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The development of nanozymes (NZ) for the simultaneous detection of multiple target chemicals is gaining paramount attention in the field of food and health sciences, and waste management industries. Nanozymes (NZ) effectively compensate for the environmental vulnerability of natural enzymes. Considering the development gap of NZ with diverse applications, we synthesized versatile Schiff's base ligands following a facile route and readily available starting reagents (glutaraldehyde, aminopyridines). DPDI, one of the synthesized ligands, readily reacted with transition metal ions (Cu+2, Ag+1, Zn+2 in specific) under ambient conditions, yielding the corresponding nanoparticles/MOF. The structures of ligands and their products were confirmed using various analytical techniques. The enzymatic efficacy of DPDI-Cu (k m 0.25 mM=, V max = 10.75 µM/sec) surpassed Tremetese versicolor laccase efficacy (k m 0. 5 mM=, V max = 2.15 µM/sec). Additionally, DPDI-Cu proved resilient to changing pH, temperature, ionic strength, organic solvent, and storage time compared to laccase and provided reusability. DPDI-Cu proved promising for colorimetric detection of dopamine, epinephrine, catechol, tetracycline, and quercetin. The mechanism of oxidative detection of TC was studied through LC/MS analysis. DPDI-Cu-bentonite composite efficiently adsorbed tetracycline with maximum Langmuir adsorption of 208 mg/g. Moreover, DPDI/Cu and DPDI-Ag nanoparticles possessed antifungal activity exhibiting a minimum inhibitory concentration of 400 µg/mL and 3.12 µg/mL against Aspergillus flavus. Florescent dye tracking and SEM/TEM analysis confirmed that DPDI-Ag caused disruption of the plasma membrane and triggered ROS generation and apoptosis-like death in fungal cells. The DPDI-Ag coating treatment of wheat seeds confirmed the non-phytotoxicity of Ag-NPs. [Display omitted] • Glutaraldehyde-aminopyridine based Schiff's base ligands were synthesized. • The ligand-Cu(II) product unearthed excellent catecholase/laccase-mimic nanozyme. • Highly sensitive detection of neurotransmitters was also achieved. • Nanozyme-bentonite composite effectively removed tetracycline from aqueous medium. • Non-phytotoxic Ag-nanoparticles proved fungicidal against three distinct seed born fungi. [ABSTRACT FROM AUTHOR]

This research article presents the fabrication of NH 2 -terephthalic acid crosslinked chitosan-bentonite composite, which adopted a facile synthesis approach and offered efficient adsorption capacity for organic dyes. A novel hydrogel material named CB 5:1 demonstrated remarkable adsorption for anionic dyes (Congo red (CR) and brilliant blue (BB)) while showing a negligible affinity for cationic dyes. Adsorption isotherm studies revealed the adsorption capacity of 4950 mg/g and 2053 mg/g (per g of composite's dry weight) for CR and BB following the Langmuir adsorption model. Kinetics and thermodynamic studies were also conducted while the adsorption of anionic dyes in the presence of metal ions, cationic dyes, anionic dyes, and in simulated water remained unaffected. Laccase, an industrially important enzyme, was also immobilized on CB 5:1 to achieve enzyme stability and reusability, resulting in a staggering immobilization capacity (4782 mg/g) at pH 6.0. Laccase immobilized product was employed to perform dye degradation (> 90 % for CR and > 75 % for BB), and the reusability was tested. Overall, our crosslinked product proved appealing for removing high concentrations of anionic organic dyes from polluted water and could be envisaged for practical use. [Display omitted] [ABSTRACT FROM AUTHOR]

The massive generation of medical waste (MW) results in a series of environmental, social, and ecological problems. Pyrolysis is one such approach that has attracted more attention because of the production of value-added products with lesser environmental risk. In this study, the activated biochar (ABC600) was obtained from MW pyrolysis and activated with KOH. The adsorption mechanism of activated biochar on cationic (methylene blue) and anionic (reactive yellow) dyes were studied. The physicochemical characterization of biochar showed that increasing pyrolysis temperature and KOH activation resulted in increased surface area, a rough surface with a clear porous structure, and sufficient functional groups. MB and RYD-145 adsorption on ABC600 was more consistent with Langmuir isotherm (R2 ≥ 0.996) and pseudo-second-order kinetics (R2 ≥ 0.998), indicating chemisorption with monolayer characteristics. The Langmuir model fitting demonstrated that MB and RYD-145 had maximum uptake capacities of 922.2 and 343.4 mg⋅g−1. The thermodynamics study of both dyes showed a positive change in enthalpy (ΔH°) and entropy (ΔS°), revealing the endothermic adsorption behavior and randomness in dye molecule arrangement on activated-biochar/solution surface. The activated biochar has excellent adsorption potential for cationic and anionic dyes; hence, it can be considered an economical and efficient adsorbent. [Display omitted] • The activated biochar derived from medical waste served as an adsorbent. • The optimum pH for the adsorption of MB and RYD-145 was 8 and 2. • The maximum adsorption capacity for MB and RYD-145 was 922.2 mg/g and 343.4 mg/g. • The maximum removal efficiency for MB and RYD-145 was 99.9% and 92.5%. • Langmuir isotherm shows the best model fit on activated biochar dye adsorption. [ABSTRACT FROM AUTHOR]

[Display omitted] Tannic acid (TA) is a hydrolysable polyphenol with established antioxidant and antibacterial activity along with its tendency to bind both organic and inorganic ions/molecules. In the present study, the sequestration performance of TA pillared bentonite for various aflatoxins (AFs) including AFB1, AFB2, AFG1 and AFG2 from aqueous solutions and simulated poultry gastrointestinal model solution was studied via adsorption. The adsorbents were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), N 2 adsorption-desorption study and X-ray photoelectron spectroscopy (XPS). The reaction conditions including pH, agitation time, initial toxin concentration and temperature were systematically optimized. The Langmuir adsorption capacity of the adsorbent reached to 86, 71, 74 and 149 mg/g for AFB1, AFB2, AFG1 and AFG2 respectively. Adsorption kinetics and thermodynamic studies showed rapid AFs uptake and the exothermicity of the adsorption reaction respectively. Simultaneous removal of AFs by BTA3 revealed their independent and uninterrupted adsorption and the adsorption mechanism of AFs over BTA3 was elaborated with the help of XPS results. The outstanding AFs sequestering capability of BTA3 in aqueous solution and simulated poultry gastrointestinal model can be envisioned of great promise for the remediation of AFs and other hazardous pollutants from food and poultry industrial products. [ABSTRACT FROM AUTHOR]

This study reports the fabrication of orange peels (OP) extract (water:ethanol:acetonitrile) modified organic-inorganic hybrid bentonite (OP-bentonite). The synthesized composite was employed for the adsorptive removal of carcinogenic mycotoxins (aflatoxin B1 (AFB1), fumonisin B1(FB1) and ochratoxin (OTA)). The product was texturally characterized by BET, FTIR, XRD, TGA, SEM, EDX and XPS techniques while quantification of toxins was performed using HPLC/LC-MS. The effect of reaction temperature, pH, adsorbent dosage, coexisting mycotoxins and gastro-intestinal fluids on the adsorption performance of OP-bentonite was systematically investigated. Isothermal data (pH 2.5 and 7.0) for toxins adsorption agreed well with the Langmuir isotherm model revealing maximum adsorption capacity (q max) (mg/g) of 166 and 121 for AFB1, 3.87 and 1.78 for FB1 and 1.97 and 3.19 for OTA respectively. The adsorption kinetics followed pseudo-second-order kinetic model while its adsorption capacity surpassed many adsorbents reported for AFB1, FB1 and OTA with orders of magnitude. Therefore, attributed to the advantages of being efficient, green and simplified synthesis, OP-bentonite could be envisaged as a promising adsorbent for the enhanced sequestration of mycotoxins. Image 1 [ABSTRACT FROM AUTHOR]

• Magnetite impregnated quaternary-ammonium salt-bentonite composite was prepared. • Textural characterization confirmed the impregnation of magnetite into clay matrix. • The composite realized ultrahigh adsorptive removal capacity for tested dyes. • The enhanced adsorption was due to the surface functionalities of magnetic composite. • Co-existence of other dyes affected the adsorption of Crystal violet and Congo red. Decontamination of dye loaded water has become an issue of intensive interest on both, basic research and industrial scale. Herein, we report the fabrication of bentonite/APTMA and Fe 3 O 4 -bentonite/APTMA adsorbents via a facile synthesis route and commonly available raw materials. The structural and morphological characteristics of the synthesized adsorbents were studied by BET, XRD, FTIR, VSM, SEM, EDX and XPS techniques and were tested for their adsorption capacity for cationic Crystal violet (CV) and anionic Congo red (CR) dyes. Fe 3 O 4 -bentonite/APTMA exhibited BET surface area and pore volume of 27.8 m2/g and 0.012 cm3/g respectively and superior adsorption than bentonite/APTMA with maximum calculated adsorption capacity of 2286 and 1210 mg/g for CV and CR respectively. Behavior of both the adsorbents revealed the hydrophobic nature of bentonite/APTMA which could be attributed to its lower adsorption capacity as compared to super-hydrophilic Fe 3 O 4 -bentonite/APTMA. Effect of operating parameters like pH, adsorbent dosage, dye concentration and temperature were studied, and it was observed that the efficiency of adsorbents was further enhanced towards dye removal in the presence of heavy metal ions and in model wastewater which was attributed to the synergistic effect of metal ions during adsorption process. Adsorption process was endothermic with fast reaction kinetics suggesting the predominant occurrence of chemisorption. Adsorption mechanism was dominated by the occurrence of hydrogen bonding and the electrostatic interactions between adsorbent and dye molecules. This study can be of great industrial prospects for the remediation of CR and CV and other similar dyes and organic pollutants from wastewater both, in the presence as well as absence of heavy metals ions. [ABSTRACT FROM AUTHOR]

This study reports a facile fabrication route for hydroxyapatite (HAp) nanoparticles impregnated magnetic bentonite (HAp@Fe 3 O 4 @bentonite) composite, which was in turn applied for the removal of Pb(II), Cd(II) and crystal violet (CV) dye from aqueous solution. Adsorption isotherm data best fitted with Freundlich isotherm model and kinetic behavior adopted pseudo-second order adsorption mechanism attaining equilibrium in 60 min over a wide pH range (2.0–13). HAp@Fe 3 O 4 @bentonite was magnetically separable and realized higher adsorption capacity for Pb(II) (404.56 mg/g), Cd(II) (310.36 mg/g) and CV (1201.30 mg/g) than those of acid-treated bentonite (161.28, 155.7 and 740.14 mg/g, respectively). Similarly, the higher Langmuir maximum adsorption capacity exhibited by HAp@Fe 3 O 4 @bentonite for Pb(II), Cd(II) and CV (482, 309 and 1290 mg/g respectively) was attributed to –OH, NH 2 , PO 4 3− surface functionalities. Fresh and spent adsorbents were characterized by Fourier transform infra-red (FTIR) spectroscopy, X-ray diffraction (XRD), differential thermogravimetry, Brunauer–Emmett–Teller (BET) surface area analysis, scanning electron microscopy, energy dispersive X-ray analysis, X-ray photoelectron spectroscopy and vibrating-sample magnetometry techniques. HAp@Fe 3 O 4 @bentonite composite exhibited BET surface area of 73.72 m2/g, pore volume of 0.026 cm³/g and an average particle size of 81.39 nm. The composite remained active for five successive adsorption reuses with minimal loss in adsorption capacity as confirmed by FTIR and XRD analyses. The newly synthesized HAp@Fe 3 O 4 @bentonite composite possessing high adsorption efficiency for Pb(II), Cd(II) and CV can be envisaged as a promising solution for wastewater treatment. Image 1 • Hydroxyapatite-impregnated magnetite-bentonite composite was synthesized. • Adsorption capacity for Pb(II) (482 mg/g) and Cd(II) (309 mg/g) was achieved. • Composite remained stable in pH range 2.0–13.0 and was thermally stable. • Enhanced adsorption of composite was due to -OH-, -PO 4 3- and –NH 2 surface groups. [ABSTRACT FROM AUTHOR]