Evaluation of biochars in reducing the bioavailability of flubendiamide in water/sediment using passive sampling with polyoxymethylene.

An equilibrium passive sampler based on POM was first used to determine the Cfree of flubendiamide in water/sediment systems. The adsorption of flubendiamide by POM followed a first-order one-compartment uptake model and the POM-water partition coefficient was 1.90. The method was used to compare the efficiency of three biochars which were produced from crofton weed (BC-1, ∼500°C), macadamia (BC-2, 550-660°C) and wheat straw (BC-3, 550°C). The Freundlich fit the sorption isotherm data well and the adsorption capacity was BC-1>BC-3>BC-2. The percent removal of the BC-1 was higher in acidic solutions. When different doses of BC-1 were added to two sediments, the Cfree of the flubendiamide was higher in the sediment with a low organic matter content (S-1). With an increase of BC-1, the Cfree was significantly reduced in S-1. A 30-day period of biochar-sediment contact time was sufficient for a reduction of freely dissolved flubendiamide in the case of the two sediments tested. In the combination of biochar addition (5%) and aging time (30days), the maximum reductions were 87% and 60% in S-1 and S-2. Therefore, the reduction of bioavailability of the flubendiamide and pollution repair can be achieved by this process.