镁铝氢氧化物改性生物炭对水体中氮磷的吸附效果研究

Adsorption Eff ects of Phosphate and Nitrate from Aqueous Solution Using Mg/Al-Hydroxides Modifi ed Hard Biochars

为提高硬质枣核生物炭(ZC)对水体氮磷的去除性能,采用两步溶液浸渍法制备了一组不同Mg/Al比(x)的双氢氧化物改性生物炭(ZC-x,x=2,3,4)。利用XRD、SEM/EDS、FTIR和N2吸附/脱附手段对吸附材料进行了表征。结果表明,镁铝改性剂以低结晶度层状双氢氧化物的形态负载到ZC表面;ZC-x的比表面积和孔容积均大于ZC;在30mg·L^(-1)、pH=6.5及3℃条件下ZC-3对PO_(4)^(3-)和NO_(3)^(-)的去除率最高,分别为47.5%和27.7%,具有更高的吸附速率和更强的亲和力ZC-3。研究结果为发展水体脱氮除磷碳基吸附材料及应用技术提供了实验依据。

To increase the removal of nitrate and phosphate nutrients in wastewater with hard date stone biochar,a two-step wet impregnation method was used to prepare a series of modified date stone biochar(Z)having different atomic ratios(x)of Mg/Al hydroxides(ZC-x).Several techniques(XRD,SEM/EDS,FTIR and N2 adsorption/desorption)were used to characterize the structure and adsorption behavior of the adsorbents.The results showed that both Mg/Al hydroxides were successfully introduced onto the surface of ZC in the form of the low crystallinity Mg/Al-layered double hydroxide form.Optimum adsorption rates for phosphate(47.5%)and nitrate(27.7%)were attained when x was equal to three(ZC-3).The specific surface area(5.8 m^(2)·g^(-1))and total pore volume(0.033 cm^(3)·g^(-1))of ZC-3 were greater than those of ZC(2.1 m^(2)·g^(-1),0.011 cm^(3)·g^(-1)).Adsorption kinetics and isotherm studies also showed that ZC-3 had an improved rate of adsorption,affinity and capacity for phosphate and nitrate.ZC-3 may provide a potential alternative to carbon-based adsorbents for the removal of phosphates and nitrates from aqueous solutions.