Abstract
The main aim of this work is to synthesise barium sulphate (BaS04) that are tiny in size (nanoparticles). BaS04 scaling is a known problem in the context of offshore oil recovery. Different methods of scale control have been suggested in the literature, none has solved the BaS04 scaling problem dramatically. In this work several methods were assessed, but only one of them seemed to work well. The methods studied were: 1) Formation of colloidal BaS04 in an aqueous alcohol medium using BaCh and Na2S04 as precursors. The precursors were mixed rapidly forming rhombohedral BaS04 and by tubular reactor forming dendrite-like particles. 2) Inhibition of Ba2+ using phosphino (carboxylic acids)prior to the sol- addition induced the formation of broom-stick-like BaS04 particles. 3)Formation of BaS04 microemulsions using different surfactants. Cationic surfactants (sodium bis-2-thylhexylsulfosuccinate) (AOT) induced the formation of BaS04 platelets and nanofilaments. While non-ionic surfactants (polyoxyethylene-4-dodecyl ether)(C12E04) and SEs different HLB values (2,6,15 and 16), induced the formation of BaS04 platelets with the former and BaS04 nanobaguettes with HLB 2 and platelet-like particles,defined nanorods and interconnected nanoparticles with HLB 6, 15 and 16 respectively. TX-lOO (polyethylene glycol p(1,1,3,3-tetramethylbutyl)- phenylether) formed small BaS04 nanoparticles. Anionic didodecyldimethylammonium bromide (DDAB) formed cylindrical BaS04 nanoparticles. 4) (SOl) in H20 was added to Ba2+ adsorbed on Stober silica producing spherical BaS04 nanoparticles in StOber silica spheres. 5) Ba2 + in H20 was added to (SOl)/AIO(OH). This is a new method to the best of our knowledge. It formed small BaS04 nanoparticles at 2 and 4 J.lmol (BaCh and Na2S04) and big bow-tie structured BaS04 particles at 6 J.lmol concentration per 5cm3 of AIO(OH). Since BaSOJAIO(OH) produced with SOlIAIO(OH)(aq) + Ba2+(aq) showed higher yields its scaling inhibition efficiency was studied in detail at three different concentrations of Ba2+ (64, 90 and 121 ppm) at 298 K and 320 K. This novel approach to scale control using chaperoning AIO(OH) is promising. A comparison study using 2-D imaging took place in BaS04 in AIOOH and BaS04 in H20 showed that the former remained longer as a sol. This suggests that BaS04 based in AIOOH can be used in medical diagnosis. BaS04 in AIOOH was used as a catalyst (prior to freeze drying) in an exhaust engine to test its efficiency in detoxifying the exhaust engine from CO, HC and NO" under stoichiometric conditions. Catalytic activates were also investigated after activation with Pt and Au.