为了提高膨润土的吸附性能,采用羟基铝离子改性制成羟基铝柱撑膨润土。在利用红外光谱、BET&BJH、扫描电镜及Zeta电位表征其物理化学特性的基础上,考察吸附Cr(Ⅵ)的主要因素,通过吸附动力学、等温吸附过程、吸附热力学探讨作用机理。结果表明:羟基铝离子进入膨润土层间;片状结构出现剥裂现象,表面变得粗糙和疏松、孔洞增多;BET比表面积与微孔面积分别由49.56m2/g增至247.52m2/g、11.35m2/g增至181.61m2/g,孔体积增大,平均孔径变小。经过改性后对Cr(Ⅵ)的吸附能力明显增强;在40℃与pH=4条件下,用10g/L吸附剂处理30mg/L含Cr(Ⅵ)废水,去除率达到95.50%。吸附作用机理包括化学吸附和离子交换;吸附属于吸热反应,升温促进吸附反应。
In order to improve the adsorption performance of sodium bentonite,hydroxyl-Al pillared bentonite was prepared with hydroxyl aluminium cations.The physical and chemical properties were characterized by using FT-IR,BET&BJH,SEM and Zeta potential.The effects of several processing variables on the adsorption performance were studied in detail.The adsorption mechanism was discussed with respect to a number of kinetic/adsorption isotherm models and thermodynamic analysis.The characterization results indicated that hydroxyl-Al cations intercalated to the layers of bentonite.The layers were separated with larger spacing after modification,and the porosity and roughness of the surface increased.The BET specific surface area increased from 49.56m2/g to 247.52m2/g,and micropore area increased from 11.35m2/g to 181.61m2/g.The pore volume increased and the average pore size decreased.At pH 4,temperature 40℃ with adsorbent dosage of 10g/L,the treatment to 30mg/L of Cr(Ⅵ) reached the highest removal rate of 95.50% after contacting 60min.The adsorption process mainly corresponded to chemical adsorption and ionic exchange.The adsorption process was endothermic and spontaneous,and increasing temperature promoted the adsorption.
[1] Owlad M,Aroua M K,Wan A W D,et al.Removal of hexavalent chromium-contaminated water and wastewater:a review[J].Water Air and Soil Pollution,2009,200(1):59-77.
[2] 宋珍霞,殷齐贺,穆晓斐.膨润土负载纳米零价铁去除废水中Cr(Ⅵ)的动力学特性研究[J].化工新型材料,2018,46(5):205-209.
[3] Namasivayam C,Sureshkumar M V.Removal of chromium (Ⅵ) from water and wastewater using surfactant modified coconut coir pith as a biosorbent[J].Bioresource Technology,2008,99(7):2218-2225.
[4] Farooq U,Kozinski J A,Khan M A,et al.Biosorption of heavy metal ions using wheat based biosorbents—a review of the recent literature[J].Bioresource Technology,2010,101(14):5043.
[5] Fu F L,Wang Q.Removal of heavy metal ions from wastewaters:a review[J].Journal of Environmental Management,2011,92(3):407-418.
[6] Xia W,Hu J,Zhang B,et al.A case-control study of maternal exposure to chromium and infant low birth weight in China[J].Chemosphere,2015,144:1484-1489.
[7] Kumar J P,Ramacharyulu P V R K,Prasad G K,et al.Montmorillonites supported with metal oxide nanoparticles for decontamination of sulfur mustard[J].Applied Clay Science,2015,116-117:263-272.
[8] 关文斌,赵彬侠,邱爽,等.Cr(Ⅵ)在改性蒙脱土上吸附行为的研究[J].西北大学学报:自然科学版,2016,46(3):375-380.
[9] 王桂芳.铝柱撑蒙脱石的制备、结构及其吸附性能研究[D].济南:山东科技大学,2010.
[10] 姚培,李树白,刘媛,等.HTMAC/KH550/膨润土吸附剂的制备、表征及其在甲基橙废水的吸附行为[J].化工进展,2017,36(4):1374-1380.
[11] Daou I,Zegaoui O,Amachrouq A.Study of the effect of an acid treatment of a natural Moroccan bentonite on its physicochemical and adsorption properties[J].Water Science & Technology,2017,75(5):1098-1117.
[12] Yi Z J,Yao J,Kuang Y F,et al.Removal of Pb(Ⅱ) by adsorption onto Chinese walnut shell activated carbon[J].Water Science & Technology,2015,72(6):983.
[13] 曹晓强,颜炳琪,王倩,等.硅酸镁锂的有机改性及对Cr(Ⅵ)的吸附特性[J].高等学校化学学报,2017,37(2):173-181.
[14] Milonjic S K.A consideration of the correct calculation of thermodynamic parameters of adsorption[J].Journal of the Serbian Chemical Society,2007),72(12):1363-1367.
[15] Fan Q H,Tan X L,Li J X,et al.Sorption of Eu(Ⅲ) on attapulgite studied by batch,XPS,and EXAFS techniques[J].Environmental Science & Technology,2009,43(15):5776.
[16] Liu M,Hou L A,Xi B,et al.Synthesis,characterization,and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash[J].Applied Surface Science,2013,273(100):706-716.
[17] Hamane D,Arous O,Kaouah F,et al.Adsorption/photo-electrodialysis combination system for Pb2+ removal using bentonite/membrane/semiconductor[J].Journal of Environmental Chemical Engineering,2015,3(1):60-69.
