Synthesis Of Unoxidized Magnetic Multi-walled Carbon Nanotube For Atrazine And Cu (Ⅱ) Removal Of From Wastewater

Nowadays, the combined pollution of organic compounds and heavy metals is so widespread that it has become one of the most important source of environmental pollution. Owing to large specific surface areas and unique structures, carbon nanotubes have attracted increasing attention of researchers in removing both organic compounds and heavy metals, but it’s difficult for them to be separated from aqueous solutions. In this case, it should be noted that magnetic technology is a novel and effective method in wastewater treatment. Thus, combining the convenient magnetic property of iron oxides with excellent adsorption property of carbon nanotubes has great significance in removing hazardous pollutants from waters.In this study, unoxidized magnetic multi-walled carbon nanotubes (MMWCNTs) combining properties of carbon nanotubes and magnetism were synthesized and investigated to explore the possible application in the removal of atrazine and Cu(II) from waters including ultrapure water, tap water and river water. Various adsorption conditions were optimized. The main work and experimental results were divided into four parts.In the first part, MMWCNTs were synthesized and characterized. The process using coprecipitation method to prepare MMWCNTs was introduced. The scanning electron microscopy (SEM), X-Ray Diffraction (XRD), Thermo-gravimetric Analysis (TGA), Brunauer-Emmett-Teller (BET) specific surface area, X-ray photoelectron spectroscopy (XPS), magnetization measurement and zeta potential measurement were used to characterize the adsorbent. The results indicated that iron oxides were successfully loaded on the surface of multi-walled carbon nanotubes to produce MMWCNTs; The percent of iron oxides in the MMWCNTs was around20%; The specific surface area (SSA) of MMWCNTs was138.66m2g-1; The isoelectric point of MMWCNTs was about5.2; The saturated magnetization of MMWCNTs was8.06emu g"1, which is sufficient enough to be separated from aqueous solutions using high density magnet.The second part and the third part introduced the removal of atrazine and Cu(II) from waters using MMWCNTs, respectively. Batch adsorption experiments were conducted to study the sorption performance of MMWCNTs, including adsorption kinetics, adsorption isotherms, effects of dosages of MMWCNTs and effects of solution pH on the adsorption capacity of the adsorbent. In addition, the performance of MMWCNTs to treat atrazine and Cu(Ⅱ) in real water samples (e.g. Tap water and river water) and regeneration of MMWCNTs were investigated. It was found that the optimum dosage of MMWCNTs was0.2g/L; Ultrasonic pretreatment was beneficial to the adsorption of both atrazine and Cu(Ⅱ); The adsorption of atrazine and Cu (Ⅱ) were both unfavorable under acidic conditions; The adsorption of atrazine and Cu (Ⅱ) were very fast and the sorption kinetics data were well described by pseudo-second-order kinetic model; MMWCNTs exhibited good adsorption behavior for atrazine and Cu (Ⅱ), and the sorption isotherms for atrazine and Cu (Ⅱ) were better fitted by Freundlich model and Langmuir model with maximum adsorption capacity40.16mg g-1and38.91mg g-1, respectively; MMWCNTs showed great potential in removing atrazine and Cu(Ⅱ) from real water samples; MMWCNTs could be regenerated effectively by20%acidic ethanol (pH3.0) and thus be reused repeatedly.The fourth part was focused on multi-component adsorption of atrazine and Cu(Ⅱ) by MMWCNTs as well as mutual interaction involved between atrazine and Cu(Ⅱ). The multi-component adsorption include two parts:One is simultaneous sorption of atrazine and Cu(Ⅱ); The other is preloading atrazine or Cu(Ⅱ). The results indicated that Cu(Ⅱ) had a strong suppression effect on atrazine uptake in the simultaneous adsorption and atrazine preloading experiment. As for Cu(Ⅱ) preloading, the impact of atrazine on Cu(Ⅱ) desorption was almost negligible. There was a stronger affinity between Cu(Ⅱ) and MMWCNTs.In sum, great efforts were made to prepare unoxidized magnetic multi-walled carbon nanotubes to remove atrazine and Cu(Ⅱ) from waters, which is beneficial to the progress of wastewater treatment in combined pollution of organic compounds and heavy metals. Exploration for possible applications of the adsorbent has great theoretical guiding significance and remarkable environmental and social benefits.