Phosphorylated biomass-derived porous carbon material for efficient removal of U(VI) in wastewater

Cuprous oxide-functionalized activated porous carbon-modified screen-printed carbon electrode integrated with a smartphone for portable electrochemical nitrate detection

Nitrate (NO3-) is a widespread contaminant in drinking water. An electrochemical NO3- sensor was developed based on a first-time application of materials. Activated porous carbon (APC) was synthesized by carbonizing orange peel (OP) activated with KOH. Cuprous oxide crystals were uniformly decorated by electrodeposition on a screen-printed carbon electrode modified with the synthesized APC (Cu2O@APC/SPE). The modified electrode was integrated with a portable potentiostat interfaced with a smartphone to create a chronoamperometric nitrate sensor. The modified electrodes were structurally and morphologically characterized using conventional techniques, while electrochemical tests were performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA). The electrode material exhibited a highly porous structure, large accessible active surface areas, and excellent conductivity, which enhanced electrocatalytic performances. The developed NO3- sensor displayed a wide linear range (4-1000 μM) and a low limit of detection (LOD) of 1.2 μM. The sensor demonstrated good precision, selectivity, and reasonable recoveries. The real-world application of the NO3- sensor was validated using water samples. The sensor shows promise for applications in pharmaceuticals, agriculture, forensic investigations, and environmental monitoring.

High-efficient removal of tebuconazole from aqueous solutions using P-doped corn straw biochar: Performance, mechanism and application

Due to the serious threat posed by tebuconazole to the aquatic ecosystem, it is imperative to develop a highly efficient adsorbent material for the sustainable remediation of tebuconazole-contaminated water. Herein, a phosphorus (P)-doped biochar from corn straw and H3PO4 was fabricated by one-step pyrolysis for tebuconazole adsorption. Results showed that the P-doped biochar produced at 500℃ (PBC500) possesses a large specific surface area (SSA=869.6 m2/g), abundant surface functional groups, and the highest tebuconazole adsorption capacity (429.6 mg/g). The adsorption of tebuconazole on PBC500 followed pseudo-second-order kinetics and Langmuir adsorption isotherm models. Thermodynamic calculations indicated that the adsorption of tebuconazole by PBC500 was a spontaneous, endothermic process with a random increase. Adsorption mechanism mainly involves pore filling, π-π interactions, hydrogen bonding, and hydrophobic interaction. Moreover, PBC500 demonstrated robust anti-interference capabilities in adsorbing tebuconazole from diverse water sources and exhibited excellent reusability, underscoring its potential for a broad array of practical applications.

Boosting uranium extraction from Seawater by micro-redox reactors anchored in a seaweed-like adsorbent

Efficient extraction of uranium from seawater is expected to provide virtually infinite fuel sources to power nuclear reactors and thus enable sustainable development of nuclear energy. The extraction efficiency for uranium greatly depends on the availability of active adsorption sites on the adsorbents. Maximization of the utilization rate of the binding sites in the adsorbent is vital for improving adsorption capacity. Herein, micro-redox reactors functioned by Cu(I)/Cu(II) conversion are constructed internally in an adsorbent bearing both amidoxime and carboxyl groups to induce active regeneration of the inactivated binding sites to enhance uranium capture. This adsorbent has high adsorption capacity (962.40 mg-U/g-Ads), superior anti-fouling ability as well as excellent uranium uptake (14.62 mg-U/g-Ads) in natural seawater after 56 days, placing it at the top of high-performance sorbent materials for uranium harvest from seawater.

One-step synthesis of phospho-rich, silica-enhanced chitosan aerogel for the efficient adsorption of uranium(VI)

In this study, an amorphous silica reinforced, phosphoric-crosslinked chitosan foam (P-CTS@SixOy) was prepared. The introduction of amorphous silica not only increased the affinity of the adsorbent for uranium, but also improved the stability of the material. The number of active sites of P-CTS@SixOy was increased by the introduction of phosphate groups. The material exhibited excellent uranium adsorption performance with the removal capacity and efficiency of 850.5 mg g-1 and 98.1 %, respectively. After regenerations, the morphology of P-CTS@SixOy still maintained, and the uranium adsorption efficiency remained above 90 %, manifesting the excellent cycle performance of P-CTS@SixOy. In the dynamic adsorption experiment, P-CTS@SixOy successfully concentrated the volume of uranium-containing solution, and exhibited excellent uranium adsorption performance. The analysis of kinetics, isotherms, and thermodynamics manifested that the uranium adsorption behavior of P-CTS@SixOy was a spontaneous, endothermic, monolayer chemical adsorption process. X-ray photoelectron spectroscopy, Scanning Electron Microscope, and Fourier Transform Infrared Spectrometer were used to characterized the P-CTS@SixOy before and after adsorption, which demonstrated that the main interaction mechanism between uranium and P-CTS@SixOy was the complexation. These studies indicated the huge application prospect of P-CTS@SixOy in the treatment of large-scale uranium-containing wastewater.

Insights into Preparation Methods and Functions of Carbon-Based Solid Acids

With the growing emphasis on green chemistry and the ecological environment, researchers are increasingly paying attention to greening materials through the use of carbon-based solid acids. The diverse characteristics of carbon-based solid acids can be produced through different preparation conditions and modification methods. This paper presents a comprehensive summary of the current research progress on carbon-based solid acids, encompassing common carbonization methods, such as one-step, two-step, hydrothermal, and template methods. The composition of carbon source material may be the main factor affecting its carbonization method and carbonization temperature. Additionally, acidification types including sulfonating agent, phosphoric acid, heteropoly acid, and nitric acid are explored. Furthermore, the functions of carbon-based solid acids in esterification, hydrolysis, condensation, and alkylation are thoroughly analyzed. This study concludes by addressing the existing drawbacks and outlining potential future development prospects for carbon-based solid acids in the context of their important role in sustainable chemistry and environmental preservation.

Ultrathick GeP Anode To Balance the Extreme Load and Compliance for High Areal Capacity Flexible Sodium-Ion Batteries

The ever-growing application of miniaturized electric devices calls for the manufacturing of energy storage systems with a high areal energy density. Thick electrode design is a promising strategy to acquire high areal energy density by enhancing active mass loading and minimizing inactive components. However, the sluggish reaction kinetics and poor electrode mechanical stability that are accompanied by the increased electrode thickness remain unsolved problems. Herein, for the first time, we propose a novel chemical cross-linking strategy to fabricate GeP thick electrodes with adjustable electrode thicknesses and active mass loadings for high areal capacity sodium-ion batteries (SIBs). The chemical cross-linking between carboxylic multiwalled carbon nanotubes (CNTs) and pyrolysis cellulose nanofibers (CNFs) forms a 3D network that encloses GeP nanoparticles, which guarantees fast charge transfer, efficient stress relief, and alleviated volume expansion/shrinkage of the electrode. The hierarchical porous structure generates numerous interconnected channels for unfettered Na+ diffusion, ensuring uncompromised reaction kinetics as the electrode thickness increases. As a result, the ultrathick 1031 μm GeP@C-CNTs-CNFs electrode featuring a mass loading of 18.3 mg cm-2 delivers an ultrahigh areal capacity of 10.58 mAh cm-2 accompanied by superior cycling stability, which outperforms all reported Ge-based electrodes (generally below 1.5 mAh cm-2). This work sheds insightful light on designing high areal capacity flexible thick electrodes for the applications of miniaturized electric devices.

Natural Products Derived Porous Carbons for CO2 Capture

As it is now established that global warming and climate change are a reality, international investments are pouring in and rightfully so for climate change mitigation. Carbon capture and separation (CCS) is therefore gaining paramount importance as it is considered one of the powerful solutions for global warming. Sorption on porous materials is a promising alternative to traditional carbon dioxide (CO2 ) capture technologies. Owing to their sustainable availability, economic viability, and important recyclability, natural products-derived porous carbons have emerged as favorable and competitive materials for CO2 sorption. Furthermore, the fabrication of high-quality value-added functional porous carbon-based materials using renewable precursors and waste materials is an environmentally friendly approach. This review provides crucial insights and analyses to enhance the understanding of the application of porous carbons in CO2 capture. Various methods for the synthesis of porous carbon, their structural characterization, and parameters that influence their sorption properties are discussed. The review also delves into the utilization of molecular dynamics (MD), Monte Carlo (MC), density functional theory (DFT), and machine learning techniques for simulating adsorption and validating experimental results. Lastly, the review provides future outlook and research directions for progressing the use of natural products-derived porous carbons for CO2 capture.

Ultra-fast uranium capture via the synergistic interaction of the intrinsic sulfur atoms and the phosphoric acid groups adhered to edge sulfur of MoS2

In order to deal with the sudden nuclear leakage event to suppress the spread of radioactive contaminants in a short period of time, it is extremely urgent needed to explore an adsorbent that could be capable of in-situ remedial actions to rapidly capture the leaked radionuclides in split second. An adsorbent was developed that MoS₂ via ultrasonic to expose more surface defects afterwards functionalized by phosphoric acid resulting in more active sites being endowed on the edge S atoms of Mo-vacancy defects, while simultaneously increased the hydrophilicity and interlayer spacing. Hence, an overwhelming fast adsorption rates (adsorption equilibrium within 30 s) are presented and place the MoS₂-PO₄ at the top of performing sorbent materials. Moreover, the maximum capacity calculated from Langmuir model is as high as 354.61 mg·g^-1, the selective adsorption capacity (S_U) achieving 71.2% in the multi-ion system and with more than 91% capacity retention after 5 cycles of recycling. Finally, XPS and DFT insight into the adsorption mechanism, which can be explained as interaction of UO₂²⁺ on the surface of MoS₂-PO₄ by forming U-O and U-S bonds. The successful fabrication of such a material may provide a promising solution for emergency treatment of radioactive wastewater during nuclear leakage events.

Efficient removal of uranium(VI) from aqueous solution by a novel phosphate-modified biochar supporting zero-valent iron composite

Uranium (U) is an important strategic resource as well as a heavy metal element with both chemical and radiotoxicity. At present, the rapid and efficient removal of uranium from wastewater remains a huge challenge for environmental protection and ecological security. In this paper, phosphate-modified biochar supporting nano zero-valent iron (PBC/nZVI) was triumphantly prepared and fully characterized. The introduction of polyphosphate can greatly increase the specific surface area of biochar pores, and then the zero-valent iron can be evenly distributed on the surface of material, thus leading to excellent removal performance of the PBC/nZVI for U(VI). The theoretical maximum U(VI) removal capacity of PBC/nZVI was up to 967.53 mg/g at pH 5. The results of adsorption kinetics, isotherm, and thermodynamics showed that the adsorption of uranium by PBC/nZVI was a monolayer physical adsorption and endothermic reaction. And the PBC/nZVI has favorable selectivity toward uranium against the interference of coexisting metal ions. Further mechanism studies show that the excellent uranium removal performance of PBC/nZVI is mainly attributed to the synergistic effect of physical adsorption and chemical reduction. This work proves that the PBC/nZVI has a wide application prospect in the field of uranium wastewater treatment.

High-speed and efficient removal of uranium (VI) from aqueous solution by hydroxyapatite-modified ordered mesoporous carbon (CMK-3)

In recent years, the synthesis and application of green, cost-effective, and sustainable materials for uranium (VI) removal was significant to environmental protection. The ordered mesoporous carbon (CMK-3) supported different mass of hydroxyapatite materials (HAP@CMK-3) were facilely synthesized via hydrothermal method. The resultant materials were characterized by XRD, FT-IR, BET, SEM, TEM mapping, and XPS, and implemented for immobilizing U(VI). Not only the specific surface area of HAP (7.01 m²/g) was increased by the loading on CMK-3 (818.37 m²/g), but also the adsorption capacity of CMK-3 was increased by HAP modification. Impressively, HAP@CMK-3 exhibited highly adsorption capacity of U(VI) with the increase of HAP deposition and was capable of achieving fast reaction. Therein to, the specific surface area of HAP@CMK-3(2:1) was 253.68 m²/g, as well as the adsorption capacity was up to 1072 mg/g (fitted by Langmuir isotherm, at pH=3.0, 298 K) and the adsorption process was completed in 30 min (followed by pseudo-second-order kinetic). The adsorption mechanisms of U(VI) on HAP@CMK-3 involved electrostatic forces, ionic interactions, and chemical complexation. This work offered new avenues to address the limitations of cost and less secondary pollution for the removal of U(IV) from 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.

Acid Neutralization and Immune Regulation by Calcium-Aluminum-Layered Double Hydroxide for Osteoporosis Reversion

Osteoporosis is a kind of global chronic bone disease characterized by progressive loss of bone mass and bone quality reduction, leading to a largely increased risk of bone fragility. In clinics, the current treatment of osteoporosis relies on the inhibition of bone damage by osteoclasts but ignores the function of immune cells in the progress of osteoporosis, leading to much compromised therapeutic efficacy. In this work, a highly effective osteoporosis-immunotherapeutic modality is established for the treatment of osteoporosis based on acid neutralization in synergy with immune microenvironment regulation by a specially designed nanocatalytic medicine, calcein functionalized calcium-aluminum-layered double hydroxide (CALC) nanosheets. Briefly, the mildly alkaline CALC nanosheets could neutralize the acidic microenvironment of osteoporosis accompanying the acidity-responsive LDH degradation. Subsequently, calcium phosphate nanoparticles (CAPs) are generated by the reaction between the released Ca²⁺ from LDH degradation and endogenous phosphates, resulting in M2 phenotype anti-inflammatory differentiation of bone macrophages through a c-Maf transcriptional factor pathway and the following activity enhancements of regulatory T cells (T_reg) and the deactivation of T helper 17 cells (T_H17). Both in vitro and in vivo results show an excellent therapeutic efficacy on osteoporosis featuring a significant BV/TV (%) enhancement of femurs from 6.2 to 10.7, demonstrating high feasibility of this therapeutic concept through the combined acid neutralization and immune regulation. Such an inorganic nanomaterial-based strategy provides a novel, efficient, and biosafe therapeutic modality for intractable osteoporosis treatment, which will benefit patients suffering from osteoporosis.

Synergistic removal of fluoride from groundwater by seed crystals and bacteria based on microbially induced calcium precipitation

A new hypothesis that seed crystals (SC) and bacteria based on microbially induced calcium precipitation (MICP) synergistically remove fluoride (F^-) from groundwater was proposed, with a focus on evaluating the defluoridation potential of this method and revealing its F^- removal mechanism. The crucial conditions were optimized to reduce preparation and operation costs. SC furnished more available binding sites due to the existence of bacteria, and the reuse experiments showed that the defluoridation efficiency of SC still remained a high level after 14 cycles (70.10%), with a residual F^- concentration of 0.96 mg L^-1. The SEM-EDS, FTIR and XRD analyses indicated the predominant F^- removal mechanism of SC could be ascribed to the chemisorption, ion exchange, and co-precipitation. Moreover, ion exchange and co-precipitation (PO₄^3- involvement) were validated more contributive than chemisorption (CaCO₃ and CaSO₄ involvement). As a feasible, reusable, and eco-friendly technique, SC suggests promising applications in the treatment of fluoride-contaminated groundwater.

Effectiveness and mechanism of aluminum/iron co-modified calcite capping and amendment for controlling phosphorus release from sediments

The effectiveness and mechanism of aluminum/iron co-modified calcite (Al/Fe-CA) for the control of phosphorus (P) liberation from sediments was investigated. The results showed that Al/Fe-CA possessed good sorption performance for phosphate, and the maximum phosphate sorption capacity for Al/Fe-CA could reach 27.0 mg/g. The major mechanisms involved the surface adsorption of phosphate on calcite, the precipitation between phosphate and Ca²⁺ leached from calcite, and the ligand exchange between Al/Fe-bound hydroxyl groups and phosphate to form the Al-O-P and Fe-O-P inner-sphere complexes. The re-releasing risk of Al/Fe-CA-bound P under the circumstances of normal pH (5-9) and reducing environment was very low. Al/Fe-CA addition could significantly reduce the risk of P releasing from sediment to overlying water (OL-water), and the inactivation of mobile P, reactive soluble P (SRP) and diffusive gradient in thin-films (DGT)-labile P in sediment by Al/Fe-CA had a great part in the suppression of sediment-P liberation to OL-water by the Al/Fe-CA amendment. Al/Fe-CA capping and fabric-wrapped Al/Fe-CA capping both could greatly reduce the risk of P releasing from sediment into OL-water, and the formation of a static layer with low concentrations of SRP and DGT-labile P in the upper sediment was the key to sustaining a high P controlling efficiency. When the applied mode of Al/Fe-CA varied from capping to amendment, although the inactivation efficiency of DGT-labile P in the overlying water and upper sediment by Al/Fe-CA would decrease to a certain degree, the inactivation efficiency of DGT-labile P in the lower sediment by Al/Fe-CA would increase. Results of this study suggest that Al/Fe-CA has the high potential to be used as an active capping or amendment material for the management of internal P loading in surface water bodies.