هادي شايسته

Synthesis of nickel magnetic superhydrophobic nanostructure and investigation of the factors affecting the morphology and wettability of nanostructure for oil-in-water separation were the main purposes of this study. Firstly, the effect of synthesis parameters in the hydrothermal method by Taguchi L16 experimental design was investigated and after modification as-prepared samples with octadecyltrichlorosilane (ODTS) coupling agent, the optimum conditions to achieve superhydrophobic properties were investigated. The result showed that the optimum sample prepared at 100 mM of NiCl2.6H2O solution, 1250 mM of N2H4.H2O, reaction time of 8 h, and temperature of 80◦C exhibited superhydrophobicity-superoleophilicity behavior with water contact angle of 162.78º±2.4º, contact angle hysteresis of 4.32º±0.9º, and oil contact angle of 0º. FESEM, EDX, XPS, FTIR, VSM, XRD, TGA-DTA, and Zeta potential analyses were conducted to eva‎luate the morphological, chemical, and physical features of the produced sample. The results of FESEM and XRD analysis showed that optimum samples formed into microrods with dense narrow nanospikes on the surface with conical growth have length of 600±75 nm and a width of 75±15 nm perpendicularly standing along the radial directions. In the step, In order to study wettability changes, silane compounds and fatty acids were used. The results showed that with increasing the carbon chain of the modifiers, hydrophobicity increased and the best-operating conditions were obtained at ODTS concentration of 12.5 mM, reaction time of 60 min, and ODTS/toluene solution volume of 10 mL. Finally, the as-synthesized nickel nanostructured microrods with superhydrophobicity and superoleophilicity were applied for oil–in–water mixture and emulsion separation in dead-end and batch process. The results illustrated that the oils with higher density than water such as dichloromethane and chloroform can be separated with efficiency higher than 95% and high permeate flux even after twenty cycles in the dead-end system. Also, superhydrophobic micro/nano structure nickel demonstrated outstanding separation capacity ranging from 3.86 to 5.27 g/g for a wide range of oil spills which had a good capacity compared to other materials studied in this field. Furthermore, the results of separation of oil from different oil-in-water emulsions in a batch system showed superhydrophobic/superoleophilic nickel particles can be removed micrometer-sized oil droplets due to the the nanospikes present on the surface. Also, chemical stability in acidic, alkaline, and corrosive media and the reusability of synthesized nanostructures indicated high chemical durability and the ability to reuse particles in sequential processes. The appropriate resistance of hedgehog-like micro/nanostructure nickel particles to various environmental conditions as well as reusability and recyclability provides good opportunities for industrial applications of oil uptake from the oil/water mixture and emulsion.

ميكروميله نانوتيغ¬دار , جداسازي روغن از آب , فوق آب¬گريز- فوق روغن¬دوست , امولسيون روغن در آب , ترشوندگي

Nanospiky microrod , Separation oil from water , Superhydrophobic-superoleophilic , Oil-in-water emulsion , Wettability

Hadi Shayesteh

Dr. Reza Norouzbeigi, Dr. Ahmad Rahbar-Kelishami