Porphyrin-Based Conjugated Microporous Polymer Loaded with Nanoscale Zerovalent Iron for the Degradation of Organic Pollutants under Visible Light.

The degradation of organic dye from waterbodies is of great significance for clean production and environmental remediation. Herein, two porphyrin-based conjugated microporous polymers (CMPs) loaded with nanoscale zerovalent iron (named as Por-CMPs-1-2@nZVI) were successfully fabricated by Sonogashira-Hagihara coupling reactions and the liquid-phase method. The as-synthesized Por-CMPs-1-2@nZVI composites were characterized by various means of analysis, and it was confirmed that Por-CMPs-1-2 loaded with nZVI had good photocatalytic performance. Calculated by ultraviolet-visible spectrum, the band-gap energies of Por-CMPs-1@nZVI and Por-CMPs-2@nZVI were 1.45 and 1.32 eV, respectively, indicating that both can be activated by visible light. The photodegradation of organic dye experiments demonstrated that Por-CMPs-2@nZVI degraded 98.0% of 10 ppm Methylene Blue (MB) within 150 min, which is higher than that of Por-CMPs-1-2 and Por-CMPs-1@nZVI. The experiment of active substance capture and mechanism of ESR confirmed that superoxide anion and hydroxyl radical were the primary valid substances in the photodegradation process of MB. In addition, the preparation of membrane materials was shown to be a successful strategy to realize engineered scale-up production.

Preparation of a Magnetic Core-Shell Bioreactor for Oil/Water Separation and Biodegradation.

With the frequent occurrence of offshore oil spills, the effective separation and treatment of oily wastewater are essential to the environment. In this work, the core-shell bioreactor (abbreviated as Fe3O4/MHNTs-CNF@aerogel) was prepared with a core composed of camphor leaf cellulose-based aerogels for loading microorganisms and a shell derived from hydrophobic silane-modified halloysite doping with Fe3O4 for selective absorption of oil and maganetic recycling. The core-shell-structured bioreactor Fe3O4/MHNTs-CNF@aerogel has excellent self-floating properties and can float on water for up to 100 days. The whole core-shell structure not only has excellent oil/water separation performance but also has good microbial degradation performance. By applying it in water containing 5% diesel for the biodegradation test, the biodegradation efficiency of Fe3O4/MHNTs-CNF@aerogel for diesel can reach 82.4% in 10 days. The efficiency was 20% higher than for free microorganisms, and it still had excellent degradation ability after three degradation cycles, with a degradation rate of over 75%. In addition, the result obtained from the study on environmental tolerance shows that Fe3O4/MHNTs-CNF@aerogel possessed a strong tolerance ability under different pH and salinity conditions. The Fe3O4/MHNTs-CNF@aerogel also has superior mechanical properties; i.e., nearly no deformation occurs at 30 kPa. Compared with those conventional oil/water separation materials which can only absorb or separate the oils for water with limited capacity and taking the risk of secondary contamination, our core-shell-structured bioreactor is capable of not only selectively absorbing oil from water through its hydrophobic shell but also degrading it into a nontoxic substance by its microorganism-loaded core, thus showing great potential for practical application in oily wastewater treatment.

Coffee Grounds-Doped Alginate Porous Materials for Efficient Solar Steam Generation.

Solar steam generation (SSG) devices have emerged as one of the promising technologies for seawater desalination to meet the worldwide demand for clean water. Herein, we fabricated a new monolithic SSG system derived from waste coffee grounds (CG) through a simple carbonization followed by a freeze-drying process (named as CCGA). The as-prepared CCGA possesses a porous structure with superhydrophilic, abundant porosity (81.7%); low thermal conductivity (0.129 W m-1 K-1) in a wet state; low apparent density (25 mg cm-3); and broad sunlight absorption in a wet state (ca. 93%). The combination of its carbon nature and abundant porous structure endowed barrier-free water transmission channels, a self-floating property, and a superb photothermal conversion performance to the SSG. The temperature of the CCGA's upper surface can reach up to 42.6 °C under 1 sun irradiation, and for pure water, the evaporation rate of CCGA can be up to 1.486 kg m-2 h-1, corresponding to a good photothermal conversion efficiency of 86.96%. It also exhibits an excellent desalination capability; e.g., the photothermal conversion efficiency of CCGA in NaCl (20 wt %) brine is measured to be 75.77% under 1 sun irradiation, and the fresh water obtained from artificial seawater can achieve the WHO's standard for domestic water. With the advantages of low cost and a simple preparation process, such biomass-based CCGA materials may have great potential as an efficient SSG device for seawater desalination.

Porphyrin-Based Conjugated Microporous Polymers for Highly Efficient Adsorption of Metal Ions.

The capture and elimination of anions and cations from water have attracted a great deal of attention and are quite vital for clean production and environmental remediation. In this work, we present the synthesis of four porphyrin (Por)-based conjugated microporous polymers (CMPs, namely, Por-CMP-1-4), which were produced through a Sonogashira-Hagihara linked response using porphyrin and acetylene aromatic compounds as building blocks and used as absorbents to eliminate metal ions from water. The as-synthesized Por-CMP-1-4 exhibit an amorphous porous structure and outstanding caloric and physicochemical properties. Taking advantage of their larger specific surface areas, i.e., 541.47, 614.58, 382.38, and 677.90 m2 g-1 for Por-CMP-1-4, respectively, and their chelating active site that originated from the porphyrin ring, Por-CMP-1-4 show better Zn2+, Cu2+, and Pb2+ adsorption ability. Among them, Por-CMP-3 has the greatest adsorbability of 640 mg g-1 for Zn2+, with an adsorption efficiency of 80%, whereas its adsorption capacities for Cu2+ and Pb2+ ions were both 334 mg g-1, with an adsorption efficiency of 42% for Cu2+ and Pb2+. Employing Por-CMP-3 as a representative example, its adsorption kinetics has been systematically investigated. The adsorption behavior of Por-CMP-3 with respect to the Zn2+ ion is shown to exhibit pseudo-first-order kinetics and Langmuir isotherm modes. Meanwhile, the adsorption mechanism is discussed in detail, and it was thought it might be chelation, in which the nitrogen atoms with a single pair of electrons on the porphyrin ring interacted with metal ions to form stable chelation coordination bonds, thus removing metal ions selectively and effectively. Furthermore, Por-CMP-3 exhibited good reusability, retaining 60% of its Zn2+ removal rate after four continuous adsorptions.

Dual-Functional Graphene Oxide-Based Photothermal Materials with Aligned Channels and Oleophobicity for Efficient Solar Steam Generation.

Desalination by solar steam generation (SSG) has emerged as one of the most efficient approaches to address the issue of global water shortage. In this work, novel graphene oxide (GO)-based solar steam generators (GO-SSGs) with aligned channels were prepared by directional freezing and simple carbonization of a hydrogel composed of GO and poly(vinyl alcohol) (PVA). Benefitting from their excellent light absorption (light absorption efficiency exceeds 94%), better thermal insulation (thermal conductivity, 0.259 W/(m K)), and suitable porous structure, which facilitates rapid water transportation, the GO-SSGs show superior SSG performance with a high solar energy conversion efficiency of up to 92% achieved under an irradiation of 1.0 kW/m2. Interestingly, uniquely aligned channels endow them with good salt-rejection performance; the solar energy conversion efficiency of GO-SSGs in 20 wt % NaCl, KCl, and MgCl2 brine can reach more than 85%. To improve their antifouling performance, a chemically hydrophilic and oleophobic modification was conducted, making it possible to run SSG even in oily wastewater; for instance, a solar energy conversion efficiency of 84% was obtained in an aqueous solution containing 10 wt % n-hexadecane. Compared with the existing photothermal materials, these materials show advantages of simple manufacture, high SSG efficiency, superior salt tolerance, and antifouling performance, which make them promising candidates as a kind of new high-performance photothermal materials for desalination even in oily wastewater, thus further expanding the scope of their practical SSG application.

Porous Carbon Nanofoam Derived From Pitch as Solar Receiver for Efficient Solar Steam Generation.

Photothermal-material-assisted solar-steam generation has recently attracted intensive attention due to its superior evaporation rate with high energy conversion efficiency for desalination. In this work, a simple approach for fabrication of porous carbon nanofoam (PCN) is reported, which is prepared by the carbonization of pitch using a combination of CaCO3 and NaCl templates, Meanwhile, NaCl saturated solution acts as a porogen to produce micropores and mesopores as solar receiver for efficient solar steam generation. The as-prepared PCN shows excellent porosity and mesoporous feature with an average pore size of 26.8 nm. It also shows superior light absorption of 88% and better thermal insulation (thermal conductivity 0.993 W m-1 K-1). Based on these characteristics, the as-prepared PCN can be used as a promising solar receiver. Under 1 sun, 2 sun, and 3 sun irradiation, the PCN-based solar receiver shows high energy conversion efficiencies of 88%, 86%, and 84%, respectively. Taking advantage of the abundant, low-cost, and commercial availability of pitch as well as its simple and cost-effective manufacture method, the PCN-based solar receiver may hold great potential for a broad variety of solar-steam generation applications, for instance, fresh water production, power generation, desalination, and so on.

Two new two-dimensional coordination polymers based on isophthalate and a flexible N-donor ligand containing benzimidazole and pyridine rings: synthesis, crystal structures and a solid-state UV-Vis study.

In coordination chemistry and crystal engineering, many factors influence the construction of coordination polymers and the final frameworks depend greatly on the organic ligands used. N-Donor ligands with diverse coordination modes and conformations have been employed to assemble metal-organic frameworks. Carboxylic acid ligands can deprotonate completely or partially when bonding to metal ions and can also act as donors or acceptors of hydrogen bonds and are thus good candidates for the construction of supramolecular architectures. Two new transition metal complexes, namely poly[diaqua(µ4-1,4-bis{[1-(pyridin-3-ylmethyl)-1H-benz[d]imidazol-2-yl]methoxy}benzene)bis(µ2-isophthalato)dicobalt(II)], [Co(C8H4O4)(C34H28N6O2)0.5(H2O)]n, (1), and poly[diaqua(µ4-1,4-bis{[1-(pyridin-3-ylmethyl)-1H-benz[d]imidazol-2-yl]methoxy}benzene)bis(µ2-isophthalato)dicadmium(II)], [Cd(C8H4O4)(C34H28N6O2)0.5(H2O)]n, have been constructed using a symmetric N-donor ligand and a carboxylate ligand under hydrothermal conditions. X-ray crystallographic studies reveal that complexes (1) and (2) are isostructural, both of them exhibiting three-dimensional supramolecular architectures built by hydrogen bonds in which the coordinated water molecules serve as donors, while the O atoms of the carboxylate groups act as acceptors. Furthermore, (1) and (2) have been characterized by elemental, IR spectroscopic, powder X-ray diffraction (PXRD) and thermogravimetric analyses. The UV-Vis absorption spectrum of complex (1) has also been investigated.