An electroactive montmorillonite/polypyrrole ion exchange film: Ultrahigh uptake capacity and ion selectivity for rapid removal of lead ions

Efficient lead ion removal from aqueous solutions for wastewater treatment using a novel cross-linked alginate-rice husk ash-graphene oxide-chitosan nanocomposite

This research introduces an innovative composite, the cross-linked alginate-rice husk ash-graphene oxide-chitosan nanoparticles (CL-ARCG-CNP), designed for the effective adsorption of lead ions (Pb2+) in water treatment applications. Comprehensive characterization was performed using techniques such as Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), High-Resolution Transmission Electron Microscopy (HR TEM), Selected Area Electron Diffraction (SAED), Atomic Force Microscopy (AFM), Thermogravimetric Analysis (TGA), and Brunauer-Emmett-Teller (BET) analysis. These analyses revealed notable structural and morphological features. The CL-ARCG-CNP composite demonstrated a significant surface area of approximately 148.44 m2/g, achieving an impressive adsorption capacity of 242.5 mg/g and a removal efficiency of 95.2 % after 240 min of contact duration. The adsorption process conformed to the Freundlich isotherm model (R2: 0.998) and the pseudo-second-order kinetic model (R2: 0.9992). Thermodynamic studies confirmed the spontaneity and endothermic nature of the adsorption process. Reusability tests showed that the composite could be reused for up to five cycles with minimal loss in adsorption capacity. These findings indicate that the CL-ARCG-CNP composite is highly effective for the removal of Pb2+ ions from aqueous solutions, making it a promising material for wastewater treatment.

Fabrication and characterization of xanthan gum nanofibers reinforced with thiosemicarbazide: adsorption of Pb2+ from an aqueous medium

In this study, electrospinning was used to fabricate xanthan gum (XF) and thiosemicarbazide/xanthan gum (TXF) nanofibers crosslinked with ferric ions for effective Pb2+ adsorption. The produced nanofibers were investigated using several physicochemical methods. Both XF and TXF demonstrated thermal stability up to 800 °C, with mass losses of 79% and 75%, respectively. TXF had a surface area of 153.4 m2 g-1 and point of zero charge at pH 6.7. ATR-FTIR analysis revealed the existence of surface chemical functional groups such as -NH2, -NH, and -C[double bond, length as m-dash]S owing to thiosemicarbazide reinforcement. XF and TXF displayed maximum adsorption capacities of 211.65 and 289.18 mg g-1 at pH 6, 2.0 g L-1 nanofiber dose, 22 °C, and after 40 min of contact shaking time. The adsorption process was investigated using several nonlinear adsorption models as well as by desorption and reusability investigations. Thermodynamics examination demonstrated the spontaneous, endothermic physisorption of Pb2+ onto XF and TXF. Ethylenediaminetetraacetic acid was selected as the most efficient eluent for Pb2+ removal from the nanofiber surfaces, with desorption efficiencies of 100% and 97% for XF and TXF, respectively. TXF and XF revealed remarkable sustainability, with reductions in adsorption capacities of only 7% and 12% of the initial removal efficiency after 10 cycles of adsorption/desorption, respectively. As a solid adsorbent for the removal of heavy metal cations, the produced TXF nanofiber demonstrated great sustainability and environmental friendliness.

Simultaneous Removal of As(iii) and As(v) from Aqueous Solution by Using Iron-Functionalized Polythiophene: A Novel Approach toward Water Treatment

Arsenic contamination in groundwater poses a significant threat to human health, affecting millions worldwide. This study presents a novel approach for simultaneous remediation of both As(III) and As(V) by using iron-functionalized polythiophene (PTh@Fe) composites. The PTh@Fe composite was synthesized by a reduction process involving FeCl2/FeCl3 byproducts of polymerization, resulting in a highly efficient adsorbent for both As(III) and As(V) species. The investigation systematically examined key parameters influencing arsenic removal, including adsorbent dosage, pH, initial arsenic concentration, and contact time. The composite exhibited exceptional adsorption capacities, with maximum removal percentages of 98.7% for As(III) and 98.8% for As(V) under the optimized conditions. Thermodynamic and kinetic analyses suggested endothermic and spontaneous adsorption processes following a pseudo 2nd-order mechanism. Furthermore, the Langmuir isotherm model provided an excellent fit to the experimental data, with maximum adsorption capacities of 8.62 mg/g for As(V) and 7.57 mg/g for As(III). Density functional theory (DFT) calculations confirmed the feasibility of arsenic adsorption onto iron species in various oxidation states, offering valuable theoretical insights into the process. Furthermore, the composite demonstrated good reusability over multiple adsorption-desorption cycles and tolerance to coexisting anions, highlighting its practical applicability for water purification. This research demonstrates the potential of iron-functionalized polythiophene composites as a promising solution for addressing arsenic contamination in water sources, bridging the gap between innovative materials and theoretical understanding in environmental science and water treatment technologies.

Fabrication and characterization of Araucaria gum/calcium alginate composite beads for batch and column adsorption of lead ions

In this work, we developed five solid adsorbents such as calcium alginate beads (CG), Araucaria gum (AR) extracted from Araucaria heterophylla tree by chemical precipitation procedures, and Araucaria gum/calcium alginate composite beads (CR21, CR12, and CR11) prepared with different calcium alginate: Araucaria gum ratios (2:1, 1:2, and 1:1, respectively). The synthesized solid adsorbents were characterized utilizing TGA, XRD, nitrogen adsorption/desorption analysis, ATR-FTIR, pHPZC, swelling ratio, SEM, and TEM. Through the batch and column adsorption strategies, we evaluated the effect of adsorbent dose, pH, initial Pb (II) concentration, shaking time, bed height, and flow rate. The data of batch technique indicated that CR11 demonstrated a maximum batch adsorption capacity of 149.95 mg/g at 25 °C. Lead ions adsorption was well fitted by pseudo-second order and Elovich according to kinetic studies, in addition to Langmuir and Temkin models based on adsorption isotherm studies onto all the samples. Thermodynamic investigation showed that Pb (II) adsorption process is an endothermic, physical, and spontaneous process. The highest column adsorption capacity (161.1 mg/g) was achieved by CR11 at a bed height of 3 cm, flow rate of 10 mL/min, and initial Pb+2 concentration of 225 mg/L with 68 min as breakthrough time and 180 min as exhaustion time. Yoon-Nelson and Thomas models applied well the breakthrough curves of Pb (II) column adsorption. The maximum column adsorption capacity was decreased by 11.4 % after four column adsorption/desorption processes. Our results revealed that CR11 had an excellent adsorption capacity, fast kinetics, and good selectivity, emphasizing its potential for its applications in water treatment.

Silk fibroin/polyvinyl alcohol composite film loaded with antibacterial AgNP/polydopamine-modified montmorillonite; characterization and antibacterial properties

In this study, a kind of nanocomposite film was fabricated via combining silk fibroin, polyvinyl alcohol (SF/PVA) and AgNP/polydopamine-modified Montmorillonite (AgNP/PDA-Mt). The structural characteristics and properties of the SF/PVA/AgNP/PDA-Mt nanocomposites films were identified using X-ray diffraction (XRD), Thermal gravimetric analyzer (TGA), Fourier transform infrared spectroscopy (FTIR), EDS-mapping analyses and Scanning electron microscope (SEM). The results indicated enhanced thermal performance of SF/PVA/AgNP/PDA-Mt nanocomposites with increased AgNP/PDA-Mt weight. The nanocomposite film exhibited excellent antibacterial activity against E. coli and S. aureus. The 2 % SF/PVA/AgNP/PDA-Mt film showed the highest zone of inhibition with an average inhibition circle diameter of 26.1 mm against E. coli and 20.61 mm against S. aureus. Cytotoxicity test results indicated that the nanocomposites films were biocompatible with L929 cells with a 100 % survival rate, which can be considered as one of the advantages of new nanocomposites films. These findings suggest that SF/PVA/AgNP/PDA-Mt films have potential clinical applications in wound dressing and antibacterial biomedical applications.

Polypyrrole-Modified Nanocellulose Exhibits Superior Performance for Hg(II) Adsorption

Cellulose, a kind of polymer containing abundant functional groups, has widespread use in the adsorptive removal of environmental pollutants. An efficient and environmental friendly polypyrrole (PPy) coating approach is employed to modify the agricultural by-product straw derived cellulose nanocrystal (CNC) into excellent property adsorbents for removing the heavy metal ion of Hg(II). The FT-IR and SEM-EDS results demonstrated that PPy is formed on the surface of CNC. Consequently, the adsorption measurements proved that the obtained PPy-modified CNC (CNC@PPy) possesses a remarkably enhanced Hg(II) adsorption capacity of 1095 mg g^-1, owing to a plentiful functional group of doped Cl element on the surface of CNC@PPy by forming Hg₂Cl₂ precipitate. The results of the study suggest that the Freundlich model is more effective than the Langmuir model at describing the isotherms, while the pseudo-second order kinetic model is better suited to correlating with the experimental data compared to the pseudo-first order model. Further, the CNC@PPy exhibits an outstanding reusability, capable of maintaining 82.3% of its original Hg(II) adsorption capacity after five successive adsorption cycles. The findings of this work reveal a method to convert the agricultural by-product into high performance environmental remediation materials.

Biomimetic Polylactic Acid Electrospun Fibers Grafted with Polyethyleneimine for Highly Efficient Methyl Orange and Cr(VI) Removal

The rapid growth of industrialization has resulted in the release of large quantities of pollutants into the environment, especially dyes and heavy metals, which are environmentally hazardous for humans and animals. It is considered as the most promising and environmentally friendly route to develop green materials by using the green modification method, which has no negative impact on the environment. In this work, the green material of polylactic acid (PLA) was used as the substrate material, and a novel modification method of polydopamine (PDA)-assisted polyethyleneimine (PEI) grafting was developed. The electrospun PLA fibers are mainly composed of stereocomplex crystallites, which were achieved via the electrospinning of poly(l-lactic acid) and poly(d-lactic acid). The water-soluble PEI was grafted onto the PDA-modified PLA fibers through the glutaraldehyde-assisted cross-linking reaction. The prepared composite fibers can be degraded, which is environmentally friendly and meets the requirements of sustainable development. The potential application of such PLA composite fibers in wastewater treatment was intensively evaluated. The results show that at appropriate fabrication conditions (PDA concentration of 3 g·L^-1 and a PEI molecular weight of 70,000 g·mol^-1), the composite fibers exhibit the maximum adsorption capacities of 612 and 398.41 mg·g^-1 for methyl orange (MO) and hexavalent chromium [Cr(VI)], respectively. Simultaneously, about 64.79% of Cr(VI) adsorbed on the composite fibers was reduced to Cr(III). The above results show that the PLA composite fibers have a good development prospect in the field of wastewater treatment.

Application of Polypyrrole-Based Electrochemical Biosensor for the Early Diagnosis of Colorectal Cancer

Although colorectal cancer (CRC) is easy to treat surgically and can be combined with postoperative chemotherapy, its five-year survival rate is still not optimistic. Therefore, developing sensitive, efficient, and compliant detection technology is essential to diagnose CRC at an early stage, providing more opportunities for effective treatment and intervention. Currently, the widely used clinical CRC detection methods include endoscopy, stool examination, imaging modalities, and tumor biomarker detection; among them, blood biomarkers, a noninvasive strategy for CRC screening, have shown significant potential for early diagnosis, prediction, prognosis, and staging of cancer. As shown by recent studies, electrochemical biosensors have attracted extensive attention for the detection of blood biomarkers because of their advantages of being cost-effective and having sound sensitivity, good versatility, high selectivity, and a fast response. Among these, nano-conductive polymer materials, especially the conductive polymer polypyrrole (PPy), have been broadly applied to improve sensing performance due to their excellent electrical properties and the flexibility of their surface properties, as well as their easy preparation and functionalization and good biocompatibility. This review mainly discusses the characteristics of PPy-based biosensors, their synthetic methods, and their application for the detection of CRC biomarkers. Finally, the opportunities and challenges related to the use of PPy-based sensors for diagnosing CRC are also discussed.

Design of Zr-MOFs by Introducing Multiple Ligands for Efficient and Selective Capturing of Pb(II) from Aqueous Solutions

The existence of lead ions seriously affects the quality of many metal products in metallurgical enterprises. Currently, the various methods of lead-ion removal tried by researchers will affect valuable metals in the removal process, thus resulting in low economic efficiency. In this study, a novel metal-organic framework adsorbent (UiO-FHD) which efficiently and selectively captures lead ions is developed by introducing multiple ligands. The maximum adsorption capacity of lead ions is 433.15 mg/g at pH 5. The adsorption process accords with the pseudo-second-order kinetic and the Langmuir isotherm models at room temperature. Thermodynamic experiments indicate that the removal of Pb(II) is facilitated by appropriate temperature reduction. The performance tests indicate that UiO-FHD maintains a high removal rate of 90.35% for Pb(II) after four consecutive adsorption-desorption cycles. The distribution coefficient of lead ions (26.7 L/g) shows that UiO-FHD has excellent selective adsorption for lead ions. It is revealed that the chelation of the sulfhydryl groups and the electrostatic interaction of the hydroxyl groups are the dominant factors to improve the removal rate of Pb(II) by density functional theory calculations. This study clarifies the value of self-designed novel organic ligands in metal-organic framework materials that selectively capture heavy-metal ions.