Superhydrophobic melamine sponge-sorbent fabricated using WS2, halloysite nanotube, octyltriethoxysilane, tetraethoxysilane, and polydimethylsiloxane for the selective uptake of oil from water

Here, a novel coating formulation was developed using WS2, halloysite nanotube (HNT), octyltriethoxysilane (OTES), tetraethoxysilane (TEOS), and polydimethylsiloxane (PDMS) to fabricate a new melamine sponge (MS)-based superhydrophobic sorbent material for the treatment of wastewater polluted with oily substances and organic solvents. The innovative aspect of this study lies in the alteration of WS2 particle size within the sorbent material and the chemical modification of HNT with silane compounds through the formation of reactive -OH groups on the cylindrical outer surface of clay mineral by chemical activation. The effect of nano- and micro-WS2 particle sizes on the wettability of sorbent material was investigated systematically. Successful coating of MS with the developed coating formulation was confirmed using SEM, mapping, EDS, and FTIR analyses. Sorbent material showed remarkable superhydrophobicity (WCA: 170.3 degrees), excellent thermal and mechanical stability, good chemical durability, high sorption capacity (34.0-73.8 g/g), good reusability, outstanding oil-water separation ability (>99.8 %) and flux (11,774 L/(m(2).h)), and efficient separation ability for water-in-oil emulsions (up to 99.6 %). The results of this study exhibit that MS/WS2/HNT/OTES-TEOS/PDMS sorbent material is of a great potential for the selective and effective removal of oily substance and organic solvent spills from water.Scientific Research Projects Coordination Unit of Akdeniz University [FBA-2022-6102]; Scientific and Technological Research Council of Turkey (TUBITAK) BIDEB 2211-A National Ph.D. Scholarship ProgramThis work was supported by the Scientific Research Projects Coordination Unit of Akdeniz University (Project Number: FBA-2022-6102) . C. Ozcan Diker thanks the Scientific and Technological Research Council of Turkey (TUBITAK) BIDEB 2211-A National Ph.D. Scholarship Program for the financial support

Fabrication of superhydrophobic melamine sponge composite sorbent in supercritical carbon dioxide atmosphere for selective and effective oil removal from water

In this study, both the modification of activated halloysite nanotube (HNT) with methyltriethoxysilane (METES) and the fabrication of durable, superhydrophobic (water contact angle: 153.0 degrees) and superoleophilic (oil contact angle: 0 degrees) melamine sponge (MS)-HNT-METES sorbent material (MS-METES) were achieved in supercritical carbon dioxide (scCO2) atmosphere. For the coating of MS with clay mineral and METES through sol-gel reaction in scCO2, optimal process conditions were determined to be pressure difference of 60 bars at 35 degrees C, solvent/ METES mass ratio of 7.5, METES/MS mass ratio of 10, and degas time of 400 s. Successful preparation of MSMETES was proven by XPS, FTIR, 29Si-MAS NMR, SEM, and contact angle measurements. MS-METES displayed excellent sorption capacity for various petroleum products, oils, and organic solvents (49.6-122.4 g/g), remarkable oil-water separation efficiency (99.1%, for continuous separation technique), high selectivity for oil/ organic solvent in acidic, salty, and alkaline solution conditions, good reusability, chemical stability and robustness, and outstanding flexibility and mechanical stability. We believe that the innovative process used in this study will have great potential to be used by researchers in the direct fabrication of new superhydrophobic and superoleophilic sorbent materials for the selective removal of oil and organic solvent spills from water.The Scientific and Technological Research Council of Turkey (TUBITAK) [221M385]This work was financially supported by The Scientific and Technological Research Council of Turkey (TUBITAK Project Number: 221M385). C. Ozcan Diker thanks the Scientific and Technological Research Council of Turkey (TUBITAK) BIDEB 2211-A National Ph.D. Scholarship Program for the financial support.r Research Council of Turkey (TUBITAK) BIDEB 2211-A National Ph.D. Scholarship Program for the financial support

Influence of reaction conditions on the rate of enzymic polymerization of pyrogallol using laccase

Laccase produced from Trametes versicolor (ATCC 200801) was utilized to synthesize poly (pyrogallol) in aqueous solution. The polymerization reaction was conducted batchwise in a closed, temperature controlled system containing sodium acetate buffer for pH stability. The effects of monomer (pyrogallol), enzyme and dissolved oxygen concentrations, reaction mixture pH and temperature on the polymerization rate were investigated with respect to initial reaction conditions and depletion rate of dissolved oxygen in the reaction mixture. Maximum initial oxygen consumption rates. defined as initial polymerization reaction rate, were achieved with sodium acetate buffer of pH 4.5, temperature at 45 degreesC and 18 mg/L of dissolved oxygen concentration. Typical saturation enzyme kinetics were observed for enzymic polymerization using 1000 mg/L initial pyrogallol and 216 U/L enzyme. The initial dissolved oxygen consumption rate increased with temperature up to 45 degreesC, after which the rate decreased due to apparent enzyme denaturation. (C) 2004 Elsevier Ltd. All rights reserved