The sorption behaviour of tributyltin (TBT) from reconstituted seawater onto municipal solid waste (MSW) compost was investigated to give first insights into the equilibrium and kinetic behaviour of this process. The rate of adsorption, as well as the influence of pH, salinity and adsorbate hydrophobicity on the partitioning process were investigated: adsorption isotherms were fitted to Freundlich and Langmuir adsorption equations for the solid / liquid interface process. Isotherms from 24 h equilibrations were mostly linear, with sorption coefficients between 1.86103 and 11.1103 L kg-1 depending on the experimental conditions. The similarity of sorption and desorption coefficients for TBT showed that the sorption process is reversible, similar to that for the adsorption of TBT onto sediments. It was found that the adsorption capacity for TBT onto compost was highest at pH 6.7, and moreover did not show any variation with increasing salinity over the range 0 to 40 ‰. The adsorptive capacity also increased with increasing adsorbate hydrophobicity, following the trend tripropyltin (TPrT) < tributyltin (TBT) < tripentyltin (TPeT). Adsorption kinetics indicated an initial fast rate followed by a slower rate of adsorption. The effect of the formation of complexes between the dissolved organic matter from compost and TBT in solution was also investigated. The use of washed MSW compost as sorbent for the purification of TBT-contaminated wash waters as generated in large quantities during hull-cleaning in dry docks is suggested as a mitigatory measure against the impact of TBT on the coastal marine environment.
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