Fabrication And Adsorption Behavior Of Nickel-based Bimetallic Hydroxides

With the rapid development of manufacturing industry,industrial wastewater has become a global problem.The discharge of industrial wastewater will cause serious pollution to the environment.At present,water pollution poses a great threat to human existence and has aroused great concern of all countries.In order to solve the problem of water pollution,various sewage treatment methods have been developed,such as electrochemical,membrane separation,photocatalytic,biodegradation,adsorption,etc.However,adsorption is the most widely used sewage treatment method because of its simple process and low investment cost.The key of adsorption method is how to prepare environmental-friendly adsorption materials with low price and excellent adsorption performance.Therefore,the starting point of this paper is to prepare hierarchical porous adsorption materials from bimetallic hydroxides by simple synthesis method and its adsorption and cycling properties were also studied.The details are as follows:Firstly,hierarchical porous Ni/Co-layered double hydroxide?NiCo-LDH?hollow dodecahedra were synthesised by etching zeolitic imidazolate framework-67 as a self-sacrificing template with Ni?NO3?2 at room temperature.The synthesised NiCo-LDH is relatively uniform in size and has good adsorption property for adsorbing Congo red and Cr???ions.After systematically studying the adsorption data,we find that the adsorption kinetics well match the pseudo-second-order model and the adsorption isotherms well fit the Langmuir model.Building on the Langmuir model,the maximum capacities of Congo red and Cr???ions on as-synthesised NiCo-LDH are determined to be 909.2 and 99.9 mg g^–1 at 30°C and neutral environment,respectively.In addition,the circulation experiments indicate that the sample NiCo-LDH is recyclable and the selectivity experiment suggests that the synthesized NiCo-LDH preferentially adsorb anionic dyes and has high selectivity.These results show that the synthesized NiCo-LDH can be used as a potential adsorbent for industrial wastewater treatment.Secondly,the NiFe-LDH nanosheets were successfully grown on the surface of prepared carbon fiber by a simple hydrothermal method.It was found that carbon fiber could support the uniform growth of NiFe-LDH nanosheets on its surface,which could prevent the agglomeration of nanosheets.Thus,the C/NiFe-LDH composite have high specific surface area and hierarchical porous structure.By studying the adsorption behavior of as-prepared samples for methyl orange and Congo red removal,we find that the adsorption kinetic data can be described by the pseudo-second-order model and the adsorption isotherms well match the Langmuir model.According to the Langmuir model,the maximum adsorption capacities of methyl orange and Congo red on C/NiFe-LDH composite are 323.6 and 448.4 mg g^–1at 30°C and neutral environment,respectively.In addition,cyclic experiments show that the C/NiFe-LDH composite has good cycling performance for methyl orange and Congo red removal.Therefore,the synthesized C/NiFe-LDH can be used as an effective adsorbent for the removal of anionic dyes from industrial wastewater.