NaOH-Induced Fabrication of a Superhydrophilic and Underwater Superoleophobic Styrene-Acrylate Copolymer Filtration Membrane for Effective Separation of Emulsified Light Oil-Polluted Water Mixtures.

Oil-polluted water mixtures are difficult to separate, and thus, they are considered as a global challenge. A superior superhydrophilic and low-adhesive underwater superoleophobic styrene-acrylate copolymer filtration membrane is constructed using a salt (NaOH)-induced phase-inversion approach. The as-fabricated filtration membrane provides a hierarchical-structured surface morphology and three-dimensional high density open-rough porous geometry with a special chemical composition including highly accessible hydrophilic -COO- agents, which all are of great importance for long-term usage of immiscible/emulsified (light) oil-polluted wastewater separation. The separation is performed with a high efficiency and a high flux under either a gravity-driven force or a small applied pressure of 0.1 bar. The filtration membrane indicates an excellent anti-fouling property and is easily recycled during multiple cycles. The outstanding performance of the filtration membrane in separating oil-polluted water mixtures and the cost-effective synthetic approach as well as commercially scaled-up initial materials all highlight its potential for practical applications.

Removal of NO3- ions from water using bioadsorbent based on gum tragacanth carbohydrate biopolymer.

In this study, functionalized hydrogel bioadsorbents were produced from gum tragacanth (GT) carbohydrate and quaternary ammonium salt (TMSQA) as a crosslinker. The prepared bioadsorbents were used for the removal of NO3- ions from water through the electrostatic and ion exchange mechanism and antibacterial activity. The effect of quaternary ammonium content on the adsorption capacity was studied. The bioadsorbents were characterized by using FE-SEM, energy dispersive X-Ray (EDX), FT-IR, and TGA techniques. The equilibrium time and the most effective pH value for maximum NO3- removal (20 mg g-1) were 21 min and 7, respectively. A series of isotherms and kinetics models were undertaken and the obtained data were fitted well to the Langmuir isotherm and pseudo-second-order rate kinetic. The thermodynamic study confirmed the suitability of NO3- removal by the as-prepared bioadsorbent at room temperature, and also the negative value of ΔGº = -89.1 kJ mol-1 demonstrating the spontaneous nature of adsorption.

Wool-Like Fibrous Nonwoven Mesh with Ethanol-Triggered Transition between Antiwater and Antioil Superwetting States for Immiscible and Emulsified Light Oil-Water Separation.

Superwetting antiwater and antioil textiles are not only very attractive for efficient and cost-effective oil-water separation but also very challenging to be prepared. A well-designed polystyrene wool-like fibrous mesh was fabricated by a controlled electrospinning setup to provide simple and quick reversible ethanol-triggered switching between antiwater and antioil superwetting states in various media such as air, water, and oil. Additionally, it exhibits a long-term stability against acid, alkaline, and salt at high concentrations. Such characteristics will prove unusual capabilities for controllable gravity-driven separation of both immiscible and emulsified oil-water mixtures with a separation efficiency more than 99.0%, as well as a prolonged antifouling property and an excellent recyclability; all will be advantageous for technical applications including oil removing and water removing. Furthermore, light oil-polluted water and water-soluble pollutants can be simultaneously cleaned well by the antioil mesh acting in the water-removing mode.

Enhanced adsorption of nitrate from water by modified wheat straw: equilibrium, kinetic and thermodynamic studies.

This study represents the first attempt to chemically modify wheat straw (WS) using 3-chloropropyltrimethoxysilane (CPTMS) and (1,4-diazabicyclo[2.2.2]octane) (DABCO). Field emission scanning electron micrographs (FESEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectra confirmed the successful morphological and structural modification of WS and the thermal stability of the modified WS (MWS). The MWS was used to remove nitrate from water. The optimum conditions of nitrate adsorption onto MWS were examined by conducting batch experiments. The results indicated that 85% of nitrate was removed under the conditions of initial nitrate concentration = 20 mg L-1, initial solution pH = 7, contact time = 10 min, MWS dosage = 2 g L-1 and temperature ≈ 25 °C. The kinetic adsorption data were best fitted to the general order model and the adsorption process occurred in three distinct stages. The equilibrium adsorption data were well described by the Langmuir isotherm. Additionally, separation factor values were smaller than 1, implying that the adsorption process was favorable. The presence of competing anions impeded the nitrate adsorption in the order of sulfate > chloride > bicarbonate> phosphate. Thermodynamic parameters suggested that the adsorption process was exothermic, feasible and spontaneous in nature. Overall, the MWS could achieve efficient removal of nitrate under the simplest operating conditions.

Structure-Property Relationships of Nanosheeted 3D Hierarchical Roughness MgAl-Layered Double Hydroxide Branched to an Electrospun Porous Nanomembrane: A Superior Oil-Removing Nanofabric.

A straightforward approach was successfully developed to fabricate a well-designed three-dimensional rough sheetlike MgAl-layered double hydroxide (LDH) array to stand vertically on poly(acrylonitrile) porous nanofibrous membranes based on an electrospun-nanofiber-templated in situ hydrothermal strategy, and then the surface was modified with cyclohexanecarboxylic acid. The as-spun highly dense ordered sheetlike LDH porous nanofabric exhibited a superior durability in superhydrophobicity and superoleophilicity, which has achieved high oil-removing capability including both oil harvesting and oil separation to harvest/separate a wide range of organic solvents and oils from an oil-water mixture and, especially, exhibited a very good recycling and reusing performance. Interestingly, a steady water repellency was obtained against both drinkable hot (about 95 °C) and cool water. Outstanding oil harvesting, oil separation, and highly durable water repellant can be attributed to an effective synergistic effect between the high-density roughness of LDH nanosheets modified with acid and the very high porosity in the electrospun nanofibers, as well as the interspace between LDH nanosheets that acted as both a textile for selective oil separation and a container for penetrated oil storage, leading to special wettability, making the as-spun nanofabric a promising textile for large-scale removal and recollection of hydrophobic spillage on the water surface.