磷酸钾改性秸秆生物炭高效去除酸性矿山废水中的镉

Efficient removal of Cd(Ⅱ)from acid mine wastewater by potassium phosphate modified straw biochar

目的:磷酸盐改性被认为是提高秸秆生物炭(RBC)去除酸性矿山废水中Cd(Ⅱ)性能的潜在策略,本研究采用磷酸钾对水稻秸秆生物炭(KRBC)进行改性,以提高其对酸性矿山废水中Cd(Ⅱ)的吸附性能。方法:采用批量吸附试验探究溶液初始pH、共存离子、腐殖酸浓度、吸附时间及Cd(Ⅱ)初始浓度对吸附剂去除Cd(Ⅱ)影响,并调查改性生物炭对Cd(Ⅱ)去除的潜在机理。结果:吸附试验表明在溶液pH为5.0~7.0时,KRBC对水溶液中Cd(Ⅱ)具有较好去除性能。此外,共存离子K^(+)、Na^(+)、Ca^(2+)、Mg^(2+)、NO-3和SiO_(3)^(2-)对RBC和KRBC去除Cd(Ⅱ)没有影响,而PO_(4)^(3-)、CO_(3)^(2-)及腐殖酸对去除Cd(Ⅱ)具有促进作用。拟二阶动力学模型和Langmuir模型可以更好地描述Cd(Ⅱ)的吸附过程。RBC和KRBC对Cd(Ⅱ)的最大吸附能力分别为57.93 mg/g和159.46 mg/g。潜在的去除机理包括络合、静电作用、阳离子-π相互作用及共沉淀。在经过三次再生性试验后,RBC和KRBC对50 mg/L的Cd(Ⅱ)去除率分别为20.18%和86.75%。结论:以上结果表明磷酸钾改性生物炭在去除酸性矿山废水中的Cd(Ⅱ)具有更大的潜力。

Purpose:Phosphate modification is considered as a potential strategy to improve the performance of straw biochar(RBC)for removing Cd(Ⅱ)from acid mine wastewater.In this work,K_( 3) PO _(4) was employed to modify rice straw biochar(KRBC)to improve its adsorption performance of Cd(Ⅱ)from wastewater.Method:Batch adsorption experiments were used to investigate the effects of initial solution pH,co-existing ions,humic acid concentration,adsorption time and initial concentration of Cd(Ⅱ)on removing Cd(Ⅱ)and the potential mechanism of Cd(Ⅱ)removal by modified biochar was researched.Result:The adsorption experiments showed that KRBC had good removal performance of Cd(Ⅱ)at a solution pH of 5.0~7.0.Additionally,the co-existing ions of K^(+),Na^(+),Ca^(2+),Mg^(2+),NO-3and SiO_(3)^(2-)had no effect on removing Cd(Ⅱ)for RBC and KRBC,whereas PO_(4)^(3-),CO_(3)^(2-)and humic acid promoted the removal of Cd(Ⅱ).The proposed second-order kinetic model and Langmuir model could better describe the adsorption process of Cd(Ⅱ).The maximum adsorption capacity of RBC and KRBC for Cd(Ⅱ)was 57.93 mg/g and 159.46 mg/g,respectively.Potential removal mechanisms included complexation,electrostatic interaction,cation-πinteraction,and co-precipitation.After three regenerative experiments,the removal efficiencies of Cd(Ⅱ)at 50 mg/L by RBC and KRBC were 20.18%and 86.75%,respectively.Conclusion:The above results indicate that K 3 PO 4 modified biochar has more potential for the removal of Cd(Ⅱ)from acid mine wastewater.