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首页> 外文期刊>Environmental Science & Technology >Effect of Strongly Competing Background Compounds on the Kinetics of Trace Organic Contaminant Desorption from Activated Carbon
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Effect of Strongly Competing Background Compounds on the Kinetics of Trace Organic Contaminant Desorption from Activated Carbon

机译：竞争激烈的背景化合物对活性炭中微量有机污染物解吸动力学的影响

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Strongly competing (SC) compounds, naturally found in any drinking water source, are known to decrease the adsorption capacity of activated carbon for trace contaminants. While the effect of these substances on the capacity and adsorption kinetics of trace contaminants is fairly well studied, relatively little is known about their impact on desorption kinetics. The purpose of this study was to investigate the relationship between SC matter and trace compound desorption kinetics. A surrogate SC compound, 1,4-dichlorobenzene (p-DCB), was used to displace the preadsorbed target trace contaminant atrazine, from powdered activated carbon (PAC). The initial concentrations of p-DCB and atrazine were varied to achieve different degrees of competition to atrazine. Atrazine's desorption diffusion coefficient was found to increase with increasing adsorbed concentration of the SC matter, expressed as an equivalent background compound (EBC). The EBC was modeled with atrazine-like adsorption properties, thus representing the portion of p-DCB that competed to occupy atrazine adsorption sites. The increase in atrazine diffusion rate can be explained by a shift from surface diffusion to diffusion through the carbon's pores as the availability of surface sites decreased due to the EBC's competition. The observed desorption kinetic relationship was consistent with the effect of SC competition on adsorption kinetics; further, the effect was consistent for three different types of SC matter. These findings highlight that the impact of SC matter on activated carbon applications could be either detrimental (displacing adsorbed trace contaminants and enhancing their rate of release) or beneficial (offsetting pore constriction effects by enhancing their rate of uptake).
机译：在任何饮用水源中自然存在的强竞争性（SC）化合物已知会降低活性炭对痕量污染物的吸附能力。尽管这些物质对痕量污染物的容量和吸附动力学的影响已得到很好的研究，但对它们对解吸动力学的影响知之甚少。这项研究的目的是研究SC物质与痕量化合物解吸动力学之间的关系。替代品SC化合物1,4-二氯苯（p-DCB）用于从粉末状活性炭（PAC）替代预先吸附的目标痕量污染物阿特拉津。对-DCB和at去津的初始浓度有所不同，以实现与at去津不同程度的竞争。发现去津的解吸扩散系数随着SC物质吸附浓度的增加而增加，表示为当量背景化合物（EBC）。对EBC进行建模，使其具有类似阿特拉津的吸附特性，因此代表了p-DCB竞争占据阿特拉津吸附位点的部分。 r去津扩散速率的增加可以解释为，由于EBC的竞争，表面位点的可利用性下降，导致从表面扩散转变为通过碳孔扩散。观察到的解吸动力学关系与SC竞争对吸附动力学的影响一致。此外，对于三种不同类型的SC物质，效果是一致的。这些发现表明，SC物质对活性炭应用的影响可能是有害的（取代吸附的痕量污染物并提高其释放速率），也可能是有益的（通过提高其吸收速率来抵消孔收缩效应）。

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