3‐ couple in alkaline electrolytes for the first time and propose that Bi/Bi2O3 acts as a redox mediator (RM) to “catalyze” the reduction of IO3‐. This mediation significantly reduces the voltage gap between charge/discharge from 1.6 V to 1 V with improved conversion efficiency and rate capability. By pairing the Zn anode and the Bi/Bi2O3 RM cathode, the full battery with I‐/IO3‐ redox mechanism achieves high areal capacity of 12 mAh cm‐2 and stable operation at 5 mAh cm‐2 for over 400 cycles.

High Efficiency Alkaline Iodine Batteries with Multi-Electron Transfer Enabled by Bi/Bi2O3 Redox Mediator.

The multi-electron transfer I-/IO3- redox couple is attractive for high energy aqueous batteries. Shifting from an acidic to an alkaline electrolyte significantly enhances the IO3- formation kinetics due to the spontaneous disproportionation reaction, while the alkaline environment also offers more favorable Zn anode compatibility. However, sluggish kinetics during the reduction of IO3- persists in both acidic and alkaline electrolytes, compromising the energy efficiency of this glorious redox couple. Here, we establish the fundamental redox mechanism of the I-/IO3- couple in alkaline electrolytes for the first time and propose that Bi/Bi2O3 acts as a redox mediator (RM) to "catalyze" the reduction of IO3-. This mediation significantly reduces the voltage gap between charge/discharge from 1.6 V to 1 V with improved conversion efficiency and rate capability. By pairing the Zn anode and the Bi/Bi2O3 RM cathode, the full battery with I-/IO3- redox mechanism achieves high areal capacity of 12 mAh cm-2 and stable operation at 5 mAh cm-2 for over 400 cycles.

The effects of pH regulators on the flotation separation of sphalerite and dolomite and their interaction mechanism

pH regulators play a key role in mineral flotation. In the study, the effects of CaO, Na2CO3 and NaOH on the flotation separation of sphalerite and dolomite were investigated, and the interaction mechanisms were analyzed by flotation tests of mixed minerals, scanning electron microscope (SEM) and energy dispersion spectrum (EDS), turbidity, Zeta potential and the extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) theory. The results indicated that Na2CO3 was favorable for flotation separation of sphalerite and dolomite, but NaOH had a negligible effect. CaO improved the flotation recovery of MgO to a maximum value of 9.29%, but it was unfavorable to the enriched sphalerite. SEM-EDS results revealed that dolomite was adsorbed on the sphalerite surface in the three systems, but the amounts of dolomite attached in the CaO system was higher than those of the other two systems. Turbidity tests indicated that the turbidity in the CaO system was less than that in Na2CO3 and NaOH systems. The sphalerite surface was negatively charged regardless of the pH regulators. Na2CO3 and NaOH hardly affected the surface potentials of dolomite. However, CaO changed the surface potential of dolomite from negative value to positive value under high alkaline condition. EDLVO theoretical calculations revealed that the electrostatic forces in CaO system were stronger than that in Na2CO3 and NaOH systems, leading to the slime coating.

Optimization of Copper-Ammonia-Sulfate Electrolyte for Maximizing Cu(I):Cu(II) Ratio Using pH and Copper Solubility

An investigation has been carried out to understand the solution chemistry of the Cu-NH−-SO4−2 system, focusing on the effect of pH on the solubility of copper in the solution and maximizing the Cu(I):Cu(II) ratio. A Pourbaix diagram for the Cu-N-S system has also been created using the HSC Chemistry software for a wide range of Cu-NH3 species, unlike most other studies that focused only on Cu(NH3)42+ and Cu(NH3)52+ (Cu(II)) as the dominant species. The Pourbaix diagram demonstrated that the Cu(I) exists as Cu(NH3)2+, while the Cu(II) species are present in the system as Cu(NH3)42+ and Cu(NH3)52+, depending upon the Eh and pH of the solution. Copper precipitation was observed in the electrolyte at pH values less than 8.0, and the precipitation behavior increased as the pH became acidic. The highest Cu(I):Cu(II) ratio was observed at higher pH values of 10.05 due to the higher solubility of copper at higher alkaline pH. The maximum Cu(II) concentration can be achieved at 4.0 M NH4OH and 0.76 M (NH4)2SO4. In the case of low pH, the highest Cu(I):Cu(II) ratio obtained was 0.91 against the 4.0 M and 0.25 M concentrations of NH4OH and (NH4)2SO4, respectively. Meanwhile, at high pH, the maximum Cu(I):Cu(II) ratio was 15.11 against the 0.25 M (NH4)2SO4 and 4.0 M NH4OH. Furthermore, the low pH experiments showed the equilibrium constant (K) K &lt; 1, and the high pH experiments demonstrated K &gt; 1, which justified the lower and higher copper concentrations in the solution, respectively.

Unlocking High Capacity and Reversible Alkaline Iron Redox Using Silicate-Sodium Hydroxide Hybrid Electrolytes.

Alkaline iron (Fe) batteries are attractive due to the high abundance, low cost, and multiple valent states of Fe but show limited columbic efficiency and storage capacity when forming electrochemically inert Fe3O4 on discharging and parasitic H2 on charging. Herein, sodium silicate is found to promote Fe(OH)2/FeOOH against Fe(OH)2/Fe3O4 conversions. Electrochemical experiments, operando X-ray characterization, and atomistic simulations reveal that improved Fe(OH)2/FeOOH conversion originates from (i) strong interaction between sodium silicate and iron oxide and (ii) silicate-induced strengthening of hydrogen-bond networks in electrolytes that inhibits water transport. Furthermore, the silicate additive suppresses hydrogen evolution by impairing energetics of water dissociation and hydroxyl de-sorption on iron surfaces. This new silicate-assisted redox chemistry mitigates H2 and Fe3O4 formation, improving storage capacity (199 mAh g-1 in half-cells) and coulombic efficiency (94 % after 400 full-cell cycles), paving a path to realizing green battery systems built from earth-abundant materials.

Physical–Chemical and Thermal Properties of Clays from Porto Santo Island, Portugal

The use of clays for thermal treatments and cosmetic purposes continues to be a worldwide practice, whether through the preservation of native cultural traditions, pharmaceutical formulations or integrative health and well-being practices. Special clays, such as bentonites, are very common for healing applications due to their high cation exchange capacity (CEC), high specific surface area (SSA) and alkaline pH values and, therefore, are used in multiple therapeutic and dermocosmetic treatments. Numerous bentonitic deposits occur on Porto Santo Island with different chemical weathering degrees. This research evaluates which residual soils have the most suitable characteristics for pelotherapy. The texture of residual soils varies from silt loam to loamy sand and SSA between 39 and 90 m2/g. The pH is alkaline (8.7 to 9.6), electrical conductivity ranges from 242 to 972 µS/cm, and CEC from 50.4 to 86.8 µS/cm. The residual soils have a siliciclastic composition (41.36 to 54.02% SiO2), between 12.52 and 17.65% Al2O3 and between 52 and 82% smectite content, which are montmorillonite and nontronite. Specific heat capacity (0.5–0.9 J/g°C) and cooling kinetics (14.5–19 min) show that one residual soil has the potential to be suitable for pelotherapy according to the literature. Moreover, the residual soils have As, Cd, Co, Cr, Hg, Mn, Ni, Pb, Sb and V concentrations higher than the limits of guidelines for cosmetics and pharmaceutical products.

Physiological and molecular responses of juvenile silver crucian carp (Carassius gibelio) to long-term high alkaline stress: Growth performance, histopathology, and transcriptomic analysis

Salty-alkaline waters are widely distributed globally, and how to effectively develop saline-alkaline water to improve the utilization rate of water resources has become a global challenge. This study examined the survival performance of juvenile silver crucian carp (Carassius gibelio) under alkaline gradient acclimation conditions and explored the regulatory mechanisms for their adaptation to high alkalinity. Compared to directly immersing in high concentrations, alkaline gradient acclimation significantly improved the survival rate of juvenile silver crucian carp. Long-term high alkaline stress caused significant reduction in the growth performance of juvenile silver crucian carp. After alkaline stress, the enzyme activities of Na+-K+-ATP (NKA) and Ca2+-Mg2+-ATP (CMA) in the gills were significantly decreased. Meanwhile, histopathology of the gills showed structural changes, indicating that the physiological functions of juvenile silver crucian carp were impaired under alkaline conditions. Transcriptomic analysis found that the expression of genes related to metabolism and immune response pathways in the gill and kidney underwent significant changes. Genes related to carbohydrate metabolism were upregulated while those related to protein metabolism were downregulated, indicating that alkaline stress caused the organism to utilize carbohydrates rather than proteins as much as possible to meet enhanced metabolism. The HIF pathway that maintains the body's survival was significantly up-regulated, at the expense of high energy consumption. Dysregulation of genes related to the formation of neutrophil extracellular traps (NETosis) pathway indicated that the immune function of the fish was suppressed. Overall, this study revealed the physiological and molecular responses of juvenile silver crucian carp to alkaline stress, deepening our understanding of their adaptation strategies and the potential impact of alkaline environments on aquatic life.

Removal of sulfamethoxazole using Fe-Mn biochar filtration columns: Influence of co-existing polystyrene microplastics

Emerging contaminants, particularly antibiotics and microplastics (MPs), present significant challenges in wastewater treatment and pose large ecological risks. This study investigates the removal efficiency of sulfamethoxazole (SMX) using Fe-Mn modified biochar (BFM) in fixed bed filtration columns, emphasizing the effect of the presence of polystyrene microplastics (PS-MPs) on SMX behavior in both water (pH ≈ 5.6) and selected wastewater (pH ≈ 8) systems. Batch sorption results show that 10 mg/L SMX in 50 mL water can be completely removed by 100 mg BFM sorbent. The Bed Depth Service Time model indicated the BFM column is feasible for SMX removal in scaled-up continuous wastewater flow operations, while the Yan model best elucidates SMX filtration behavior and suggests the dominant adsorption mechanisms include external mass transfer and intraparticle diffusion. The present of both 20 mg/L and 100 mg/L PS-MPs (pH ≈ 5.6) significantly reduced SMX retention due to competitive sorption. However, at pH 3.2, competitive sorption became negligible due to electrostatic interactions driving the PS-MPs sorption, while neutral charged SMX bound through hydrogen-bonds or π-π EDA interactions. Elevated pH shifted both PS-MPs and SMX sorption to non-electrostatic thus intensifying sorption competition, highlighting the influence of pH on their interaction dynamics. In wastewater, SMX filtration was slightly inhibited by 100 mg/L PS-MPs in BFM columns, whereas PS-MPs removal remained unaffected due to the high ionic strength and alkaline pH. These findings highlight the impact of MPs on pollution removal efficiency in filtration system, essential for enhancing biochar-based wastewater treatment strategies.

Solvent-exchange-assisted activation of Cu-1,4-benzene dicarboxylate metal-organic framework for use as a bifunctional water splitting electrocatalyst

The activation of metal-organic frameworks (MOFs) to eliminate extra-coordinating and pore-filling solvent molecules is essential before using MOFs in catalysis applications. Herein, we developed a solvent-exchange-assisted technique to activate cathodically electrodeposited MOF containing Cu nodes and 1,4-benzene dicarboxylate (BDC) linkers, known as Cu(BDC). This method was initially executed by washing electrodeposited MOF film in ethanol and acetone, followed by soaking in dichloromethane and applying heat treatment at a low temperature to remove strongly coordinating N,N-dimethylformamide (DMF) molecules, thereby properly accessing a well-arranged mesoporous architecture with abundant active sites toward electrocatalysis. The emergence of open-state Cu centers through this safe activation method offers a catalyst with enhanced electrocatalytic performance that displays low overpotentials of only 212 mV and 341 mV at a current density of 10 mA.cm−2 toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Importantly, this study paves a way for developing low-cost methods for production and activation of MOFs for high efficient and stable alkaline water splitting.

Synthesis of a chitosan-based superabsorbent polymer and its influence on cement paste

To address the challenge of adaptability between cement-based materials and conventional superabsorbent polymers (sodium polyacrylate, Na-PA), a chitosan-based superabsorbent polymer (CSP) with high salt and alkaline resistance was synthesized, and the optimal synthesis process was determined by a single-factor method. The macroscopic performance and microstructure of CSP and Na-PA were compared, and their influences on cement paste were studied. The results show that CSP exhibits a gradual swelling process during water absorption, which is independent of the solution environment. The poriferous structure of CSP allows it to form a network composed of gel membranes. The introduction of amide group enhances the resistance of CSP to salt and alkaline conditions. The autogenous shrinkage of cement paste is mitigated by CSP, with a superior effect compared to Na-PA. The longer desorption time of CSP allows it to promote cement hydration for a longer period, reducing the loss of compressive strength. The heat release, chemically bound water and hydration products (portlandite and amorphous substances) of CSP pastes are higher than those of Na-PA pastes. The water desorption from CSP fills some middle capillary pores and mesopores, leading to the pores in the hardened cement paste being more concentrated in smaller sizes.

PHARMACEUTICAL ANALYTICAL STUDY OF CHURNODAKA

Introduction: Churnodaka a unique formulation quoted in Rasatarangini, is an uncommon liquid dosage form encompassed under rasashastra. Amlapitta is a disorder of vitiated agni caused by untimely, over intake of food when full, etc. Moreover, stressful life has further enhanced the risk. To imply, it is a lifestyle disorder. Churnodaka is one of the easy to prepare, simple formulations indicated in amlapitta &amp; other koshta roga. A Special emphasis was given to preparation and analysis. Materials and Methods: Churnodaka was prepared by adding 2 ratti of sudha churna to 5 tola of water, left undisturbed for 3 yama, later filtered and stored. Observation and Results: Churnodaka is a transparent liquid. Physico-chemical parameters were analysed, under which pH of sudha churna, churnodaka and churnodaka with milk were importantly marked. Both sudha &amp; churnodaka have alkaline pH, but of churnodaka is less compared to sudha. Discussion: pH of sudha churna suggests the high alkaline nature, which might have corroded the inner lining of GIT on ingestion. Hence a Formulation to dilute sudha to an extent that doesn’t burn the mucosa was formulated. Conclusion: A simple formulation with unique method of preparation where sudha is brought into therapeutically fit form.

Structural and functional design of CTAB-geopolymer adsorbents for rapid removal of tetracycline: A comparative study

A powder, inorganic membrane and 3D printing cetyltrimethylammonium bromide (CTAB)-geopolymer adsorbents system for adsorbing tetracycline (TC) was developed. And the adsorption properties, adsorption mechanism, adsorption cycle application based on the dynamic pH of adsorption system were systematically investigated by experiment, characterization and density functional theory (DFT) calculation. The introduction of CTAB significantly increased the adsorption response to TC in the high alkaline environment caused by spontaneous alkali release of geopolymer. The adsorption of CTAB-geopolymer for TC was most efficient in the dynamic pH range corresponding to TC- species. The predominant influencing mechanism between CTAB-geopolymer with TC was electrostatic interaction assisted by the hydrogen bonding and n-π interaction. The powder adsorbent with 11 wt% CTAB can capture 92.38 % TC at 2 min and fitted the pseudo-second-order model, and was also suitable for adsorption of trace TC. Although the extension of the diffusion path of the monolithic adsorbents limited the adsorption rate, the 3D printed adsorbent showed an adsorption efficiency of 84.20 % at 302 min. The outstanding adsorption (4 times)-desorption (3 times) cycle properties of 11 %CT-GA (81.15 % at 24 min, 4th adsorption) and cycle cumulative adsorption efficiency of 11 %CT-3DP (59.23 % at 120 min, 4th adsorption) adsorbent were exhibited. Furthermore, a high accuracy performance prediction model with the mean R2 value tended to 1 and the low root mean square error (0.0747) was provided, which can provide theoretical and technical reference for the subsequent industrial application of CTAB-geopolymer adsorbents.

On-site visual sensing of antibiotics in food by new fluorescent lanthanide metal–organic frameworks

In recent years, foods that contaminated by the antibiotics is a serious threat to human health, so, the on-site visual detection of antibiotics in food is crucial. In this work, two new two-dimensional lanthanide metal–organic frameworks (2D LnMOFs) are synthesized by mild hydrothermal method and detailly characterized by single crystal structure analysis, photophysics, thermal gravimetric analysis (TGA), powder X-ray diffraction (PXRD), FT-IR spectra. Results show the two LnMOFs has high thermo-stability, strong acid and alkaline resistance. Further studies reveal that TbMOF is a highly sensitive and selective fluorescent probe for the antibiotics of enrofloxacin (Enr) and ciprofloxacin (Cip), with a very short response time of 15 s. The limits of detection (LODs) for Enr and Cip are very low values of 190 and 70 nM, respectively, based on the method of 3σ/K, which is lower than the national food safety standard (GB 31650–2019). In addition, portable test paper based on TbMOF is fabricated, which realized the visible and on-site detection of Enr and Cip in the real samples of egg and milk.