Rationally designed porous polystyrene encapsulated zirconium phosphate nanocomposite for highly efficient fluoride uptake in waters

Efficient Removal and Recovery of Ag from Wastewater Using Charged Polystyrene-Polydopamine Nanocoatings and Their Sustainable Catalytic Application in 4-Nitrophenol Reduction

This study addresses the long-standing challenges of removing and recovering trace silver (Ag) ions from wastewater while promoting their sustainable catalysis utilization. We innovatively developed a composite material by combining charged sulfonated polystyrene (PS) with a PDA coating. This composite serves a dual purpose: effectively removing and recovering trace Ag+ from wastewater and enabling reused Ag for sustainable applications, particularly in the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The PS-PDA demonstrated exceptional selectivity to trace Ag+ recycling, which is equal to 14 times greater than the commercial ion exchanger. We emphasize the distinct roles of different charged functional groups in Ag+ removal and catalytic reduction performance. The negatively charged SO3H groups exhibited the remarkable ability to rapidly enrich trace Ag ions from wastewater, with a capacity 2-3 times higher than that of positively-N+(CH3)3Cl and netural-CH2Cl-modified composites; this resulted in an impressive 96% conversion of 4-NP to 4-AP within just 25 min. The fixed-bed application further confirmed the effective treatment capacity of approximately 4400 L of water per kilogram of adsorbent, while maintaining an extremely low effluent Ag+ concentration of less than 0.1 mg/L. XPS investigations provided valuable insights into the conversion of Ag+ ions into metallic Ag through the enticement of negatively charged SO3H groups and the in situ reduction facilitated by PDA. This breakthrough not only facilitates the efficient extraction of Ag from wastewater but also paves the way for its environmentally responsible utilization in catalytic reactions.

One-pot facile approach to design an efficient macro-porous polymeric matrix to remediate Hg(II)and Pb(II) from aqueous medium and its performance evaluation study by mathematical modelling

In the present scenario discharge of heavy-metal ions into water bodies is a global threat that is causing serious health hazards even in low concentrations. Thus, in order to remediate the heavy-metal [Hg(II) and Pb(II)] toxicity, an organic-inorganic hybrid functional porous metallo-polymeric network i. e, poly(Zirconyl methacrylate-co-1-vinyl imidazole) (pZrVIm) was fabricated via one-pot facile synthesis approach. The pZrVIm architecture has shown high removal efficiency for Hg(II) and Pb(II) aqueous medium even in extremely low quantities. Advanced instrumental techniques were used to characterize the structural and morphological characteristics of pZrVIm. Different experimental variables i.e., reaction time, pH, initial feed concentration, co-ion effects etc. were explored to examine adsorption behaviour. The maximum adsorption capacities (q_max) of pZrVIm5 were calculated as 168.06 and 162.34 mg g^-1 for Hg(II) and Pb(II) respectively by the Langmuir isotherm model. Data from isotherms showed that monolayer adsorption on a homogeneous surface is the rate-limiting stage and followed pseudo-second-order kinetic process. The Artificial Neural Network (ANN) modelling was used to validate kinetics and isotherm data which revealed high accuracy of the model with correlation coefficient values (R = 0.99). Various types of isotherm models such as Langmuir, Freundlich, Dubinin-Radushkevich, Temkin, Redlich-Peterson, Toth and Koble-Corigen have been studied to determine the adsorption phenomena. The pore diffusion model revealed breakthrough time of 91 h and 84 h, Hg(II) and Pb(II) with the feed concentration of 15 mg L^-1 respectively. The study revealed that pZrVIm5 has great potential for heavy metal ions remediation for water treatment.

Synchronous Removal of Arsenic and Fluoride from Aqueous Solution: A Facile Approach to Fabricate Novel Functional Metallopolymer Microspheres

Concurrence of arsenic (As) and fluoride (F^-) ions in groundwater is a serious concern due to their fatal effects. Herein, an attempt was made to fabricate quaternized poly(zirconyl dimethacrylate-co-vinylbenzyl chloride)] (ZrVBZ), a metallopolymeric microsphere in three-dimensional shape with a porous texture. The synthesized ZrVBZ was utilized for the synchronal removal of As and F^- from water. Techniques such as Fourier transform infrared spectroscopy, ¹³C-nuclear magnetic resonance, scanning electron microscopy, and Brunauer-Emmett-Teller surface area were used to characterize the ZrVBZ. The maximum adsorption capacity of ZrVBZ for both fluoride and arsenic (q _max F^-: 116.5 mg g^-1, q _max As(V): 7.0 mg g^-1, and q _max As(III): 6.5 mg g^-1) at given experimental conditions (adsorbents' dose: 0.250 g L^-1, feed of F^-: 50 mg L^-1, As(V)/As(III): 2000 μg L^-1, and pH: 7.0 ± 0.2) was ascribed to the porous spherical architecture with dual functional sites to facilitate adsorption. The adsorption followed pseudo-second-order kinetics with a correlation coefficient of 0.996, 0.997, and 0.990 for F^-, As(V), and As(III), respectively. The isotherm data fitted to the Langmuir isotherm model, and the maximum capacity was 121.5, 7.246, and 6.68 mg g^-1 for F^-, As(V), and As(III), respectively. The results of this study indicated that ZrVBZ could be used as an effective adsorbent for the simultaneous removal of F^-, As(V), and As(III) from an aqueous medium.

Transparency Change Mechanochromism Based on a Robust PDMS-Hydrogel Bilayer Structure

Hydrogels and polydimethylsiloxane (PDMS) are complementary to each other, since the hydrophobic PDMS provides a more stable and rigid substrate, while the water-rich hydrogel possesses remarkable hydrophilicity, biocompatibility, and similarity to biological tissues. Herein a transparent and stretchable covalently bonded PDMS-hydrogel bilayer (PHB) structure is prepared via in situ free radical copolymerization of acrylamide and allylamine-exfoliated-ZrP (AA-e-ZrP) on a functionalized PDMS surface. The AA-e-ZrP serves as cross-linking nano-patches in the polymer gel network. The covalently bonded structure is constructed through the addition reaction of vinyl groups of PDMS surface and monomers, obtaining a strong interfacial adhesion between the PDMS and the hydrogel. A mechanical-responsive wrinkle surface, which exhibs transparency change mechanochromism, is created via introducing a cross-linked polyvinyl alcohol film atop the PHB structure. A finite element model is implemented to simulate the wrinkle formation process. The implication of the present finding for the interfacial design of the PHB and PDMS-hydrogel-PVA trilayer (PHPT) structures is discussed.

Efficient phosphate sequestration for water purification by unique sandwich-like MXene/magnetic iron oxide nanocomposites

Rationally tailored intercalation for two-dimensional (2D) layered MXene materials has aroused extraordinary enthusiasm for broadening their applications. Herein, a novel sandwiched structural 2D MXene-iron oxide (MXI) material, prepared by selectively exfoliating an Al layer followed by magnetic ferric oxide intercalation, exhibits remarkable applicability to trace phosphate sequestration in the environmental remediation realm. Compared with commercial adsorbents, the resultant MXI nanocomposite exhibits a fast separation in 120 s together with the superior treatment capacities of 2100 kg and 2400 kg per kg in simulated and real phosphate wastewater applications, respectively. Such efficient sequestration is ascribed to the formation of a unique nano-ferric oxide morphology. The ultrafine nano-Fe2O3 particles can intercalate into the interior layers of MXene, widening the layer distance, and stimulating the available overlapping activated layers; while the efficient phosphate removal can be achieved by the strong complexation onto the embedded magnetic nano-Fe3O4 with a unique sandwich-structure as well as the stimulated Ti-O terminal within MXene. Apart from the fact that this approach suggests a complementary means for environmental remediation, it opens a new trajectory to achieve the functionalization of MXene.

Rational design of nanomaterials for water treatment

The ever-increasing human demand for safe and clean water is gradually pushing conventional water treatment technologies to their limits. It is now a popular perception that the solutions to the existing and future water challenges will hinge upon further developments in nanomaterial sciences. The concept of rational design emphasizes on 'design-for-purpose' and it necessitates a scientifically clear problem definition to initiate the nanomaterial design. The field of rational design of nanomaterials for water treatment has experienced a significant growth in the past decade and is poised to make its contribution in creating advanced next-generation water treatment technologies in the years to come. Within the water treatment context, this review offers a comprehensive and in-depth overview of the latest progress in rational design, synthesis and applications of nanomaterials in adsorption, chemical oxidation and reduction reactions, membrane-based separation, oil-water separation, and synergistic multifunctional all-in-one nanomaterials/nanodevices. Special attention is paid to the chemical concepts related to nanomaterial design throughout the review.

Development Trends in Porous Adsorbents for Carbon Capture

Accumulation of greenhouse gases especially CO2 in the atmosphere leading to global warming with undesirable climate changes has been a serious global concern. Major power generation in the world is from coal based power plants. Carbon capture through pre- and post- combustion technologies with various technical options like adsorption, absorption, membrane separations, and chemical looping combustion with and without oxygen uncoupling have received considerable attention of researchers, environmentalists and the stake holders. Carbon capture from flue gases can be achieved with micro and meso porous adsorbents. This review covers carbonaceous (organic and metal organic frameworks) and noncarbonaceous (inorganic) porous adsorbents for CO2 adsorption at different process conditions and pore sizes. Focus is also given to noncarbonaceous micro and meso porous adsorbents in chemical looping combustion involving insitu CO2 capture at high temperature (>400 °C). Adsorption mechanisms, material characteristics, and synthesis methods are discussed. Attention is given to isosteric heats and characterization techniques. The options to enhance the techno-economic viability of carbon capture techniques by integrating with CO2 utilization to produce industrially important chemicals like ammonia and urea are analyzed. From the reader's perspective, for different classes of materials, each section has been summarized in the form of tables or figures to get a quick glance of the developments.

Facile and Scalable Preparation of Graphene Oxide-Based Magnetic Hybrids for Fast and Highly Efficient Removal of Organic Dyes

This study reports the facile preparation and the dye removal efficiency of nanohybrids composed of graphene oxide (GO) and Fe3O4 nanoparticles with various geometrical structures. In comparison to previously reported GO/Fe3O4 composites prepared through the one-pot, in situ deposition of Fe3O4 nanoparticles, the GO/Fe3O4 nanohybrids reported here were obtained by taking advantage of the physical affinities between sulfonated GO and Fe3O4 nanoparticles, which allows tuning the dimensions and geometries of Fe3O4 nanoparticles in order to decrease their contact area with GO, while still maintaining the magnetic properties of the nanohybrids for easy separation and adsorbent recycling. Both the as-prepared and regenerated nanohybrids demonstrate a nearly 100% removal rate for methylene blue and an impressively high removal rate for Rhodamine B. This study provides new insights into the facile and controllable industrial scale fabrication of safe and highly efficient GO-based adsorbents for dye or other organic pollutants in a wide range of environmental-related applications.

Accelerated Sorption Diffusion for Cu(II) Retention by Anchorage of Nano-zirconium Dioxide onto Highly charged Polystyrene Material

The development of nanocomposite with strong adsorption ability exhibits great potential applications for environmental remediation. However, the pore blocking in preparation frequently constrains sorption diffusion, resulting in low utilization efficiency. Here we synthesized a new nano-ZrO₂/Polystyrene (NZO-PS) material tailored with a specific fixed SO₃-Na group to enhance Cu(II) removal. The NZO-PS exhibits efficient Cu(II) sequestration in a wide pH range (3.0–6.5) and preferential sorption performances. The efficient kinetic behavior and column applicability suggest the blocked pore channel is not a matter when presence of negatively charged moiety, which accelerates Cu(II) sorption diffusion and enrichment toward target active site. Moreover, the exhausted NZO-PS can be readily regenerated through HCl-NaCl binary solution. The preparation route can be extended to synthesize other functional composited materials. Simultaneously, the characteristics of simplicity, high-yield and regeneration provide some promising industrial merits.

Cyclic tetra[(indolyl)-tetra methyl]-diethane-1,2-diamine (CTet) impregnated hydrous zirconium oxide as a novel hybrid material for enhanced removal of fluoride from water samples

A hybrid material was prepared by incorporating cyclic tetra[(indolyl)-tetra methyl]-diethane-1,2-diamine (CTet) into hydrous zirconium oxide (HZO) via thorough mixing of previously prepared CTet in methanol and stirred for 7 h at 27 °C.

Unique lead adsorption behavior of activated hydroxyl group in two-dimensional titanium carbide

The functional groups and site interactions on the surfaces of two-dimensional (2D) layered titanium carbide can be tailored to attain some extraordinary physical properties. Herein a 2D alk-MXene (Ti3C2(OH/ONa)(x)F(2-x)) material, prepared by chemical exfoliation followed by alkalization intercalation, exhibits preferential Pb(II) sorption behavior when competing cations (Ca(II)/Mg(II)) coexisted at high levels. Kinetic tests show that the sorption equilibrium is achieved in as short a time as 120 s. Attractively, the alk-MXene presents efficient Pb(II) uptake performance with the applied sorption capacities of 4500 kg water per alk-MXene, and the effluent Pb(II) contents are below the drinking water standard recommended by the World Health Organization (10 μg/L). Experimental and computational studies suggest that the sorption behavior is related to the hydroxyl groups in activated Ti sites, where Pb(II) ion exchange is facilitated by the formation of a hexagonal potential trap.