温度对生物炭吸附重金属特性的影响研究

Impact of Temperature on Adsorption Characteristics of Biochar on Heavy Metals

为探究温度条件对生物炭吸附重金属离子特性的影响,采用吸附试验研究25、45和65℃3种温度条件下生物炭对单一重金属离子溶液和多种重金属离子混合溶液的吸附能力变化。结果表明:生物炭对4种重金属的吸附均可采用Langmuir和Freundlich方程进行描述;温度是影响生物炭吸附重金属的重要因素,生物炭对Cu的吸附能力随温度的升高而减小,在25℃时吸附量最大,为5.27 mg·g^-1,去除率达到36.17%;生物炭对Zn的吸附能力随温度的升高而增加,在65℃时吸附量最大,为4.94 mg·g^-1,去除率达到45.36%;生物炭对Cd的吸附能力随温度的升高呈现先增加后降低的趋势,在45℃时吸附量最大,为5.82 mg·g^-1,去除率达到53.85%;生物炭对Pb的吸附能力随温度的升高而增加,在65℃时吸附量最大,为21.35 mg·g^-1,去除率达到98.61%。混合溶液中,生物炭对4种重金属的吸附强弱顺序为:Pb>Cu>Zn>Cd。温度升高能促进竞争吸附中生物炭对各重金属离子的吸附,对混合重金属离子的总吸附量也增大。

In order to explore the effect of temperature on adsorption ability of biochar on heavy metals,this paper conducted the equilibrium adsorption experiments of biochar on single and multiple heavy metals at 25,45 and 65℃,respectively.The results indicated that:the adsorption characteristics of heavy metals(Cd,Pb,Cu,Zn)by biochar could be fitted by Langmuir and Freundlich equation.Temperature was an important factor affecting the adsorption of heavy metals by biochar.The adsorption capacities of biochar on Cu decreased with temperature increasing,the maximum adsorption capacity was 5.27 mg·g^-1 at 25℃,and the removal rate reached 36.17%;the adsorption capacities of biochar on Zn increased with temperature increasing,and the maximum adsorption capacity was 4.94 mg·g^-1 at 65℃,and the removal rate reached 45.36%;the adsorption capacity of biochar of on Cd increased first followed by a decline with temperature increasing,and the maximum adsorption capacity was 5.82 mg·g^-1 at 45℃,and the removal rate reached 53.85%;the adsorption capacities of biochar on Pb were increased with temperature increasing,and the maximum adsorption capacity was 21.35 mg·g^-1 at 65℃,and the removal rate was reached 98.61%.In multiple heavy metals solution,the adsorption capacity of biochar was Pb>Cu>Zn>Cd.The adsorption of heavy metals were enhanced by the increase of the temperature,and the total adsorption amounts of biochar on heavy metals increased.