Liao Wei, Wang He, Li Hui-Qiang, Yang Ping
College of Architecture and Environment, Sichuan University Chengdu 610065 China
RSC Adv. 2019 Nov 28;9(67):38982-38989. doi: 10.1039/c9ra07305a. eCollection 2019 Nov 27.
Cd(ii) adsorption onto Fe(ii) modified Layered double hydroxide-graphene oxide (LDH-GO@Fe(ii)) was investigated using batch experiments. With the modification of Fe(ii), LDH-GO maintained its structure, while Fe(ii) species formed non-crystalline iron oxide clusters on the surface of the LDH/GO. A kinetics study indicated that adsorption obeyed a pseudo-second-order rate law. The equilibrium data were fitted well with the Langmuir isotherm model. The maximum adsorption capacity of LDH-GO@Fe(ii) was 28.98 mg g, higher those that of pure LDH-GO and LDH-GO@Fe(ii). The increased sorption capacities could be explained by the increased specific surface area. Modification with Fe(ii) would lead to the generation of amorphous Fe oxides and Fe could occupy the binding sites for Cd(ii), thus excess Fe in the structure will restrain the adsorption of Cd(ii). The XRD and XPS patterns revealed the formation of Cd(OH) after adsorption. Batch experiments indicated that precipitation and surface complexation were the main pathways for Cd(ii) removal.
采用批量实验研究了Cd(ii)在Fe(ii)改性的层状双氢氧化物-氧化石墨烯(LDH-GO@Fe(ii))上的吸附情况。通过Fe(ii)改性，LDH-GO保持了其结构，而Fe(ii)物种在LDH/GO表面形成了非晶态氧化铁簇。动力学研究表明，吸附遵循准二级速率定律。平衡数据与Langmuir等温线模型拟合良好。LDH-GO@Fe(ii)的最大吸附容量为28.98 mg/g，高于纯LDH-GO和LDH-GO@Fe(ii)。吸附容量的增加可以用比表面积的增加来解释。用Fe(ii)改性会导致非晶态Fe氧化物的生成，Fe会占据Cd(ii)的结合位点，因此结构中过量的Fe会抑制Cd(ii)的吸附。XRD和XPS图谱显示吸附后形成了Cd(OH)。批量实验表明，沉淀和表面络合是去除Cd(ii)的主要途径。
