氟离子在脱硫石膏表面的吸附转化行为及高浓度含氟废水净化技术
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摘要
以烟气脱硫(FGD)石膏作为除氟剂,通过沉淀法去除高浓度含氟废水中的氟离子,并对FGD石膏除氟机理进行了探讨。单因素条件实验结果表明,在FGD石膏用量10.744 g/L、pH=7、反应时间30 min、反应温度25℃的最佳实验条件下,含氟废水的F~-浓度可从1 500 mg/L降至89.13 mg/L,除氟率可达94.06%。溶液化学分析结果表明,当溶液pH=5～11时,溶液中Ca~(2+)与F~-的浓度较高,而CaF_2的溶解度较小,FGD石膏在溶液中释放出的Ca~(2+)与F~-结合生成难溶的CaF_2沉淀,从而将F~-从溶液中去除。XRD、SEM-EDS等结果表明,反应生成的难溶CaF_2以壳状形式均匀稳定地包裹在FGD石膏表面,从而实现高浓度含氟废水的净化。
Flue gas desulfurization(FGD) gypsum was used as a defluoridation agent to remove fluoride ions from wastewater with high content of fluorine by precipitation, and the fluorine removal mechanism was also discussed. The results of single factor experiment showed that the F~- concentration of fluorine-containing wastewater was reduced from 1 500 mg/L to 89.13 mg/L under the optimal conditions including the FGD gypsum dosage at 10.744 g/L, pH=7, reaction time of 30 min and reaction temperature at 25 ℃, with the fluoride removal rate reaching 94.06%. The chemical analysis of the solution showed concentration of Ca~(2+) and F~- was higher and solubility of CaF_2 was lower in the solution with pH=5～11. The Ca~(2+) released from FGD gypsum in the solution combined with F~-, forming an insoluble CaF_2 precipitates, consequently resulting in F~- removed from the solution. XRD and SEM-EDS results showed that the insoluble CaF_2 formed by the reaction uniformly and stably wrapped on the surface of FGD gypsum as a shell, thus achieving the purpose of purification of such high-fluorine-content wastewater.
Flue gas desulfurization(FGD) gypsum was used as a defluoridation agent to remove fluoride ions from wastewater with high content of fluorine by precipitation, and the fluorine removal mechanism was also discussed. The results of single factor experiment showed that the F~- concentration of fluorine-containing wastewater was reduced from 1 500 mg/L to 89.13 mg/L under the optimal conditions including the FGD gypsum dosage at 10.744 g/L, pH=7, reaction time of 30 min and reaction temperature at 25 ℃, with the fluoride removal rate reaching 94.06%. The chemical analysis of the solution showed concentration of Ca~(2+) and F~- was higher and solubility of CaF_2 was lower in the solution with pH=5～11. The Ca~(2+) released from FGD gypsum in the solution combined with F~-, forming an insoluble CaF_2 precipitates, consequently resulting in F~- removed from the solution. XRD and SEM-EDS results showed that the insoluble CaF_2 formed by the reaction uniformly and stably wrapped on the surface of FGD gypsum as a shell, thus achieving the purpose of purification of such high-fluorine-content wastewater.
引文
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[3] 褚衍洋,苗娟,姜勇.壳聚糖混凝剂除氟的研究[J].安全与环境工程,2007,14(3):43-47.
[4] Araga R,Soni S,Sharma C S.Fluoride adsorption from aqueous solution using activated carbon obtained from KOH-treated jamun (Syzygium cumini) seed[J].Journal of Environmental Chemical Engineering,2017,5(6):5608-5616.
[5] 马兴冠,贺一达,高强,等.活性氧化铝吸附法处理含氟污水工况研究及应用[J].沈阳建筑大学学报(自然科学版),2015,31(6):1120-1128.
[6] 王辉.粉煤灰处理废水研究进展[J].山西化工,2018,38(1):40-44.
[7] 刘鸿飞.高氟废水除氟新技术研究[D].昆明:昆明理工大学冶金与能源工程学院,2017.
[8] Budyanto S,Kuo Y L,Liu J C.Adsorption and precipitation of fluoride on calcite nanoparticles:A spectroscopic study[J].Separation & Purification Technology,2015,150:325-331.
[9] Lu N C,Liu J C.Removal of phosphate and fluoride from wastewater by a hybrid precipitation-microfiltration process[J].Separation & Purification Technology,2010,74:329-335.
[10] Liu C C,Liu J C.Coupled precipitation-ultrafiltration for treatment of high fluoridecontent wastewater[J].Journal of the Taiwan Institute of Chemical Engnieer,2016,58:259-263.
[11] Guo D J,Yuan Y F,Hu H R,et al.Influence of FGD gypsum on the properties of Portlandcement[J].Bulletin of the Chinese Ceramic Society,2010(2):357-360.
[12] 金彪,汪潇,杨留栓.粉煤灰提铝残渣、脱硫石膏、矿渣制备轻质保温板试验研究[J].无机盐工业,2018,50(6):71-74.
[13] 马义,杨晋,韩凤兰,等.脱硫石膏吸附水体中重金属离子行为的研究[J].硅酸盐通报,2018,37(6):1868-1896.
[14] 王国庆,张亚鹏,关宏艳,等.离子选择电极法检测水中氟离子的若干经验[J].分析仪器,2006(3):56-57.
[15] Lei D Y,Guo L P,Sun W.Study on properties of untreated FGD gypsum-based high-strength building materials[J].Construction and Building Materials,2017,153:765-773.