Immobilization of dopamine on Aspergillus niger microspheres (AM/PDA) and its effect on the U(VI) adsorption capacity in aqueous solutions

A promising approach for the removal of hexavalent and trivalent chromium from aqueous solution using low-cost biomaterial

Heavy metal pollution is an enduring environmental challenge that calls for sustainable and eco-friendly solutions. One promising approach is to harness discarded plant biomass as a highly efficient environmental friendly adsorbents. In this context, a noteworthy study has spotlighted the employment of Euryale ferox Salisbury seed coat (E.feroxSC) for the exclusion of trivalent and hexavalent chromium ions. This study aims to transform discarded plant residue into a novel, environmentally friendly, and cost-effective alternative adsorbent, offering a compelling alternative to more expensive adsorption methods. By repurposing natural materials, we can contribute to mitigating heavy-metal pollution while promoting sustainable and economically viable solutions in environmental remediation. The effect of different parameters, i.e., chromium ions' initial concentration (5-25 mg L-1), solution pH (2-7), adsorbent dosage (0.2-2.4 g L-1), contact time (20-240 min), and temperature (298-313 K), were investigated. E.feroxSC proved highly effective, achieving 96.5% removal of Cr(III) ions at pH 6 and 97.7% removal of Cr(VI) ions at pH 2, with a maximum biosorption capacity of 18.33 mg/g for Cr(III) and 13.64 mg/g for Cr(VI), making it a promising, eco-friendly adsorbent for tackling heavy-metal pollution. The adsorption process followed the pseudo-second-order kinetic model, aligning well with the Langmuir isotherm, exhibited favorable thermodynamics, and was characterized as feasible, spontaneous, and endothermic with physisorption mechanisms. The investigation revealed that E.feroxSC effectively adsorbed Cr(VI) which could be rejuvenated in a basic solution with minimal depletion in its adsorption capacity. Conversely, E.feroxSC's adsorption of Cr(III) demanded rejuvenation in an acidic milieu, exhibiting comparatively less efficient restoration.

Screening of Ionic Liquids against Bamboo Mildew and Its Inhibition Mechanism

Ionic liquids are a class of organic molten salts that consist entirely of cations and anions. They are characterized by their low vapor pressure, low viscosity, low toxicity, high thermal stability, and strong antifungal potential. In this study, the inhibitory performance of ionic liquid cations against Penicillium citrinum, Trichoderma viride, and Aspergillus niger was investigated, along with the mechanism of cell membrane disruption. The Oxford cup method, SEM, and TEM were employed to examine the extent of damage and the specific site of action of ionic liquids on the mycelium and cell structure of these fungi. The results showed that 1-decyl-3-methylimidazole had a strong inhibitory effect on TV; benzyldimethyldodecylammonium chloride had a weak inhibitory effect on PC, TV, AN, and a mixed culture; while dodecylpyridinium chloride exhibited significant inhibitory effects on PC, TV, AN, and Mix, with more prominent effects observed on AN and Mix, exhibiting MIC values of 5.37 mg/mL, 5.05 mg/mL, 5.10 mg/mL, and 5.23 mg/mL, respectively. The mycelium of the mildews showed drying, partial loss, distortion, and uneven thickness. The cell structure showed separation of the plasma wall. The absorbance of the extracellular fluid of PC and TV reached the maximum after 30 min, while that of AN reached the maximum after 60 min. The pH of the extracellular fluid decreased initially and then increased within 60 min, followed by a continuous decrease. These findings provide important insights for the application of ionic liquid antifungal agents in bamboo, medicine, and food.

Fungi-enabled pore channel regulation and defect engineering of a novel micro-reactor for treating complex effluents

Defect engineering has become a significant research area in recent years; however, little has been reported on the biological method for modulating the intrinsic carbon defects of the biochar framework. Herein, a fungi-enabled method for the fabrication of porous carbon/Fe₃O₄/Ag (PC/Fe₃O₄/Ag) composites was developed, and the mechanism underlying the hierarchical structure is elucidated for the first time. By regulating the cultivation process of fungi on water hyacinth biomass, a well-developed interconnected structure and carbon defects acting as potential catalytic active sites were formed. This new material with antibacterial, adsorption and photodegradation properties could be an excellent choice for treating the mixed dyestuff effluents with oils and bacteria, also guiding pore channel regulation and defect engineering in materials science. Numerical simulations were carried out to demonstrate the remarkable catalytic activity.

Magnetic solid-phase extraction of warfarin and gemfibrozil in biological samples using polydopamine-coated magnetic nanoparticles via core-shell nanostructure

Herein, polydopamine-coated Fe₃ O₄ spheres were synthesized using a very simple, easy, cost-effective, efficient, and fast method. First, magnetic nanoparticles (Fe₃ O₄ ) were synthesized and were followed by accommodating polydopamine on the surface of the prepared Fe₃ O₄ . The prepared polydopamine-coated Fe₃ O₄ spheres were utilized as a sorbent in magnetic solid phase extraction of gemfibrozil and warfarin (as the model analytes). The extracted model analytes were desorbed by a suitable organic solvent and were analyzed by high-performance liquid chromatography. Under optimized condition, the linearity of the method was in the range of 0.1-200.0 μg/L for the selected analytes in water. The limits of detection were calculated to be in the range of 0.026-0.055 μg/L for warfarin and gemfibrozil, respectively. The limits of quantification were calculated to be in the range of 0.089-0.185 μg/L. The inter-day and intra-day relative standard deviations were determined to be in the range of 1.4%-3.3% in three concentrations in order to calculate the method precision. Furthermore, the enrichment factors were found to be 78 and 81 for warfarin and gemfibrozil, respectively. Moreover, the calculated absolute recoveries were between 78% and 81%. The obtained recoveries indicated that the method was useful and applicable in complicated real samples.

1-aza-18-crown-6 ether tailored graphene oxide for Cs(I) removal from wastewater

Due to the relative abundance, long half-life and high mobility of radioactive cesium (Cs), new adsorbents are urgently needed to treat Cs to ensure public health. In this study, a graphene oxide (GO) based adsorbent for Cs(I) adsorption was prepared by 1-aza-18-crown-6 ether modification. XRD, FT-IR, XPS and SEM results showed that the properties of 1-aza-18-crown 6 ether modified GO (18C6-GO) changed dramatically compared with that of raw graphite. The adsorption properties of 18C6-GO for Cs(I) were studied by batch static adsorption experiments. The results showed that the adsorption equilibrium time of 18C6-GO was 20 h. Kinetic study revealed that the adsorption rate of Cs(I) conformed to pseudo-second-order kinetic model. Langmuir adsorption isotherm simulation indicated that the adsorption arises at homogeneous adsorption sites on 18C6-GO. Therefore, crown ether modified GO may have implications for the treatment of wastewater.

Efficient extraction of U(VI) from uranium enrichment process wastewater by amine-aminophosphonate-modified polyacrylonitrile fibers

The enrichment and recovery of U(VI) from low-level radioactive wastewater in the process of uranium enrichment is important for the sustainable development of nuclear energy and environmental protection. Herein, a novel amine-aminophosphonate bifunctionalized polyacrylonitrile fiber (AAP-PAN), was prepared for the extraction of U(VI) from simulated and real uranium-containing process wastewater. The AAP-PAN fiber demonstrated a maximum adsorption capacity of 313.6 mg g^-1 at pH = 6.0 and 318 K in the batch experiments. During the dynamic column experiment, over 99.99% removal of U(VI) could be achieved by the fiber using multi-ion simulated solution and real wastewater with an excellent saturation adsorption capacity of 132.0 mg g^-1 and 72.5 mg g^-1, respectively. It also exhibited an outstanding reusability for at least 5 cycles of adsorption process. The mechanism for U(VI) removal was studied by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis in the assist of simulation calculation. It suggested that the amine and aminophosphonate groups can easily bind uranyl ions due to U(VI) is more likely to combine with oxygen atoms of CO and PO, respectively.

A review on mycelial pellets as biological carriers: Wastewater treatment and recovery for resource and energy

Mycelial pellets, a new environment friendly biological carrier, have received wide attention from researchers due to porosity, stability and unique biocompatibility. In this article, the theoretical basis and mechanism of mycelial pellets as a biological carrier were analyzed from the properties of mycelial pellets and the interaction between mycelial pellets and other microorganisms. This article aims to collate and present the current application and development trend of mycelial pellets as biological carriers in wastewater treatment, resource and energy recovery, especially the symbiotic particle system formed by mycelial pellets and microalgae is an important way to break through the technical bottleneck of biodiesel recovery from wastewater. This review also analyzes the research hotspots and trends of mycelial pellets as carriers in recent years, discusses the challenges faced by this technology, and puts forward corresponding solutions.

Simultaneous removal of typical flotation reagent 8-hydroxyquinoline and Cr(VI) through heterogeneous Fenton-like processes mediated by polydopamine functionalized ATP supported nZVI

The heavy metal and organic pollution caused by mining activities keep attracting attention, thus an economic and efficient treatment for combined pollution is pressing. In this study, the simultaneous removal performance of typical organic flotation reagent 8-hydroxyquinoline (8-HQ) and Cr(VI) was investigated via heterogeneous Fenton process induced by a novel polydopamine (PDA) functionalized attapulgite supported nano sized zero-valent iron (nZVI) composite (PDA/ATP-nZVI). Batch experiments showed that PDA/ATP-nZVI had better catalytic reactivity and reduction ability than both ATP-nZVI and nZVI. Under acidic condition, 96.0% of 8-HQ was degraded accompanied with the 42.5% of total organic carbon (TOC) decrease, while 95.8% of Cr(VI) removal efficiency was accomplished by PDA/ATP-nZVI. PDA not only served as redox mediator in expediting electron transfer, but also acted as electron donor that accelerated transformation from Fe(III) to both dissolved Fe(II) and surface Fe(II), which resulted in the increased degradation of 8-HQ. The synergic removal behavior between 8-HQ and Cr(VI) was discussed and the reaction mechanism in the persulfate (PS)-PDA/ATP-nZVI system was also explored. This study developed a highly efficient heterogeneous catalyst, and demonstrated that the PS-PDA/ATP-nZVI system had a potential for remediation of mine environment polluted by both heavy metals and organic flotation reagents.

New insights into the sorption of U(VI) on kaolinite and illite in the presence of Aspergillus niger

The regulation effect of Aspergillus niger to the sorption behavior of U(VI) on kaolinite and illite was studied through investigating the enrichment of U(VI) on kaolinite-Aspergillus niger and illite-Aspergillus niger composites. Kaolinite- or illite-A. niger composites were prepared through co-culturation method. Results showed that U(VI) sorption on kaolinite and illite in different pH ranges could be attributed to ion exchange, outer-sphere complexes (OSCs), and inner-sphere complexes (ISCs), while only the ISCs on the bio-composites. Moreover, micro-spectroscopy tests revealed that U(VI) coordinate with phosphate, amide, and carboxyl groups on illite- and kaolinite- A. niger composites. X-ray photoelectron spectroscopy (XPS) further found that U(VI) was partly reduced to non-crystalline U(IV) by A. niger in the bio-composites, occurring as phosphate coordination polymers or biomass-associated monomers. The findings herein provide further insight into the immobilization and migration of uranium in environments.

Removal of Uranyl Ion from Wastewater by Magnetic Adsorption Material of Polyaniline Combined with CuFe2O4

The magnetic adsorption material of polyaniline (PANI) with amino functional group combined with CuFe2O4 (CuFe2O4/PANI nanocomposite) has been described in this work. It has been characterized by TEM, XRD, XPS, BET, FTIR, and VSM, respectively. Significantly, it exhibits extremely high maximum adsorption capacity (322.6 mg/g) for removal of uranyl ions from wastewater at a pH of 4. The adsorption process is consistent with the quasisecond-order kinetic equation, and the isotherm and kinetic data are accurately described by the Langmuir isothermal adsorption model. Furthermore, the magnetic CuFe2O4/PANI displays stable adsorption performance for uranyl ions after five cycles of recovery in acid medium, which indicates it possesses good recovery due to its magnetism and excellent regeneration ability for reusability.

Synthesis of selective biodegradable amidoxime chitosan for absorption of Th(IV) and U(VI) ions in solution

Radionuclide extraction from wastewater is a long-term process, in which the study on the reuse and decomposition of adsorbents provides the ability to complete the post-treatment after adsorption. Herein, A novel biodegradable amidoxime chitosan has been synthesized through one-step without crosslinking agent and characterized by FT-IR, SEM, XPS, TGA and element analysis. The batch adsorption experiments of U(VI) and Th(IV) on AO-CTS adsorbent were studied and maximum adsorption of U(VI) and Th(IV) were 97 and 56 mg/g, respectively. The U(VI) and Th(Ⅳ) can be effectively desorbed from the AO-CTS materials at low acidity, The AO-CTS can be reused 6 times without reducing absorbency for U(VI) and Th(Ⅳ). When finish the adsorption process, the AO-CTS can be degraded by lysozyme at room temperature, there were no toxic or harmful substances are produced.