A Self-Adaptive and Regenerable Hydrogel Interfacial Evaporator with Adjustable Evaporation Area for Solar Water Purification.

Solar-driven interfacial evaporation is a potential water purification solution. Here, a novel regenerable hydrogel interfacial evaporator is designed with tunable water production. Such an evaporator is fabricated by readily mixing hydroxypropyl chitosan (HPCS) and dibenzaldehyde-functional poly(ethylene glycol) (DF-PEG) at ambient conditions. Dynamic Schiff base bonds bestow on the HPCS/DF-PEG hydrogel (HDH) evaporator self-adaptivity and pH responsiveness. The as-prepared HDH is enabled to spontaneously change shape to adapt to different molds, endowing the evaporator with adjustable evaporation area. The water production performance of the intelligent evaporator is first evaluated using tunable evaporation index (TEI, the tunable evaporated water mass per hour), which can be altered from 0 kg h-1 to 3.21 kg h-1 under one sun. Besides, the large-scale evaporator can be expediently fabricated by virtue of the self-adaptivity. Benefiting from the pH responsiveness, the HDH evaporator is successfully regenerated with the removal of organic dye by the liquefaction-dialysis-regeneration operations. Meanwhile, the re-created evaporator maintains the self-adaptive characteristic and almost constant water evaporation rate compared to that of the initial evaporator. Therefore, this distinctive concept provides a facile strategy to develop smart and recyclable solar-driven interfacial evaporators for flexible water purification.

Daphnia-inspired dynamic slippery chemically bonded liquid surface for the active prevention of covalently attached foulant adhesion.

Engineering anti-adhesion coatings always focuses on a specific hierarchy and surface free energy, which passively endures water scouring to wash away the loosely attached foulants. Certain foulants, however, especially those that are highly adhesive or covalently attached on the coatings, cannot be removed off the designed surfaces easily. Inspired by the active self-hunting behavior of the filter-feeding animal Daphnia, herein, we propose a universal antifouling strategy with both passive and active adhesion repellency capabilities. The premise for this protocol is that the as-fabricated liquid-like surface is able to repel the settlement of general foulants upon static conditions. Under steady thermal stimuli, the dynamic liquid-like surface behaves like a boxer with an active prevention ability against highly adhesive foulant adhesion, e.g., proteins, crude oils, and even covalently adhered mussel species. The enhanced biocide-free anti-adhesion performance is attributed to the reversible non-covalent interactions of pollutants in the initial contact with the surface, which was innovatively proved by AFM tapping tests to elucidate the physicochemical interactions between the foulants and coating surfaces. We envision that such an active anti-covalent adhesion surface may have great potential in diverse fields, including marine antifouling, fluid handling and transportation, and energy-harvesting devices.

Preparation and characterization of amino/thiol bifunctionalized magnetic nanoadsorbent and its application in rapid removal of Pb (II) from aqueous system.

To explore the effect of coexisted amino and thiol groups on adsorption of heavy metal, a novel magnetic nanoparticle was prepared by sequentially modification with (3-Chloropropyl) trimethoxysilan, polyetherimide, epichlorohydrin and thiourea. Subsequently, it was characterized by TEM, N2 adsorption/desorption, FTIR Spectroscopy, zeta potential, and VSM. The maximum adsorption capacity for Pb2+, Cd2+ and Cu2+ reached 110.13 mg·g-1, 40.23 mg·g-1 and 29.37 mg·g-1, respectively. The adsorption of the magnetic nanoparticles with different surface group for heavy metals were compared, which indicated that the amino and thiol group played an important role in the adsorption of heavy metals. Especially, the adsorption capacity increased dramatically after modification with the thiol group, which was attributed to the synergistic coordination of -NH2 and -SH. The adsorption kinetics is consistent with the quasi-second-order kinetics equation, and the adsorption thermodynamic process is consistent with the Langmuir isotherm equation. The effects of experimental conditions, such as pH, the concentration of metals, adsorption time and temperature, on adsorption of Pb2+ were studied in detail. In addition, over 90% of removal rate was remained after 6 cycles. The magnetic nanoadsorbents was a promising nanoadsorbent with high adsorption speed, simultaneous adsorption of various heavy metals, strong anti-interference ability and reusability.