2种改性生物炭对水体硝态氮的吸附特性

Effects of Two Kinds of Modified Biochar Adsorbing Nitrate-N in Water

以2种水生植物香蒲(Typha angustifolia)和芦苇(Phragmites communis)制备的FeCl_3改性生物炭为吸附剂,硝酸钾溶液为吸附质,研究生物炭对水体硝态氮的去除。研究了2种改性生物炭的吸附动力学与吸附等温线特性,结合红外光谱分析(IR)、扫描电镜分析(SEM)和元素分析对2种改性与未改性生物炭进行表征,并探究生物炭投加量、吸附时间、吸附质初始浓度、吸附质pH值等因素对2种改性生物炭吸附硝态氮的影响。结果表明,2种改性生物炭对硝态氮的吸附均符合伪二级吸附动力学方程。FeCl_3改性香蒲生物炭(XP-Fe)和FeCl_3改性芦苇生物炭(LW-Fe)的最大吸附量qm分别为15.55和10.63 mg·g^(-1)。吸附质pH值降低,有利于XP-Fe和LW-Fe对硝态氮的去除。XP-Fe对硝态氮的吸附性能强于LW-Fe。

Two kinds of FeCl 3 modified biochar,prepared separately out of Typha angustifolia and Phragmites communis,two aquatic plants,were used as adsorbent and potassium nitrate solution was as adsorbate in this study to simulate removal of nitrate-N by biochar,and further to analyze adsorption kinetics and adsorption isotherm characteristics of the two modified biochars and their originals,and explore effects of biochar application rate,adsorption duration,and initial concentration and pH of the adsorbate on nitrate-N adsorption by the two biochars,with the aid of infrared spectroscopy(IR),scanning electron microscopy(SEM)and elemental assay.Results showed that nitrate-N adsorption of the two modified biochars fitted the pseudo-secondary adsorption kinetics.The maximum adsorption capacity q m of the FeCl 3 modified Typha angustifolia biochar(XP-Fe)and FeCl 3 modified Phragmites communis biochar(LW-Fe)was 15.55 and 10.63 mg·g-1,respectively.Reduced pH of the adsorbate facilitated nitrate-N adsorption by XP-Fe and LW-Fe.XP-Fe was higher than LW-Fe in nitrate-N adsorption capacity.