Preparation Of Multifunctional Cotton Fiber And Its Application To Adsorption And Detection Of Copper And Cadmium Ions In Water

Heavy metal pollution in solution has become a global environmental problem.Heavy metal in the environment was non-degradable,and most of the heavy metal ions were colorless and odorless in solution with low concentration.With the heavy metal entering the food chain and forming long-term accumulation,it would cause serious consequences,e.g.,organism poisoning,which was a great threat to the environment and human health.As the heavy metal pollution was increasingly serious,it was urgently needed to develop effective materials for the removal of heavy metal ions.Furthermore,materials and methods were also needed for the detection and early warning of the heavy metal ions in water and wastewater.For the preparation of the functional materials with high adsorption capacity and simple quantitative detection of Cu²⁺ and Cd²⁺,surface initiated atom transfer radical polymerization（SI-ATRP）technology,which provided an effective way to synthesis controlled structure and new functionalized polymer materials,was used for the surface modification of the cotton fiber,which possesses a large number of hydroxyl groups.Then,Aminated Cotton Fiber（ACF）for Cu²⁺ adsorption and detection,porphyrin functional cotton fiber（Cotton-PSMP-TMPyP,CPT）for Cd²⁺ adsorption and detection,and the funcitional fiber（Cotton-PGMA（DETA）-PSMP-TMPyP,CPDPT）for enhanced adsorption and detection of Cd²⁺ were prepared in this paper.Also,optimization of the preparation conditions and characterizations of three functional fibers were carried out.The adsorption performance,adsorption mechanism and easilyheavy metal ion detection method establishment of the three materials were investigated in this paper.The main research findings of this paper were listed as follows:（1）The aminated cotton fiber（ACF）was successfully prepared via the SI-ATRP technology and the subsequent immobilization of the functional groups.Preparation conditions including SI-ATRP reaction time and amination reaction time were optimized.The characterization proved the successful grafting of the polymer brush and the immoblizaiton of the functional groups for ACF throught the analyses of SEM,FTIR,XPS,etc.Also,Cu²⁺ adsorption with ACF through complexation between N atom and Cu was proved.The adsorption kinetics,adsorption isotherms,pH effect and detection performance were investigated with ACF samples.The results showed that a linear relationship between the absorbance of ACF-Cu(CPT adsorbed with Cu²⁺)and the initial concentration of Cu²⁺ was established at the pH value of 5,which could be used for the rapid determination of Cu²⁺ concentration in solution.According to the Langmuir fitting parameter,the theoretical maximum adsorption capacities for Cu²⁺ and Cd²⁺ were 1.8406 mmol/g and 1.5723mmol/g,respectively.（2）The Cotton-PSMP-TMPyP（CPT）was successfully prepared via the SI-ATRP technology and the subsequent immobilization of the functional groups.Preparation conditions including SI-ATRP reaction time and concentrations of TMPyP were optimized.The influencing factors such as pH and the initial cadmium ion concentrations on the adsorption performances were investigated with CPT samples.Results showed that the Cd²⁺ adsorption isotherm was best fitted with the Langmuir isotherm model,with the derived maximum adsorption capacity of 0.8638 mmol/g.The thermodynamic study showed an endothermic nature for the adsorption process.In addition,the adsorption kinetics was fast with over 90% of the total Cd²⁺ adsorbed within the first 2 min because of special complexation between Cd²⁺ and TMPyP.Furthermore,the distinctive color response of the CPT to Cd²⁺ in aqueous solutions was clearly displayed.A linear relationship between the absorbance of CPT-Cd(CPT adsorbed with Cd²⁺)and the initial concentrations of Cd²⁺ was successfully established,which could be used for the fast determination of the Cd²⁺ concentrations in aqueous solutions.（3）The Cotton-PGMA（DETA）-SPMP-TMPyP（CPDPT）was successfully prepared via the SI-ATRP technology and the subsequent immobilization of the functional groups.Preparation conditions including SI-ATRP reaction time and concentrations of TMPyP were optimized.The characterization proved the successful grafting of the polymer brush and the immoblizaiton of the functional groups for CPDPT throught the analyses of SEM,FTIR,XPS,etc.The influencing factors such as pH and the initial Cd²⁺ concentrations on the adsorption performances were investigated with CPDPT samples.The CPDPT sample showed enhanced adsorption with the maximum adsorption capacity of 1.2000 mmol/g as it derived from the Langmuir model fitting.The simple visual detection with a remarkable color change from brown to green was observed.In addition,the adsorption kinetics was fast with over 90% of the total Cd²⁺ adsorbed in the first 2 min.Furthermore,a linear relationship between the light absorbance of CPDPT-Cd(CPDPT adsorbed with Cd²⁺)and the initial concentrations of Cd²⁺ was also developed,which could be used for the fast detection and determination of the Cd²⁺ concentrations in aqueous solutions.