Alder-Ene Reaction-Mediated Suppression of Tin(II) Oxidation for Efficient Tin-Lead Perovskite Solar Cells.

Despite numerous studies have reported the inhibition of tin (II) oxidation in mixed tin-lead halide perovskite, there remains a dearth of mechanistic information regarding how tin (II) undergoes oxidation in the precursor solution, particularly in terms of the involvement of DMSO. We here take advantage of density functional theory (DFT) to uncover that SnI2 can coordinate with DMSO and react with singlet oxygen, resulting in the generation of Sn (IV). Moreover, our DFT simulations reveal that benzaldehyde oxime (BZHO) competes with SnI2 in reacting with oxygen through the Alder-ene reaction, hence effectively restraining the oxidation of tin (II), which is further verified by several experimental characterizations. Besides, the introduction of BZHO has also regulated the crystallization of the perovskite film and modified the electronic structure of the perovskite surface. As a result, the perovskite solar cells with the addition of BZHO demonstrate superior performance and operational stability, retaining 82% of the initial PCE under continuous 1-sun illumination for 800 hours. Furthermore, the efficiency of all-perovskite tandem solar cells treated with BZHO reached 26.76%. Therefore, this work presents a promising strategy for designing high-performance and stable all-perovskite tandem solar cells.

Unravelling the history of mountain belts through U-Pb and Lu-Hf dating of zircon and 40Ar/39Ar dating of detrital white mica: a case study from the Eastern Alps.

Radiogenic isotopes of igneous and detrital minerals from various clastic rocks of mountain belts are used to reveal tectonic and sedimentary processes, which are otherwise difficult to detect. Here, we discuss the results of U-Pb and Lu-Hf zircon systems, and 40Ar/39Ar on detrital white mica in Eastern Alps. Zircon and white mica are chemically and mechanically stable and occur in magmatic, metamorphic and sedimentary rocks. During subsequent metamorphism, zircon is resistant against high temperature, >650 °C (U-Pb) and 900 °C (Lu-Hf). The Lu-Hf zircon system is used as a tracer of initial magma separation from the mantle, and the U-Pb zircon system records magmatic crystallization. The 40Ar/39Ar white mica system is stable up to 400-450 °C dating either formation or cooling after high-grade metamorphism. Detrital U-Pb zircon ages on two major rivers draining the Eastern Alps do not record any sign of Alpine orogeny or metamorphism. Consequently, U-Pb zircon studies can entirely miss the record of collisional orogeny in cool, magma-poor collision orogens. In contrast, 40Ar/39Ar white mica ages record Early and Late Alpine metamorphism but are limited to revealing the pre-orogenic history. U-Pb zircon and 40Ar/39Ar white mica yield different information in provenance studies. In the Eastern Alps, U-Pb zircon dating of magmatic and clastic rocks indicates intense formation of magmatic rocks between 630 and 230 Ma. Felsic rocks dominate the older age groups, and increasingly young mafic rocks were dated, specifically between 265 and 230 Ma. Hf isotopes record increasing juvenile input since ∼630 Ma. Two different groups with respect to Mesoproterozoic depleted mantle ages are shown: (1) one group with a Mesoproterozoic age gap typical for Gondwana-derived units, and (2) a rare group with Mesoproterozoic ages recording a new tectonic element in the Austroalpine basement in Alps.

Adsorption of Pb(II) in water by modified chitosan-based microspheres and the study of mechanism.

In this study, a fresh three-dimensional microsphere adsorbent (CATP@SA3) was successfully synthesized by Attapulgite (ATP) and combining Chitosan (CS), incorporating them into a Sodium alginate (SA) solution, and crosslinking them in a CaCl2 solution. Multiple analyses, including XRD, TGA, FTIR, XPS, SEM-EDS, and BET were utilized to comprehensively characterize the structural makeup of CATP@SA3. These analyses revealed the presence of beneficial functional groups like hydroxyl, amino, and carboxyl groups that enhance the adsorption efficiency in adsorption procedures. CATP@SA3 was evaluated by studying different factors, including material ratio, contact time, dosage, solution pH, Pb(II) concentration, temperature, ionic strength, and aqueous environment. Three adsorption models, including kinetic, isotherm, and thermodynamic, were fitted to the experimental data. The findings demonstrated that the maximum Pb(II) adsorption capacity of CATP@SA3 was 1081.36 mg/g, with a removal rate that exceeded 70 % even after 5 cycles of use. Furthermore, correlation adsorption models revealed that the adsorption process of Pb(II) with CATP@SA3 was driven by a chemical predominantly reaction.

Evaluating Pb-based and Pb-free Halide Perovskites for Solar-Cell Applications: A Simulation Study.

Metal halide Pb-based and Pb-free perovskite crystal structures are an essential class of optoelectronic materials due to their significant optoelectronic properties, optical absorption and tuneable emission spectrum properties. However, the most efficient optoelectronic devices were based on the Pb as a monovalent cation, but its toxicity is a significant hurdle for commercial device applications. Thus, replacing the toxic Pb with Pb-free alternatives (such as tin (Sn)) for diverse photovoltaic and optoelectronic applications is essential. Moreover, replacing the volatile methylammonium (MA) with cesium (Cs) leads to the development of an efficient perovskite absorber layer with improved optical & thermal stability and stabilized photoconversion efficiency. This paper discusses the correlation between the experimental and theoretical work for the Pb-based and Pb-free perovskites synthesised using the hot-injection method at different temperatures. Here, simulation is also carried out using the help of SCAPS-1D software to study the effect of various parameters of CsSnI3 and CsPbI3 layers on solar cell performance. This experimental and theoretical comparative study of the Hot-injection method synthesised CsPbI3 and CsSnI3 perovskites is rarely investigated for optoelectronic applications.

In Situ Buried Interface Engineering towards Printable Pb-Sn Perovskite Solar Cells.

High-efficiency Pb-Sn narrow-bandgap perovskite solar cells (PSCs) heavily rely on PEDOT:PSS as the hole-transport layer (HTL) owing to its excellent electrical conductivity, dopant-free nature, and facile solution processability. However, the shallow work function (WF) of PEDOT:PSS consequently results in severe minority carrier recombination at the perovskite/HTL interface. Here, we tackle this issue by an in situ interface engineering strategy using a new molecule called 2-fluoro benzylammonium iodide (FBI) that suppresses nonradiative recombination near the Pb-Sn perovskite (FA0.6MA0.4Pb0.4Sn0.6I3)/HTL bottom interface. The WF of PEDOT:PSS increases by 0.1 eV with FBI modification, resulting in Pb-Sn PSCs with 20.5% efficiency and an impressive VOC of 0.843 V. Finally, we have successfully transferred our in situ buried interface modification strategy to fabricate blade-coated FA0.6MA0.4Pb0.4Sn0.6I3 PSCs with 18.3% efficiency and an exceptionally high VOC of 0.845 V.

Suppressed Defects by Functional Thermally Cross-Linked Fullerene for High-Efficiency Tin-Lead Perovskite Solar Cells.

Mixed tin-lead (Sn-Pb) perovskites have attracted the attention of the community due to their narrow bandgap, ideal for photovoltaic applications, especially tandem solar cells. However, the oxidation and rapid crystallization of Sn2+ and the interfacial traps hinder their development. Here, cross-linkable [6,6]-phenyl-C61-butyric styryl dendron ester (C-PCBSD) is introduced during the quenching step of perovskite thin film processing to suppress the generation of surface defects at the electron transport layer interface and improve the bulk crystallinity. The C-PCBSD has strong coordination ability with Sn2+ and Pb2+ perovskite precursors, which retards the crystallization process, suppresses the oxidation of Sn2+, and improves the perovskite bulk and surface crystallinity, yielding films with reduced nonradiative recombination and enhanced interface charge extraction. Besides, the C-PCBSD network deposited on the perovskite surface displays superior hydrophobicity and oxygen resistance. Consequently, the devices with C-PCBSD obtain PCEs of up to 23.4% and retained 97% of initial efficiency after 2000 h of storage in a N2 atmosphere.

Compost amendment in urban gardens: elemental and isotopic analysis of soils and vegetable tissues.

Urban horticulture poses a sustainable form of food production, fosters community engagement and mitigates the impacts of climate change on cities. Yet, it can also be tied to health challenges related to soil contamination. This work builds on a previous study conducted on eleven urban gardens in the city of Vienna, Austria. Following the findings of elevated Pb levels in some soil and plant samples within that project, the present study investigates the elemental composition of soil and plants from two affected gardens 1 year after compost amendment. Inductively coupled plasma mass spectrometry (ICP-MS) analysis of skin, pulp and seeds of tomato fruits revealed minor variations in elemental composition which are unlikely to have an impact on food safety. In turn, a tendency of contaminant accumulation in root tips and leaves of radishes was found. Washing of lettuce led to a significant reduction in the contents of potentially toxic elements such as Be, Al, V, Ni, Ga and Tl, underscoring the significance of washing garden products before consumption. Furthermore, compost amendments led to promising results, with reduced Zn, Cd and Pb levels in radish bulbs. Pb isotope ratios in soil and spinach leaf samples taken in the previous study were assessed by multi-collector (MC-) ICP-MS to trace Pb uptake from soils into food. A direct linkage between the Pb isotopic signatures in soil and those in spinach leaves was observed, underscoring their effectiveness as tracers of Pb sources in the environment.

Synthesis of Hybrid Tin-Based Perovskite Microcrystals for LED Applications.

Considerable focus on tin-based perovskites lies on substitution to leadhalide perovskites for the fabrication of eco-friendly optoelectronic devices.The major concern related to tin-based perovskite devices are mainly thestability and the efficiency. However, thinking on the final commercializationscope, other considerations such as precursor stability and cost are majorfactors to carry about. In this regard, this work presents a robust and facilesynthesis of 2D A2SnX4 (A = 4-fluorophenethylammonium(4-FPEA); X = I, Br, I/Br) and 3D FASnI3 perovskite microcrystals followinga developed synthesis strategy with low-cost starting materials. In thisdeveloped methodology, acetic acid is used as a solvent, which helps to protectfrom water by making a hydrophobic network over the perovskite surface, andhence provides sufficient ambient and long-term inert atmosphere stability ofthe microcrystals. Further, the microcrystals are recrystallized in thin filmsfor LED application, allowing the fabrication of orange, near-infrared and purered emitting LEDs. The two-step recrystallized devices show better performanceand stability in comparison to the reference devices made by using commercialprecursors. Importantly, the developed synthesis methodology is defined as ageneric method for the preparation of varieties of hybrid tin-based perovskitesmicrocrystals and application in optoelectronic devices.

Association of HLA-G 3'UTR polymorphisms with hepatitis B virus infection in Tunisian population.

Hepatitis B virus (HBV) infection is a major public health burden. The mechanisms of immune evasion during chronic HBV (CHB) infection are poorly understood. Human leukocyte antigen (HLA)-G, an immune checkpoint molecule, plays a crucial role in the tolerance mechanisms of various infectious diseases. The 3' untranslated region (3'UTR), including the HLA-G + 3142 C > G polymorphism (rs1063320) and the 14-pb Ins/Del (rs66554220) has been strongly suggested to influence HLA-G expression. This study conducted a case-control analysis to evaluate the potential correlation between the HLA-G + 3142 C > G polymorphism and HBV infection outcome in a Tunisian cohort. The HLA-G + 3142 C > G polymorphism was analysed by PCR-RFLP in 242 patients with chronic HBV infection (116 males and 126 females), 241 healthy controls (116 males and 125 females), and 100 spontaneously resolved subjects (52 males and 48 females). Patients with chronic HBV infection showed a higher frequency of the + 3142G allele compared to healthy controls and spontaneously resolved subjects (p = 0.001 and p = 0.002, respectively). An association between the + 3142G allele and high HBV DNA levels was observed when HBV patients were stratified based on their HBV DNA levels (p = 0.016). Furthermore, the dominant model (GG + GC vs CC) was associated with liver function parameters, including AST, ALT, and high HBV DNA levels (p = 0.04, p < 0.001 and p = 0.002, respectively). However, there was no significant association found between this polymorphism and the fibrosis stage (p = 0.32). The haplotype analysis, using a subset of previously published data on the HLA-G 14-pb Ins/Del polymorphism, revealed an association between the Ins/G haplotype and chronic HBV infection (H1: InsG, p < 0.001). Our findings suggest that the + 3142G allele is a risk factor for the persistence and progression of HBV infection, while the + 3142C allele serves as a protective allele associated with the spontaneous resolution of the infection. Additionally, the HLA-G 3'UTR haplotype Ins/G is associated with chronic HBV infection in the Tunisian population.

Polymetallic contamination drives indigenous microbial community assembly dominated by stochastic processes at Pb-Zn smelting sites.

Indigenous microbial communities in smelting areas are crucial for maintaining fragile ecosystem functions. However, the community assembly process and their responses to polymetallic pollution are poorly understood, especially the taxa in each bin from the amplicons that contributed to the assembly process. Herein, microbial diversity, co-occurrence patterns, assembly process and the intrinsic mechanisms across contamination gradients at a typical PbZn smelting site were systematically unravelled by high-throughput sequencing. The results showed a consistent compositional profile among the indigenous communities across sampling sites, wherein genera KD4-96 from Chloroflexi and Sphingomonas from Proteobacteria emerged as the most abundant taxa. Network modularity of the high- and middle-contaminated communities at Pb and Zn smelting sites was >0.44, indicating that community populations were clustered into modules to resist high heavy metal stress. Stochastic processes dominated the community assembly, with the greatest contribution from drift (DR), which was significantly correlated with Pb, Zn, Cr and Cu contents. What's particular was that the DR-controlled bins were dominated by Proteobacteria (typical r-strategists), while the HoS-controlled bins were by Chloroflexi (typical K-strategists). Furthermore, the proportion of DR in the bins dominated by Sphingomonadaceae (phylum Proteobacteria) increased gradually with the increase of heavy metal contents. These discoveries provide essential insights for community control in restoring and mitigating soil degradation at PbZn smelting sites.

Utilizing triethylenetetramine-functionalized MIP-206 for highly efficient removal of Pb(II) from wastewater.

The global concern over heavy metal pollution necessitates urgent measures to safeguard human health and the environment. This study focuses on employing triethylenetetramine (TETA)-functionalized MIP-206-OH (TMIP-206) as an effective adsorbent for removing Pb(II) from wastewater. TMIP-206 was synthesized via a hydrothermal method followed by functionalization with TETA. Kinetic studies demonstrate that lead removal on TMIP-206 conforms to the pseudo-second-order model, indicating an efficient removal process. Experimental results reveal that TMIP-206 aligns with the Langmuir isotherm, exhibiting a maximum removal capacity of 267.15 mg/g for lead ions. The sorption efficiency of TMIP-206 for Pb ions remains stable across six cycles, with a reduction of less than 15%. Optimal adsorption performance is observed at a pH of 6. These findings underscore the potential of TMIP-206 as an alternative for adsorbing Pb(II) from aqueous environments, addressing the global challenge of heavy metal pollution. Future research should explore the scalability and long-term stability of TMIP-206-based adsorbents to enhance their practical applicability in diverse environmental contexts and contribute to broader strategies for mitigating heavy metal contamination.

Investigations on the EPR g factors and local structures for the orthorhombic and tetragonal Cu2+ centers in Pb[Zr0.54Ti0.46]O3.

The defect models of the orthorhombical and tetragonal Cu2+ centers in Pb[Zr0.54Ti0.46]O3 are attributed to Cu2+ ions occupying the sixfold coordinated octahedral Ti4+ site with and without charge compensation, respectively. The electron paramagnetic resonance (EPR) g factors gi (i = x, y, z) of the Cu2+ centers in Pb[Zr0.54Ti0.46]O3 are theoretically studied by using the perturbation formulas of a 3d9 ion under orthorhombically and tetragonally elongated octahedra. Based on the calculation, the impurity off-center displacements are about 0.253 and 0.162 Å for the orthorhombical and tetragonal Cu2+ centers, respectively. Meanwhile, the planar Cu2+-O2- bonds are found to experience the relative variation ΔR (≈0.102 Å) along the a- and b-axes for the orthorhombical Cu2+ center due to the Jahn-Teller (JT) effect. The theoretical EPR g factors based on the above local structures agree well with the observed values.

Enhancing irrigation water quality efficiently with potassium feldspar-derived adsorbent: Heavy metal detoxification and nutrient augmentation.

The pollution of Pb2+ and Cd2+ in both irrigation water and soil, coupled with the scarcity of vital mineral nutrition, poses a significant hazard to the security and quality of agricultural products. An economical potassium feldspar-derived adsorbent (PFDA) was synthesized using potassium feldspar as the main raw material through ball milling-thermal activation technology to solve this problem. The synthesis process is cost-effective and the resulting adsorbent demonstrates high efficiency in removing Pb2+ and Cd2+ from water. The removal process is endothermic, spontaneous, and stochastic, and follows the quasi-second-order kinetics, intraparticle diffusion, and Langmuir model. The adsorption and elimination of Pb2+ and Cd2+ is largely dependent on monolayer chemical sorption. The maximum removal capacity of PFDA for Pb2+ and Cd2+ at room temperature is 417 and 56.3 mg·g-1, respectively, which is superior to most mineral-based adsorbents. The desorption of Pb2+/Cd2+ on PFDA is highly challenging at pH≥3, whereas PFDA and Pb2+/Cd2+ are recyclable at pH≤0.5. When Pb2+ and Cd2+ coexisted, Pb2+ was preferentially removed by PFDA. In the case of single adsorption, Pb2+ was mainly adsorbed onto PFDA as Pb2SiO4, PbSiO3·xH2O, Pb3SiO5, PbAl2O4, PbAl2SiO6, PbAl2Si2O8, Pb2SO5, and PbSO4, whereas Cd2+ was primarily adsorbed as CdSiO3, Cd2SiO4, and Cd3Al2Si3O12. After the complex adsorption, the main products were PbSiO3·xH2O, PbAl2Si2O8, Pb2SiO4, Pb4Al2Si2O11, Pb5SiO7, PbSO4, CdSiO3, and Cd3Al2Si3O12. The forms of mineral nutrients in single and complex adsorption were different. The main mechanisms by which PFDA removed Pb2+ and Cd2+ were chemical precipitation, complexation, electrostatic attraction, and ion exchange. In irrigation water, the elimination efficiencies of Pb2+ and Cd2+ by PFDA within 10 min were 96.0 % and 70.3 %, respectively, and the concentrations of K+, Si4+, Ca2+, and Mg2+ increased by 14.0 %, 12.4 %, 55.7 %, and 878 %, respectively, within 60 min. PFDA holds great potential to replace costly methods for treating heavy metal pollution and nutrient deficiency in irrigation water, offering a sustainable, cost-effective solution and paving a new way for the comprehensive utilization of potassium feldspar.

Statistical comparison for assessing agreement between two mass spectrometric methods for the analysis of polychlorinated dibenzo-p-dioxins and furans (PCDDs/Fs) in contaminated soils.

A gas chromatography coupled to high-resolution mass spectrometry (GC-HR/MS) has been used as the standard method for the quantification of polychlorinated dibenzo-p-dioxins and furans (PCDDs/Fs), which are regulated at screening and action levels in the environment. However, several alternative methods have been attempted due to the disadvantage of its high cost. Although a gas chromatography with triple quadrupole mass spectrometry (GC-QqQ-MS/MS) has been used in a wide variety of sample matrices, showing that they are interchangeable, there has been a lack of comprehensive studies on statistical agreement with GC-HR/MS. In this study, a pairwise comparison of the total concentrations of PCDDs/Fs in 90 soil field samples obtained by two mass spectrometric methods was performed using the Passing-Bablok (P&B) regression and Bland-Altman (B&A) analysis for the method comparison. According to the result of the B&A analysis, the concentration range of PCDDs/Fs was between 98.2 and 1760 pg/g showed good agreement between two methods at the 95 % confidence level (CL). Although there was a large discrepancy between the two methods in the low concentrations (<16.5 pg/g of PCDDs/Fs), this result was similar to the P&B regression analysis. As the verification results by B&A and P&B regression analysis, the interchangeable concentration range between the two methods was confirmed to be adequate for the monitoring of PCDDs/Fs regulating levels in soils.

Preparation and Immobilization Mechanism of Red Mud/Steel Slag-Based Geopolymers for Solidifying/Stabilizing Pb-Contaminated Soil.

Pb-contaminated soil poses serious hazards to humans and ecosystems and is in urgent need of remediation. However, the extensive use of traditional curing materials such as ordinary Portland cement (OPC) has negatively impacted global ecology and the climate, so there is a need to explore low-carbon and efficient green cementitious materials for the immobilization of Pb-contaminated soils. A red mud/steel slag-based (RM/SS) geopolymer was designed and the potential use of solidifying/stabilizing heavy metal Pb pollution was studied. The Box-Behnken design (BBD) model was used to design the response surface, and the optimal preparation conditions of RM/SS geopolymer (RSGP) were predicted by software of Design-Expert 8.0.6.1. The microstructure and phase composition of RSGP were studied by X-ray diffractometer, Fourier transform infrared spectrometer, scanning electron microscopy and X-ray photoelectron spectroscopy, and the immobilization mechanism of RSGP to Pb was revealed. The results showed that when the liquid-solid ratio is 0.76, the mass fraction of RM is 79.82% and the modulus of alkali activator is 1.21, the maximum unconfined compressive strength (UCS) of the solidified soil sample is 3.42 MPa and the immobilization efficiency of Pb is 71.95%. The main hydration products of RSGP are calcium aluminum silicate hydrate, calcium silicate hydrate and nekoite, which can fill the cracks in the soil, form dense structures and enhance the UCS of the solidified soil. Pb is mainly removed by lattice immobilization, that is, Pb participates in geopolymerization by replacing Na and Ca to form Si-O-Pb or Al-O-Pb. The remaining part of Pb is physically wrapped in geopolymer and forms Pb(OH)2 precipitate in a high-alkali environment.

Lead Tolerance and Remediation Potential of Four Indocalamus Species in Lead-Contaminated Soil.

Indocalamus plants are low-growing shrubby bamboos with growth advantages, such as high biomass and strong resistance, and they are rich in germplasm resources in southern China. This study conducted soil lead (Pb) stress experiments on Indocalamus latifolius (Keng) McClure (LA), Indocalamus hunanensis B.M. Yang (HU), Indocalamus chishuiensis Y.L. Yang and Hsueh (CH) and Indocalamus lacunosus Wen (LC). Five Pb treatments (0, 500, 1000, 1500 mg·kg-1 Pb, and 1000 mg·kg-1 Pb + 1000 mg·kg-1 ethylenediamine tetraacetic acid (EDTA)) were established. EDTA was applied to explore the tolerance mechanism of different Indocalamus species after absorbing large amounts of heavy metals. The results were as follows: (1) under Pb treatment, the total relative biomass of LA, HU and LC was <100%, whereas the total relative biomass of CH was >100%; (2) after applying EDTA, the bioconcentration coefficient, translocation factor, and free proline content of the four Indocalamus species increased; and (3) the Pb mobility and distribution rates of the underground parts of the four Indocalamus species were consistently greater than those of the aboveground parts. The Pb mobility and distribution rates in the stems increased after applying EDTA, while those in the leaves decreased, as the plants tended to transfer Pb to their stems, which have lower physiological activity than their leaves.

Simultaneous Hg2+ and Pb2+ detection in water samples using an electrochemical aptasensor with dual signal amplification by exonuclease III and metal-organic frameworks.

Heavy metal pollution in the environment has become a significant global concern due to its detrimental effects on human health and the environment. In this study, we report an electrochemical aptasensor for the simultaneous detection of Hg2+ and Pb2+. Gold nanoflower/polyethyleneimine-reduced graphene oxide (AuNFs/PEI-rGO) was introduced on the surface of a gold electrode to improve sensing performance. The aptasensor is based on the formation of a T-Hg2+-T mismatch structure and specific cleavage of the Pb2+-dependent DNAzyme, resulting in a dual signal generated by the Exo III specific digestion of methylene blue (MB) labeled at the 3' end of probe DNA-1 and the reduction of the substrate ascorbic acid (AA) catalyzed by the signal label. The decrease of MB signal and the increase of AA oxidation peak was used to indicate the content of Hg2+ and Pb2+, respectively, with detection limits of 0.11 pM (Hg2+) and 0.093 pM (Pb2+). The aptasensor was also used for detecting Hg2+ and Pb2+ in water samples with good recoveries. Overall, this electrochemical aptasensor shows promising potential for sensitive and selective detection of heavy metals in environmental samples.

Pb(II) Adsorption Properties of a Three-Dimensional Porous Bacterial Cellulose/Graphene Oxide Composite Hydrogel Subjected to Ultrasonic Treatment.

A three-dimensional porous bacterial cellulose/graphene oxide (BC/GO) composite hydrogel (BC/GO) was synthesized with multi-layer graphene oxide (GO) as the modifier and bacterial cellulose as the skeleton via an ultrasonic shaking process to absorb lead ions effectively. The characteristics of BC/GO were investigated through TEM, SEM, FT-IR, NMR and Zeta potential experiments. Compared to bacterial cellulose, the ultrasonic method and the carboxyl groups stemming from GO helped to enhance the availability of O(3)H of BC, in addition to the looser three-dimensional structure and enriched oxygen-containing groups, leading to a significantly higher adsorption capacity for Pb(II). In this paper, the adsorption behavior of BC/GO is influenced by the GO concentration, adsorption time, and initial concentration. The highest adsorption capacity for Pb(II) on BC/GO found in this study was 224.5 mg/g. The findings implied that the pseudo-second-order model explained the BC/GO adsorption dynamics and that the data of its adsorption isotherm fit the Freundlich model. Because of the looser three-dimensional structure, the complexation of carboxyl groups, and the enhanced availability of O(3)H, bacterial cellulose exhibited a much better adsorption capacity.

Construction of heterogeneously connected cobalt-based MOF-COF and its application in highly selective separation of trace lead ions.

As a new type of porous crystalline composite material, MOF-COF has shown great advantages in metal separation. Herein, a CoMOF-COF was designed for highly selective separation of trace Pb2+ ions. The designed CoMOF-COF has a high density of nitrogen-oxygen functional groups and can selectively separate metal ions. There is a strong affinity between the designed CoMOF-COF material and metal Pb2+ ions, which can be attributed to the ordered heterogeneous porous structure and large amounts of nitrogen-and oxygen-containing functional groups. The composite showed high adsorption selectivity for Pb2+ ions and had adsorption capacity of 33 mg g-1, with high chemical stability. Based on this solid phase extraction material, a high sensitivity detection method for Pb2+ ions was established, which has the detection limit of 37.3 ng L-1, precision of 1.9 %. Linear detection range is 0.2-10 ng mL-1, and the detection of Pb2+ ions in actual water samples was realized. Through this study, it is proved that the strong affinity between the designed CoMOF-COF materials and metal Pb2+ ions can be attributed to the soft and hard acid-base theory, which reveals the structure-activity relationship between the porous heterostructure of such materials and metal separation, providing a highly selective separation material for the separation of other environmental pollutants.

Mechanisms of enhancing MgO for stabilization/solidification of Pb-contaminated red clay through CO2 sequestration.

Pb-contaminated soil poses significant environmental and health risks as well as soil stability issues. Research on sandy soils highlights CO2-enhanced reactive MgO as a promising solution for improving the solidification of Pb-contaminated soils. However, carbonation effects can differ markedly between soil types owing to varying soil properties. In this study, we evaluated the effects of CO2-enhanced reactive MgO on the engineering and environmental characteristics of Pb-contaminated red clay and explored its mechanism of carbonation solidification. The results showed that CO2-enhanced reactive MgO increased the strength of Pb-contaminated red clay to over 3 MPa within 1 h, which was approximately 25 times the strength of untreated soil (0.2 MPa) and significantly higher than that of reactive MgO-treated, uncarbonated soil (0.8 MPa). The pH of the carbonated soil (9-10) facilitated Pb2+ immobilization, and the increase over the initial parameter elevated the electrical conductivity value. Moreover, CO2-enhanced reactive MgO reduced the Pb2+ leaching concentration to below 0.1 mg/L, even at high Pb concentrations (10,000 mg/kg). Pb2+ transformed into lead carbonates during the carbonation process, with the hydrated magnesium carbonates forming a dense internal structure. This solidification mechanism included chemical precipitation, physical adsorption, and encapsulation. Notably, the carbonation time should be controlled within 1 h to prevent soil expansion. Together, these findings support the potential of CO2-enhanced reactive MgO for efficient and low-carbon application in the solidification of Pb-contaminated red clay.