| Heavy metal ions and arsenic pollutants in water environment pose a serious threat to human health and the safety of entire ecosystem,due to their environmental persistence,difficult degradation and biological enrichment characteristics.The removal of highly toxic heavy metals and arsenic under different concentrations,forms and valence states has always been a major challenge in water purification technology.In recent years,the development of nanomaterials for water purification and environmental remediation has attracted extensive attention for many researchers.However,the poor performance,easy agglomeration and difficult separation properties of engineered nanomaterials largely restrict their practical application.Therefore,the construction of macroscopic nanocomposites with specific properties and functions is of great practical significance for the removal of pollutants in water purification.In this paper,different types of Iron-based micro/nanomaterials/porous carbon composites were constructed for the removal of pollutants in water at a macro scale.The mass transfer and adsorption of metal ions on the surface of the adsorbent material can be impoved,and the kinetic process of adsorption and interface reaction can be enhanced to achieve efficient pollutants removal by various means including nanostructured regulation,group regulation,electrochemical enhancement,etc.The development of nanocomposites with specific properties and functions is of great importance in sustainable water purification for pollutants removal.In this paper,a 3D NiFe-MoS42--LDH/CF hybrid monolith was prepared for highly toxic Hg2+,Pb2+and Cu2+removal,and its adsorption performance and mechanism for different heavy metal ions were investigated.Then,amorphous FeOOH nanosheets grown on carbonized bamboo(denoted as FeOOH NSs/CB)was fabricated by regulation of the Fe-O group in the micro/nano structure for membrane purification of arsenite ions removal in water,As(?)removal,and the corresponding adsorption mechanism was explored.Besides,Fe/Fe3C nanoparticles(NPs)and clusters encapsulated in N,O-codoped carbon nanotubes(CNTs)anchored on carbonized wood(CW)framework was constructed for heterogeneous electro-Fenton oxidation and electrochemical removal of As(?)due to its hypertoxicity and poor affinity.The oxidation/removal performance and the corresponding mechanism for As(?)were investigated.At last,Fe3O4 nanorod arrays wrapped with ultrathin carbon layer/commercial carbon cloth composite was fabricated for separation and recovery of heavy metal lead and copper ions.Its electrochemical removal performance and interface reaction mechanism were studied.The main results are concluded as follows:1.A hierarchical porous hybrid monolith have been successfully fabricated,in which NiFe-LDH nanosheets are vertically immobilized on a CF substrate via a facile hydrothermal route,followed by the intercalation of MoS42-into the interlayers,giving rise to a hierarchical porous hybrid monolith(denoted as NiFe-MoS42--LDH/CF).Experimental results indicate that the developed hybrid monolith is highly effective for the sequestration of Hg2+,Pb2+,and Cu2+,exhibiting ultrahigh sorption capacities of 462,299,and 128 mg g-1,respectively,and outperforms most of the reported sorbents owing to the virtue of abundant binding sites,strong affinity and excellent pore accessibility.Meanwhile,the uptake kinetics of these metal ions are extremely fast,as reflected by>99%removal rates within several minutes.Remarkably,the resulting NiFe-MoS42--LDH/CF hybrid monolith can be utilized as a flow-through filter unit and continuously treat larger volumes of simulated wastewater to below the permitted level for drinking water,highlighting its feasibility for practical water purification.2.Arsenic is a widespread pollutants,it is of great practical significance to develop cheap and efficient nanocomposite film materials through the regulation of oxygen-containing groups as efficient adsorbents.Herein,a hierarchical hybrid membrane constructed by amorphous FeOOH nanosheets grown on carbonized bamboo(denoted as FeOOH NSs/CB)has been successfully fabricated via a facile and rapid electrodeposition process for arsenic removal.The thickness and loading amount of amorphous FeOOH NSs on CB were carefully modulated by varying the deposition time and applied voltage to investigate their influence on arsenic removal performance.Thanks to abundant binding sites,amorphous nature of ultrathin FeOOH NSs,and excellent pore accessibility,the optimized FeOOH NSs/CB membrane exhibits superior As(?)sequestration capability in high removal efficiency,fast kinetics,and strong anti-interfering performance.Significantly,the optimized FeOOH NSs/CB hybrid membrane can be directly utilized as an efficient filter unit to continuously treat 1160 mL of As(?)-contaminated water(100 ppb)to below the permitted threshold in drinking water,accompanied by as high as 1528.7 L m-2 h-1 of the permeate flux,which is 2 orders of magnitude higher than traditional membrane materials.Meanwhile,it also possesses excellent recycling capacity.The diffusion and adsorption of arsenate on the surface of the adsorbent material are greatly improved in this work by regulation of the structure and group for the macroscopic iron-based nanocomposites,paving a way for the practical application of arsenic removal.3.Arsenic is a widespread contaminant and has aroused global concerns due to its hypertoxicity and facile mobility.Electrochemical method which can regulate the interface reaction of nanomaterials is regard as an efficient ways to promote the migration and transformation of pollutants.Herein,an electrochemical integrated system for As(?)removal has been developed using 3D hierarchically porous hybrid monolith electrodes,constructed by Fe/Fe3C nanoparticles(NPs)and clusters encapsulated in N,O-codoped carbon nanotubes(CNTs)anchored on carbonized wood(CW)framework(denoted as Fe/Fe3C@CNTs/CW).Remarkably,the heterogeneous electro-Fenton reaction on the cathode promotes the oxidation of As(?)into As(V);while the electro-sorption on the anode is conducive to the subsequent arsenic immobilization.Under the optimized conditions,trace As(?)species(1 ppm)can be efficiently removed within 90 min.Significantly,the saturation electro-sorption capacity of the anode materials is approximately 10 times higher than that of physicochemical adsorption.The mechanism studies reveal that ·OH are the dominant free radicals responsible for the conversion of As(?)to As(?)in the cathodic electro-Fenton oxidation.Besides,the existed electric field enhances the ion migration and promotes the complexation of arsenic contaminants on the surface of the electrode.This work provides a new idea for utilization of electrochemical method as an water purification strategy to promote the migration and transformation of pollutants on the surface of micro/nano structures.4.The development of nanostructured materials electrode with high reactivity,electrical conductivity and stability is of great significance for enhancing the separation and recovery of metal ions using electrochemical methods.Herein,Fe3O4 nanoarray wrapped with ultrathin carbon layer/commercial carbon cloth composite(denoted as Fe3O4@C NRAs/CC)has been fabricated via hydrothermal and calcination route as a self-standing cathode for separation and recovery of copper and lead from wastewater by electrochemical deposition.The experimental results indicate that the unique nanoarray structure of electrode material is conducive to the tip-enhanced local electric field to promote the ion migration,futher realizing the reduction and fixtion of metal ions on the surface of cathode.The removal capacity of the electrochemical deposition method is 1-2 orders of magnitude higher than that of the traditional adsorption method.Moreover,the selectivity of different metal ions for separation and recovery can be adjusted by regulation of the applied voltage.Besides,the influences of the solution pH,coexisting ions and applied voltage were investigated on the separation efficiency of electrodeposition.The target metal can be recovered with concurrent recycle of the cathodic material by applying a reversed voltage under stirring.Based on this,we have constructed an electrochemical separation and recovery device using Fe3O4@C NRAs/CC as self-standing cathode,which can separate and recover the metal copper from electronic waste leaching solution with recovery efficiency over 90%,laying the groundwork for the practical application of metal ion separation and recovery. |
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