Preparation And Characterization Of Magnetic Nanomaterials And Its Application In The Water Environment Treatment Of Xiu Jiang River

In recent years,with the rapid development of economy,environmental problems have become increasingly prominent,especially water pollution.A large number of industrial,agricultural and domestic pollutants have been discharged into natural water bodies,causing great harm to human health and survival.In addition,pollutants in water are complex and diverse,and the interaction between different types of pollutants also brings challenges to water tretment.How to effectively remove pollutants that has become one of the hot research at home and aborad.Magentic nanomaterials have attracted extensive attention due to their large specific surface area,strong magnetic responsiveness.In this research,magentic nanometer Fe₃O₄ particles were prepared and functionalized.Then function magentic nanomaterial was used to remove organic matters and heavy metals from water.Finally,the combination of magentic material and ecological floating island were used to improve the water quality of XiuJiang river.The main conclusions are the following:?1?Magentic chitosan?MCS?was successfully synthesized by reverse phase suspension cross-linking method,and the morphological features were observed by a series of characterization methods.In single-component system,higher salicylic acid?SA?removal rate in the adsorption process was achieved due to its superior adsorption tendencies and size-exclusion effects than that of humic acid?HA?.Under the optimal adsorption conditions?dosage of 0.7 g/L,contact time for 80 min?,the maximum adsorption capacity of MCS on SA and HA was 84.82 and 8.47 mg/g.Moreover,individual SA/HA by MCS adsorption fit with pseudo-first order kinetic model Freundlich isotherm model.In bi-component system,the SA and HA removal rates were observed to decrease to varying extents due to the interaction between organics and the competition of adsorption sites.?2?Removals of SA and HA in individual and bi-component systems were investigated by MCS-coagulation.For sole coagulation,Aluminum sulfate?Alum?at sufficient dose?12.0mg/L?,although efficient in removing HA,was not desirable in removal of SA,which was associated with the charge neutralization,adsorption and sweep.The combined use of MCS and Alum led to increases in both SA and HA removals and consequently reduced the chemical concentration demand?MCS=0.5 g/L,Alum=8 mg/L?.Dynamic floc sizes during coagulation processes were studied using a laser diffraction particle sizing device.MCS added to the treat solution acted not only as an adsorbent for OM but also enhanced the settleability of flocs formed and increased the flocs sizes during the following coagulation process.?3?On the basis of high selective and sensitive interaction of 1,8-naphthalimide with Hg²⁺and the formation of stable neutral imide-Hg-imide complexes,we loaded this probe on MCS and successfully prepared multi-functional magnetic nano-fluorescent particles?MNFPs?with particle size of 20-50 nm.The morphology features of the prepared MNFPs were characterized by FTIR and TEM.Under optimal conditions,MNFPs has good fluorescence response,short detection time and higher selectivity to Hg²⁺than other heavy metal ions.Moreover,the maximum adsorption capacity of MNFPs on Hg²⁺was 92.31mg/g.MNFPs can be rapidly separated by magnetic field,and the secondary pollution was avoided.The above experimental results shown that MNFPs could be used for simple,rapid and simultaneous determination and removal of trace Hg²⁺in the environment.?4?Magnetic nanomaterials and ecological floating island were combined in the demonstration project of purifying the water quality of the XiuJiang river.The experimental results of this project shown that new ecological floating island,which was composed of many different types of water treatment methods,had a good effect on water quality and promoted the construction of ecological environment.