Tributyltin Solubilization and Degradation from Spiked Kaolin Using Different Reagents

Abstract

Conditions for tributyltin (TBT) solubilization and degradation were investigated. These conditions were optimized to remove or degrade organotin compounds (OTC) in spiked kaolin. TBT-spiked kaolin and reagents with specific chemical properties were tested in a batch reactor using a solid matrix model. The final concentrations of butyltin compounds in kaolin were determined by gas chromatography coupled with a pulsed flame photometric detector. Best results were obtained under acidic conditions (2<pH< 5) with up to 87% TBT removal from the spiked kaolin. Acids with reducing properties were more effective (ascorbic and formic acid: 87% and 82% of TBT abatement, respectively). Moreover, final monobutyltin and dibutyltin concentrations were analyzed to determine which species predominate in the solid matrix after batch experiments. OTC speciation shows that degradation of TBT occurs simultaneously with solubilization in the presence of several reagents. These results allow choosing favorable/optimal operating conditions for OTC elimination.

Three Bench-scale Tests Designed to Destroy Tributyltin (TBT) in Marine Sediments from North Queensland, Australia

“…However, results from this study do confirm that both thermochemical and thermal treatment of organotin-contaminated marine sediment destroys the TBT molecule. This finding is consistent with those suggested by Goethals and Pieters [23]. Treated TBT concentrations of <0.5 µgSn/kg observed in tests 1 and 2 are lower than allowable under ANZECC and NODG guidelines in Australia [20,27], meaning that the treated marine sediments were safe for disposal or reuse.…”

“…Without providing specific data, Howard and Gkenakou also reported that a variety of materials, including activated carbon, organically modified clays, iron, fly ash, and cement, had demonstrated promising results in immobilising TBT in sediments, but that ultrasonic destruction of TBT had only reduced TBT by 40%; the authors cite incineration as a viable method of destroying the TBT molecule, but dismiss it as being commercially impractical [22]. The adsorption capacity of TBT, DBT and MBT to kaolin under a range of acidic conditions was also investigated by Yvon, Le Hécho and Donard, with modest results [23].…”

“…Perhaps more concerning was Goethals and Pieters' observation that soil washing, even with the greatest agitation for the longest time, only reduced TBT by 30%, or from 60 μgSn/kg to 43 μgSn/kg. However, Goethals and Pieters also reported that high temperature thermal desorption "debutylated" TBT-, DBT-and MBT-contaminated marine sediments by >97% at 400°C [23]. Alrashdi [1] suggested that nanoscavenging (using a chemically modified mesoporous silica) can reduce TBT, DBT and MBT in water, and Luan, et al reported 90% degradation of TBT at concentrations of 10, 50 and 100 μgSn/L by alginate-immobilized Chlorella vulgaris beads during six, four-day treatment cycles [25].…”