Improved understanding of tributyltin sorption on natural and biochar‐amended sediments

Abstract

A poor understanding of tributyltin (TBT) sorption on sediments has hindered an accurate evaluation of its environmental fate. The present study determined TBT sorption by a freshwater sediment (BH) and a coastal marine sediment (TZ) as influenced by pH, salinity, and biochar (BC) amendment into TZ. The isotherms were essentially linear, with K(OC) values in the range of 10(4) to 10(5) L/kg. Tributyltin sorption at pH 3.56 and 8.00 occurred mainly via partitioning. It reached maxima at pH equal to its pK(a) (=6.25) because of added ion exchange. A salinity increase from 5 to 35 practical salinity units enhanced TBT sorption at pH 3.56 and 8.00 on TZ by approximately 30% and on BH by approximately 80%, ascribed to the salting-out effect that reduced the solubilities of tributyltin hydroxide (TBTOH) and tributyltin chloride (TBTCl). At pH 6.25, the same salinity increase reduced TBT sorption on TZ by approximately 20% but enhanced TBT sorption on BH by approximately 35%. This was attributed to the enhancing role of salting out and the reducing role of metal competition for ion exchange. Tributyltin was two orders of magnitude more effectively sorbed by BC than by total organic carbon of TZ, mainly because of the high level of surface area of the BC. Although BC affinity for TBT may be significantly diminished when present in TZ, it was considered to be the primary contributor to TBT sorption from water. Biochar may thus be used to immobilize TBT in sediment for potential remediation.

Effects of NaOH Activation on Adsorptive Removal of Herbicides by Biochars Prepared from Ground Coffee Residues

“…The removal rates of herbicides using the GCRB and GCRB-N were gradually increased with increasing ionic strengths (the GCRB: the removal rate of ALA = 3.6% → 6.9%, the removal rate of DIU = 2.0% → 6.3%, the removal rate of SIM = 1.5% → 6.1%; the GCRB-N: the removal rate of ALA = 61.4% → 70.2%, the removal rate of DIU = 81.4% → 87.5%, the removal rate of SIM = 47.0% → 60.3%). These observations could describe that the decreased solubility of the organic compounds with high concentrations of sodium ions might promote the adsorption capacity of the porous carbonaceous absorbents under different ionic strength conditions (salting-out effects) [43,44].…”

Insights into the Restoration of Tributyltin Contaminated Environments Using Marine Bacteria from Portuguese Fishing Ports

“…Marinas and ports are hotspots of TBT contamination due to boat traffic and shipyard activities [35,36]. Thus, it is expected that these sampling sites would be contaminated with TBT and that smaller concentrations of this highly toxic chemical might be present, particularly in sediments, where it persists [8,37]. Previous studies reported levels of butyltins in Portuguese waters.…”

Technieken en toepasbaarheid voor de sanering van dioxines en TBT in het Noordzeekanaal : fase 1

“…De adsorptie van TBT aan actief koolpoeder was wel minder sterk dan voor PAK's en PCB's. Xiao heeft laboratoriumonderzoek gedaan naar de adsorptie en desorptie van TBT aan natuurlijk sediment en aan sediment gespiked met actief kool (range 0.2 tot 1%)(Xiao et al, 2011).Uit dit onderzoek blijkt dat de desorptie van TBT sterk verminderd was bij het sediment gespiked met kool. De techniek werd hierdoor als potentiele geschikte techniek beoordeeld om TBT te immobiliseren in sediment.…”