Study On Adsorption Of Heavy Metal Ions Of Pb²⁺and Ni²⁺in Water By Modified Vermiculite

Lead,nickel and other heavy metal ions produced in mining,machinery manufacturing,chemistry,electronics and instruments will cause heavy metal ion pollution in water bodies,resulting in the enrichment of heavy metal ions in aquatic animals and plants,and causing human heavy metal poisoning in the food chain.Vermiculite is a natural and non-toxic layered silicate clay mineral.It is rich in reserves and low in price.It has the characteristics of large specific surface area,good adsorption property and simple processing technology.It is suitable to be used as adsorbent to remove heavy metal ions in water.However,the adsorptive performance of Vermiculite can be affected by Vermiculite composition,structure,morphology and other factors.Therefore,it is necessary to improve the adsorption rates of Pb²⁺、Ni²⁺through the modification of vermiculite.To this end,the composition,structure and appearance of the vermiculite in Lingshou,Hebei,were observed and analyzed by X ray fluorescence spectrometry（XRF）,X ray diffraction（XRD）,scanning electron microscope（SEM）,NOVA 2000e automatic specific surface area and porosity analyzer（BET）.Vermiculite dosage,the initial concentration of heavy metal ions solution,static contact adsorption time and the pH of the heavy metal ion solution were designed as the orthogonal experiments to explore the effect on the unmodified Vermiculite adsorption properties of Pb²⁺、Ni²⁺in water;used inductively coupled plasma emission spectroscopy（ICP-OES）detected the adsorption of Pb²⁺、Ni²⁺in water,studied the mechanism of adsorption and desorption of vermiculite.High temperature modification,calcification modification,acidation modification and Zinc Oxide modification were carried out to discuss the effect of parameters such as heating temperature,time,CaCl₂ concentration,dosage,processing time,H₂SO₄ concentration,dosage,processing time,and ZnSO₄·7H₂O and NaOH mole ratio,concentration on the adsorption properties of Pb²⁺、Ni²⁺in water.The main conclusions of this paper are as follows:（1）The main chemical composition of vermiculite were:w（SiO₂）=43.61%,w（Al₂O₃）=16.91%,w（Fe₂O₃）=14.88%,w（MgO）=13.12%,w（K₂O）=6.01%,w（CaO）=2.79%;the main mineral phases of vermiculite are phlogopite,phlogopite-vermiculite,etc.;vermiculite has a layered structure with a smooth surface.（2）Considered the utilization rate of vermiculite and the adsorption effect,when vermiculite dosage was 0.2 g,Pb²⁺、Ni²⁺initial concentration was 50 mg/L,the adsorption time was 60 min,and the solution pH was 6,the adsorption rate of unmodified vermiculite on heavy metals Pb²⁺and Ni²⁺in water were better as 86.45%and 65.86%respectively.（3）The adsorption rate of Pb²⁺and Ni²⁺in water was 97.87%and 89.20%,respectively,when the temperature was 400℃and the treatment time was 60min.（4）When CaCl₂ solution concentration was 2.5 mol/L,the modification time was2.5 h,and the dosage was 180 mL,the Pb²⁺、Ni²⁺adsorption rates were respectively as99.72%,89.98%.（5）H₂SO₄ concentration was 0.1 mol/L,H₂SO₄ dosage was 100 mL,acidation processing time was 60 min,the Pb²⁺and Ni²⁺adsorption rates reached 96.00%,83.98%respectively.（6）When ZnSO₄·7H₂O and NaOH mole ratio was 1:2,ZnSO₄·7H₂O concentration was 0.01 mol/L,the adsorption rates of Pb²⁺、Ni²⁺by modified Vermiculite were 99.79%,88.93%.（7）After high temperature modification,calcium chloride modification,sulfuric acid modification and Zinc Oxide modification,the adsorption rates of Pb²⁺、Ni²⁺in water increased.Compared with the four modified methods,it was found that the adsorption rates of Pb²⁺、Ni²⁺by Zinc Oxide modified vermiculite was the best,and the adsorption rates of Pb²⁺、Ni²⁺increased by about 13.34%and 23.07%,respectively.