Micro-Nanocomposites in Environmental Management

Recent advancement of nano-biochar for the remediation of heavy metals and emerging contaminants: Mechanism, adsorption kinetic model, plant growth and development

Even though researches have shown that biochar can improve soil-health and plant-growth even in harsh environments and get rid of harmful heavy metals and new contaminants, it is still not sustainable, affordable, or effective enough. Therefore, scientists are required to develop nanomaterials in order to preserve numerous aquatic and terrestrial species. The carbonaceous chemical known as nano-biochar (N-BC) can be used to get rid of metal contamination and emerging contaminants. However, techniques to reduce hetero-aggregation and agglomeration of nano-biochar are needed that lead to the emergence of emerging nano-biochar (EN-BC) in order to maximise its capacity for adsorption of nano-biochar. To address concerns in regards to the expanding human population and sustain a healthy community, it is imperative to address the problems associated with toxic heavy metals, emerging contaminants, and other abiotic stressors that are threatening agricultural development. Nano-biochar can provide an effective solution for removal of emerging contaminants, toxic heavy metals, and non-degradable substance. This review provides the detailed functional mechanistic and kinetics of nano-biochar, its effectiveness in promoting plant growth, and soil health under abiotic stress. Nonetheless, this review paper has comprehensively illustrated various adsorption study models that will be employed in future research.

"Quasi-In Situ Synthesis of Oxygen Vacancy-Enriched Strontium Iron Oxide Supported on Boron-Doped Reduced Graphene Oxide to Elevate the Photocatalytic Destruction of Tetracycline"

The efficient use of visible light is necessary to take advantage of photocatalytic processes in both indoor and outdoor circumstances. Precisely manipulating the in situ growth method of heterojunctions is an effective way to promote photogenerated charge separation. Herein, the SrFeO₃@B-rGO catalyst was prepared by an in situ growth method. At a loading of 10 wt % B-rGO, the nanocomposites revealed an excellent morphology and thermal, optical, electrochemical, and mechanical properties. X-ray diffraction analysis revealed the cubic spinel structure and a space group of Pm̅3m for SrFeO₃. High-resolution scanning electron microscopy and high-resolution transmission electron microscopy show the core-shell formation between SrFeO₃ and B-rGO. Furthermore, density functional theory of SrFeO₃ was performed to find its band structure and density of states. The SrFeO₃@B-rGO nanocomposite shows the degradation rate of tetracycline (TC) reaching 92% in 75 min and the highest rate constant of 0.0211 min^-1. To improve the catalytic removal rate of antibiotics, the efficiency of e^- and h ⁺ separation must be improved, as well as the generation of additional radicals. Radical trapping tests and the electron paramagnetic resonance method indicated that the combination of Fe²⁺ and Fe³⁺ in SrFeO₃ effectively separated e^- and h⁺ while also promoting the development of the superoxide anion (^•O₂^-) to accelerate TC degradation. The entire TC degradation pathway using high-performance liquid chromatography and its mechanism were discussed. As a whole, this study delineates that photocatalysis is a viable strategy for the treatment of environmental antibiotic wastewater.

Ultra-fast Piezocatalysts Enabled By Interfacial Interaction of Reduced Graphene Oxide/MoS2 Heterostructures

The catalytic activity has been investigated in 2D materials, and the unique structural and electronic properties contribute to their success in conventional heterogeneous catalysis. Heterojunction-based piezocatalysis has attracted increasing attention due to the band-structure engineering and the enhanced charge carrier separation by prominent piezoelectric effect. However, the piezocatalytic behavior of van der Waals (vdW) heterostructures is still unknown, and the finite active sites, catalyst poisoning, and poor conductivity are challenges for developing good piezocatalysts. Herein, a reduced graphene oxide (rGO)-MoS₂ heterostructure is rationally designed to tackle these challenges. The heterostructure shows a record-high piezocatalytic degradation rate of 1.40 × 10² L mol^-1 s^-1 , which is 7.86 times higher than MoS₂ nanosheets. Piezoresponse force microscope measurements and density functional theory calculation reveal that the coupling between semiconductive and piezoelectric properties in the vdW heterojunction is vital to break the metallic state screening effect at the MoS₂ edge for keeping the piezoelectric potential. The dynamic charges generated by MoS₂ and the fast charge transfer in rGO activate and maintain catalytically active sites for pollutant degradation with an ultra-fast rate and good stability. The working mechanism opens new avenues for developing efficient catalysts significant to wastewater treatments and other applications.

Scalable Fabrication of Electrospun True-Nanoscale Fiber Membranes for Effective Selective Separation

Electrospun fibers have received wide attention in various fields ranging from the environment and healthcare to energy. However, nearly all electrospun fibers suffer from a pseudonanoscale diameter, resulting in fabricated membranes with a large pore size and limited separation performance. Herein, we report a novel strategy based on manipulating the equilibrium of stretch deformation and phase separation of electrospun jets to develop true-nanoscale fibers for effective selective separation. The obtained fibers present true-nanoscale diameters (∼67 nm), 1 order of magnitude less than those of common electrospun fibers, which endows the resultant membranes with remarkable nanostructural characteristics and separation performances in areas of protective textiles (waterproofness of 113 kPa and breathability of 4.1 kg m^-2 d^-1), air filtration (efficiency of 99.3% and pressure drop of 127.4 Pa), and water purification (flux of 81.5 kg m^-2 h^-1 and salt rejection of 99.94%). This work may shed light on developing high-performance separation materials for various applications.

Excellent removal performance of 4,4'-biphenyldicarboxaldehyde m-phenylenediamine Schiff base magnetic polymer towards phenanthrene and 9-phenanthrol: Experimental, modeling and DFT calculations studies

Phenanthrene (PTH) and 9-phenanthrol (9-PTH) exhibited severe health threats and ecological hazards, for this reason, exploring a high-efficient removing strategy for PTH and 9-PTH could be considered of great urgency. Herein the 4,4'-biphenyldicarboxaldehyde m-phenylenediamine Schiff base magnetic polymer (magnetic BIPH-PHEN) was successfully fabricated via Schiff base polycondensation reaction and the subsequently one-pot embedded method. The mutual aromatic nucleus of BIPH-PHEN polymer and PTH/9-PTH could form π-π interaction, thus improving the capture ability, the embedded Fe₃O₄ nanoparticles provided the possibility for rapid separation. The physical and chemical properties of the magnetic BIPH-PHEN were systematically characterized. The removal rate of magnetic BIPH-PHEN towards PTH and 9-PTH was 85.65 % and 98.52 %, respectively (PTH or 9-PTH: 8 mg/L; Adsorbent: 0.2 g/L). The DFT calculations including energy calculations and electrostatic potential distribution analyzed the different bonding modes and proposed the most possible bonding modes in the adsorbent/adsorbate system. Moreover, the LUMO and HOMO orbits combined with energy gaps analysis proved the existence and specific types of the π-π interaction. The monolayer adsorption occurred on the homogeneous magnetic BIPH-PHEN surface, simultaneously the chemisorption was dominant. This work not only proposed new sights on assembling magnetic Schiff base polymer for removing polycyclic aromatic hydrocarbons, but also provided a deeper understanding of intramolecular interactions.

Insulator polymers achieve efficient catalysis under visible light due to contact electrification

Under the limitation of the carrier yield and mobility of semiconductor photocatalysts and the reaction domain, it seems that the photocatalytic efficiency cannot be greatly improved. Here, an efficient contact-electro-catalysis (CEC) system based on droplet triboelectric nanogenerator (TENG) is developed. Instead of using traditional semiconductor catalysts, the electric charge transferred during the electrification process of the contact between water droplets and polytetrafluoroethylene (PTFE) is used to participate in catalysis, and the output electrical signal can also monitor the degree of catalysis. The important role of light in the circulation of this CEC system is studied and discussed for the first time. It is proved that the contact electrification at the liquid-solid interface is accompanied by the generation of a large number of strong oxidizing radicals. The efficient transport of charge carriers driven by mechanical force and the active oxygen species distributed in the whole domain greatly improve the degradation rate of dyes. The experimental data show that the degradation efficiency of crystal violet (CV) reaches 90% within 38 s, and the rate constant k is as high as 3.7 min^-1. This is a breakthrough in the field of catalysis.

Synthesis of Two Porous CdS Rods by Anion Exchange Method and Their Photocatalytic Properties

Semiconductor materials with pore structure have excellent physicochemical properties for photocatalytic reactions. Here, the one-step vulcanization of Cd-based MOF solid rods was successfully developed to synthesize two kinds of CdS rods with pore structure: hollow rods (HRs) and mesoporous rods (MRs). Among the three catalysts, the CdS HRs showed the highest photocatalytic efficiency, which could remove about 96.0% of RhB in 30 min under visible light irradiation. The enhanced photocatalytic activity of CdS HRs benefits from its novel hollow structure, which enhances the visible light absorption capability and the separation efficiency of photogenerated electron-hole pairs. The successful synthesis of CdS HRs has guiding significance for the design and synthesis of other hollow structures with high photocatalytic activity.

A new visual and stable fluorescent Cu-MOF as a dual-function sensor for glyphosate and Cr2O72−

A new visual and stable Cu-MOF as a dual-function sensor with high sensitivity for the detection of glyphosate and Cr2O72−.

Robust and durable liquid-repellent surfaces

This review provides a comprehensive summary of characterization, design, fabrication, and application of robust and durable liquid-repellent surfaces.

A review on the preparation, microstructure, and photocatalytic performance of Bi2O3 in polymorphs

In recent years, the semiconductor bismuth oxide (Bi₂O₃) has attracted increasing attention as a potential visible-light-driven photocatalyst due to its simple composition, relatively narrow bandgap (2.2-2.8 eV), and high oxidation ability with deep valence band levels. Owing to the symmetry of its unit cell, Bi₂O₃ exists in more than one crystal form and exhibits phase-dependent photocatalytic properties. However, the phase-selective synthesis of Bi₂O₃ is a complex process, and its phase transformation usually occurs in a wide temperature range. Therefore, the development of Bi₂O₃ phases with a controllable microstructure and good photocatalytic properties is a great challenge. Hundreds of articles have been reported on the phase-selective synthesis and photocatalytic performance of Bi₂O₃. However, an interacting and critical review has rarely been reported, and thus it is essential to fill the gap in the literature. In this review, the phase-dependent photocatalytic performance of Bi₂O₃ is presented in detail. The phase-selective synthesis and temperature-dependent phase stability of highly active Bi₂O₃ are explored. The phase junction in Bi₂O₃ is reviewed, and the future perspective with an outlook on contemporary challenges is provided finally.

Novel Porous Rhodium Metal-Organic Aerogel for Efficient Removal of Organic Dyes and Catalysis of Si-H Insertion Reactions

Metal-organic gels (MOGs) are attracting increasing attention for removal of organic dyes from aqueous solution and for catalysis of Si-H insertion reactions. Herein, we report that a reaction of porphyrin derivative 1 with Rh₂(OAc)₄ generates stable metal-organic gels and subsequent subcritical carbon dioxide drying affords metal-organic aerogels. Owing to their micro- and mesoporosity, the aerogels adsorbed dyes. Moreover, aerogel I catalyzed Si-H insertion reactions to give organosilicon compounds in high yields.

A rational design of layered metal-organic framework towards high-performance adsorption of hazardous organic dye

Water pollution originating from organic dyes is endangering the survival and development of society; however, adsorbents with high capacity (>5000 mg g^-1) for the fast removal (≤30 min) of Congo Red (CR) in aqueous solution have been not reported to date. In the present work, an acid-base stably layered MOF, [Cd(H₂L)(BS)₂]_n·2nH₂O (L-MOF-1, H₂L = N1,N2-bis(pyridin-3-ylmethyl)ethane-1,2-diamine, BS = benzenesulfonate), was hydrothermally prepared. L-MOF-1 exhibited high-performance adsorption of CR in aqueous solution at room temperature. The experimental adsorption capacity of the L-MOF-1 adsorbent towards CR reached up to about 12 000 mg g^-1 in 20 min in the pH range of 2.2-4.7, which is the best adsorbent with the highest capacity and fastest adsorption of CR to date. The spontaneous adsorption process can be described by the pseudo-second-order kinetic and Langmuir isotherm models. Meanwhile, the L-MOF-1 absorbent possessed a highly positive zeta potential in acid condition (even at pH = 2.2, zeta potential = 36.2 mV). Its good adsorption performance mainly originates from its strong electrostatic attraction with CR in acidic condition, together with diverse hydrogen bonds and ππ stacking interactions. Furthermore, the L-MOF-1 absorbent exhibited good selectivity and could be reused five times through simply washing, where its adsorption efficiency was hardly affected. Therefore, L-MOF-1 is a potential absorbent for effectively removing CR from dye wastewater.

Hierarchical fabrication of hollow Co2P nanocages coated with ZnIn2S4 thin layer: Highly efficient noble-metal-free photocatalyst for hydrogen evolution

The directional synthesis of transition metal phosphides was considered to be an effective strategy to solve the overdependence of noble metals on photocatalytic hydrogen evolution (PHE) reactions. Inspiringly, this work reported a facile method for constructing hollow Co₂P nanocages (Co₂P NCGs) that derived from ZIF-67 by calcining and phosphiding procedure in nitrogen atmosphere to act as non-noble metal cocatalysts. Followed with further coating thin-layered ZnIn₂S₄ (ZIS) on the surface of Co₂P NCGs through a hydrothermal reaction, the hierarchical robust Co₂P/ZnIn₂S₄ nanocages (Co₂P/ZIS NCGs) were then delicately fabricated as efficient photocatalysts for PHE reactions. The uniquely hollow structure of Co₂P NCGs largely diffused the photogenerated chargers that induced from ZIS and the closely interfacial contact significantly promoted the separation and transfer of electrons from ZIS to Co₂P according to density functional theory (DFT) calculation, synergistically resulting in an efficient hydrogen generation performance. PHE results showed that an efficient H₂ evolution rate of 7.93 mmol/g/h over 10% Co₂P/ZIS NCGs was achieved, about 10 times higher than that of pristine ZnIn₂S₄. More importantly, the hierarchically hollow Co₂P/ZIS NCGs exhibited ascendant PHE activity in comparison with that of 1% noble metal (Pt, Au, Ag) loaded ZnIn₂S₄ with superior sustainability, all indicating the efficient and stable photocatalysts of Co₂P/ZIS NCGs for PHE reactions.

Hierarchically Porous WO3/CdWO4 Fiber-in-Tube Nanostructures Featuring Readily Accessible Active Sites and Enhanced Photocatalytic Effectiveness for Antibiotic Degradation in Water

The intentional design and construction of photocatalysts containing heterojunctions with readily accessible active sites will improve their ability to degrade pollutants. Herein, hierarchically porous WO₃/CdWO₄ fiber-in-tube nanostructures with three accessible surfaces (surface of core fiber and inner and outer surfaces of the porous tube shell) were fabricated by an electrospinning method. This WO₃/CdWO₄ heterostructure, assembled by interconnected nanoparticles, displays good photocatalytic degradation of ciprofloxacin (CIP, 93.4%) and tetracycline (TC, 81.6%) after 90 min of simulated sunlight irradiation, much higher than the pristine WO₃ (<75.3% for CIP and <53.6% for TC) or CdWO₄ materials (<58.9% for CIP and <39.5% for TC). The WO₃/CdWO₄ fiber-in-tube promotes the separation of photoinduced electrons and holes and also provides readily accessible reaction sites for photocatalytic degradation. The dominant active species determined by trapping active species and electron paramagnetic resonance were hydroxyl radicals followed by photogenerated holes and superoxide anions. The WO₃/CdWO₄ materials formed a Z-scheme heterojunction that generated superoxide anion and hydroxyl radicals, leading to degradation of antibiotics (CIP and TC) via photocatalysis in aqueous solution.

Enhanced Piezocatalytic Activity of Sr0.5Ba0.5Nb2O6 Nanostructures by Engineering Surface Oxygen Vacancies and Self-Generated Heterojunctions

Piezocatalysis provides a promising strategy for directly converting weak mechanical energy into chemical energy. In this work, we report a simple one-step hydrogen reduction route for the simultaneous generation of surface defects and heterojunctions in Sr_0.5Ba_0.5Nb₂O₆ nanorods fabricated by a molten salt synthesis method. The as-fabricated Sr_0.5Ba_0.5Nb₂O₆/Sr₂Nb₂O₇ nanocomposites with controllable oxygen vacancies exhibited excellent piezocatalytic activity under ultrasonic vibration, with an about 7 times enhancement of the rate constant (k = 0.0395 min^-1) for rhodamine B degradation and an about 10 times enhancement of the water-splitting efficiency for hydrogen generation (109.4 μmol g^-1 h^-1) for the optimized sample (H₂ annealed at 500 °C) compared to pristine Sr_0.5Ba_0.5Nb₂O₆ nanorods. This work demonstrates the essential role of a well-modulated oxygen vacancy concentration in the piezocatalytic activity and provides an inspiring guide for designing self-generated heterojunction piezocatalysts.

Development of Polymeric Membranes for Oil/Water Separation

In this work, the treatment of oily wastewater was investigated using developed cellulose acetate (CA) membranes blended with Nylon 66. Membrane characterization and permeation results in terms of oil rejection and flux were compared with a commercial CA membrane. The solution casting method was used to fabricate membranes composed of CA and Nylon 66. Scanning Electron Microscopy (SEM) analysis was done to examine the surface morphology of the membrane as well as the influence of solvent on the overall structure of the developed membranes. Mechanical and thermal properties of developed blended membranes and a commercial membrane were examined by thermogravimetric analysis (TGA) and universal (tensile) testing machine (UTM). Membrane characterizations revealed that the thermal and mechanical properties of the fabricated blended membranes better than those of the commercial membrane. Membrane fluxes and rejection of oil as a function of Nylon 66 compositions and transmembrane pressure were measured. Experimental results revealed that the synthetic membrane (composed of 2% Nylon 66 and Dimethyl Sulfoxide (DMSO) as a solvent) gave a permeate flux of 33 L/m²h and an oil rejection of around 90%, whereas the commercial membrane showed a permeate flux of 22 L/m²h and an oil rejection of 70%.

Facile Removal of Phytochromes and Efficient Recovery of Pesticides Using Heteropore Covalent Organic Framework-Based Magnetic Nanospheres and Electrospun Films

Nontargeted analysis of food safety requires selective removal of interference matrices and highly efficient recovery of chemical hazards. Porous materials such as covalent organic frameworks (COFs) show great promise in selective adsorption of matrix molecules via size selectivity. Considering the complexity of interference matrices, we prepared crystalline heteropore COFs whose two kinds of pores have comparable sizes to those of several common phytochromes, main interference matrices in vegetable sample analysis. By controlling the growth of COFs on the surface of Fe3O4 nanoparticles or by utilizing a facile co-electrospinning method, heteropore COF-based magnetic nanospheres or electrospun nanofiber films were prepared, respectively. Both the nanospheres and the films maintain the dual-pore structures of COFs and show good stability and excellent reusability. Via simple magnetic separation or immersion operation, respectively, they were successfully used for the complete removal of phytochromes and highly efficient recovery of 15 pesticides from the extracts of four vegetable samples, and the recoveries are in the range of 83.10-114.00 and 60.52-107.35%, respectively. Film-based immersion operation gives better sample pretreatment performance than the film-based filtration one. This work highlights the great application potentials of heteropore COFs in sample pretreatment for nontargeted analysis, thus opening up a new way to achieve high-performance sample preparation in many fields such as food safety analysis, environment monitoring, and so on.

Artificial Cytochrome c Mimics: Graphene Oxide-Fe(III) Complex-Coated Molecularly Imprinted Colloidosomes for Selective Photoreduction of Highly Toxic Pollutants

Our previous works showed that the molecularly imprinted TiO₂ photocatalyst has been one of the most efficient materials for selective photooxidation of highly toxic organic pollutants (HTOPs) from complicated wastewater. However, some highly toxic pollutants (e.g., heavy metals) are very stable under the oxidizing environment. Therefore, the design of enzyme-like catalysts to selectively reduce highly toxic pollutants is extremely needed. In this work, inspired by the bioreduction ability of cytochrome c (cyt c, a heme containing metalloprotein), we presented a simple and efficient way to generate an artificial cyt c mimic (ACM) using graphene oxide (GO)-Fe(III) complex-coated molecularly imprinted colloidosomes. Prior to loading of Fe(III) centers to GO for constructing ACMs, GO-coated molecularly imprinted colloidosomes were synthesized via Pickering emulsion polymerization. Similar to a nature cyt c, the ACM contained both the molecular recognition element (molecularly imprinted cavity) and the non-heme electron sink (GO-Fe(III) complex), which resulted in the ACMs having good selectivity toward the enzyme-like reduction of the highly toxic target Cr(VI). Moreover, by using HepG2 cells as model cells, the Cr(VI) solution after treating by ACMs was proved to be safe and nontoxic. To confirm that the present method was universal for constructing ACMs, various GO-Fe(III) complex-coated molecularly imprinted colloidosomes, which could selectively photoreduce other highly toxic inorganic ions and organic pollutants, were also investigated. The ACMs described herein will act as a vector that encourages the design of more functional non-heme enzymes in sensing, environmental separation, clinical diagnose, and delivery of therapeutic agents.

Construction of a hierarchical-structured MgO-carbon nanocomposite from a metal–organic complex for efficient CO2 capture and organic pollutant removal

A hierarchical-structured porous MgO/C nanocomposite derived from a metal–organic complex performs as a remarkable adsorbent for CO₂ adsorption and organic pollutant removal.

β-Cyclodextrin-based hollow nanoparticles with excellent adsorption performance towards organic and inorganic pollutants

In this work, β-cyclodextrin (β-CD) based hollow nanoparticles (denoted as β-CDHN) with abundant active sites and high specific surface area were first fabricated via a facile one-step method. The β-CDHN presented a maximum adsorption capacity of 2080.35, 427.35 and 120.48 mg g^-1 towards the cationic dye methylene blue (MB), heavy metal ions (Pb²⁺) and bisphenol A (BPA), respectively, much higher than those of many other adsorbents. Furthermore, β-CDHN also exhibited fast adsorption kinetics towards these pollutants with adsorption rate constants 6 to 200 times higher than those of activated carbon and other β-CD-based adsorbents, meaning the former can remove these pollutants at a much faster adsorption rate than the latter adsorbents. More importantly, the removal efficiency of these pollutants on β-CDHN almost remained stable after 10 regeneration cycles with favorable recyclability. The prepared β-CDHN show great potential in practical applications due to their low costs and high efficiency in the treatment of organic and inorganic pollutants from wastewater.

Hydrophobic nano sponge for efficient removal of diesel fuel from water and soil

Diesel fuel (DF)-contamination remediation has aroused increasing concern in environmental field. In our work, nano sponge was modified by silylation of amino silicon oil (ASO) and aminopropyltriethoxysilane (APTES) to obtain hydrophobic nano sponge (SPAA). SPAA possessed a micro/nano network structure and could efficiently adsorb DF through hydrophobic polysiloxane group. The results revealed that SPAA could effectively remove DF and control its migration in water and soil under various conditions. Importantly, SPAA could inhibit the harmful effect of DF on the growth of plants, earthworms, and fish. Therefore, this work provides a promising and low-cost approach for removal of DF from water and soil, which might have a potential application value.

Durable and Robust Self-Healing Superhydrophobic Co-PDMS@ZIF-8-Coated MWCNT Films for Extremely Efficient Emulsion Separation

The discharge of large amounts of sewage has caused enormous damage to the environment and human health. There is an urgent need for efficient and environmentally friendly materials to deal with such troubles. Materials with emulsion separation have attracted everyone's attention. In this study, zeolitic imidazolate framework (ZIF)-8- and Co-polydimethylsiloxane (PDMS)-modified multiwalled carbon nanotube films were fabricated. First, the surface of the nanotube films was modified with ZIF-8 by in situ growth, and then a Co-PDMS layer was added by dip coating. The membrane has excellent wettability, and it is superhydrophobic and superoleophilic in air. The separation efficiency of water-in-oil emulsions reaches more than 99.9%, and it has an outstanding separation ability for corrosive emulsions. Moreover, the membrane has an excellent self-healing ability, and it can rapidly heal at normal temperature after being damaged. This makes the film more suitable for practical oily wastewater treatment. We performed related research and propose a possible self-healing mechanism.

Ion exchange collaborating coordination substitution: More efficient Cr(VI) removal performance of a water-stable CuII-MOF material

An unusual water-stable cationic metal-organic framework {[Cu(L)_0.5(bpe)(H₂O)](NO₃)•(H₂O)_0.5}_n (1) (H₄L = bis(3,5-dicarboxypyridinium)-p-xylylene) was synthesized, which was developed into an effective capture material for removal chromate from water. The results show that this material efficiently traps HCrO₄^- pollutant ions via single-crystal to single-crystal (SCSC) coordination substitution process. The HCrO₄^- uptake capacity of 1 is high to 190 mg/g. Meaningfully, the structure of 1-HCrO₄ ({[Cu(L)_0.5(bpe)(HCrO₄)]}_n) can be accurately obtained by single-crystal X-ray diffraction, where the chromate enter the framework to form stable coordination with central metal ions Cu²⁺. This is the first example of a stable coordination between chromate and the framework during the capture process. The captured HCrO₄^- are not dissociated easily into the solution due to the coordination bond. This interaction makes the enrichment of HCrO₄^- more stable and the capture capacity excellent. Furthermore, the HCrO₄^- releasing process displays good regeneration in a single crystal state, which further elaborates the reversible SCSC transformation. The mechanism of Cr(VI) removal was also confirmed by DFT calculation studies. This work provides a new way to design and develop efficient MOF capture materials.

Luffa sponge-derived hierarchical meso/macroporous boron nitride fibers as superior sorbents for heavy metal sequestration

Boron nitride (BN) has received tremendous attention as a promising adsorbent material. However, unsatisfactory uptake capacities over heavy metal ions limit their practical applications. Herein, we have synthesized a novel hierarchical meso/macroporous BN fibers (MBNFs) via a simple carbothermal reduction method using luffa sponge as a template. The as-obtained MBNFs comprise densely arranged parallel macrochannels on a micrometer scale, with mesopores on the surface of the channel. The resulting MBNFs exhibited remarkable adsorption performance for different heavy metal ions including Cd²⁺, Zn²⁺, Cr³⁺, and Pb²⁺ with maximum uptake capacities as high as 2989, 1885, 723, and 453 mg/g, respectively. In particular, the adsorption capacity for Cd²⁺ and Zn²⁺ exceed the highest values reported for BN materials. In addition, the MBNFs showed excellent stability to re-use for a few times. The present MBNFs materials prepared using cheap and earth abundant luffa sponge may find broad applications such as adsorbent for environmental remediation applications.

Recyclable Polydopamine-Functionalized Sponge for High-Efficiency Clean Water Generation with Dual-Purpose Solar Evaporation and Contaminant Adsorption

Solar desalination of seawater is an attractive and environmentally friendly method to solve the long-standing water crisis. However, its efficiency is highly reliant on solar intensity. Additionally, increasing contamination in water makes it difficult to generate clean water through the solo desalination process. To address this, we propose a polydopamine (PDA)-functionalized hybrid material with dual-purpose solar evaporation and contaminant adsorption for highly efficient clean water production in all-weather conditions. The hybrid material is fabricated by polymerization of dopamine onto a commercial sponge in a facile, low-cost, and scalable manner. With excellent light absorption and chelation capabilities, the PDA film coated on sponge acts as both a photothermal material and adsorbent that allow us to achieve clean water production with solar desalination when sunshine and with contaminant adsorption when cloudy or at night. Meanwhile, the solar evaporation and contaminant adsorption of the PDA-sponge are synergized with one another, resulting in the PDA-sponge that is a desirable material with the capability of continuous clean water production in all-weather conditions. The PDA-sponge is also highly recyclable with a high retention rate of evaporation and adsorption efficiency even after 10 cycles. The promising PDA-based hybrid is believed to inspire new strategies for superior water treatment materials.

Preparation and Characterization of Cellulose Grafted with Epoxidized Soybean Oil Aerogels for Oil-Absorbing Materials

The absorbent materials synthesized from biosources with low cost and high selectivity for oils and organic solvents have attracted increasing attention in the field of oil spillage and discharge of organic chemicals. We developed a convenient surface-grafting method to prepare efficient and recyclable biobased aerogels from epoxidized soybean oil (ESO)-modified cellulose at room temperature. The porous network-like structure of the cellulose aerogel was still fully retained after undergoing hydrophobic modification with ESO. Moreover, the modified aerogels possessed excellent hydrophobicity with a water contact angle of 132.6°. Moreover, the absorbent ability of the hydrophobic cellulose aerogels was systematically assessed. The results showed that modified aerogels could retain more than 90% absorption capacity even after 30 absorption-desorption cycles, indicating that the ESO-grafted cellulose aerogels have practical applications in the oil-water separation from industrial wastewater and oil-leakage removal.

Synthesis of Particulate Hierarchical Tandem Heterojunctions toward Optimized Photocatalytic Hydrogen Production

Photocatalytic hydrogen production using semiconductors is identified as one of the most promising routes for sustainable energy; however, it is challenging to harvest the full solar spectrum in a particulate photocatalyst for high activity. Herein, a hierarchical hollow black TiO₂ /MoS₂ /CdS tandem heterojunction photocatalyst, which allows broad-spectrum absorption, thus delivering enhanced hydrogen evolution performance is designed and synthesized. The MoS₂ nanosheets not only function as a cost-effective cocatalyst but also act as a bridge to connect two light-harvesting semiconductors into a tandem heterojunction where the CdS nanoparticles and black TiO₂ spheres absorb UV and visible light on both sides efficiently, coupling with the MoS₂ cocatalyst into a particulate photocatalyst system. Consequently, the photocatalytic hydrogen rate of the black TiO₂ /MoS₂ /CdS tandem heterojunction is as high as 179 µmol h^-1 per 20 mg photocatalyst under visible-light irradiation, which is almost 3 times higher than that of black TiO₂ /MoS₂ heterojunctions (57.2 µmol h^-1 ). Most importantly, the stability of CdS nanoparticles in the black TiO₂ /MoS₂ /CdS tandem heterojunction is greatly improved compared to MoS₂ /CdS because of the formation of tandem heterojunctions and the strong UV-absorbing effect of black TiO₂ . Such a tandem architectural design provides new ways for synthesizing particulate photocatalysts with high efficiencies.

Novel encapsulation of water soluble inorganic or organic ingredients in melamine formaldehyde microcapsules to achieve their sustained release in an aqueous environment

A novel type of melamine formaldehyde microcapsule with a desirable barrier has been used to encapsulate water soluble ingredients, including potassium chloride (KCl) and allura red (dye) as models of an inorganic salt and organic molecule, respectively, via a facile method, and it has shown a sustained release of KCl and allura red for 12 h and 10 days in aqueous environment, respectively.

A novel type of melamine formaldehyde microcapsule has been used to encapsulate water-soluble ingredients: potassium chloride (KCl) and allura red (dye), which achieved a sustained release for 12 h and 10 days in aqueous environment respectively.

Cyclodextrin-functionalized Ag/AgCl foam with enhanced photocatalytic performance for water purification

The application of visible light-induced photocatalysts for photocatalytic pollution mitigation has become a promising strategy due to the inexhaustible solar energy. And how to improve pollutants degradation rate is still a meaningful work. Many researchers dealt with this issue by enhancing visible light absorption of photocatalysts. However, few studies focus on this issue by improving semiconductor's absorption property of organic pollutants. Hence, in this work, we prepared the Ag/AgCl foam coated per-6-thio-β-cyclodextrin (SH-β-CD) to improve the photocatalytic activity of Ag/AgCl foam. Here, we chose SH-β-CD because it has a special cavity that can effectively absorb and capture proper organic pollutants via host-guest interaction, which makes it an ideal pollutants surface adsorber when coated on the surface of Ag/AgCl particles. Hence, those trapped pollutants in the cavities can be attacked directly by those reactive oxidation species (ROS) that produced by Ag/AgCl particles under visible light irradiation, resulting in the significant promotion of pollution mitigation rate. The experimental results demonstrated the photodegradation rate constant of methyl orange (MO) by Ag/AgCl@β-CD foam (k = 0.120 min^-1) increased approximately 2.6 times compared with pure Ag/AgCl from (k = 0.048 min^-1). We anticipate our SH-β-CD modified Ag/AgCl foam would be a promising candidate for photodegradation of organic pollutants in wastewater remediation.

Effect of nanohydroxyapatite on cadmium leaching and environmental risks under simulated acid rain

Cadmium (Cd) contamination in soil is a global environmental pollution issue. Nanohydroxyapatite (NHAP) has been used in soil remediation to immobilize cadmium in contaminated soils. However, the effect of acid rain on the export of cadmium from topsoil and its behavior in deep soil and leachate is unclear. In this study, column experiments and development of parsimonious model were performed to estimate Cd leaching behavior from topsoil and environmental risk of groundwater after 0.5% NHAP remediation. Four leaching events were performed and total Cd, different fractions of Cd determined by sequential extraction procedure and pH were determined for each leaching. The results show that with the export of Cd in topsoil, the total Cd concentration in soil at different depths had the following vertical distributions: 0-5 cm > 5-10 cm > 10-15 cm > 15-20 cm. NHAP treatment increased the soil pH and decreased Cd leaching loss by 56.45% compared to the control, and the results fit the parabolic diffusion model. With sequential extraction it was observed that NHAP application increased the residual fraction of cadmium in soil. After leaching, there was a positive correlation between soil pH and Cd concentration with regards to the exchangeable, reducible, oxidizable and residual Cd fractions. The parabolic diffusion model showed that Cd-contaminated soil with NHAP remediation is harmless to humans after sufficient remediation duration, whereas the resultant concentrations from the CK treatment could be toxic. The results indicate that nanohydroxyapatite could significantly reduce the bioavailability of cadmium and the environmental risk. However, the release of Ca and P from the dissolution of NHAP should be carefully studied as this will impact the mobilization of Cd or colloid Cd, and high leaching of P may result in P-induced eutrophication risk.

Polyolefin-based interpenetrating polymer network absorbent for crude oil entrapment and recovery in aqueous system

In this research, a series of different two polyolefin-based interlaced polymer network material was prepared with a semi-crystalline linear low density polyethylene (LLDPE, thermoplastic) and a crosslinked 1-decene/divinylbenzene (1-D/DVB, elastomer) having high crude oil absorption capacity. The prepared absorbents, LLDPE/D/DVB, were characterized by NMR, TEM, contact angle measurement and TGA analysis. It was observed that the mixing ratio of two interlaced polymer network played a crucial role in determining its crude oil absorption capacity. The swelling capacity of absorbent prepared from a 1:1 mixing of LLDPE and D/DVB (0.2 ml) exhibit high removal efficiency in crude oil absorption over 40 g/g at both 25 °C and 0 °C. The removal of the absorbed crude oil from the water surface is effective. As the absorbent made of polyolefin materials have pure hydrocarbon content, offer significant advantages such as high absorption capacity, simple recovery, and recyclability.