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Various CoIII amine aqua hydroxo complexes have been evaluated for their ability to hydrolyse pyrophosphate to phosphate rapidly. Two very effective reagents have emerged, [Co( trpn )(OH)(OH2)]2+ ( trpn = 3,3′,3″-nitrilotris(propan-1-amine)) and [Co( tamen )(OH)-OH2)]2+ ( tamen = 6-(4-amino-2-azabutyl)-6-methyl-1,4-diazacycloheptane), and the latter has been examined closely to assess details of the mechanistic path for hydrolysis. The study shows substitution of the reagent on the substrate is fast and not rate determining. Two moles of the reagent are required to bind to [(en)2Co(P2O7)]- (en = ethane-1,2-diamine) to effect rapid hydrolysis. One supplies the coordinated OH- nucleophile to cleave the phosphorus anhydride, and the other binds as a chelate to the leaving group to assist bond rupture. An unproductive side path, to form a symmetrical dichelate of the form [(en)2Co(P2O7)Co( tamen )]2+, becomes rate limiting. However, if this path can be reduced in significance or eliminated, the study implies that polyphosphates and phosphate esters should hydrolyse on the subsecond time scale.

High-purity (98.8%, TiO 2 ) rutile nanoparticles were successfully synthesized using ilmenite sand as the initial titanium source. This novel synthesis method was cost-effective and straightforward due to the absence of the traditional gravity, magnetic, electrostatic separation, ball milling, and smelting processes. Synthesized TiO 2 nanoparticles were 99% pure. Also, highly corrosive environmentally hazardous acid leachate generated during the leaching process of ilmenite sand was effectively converted into a highly efficient visible light active photocatalyst. The prepared photocatalyst system consists of anatase-TiO 2 /rutile-TiO 2 /Fe 2 O 3 (TF-800), rutile-TiO 2 /Fe 2 TiO 5 (TFTO-800), and anatase-TiO 2 /Fe 3 O 4 (TF-450) nanocomposites, respectively. The pseudo-second-order adsorption rate of the TF-800 ternary nanocomposite was 0.126 g mg –1 min –1 in dark conditions, and a 0.044 min –1 visible light initial photodegradation rate was exhibited. The TFTO-800 binary nanocomposite adsorbed methylene blue (MB) following pseudo-second-order adsorption (0.224 g mg –1 min –1 ) in the dark, and the rate constant for photodegradation of MB in visible light was 0.006 min –1 . The prepared TF-450 nanocomposite did not display excellent adsorptive and photocatalytic performances throughout the experiment period. The synthesized TF-800 and TFTO-800 were able to degrade 93.1 and 49.8% of a 100 mL, 10 ppm MB dye solution within 180 min, respectively.

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