Ortho xylene

Nanostructured surfaces were prepared according to general block copolymer micellar nanolithography protocols (Boehm, 2008 ). Briefly, poly[styrene(x)-block-(2-vinylpyridine)(y)] [PS(x)-b-P2VP(y)] (Polymer Source, Canada) was dissolved in ortho-xylene (Merck) to a final concentration of 2–8 mg/mL (Table 1) in a precleaned glass tube (ThermoFischer). After 24 h stirring, tetrachloroaureate(III)trihydrate (HAuCl₄ × 3 H₂O, Sigma-Aldrich) was added and the solution was stirred for another 24 h.
The glass surfaces (d = 22 mm, Menzelglaeser) were cleaned over night with a 3:1 mixture of freshly prepared Caro’s acid [H₂SO₄ (Sigma-Aldrich) and H₂O₂ (30%, AppliChem)], then rinsed with ddH₂O and dried under a nitrogen stream. The slides were fixed in a spin-coater (WS-400A-6NPP/LITE/8K, Laurell) under a slight vacuum and 20 µL of the micellular solution was quickly added. Each surface was spin coated for 30 s with a speed of 3,000–4,000 rpm (Table 1). The gold salt was reduced and the polymer was removed by treatment with hydrogen plasma (W10, 350 W, 0.4 mbar, 45 min; Plasma System 100-E, PVA TePla). The hexagonality of the nanoparticles and the distance between them was analyzed using SEM (Ultra 55 SEM, Zeiss) as described previously (Boehm, 2008 ). Surfaces used in this study had nanoparticle densities of about 2,714, 540, 123, 47, and 29 particles/μm² with a hexagonality of at least 48%.

Meta-xylene, para-xylene, ortho-xylene, and ethylbenzene chemicals were purchased from Merck company with the purity of minimum 99%. These chemicals are used as received without further purification. Iso-octane was purveyed from Samchun company with the minimum purity of 98%. This material was used as the solvent. Para-diethylbenzene (PDEB) was supplied from Iranian Petrochemical Complex. In the case of the adsorbent, industrial type of Ba-faujasite exchanged namely SPX-3000 with the average particle size of 0.47 mm were utilized.