为研究功能复合材料对低浓度氨氮[ρ(NH4+-N)≤50 mg/L]废水的处理效果,采用水热法制备TiO2/生物炭复合材料,并在自制光催化反应装置中对低浓度氨氮废水进行处理,考察TiO2负载量、温度、pH等因素对NH4+-N去除过程的影响以及催化的最终降解产物.结果表明,TiO2/生物炭复合材料能有效催化去除废水中的NH4+-N,其优化处理条件:ρ(NH4+-N)为50 mg/L,TiO2/生物炭复合材料投加量为1.5 g/L,254 nm紫外灯照射120 min,TiO2负载量为20％,废水初始pH为11.0,曝气量为150 mL/min.在优化处理条件下,当温度为60℃时NH4+-N去除率可达100％,常温(30℃)下可达67％.反应最终产物中ρ(NO2--N)非常低,并且无NO3-N生成.研究显示,TiO2/生物炭复合材料具有将NH4+-N转化为N2的良好光催化氧化选择性.%In order to investigate the disposal of low concentration ammonia-nitrogen wastewater (concentration less than or equal to 50 mg/L) using a functional composite,a new photocatalyst,TiO2/biochar composite,was prepared by immobilizing TiO2 nanoparticles onto biochar synthesized by the hydrothermal method.The properties of the as-prepared TiO2/biochar were further characterized by X-ray diffraction,scanning electron microscopy,and UV-Vis diffuse reflectance spectroscopy.The photocatalytic degradation of ammonianitrogen from water was evaluated along the gradients of load ratio,pH,temperature and initial concentrations of ammonia-nitrogen.The results showed that TiO2 nanoparticles were well dispersed on the biochar,which prevented the agglomeration of TiO2 and enhanced the instability.The highest ammonia-nitrogen removal efficiency (100％ at 60 ℃ and over 70％ at 30 ℃) was observed at the conditions of 20％ TiO2 loading,150 mL/min aeration rate,pH 11.0,and under 254 nm UV light irradiation.The final product contained little nitrite and exclusive nitrate,indicating the excellent catalytic selectivity of TiO2/biochar composite,which can oxide ammonia-nitrogen to N2.In conclusion,TiO2/biochar composite is anenvironmentally-friendly and highly efficient photocatalyst complex for the removal of ammonianitrogen at low concentrations.
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