Effect of Modified Zeolite on Adsorption Characteristics of Heavy Metal Ions

The adsorption properties of natural zeolite and modified zeolite on Pb2 were studied, and the effects of different factors on the adsorption of Pb2 by zeolite were discussed. The results showed that the adsorption of Pb2 on natural zeolite could be promoted by three different modification methods. Sodium hydroxide modified zeolite adsorption Pb2 the best effect, followed by potassium nitrate modified zeolite, ammonium chloride modified zeolite adsorption Pb2 effect is slightly worse. Different initial concentration of Pb2, zeolite dosage, pH and temperature have effects on the adsorption of Pb2 by natural zeolite and modified zeolite. The isothermal adsorption of Pb2 by natural zeolite and modified zeolite can be Langmuir by equation and

Freundlich equation to fit, in which the fitting effect of Langmuir equation is better, the correlation coefficient is between 0.9203-0.840. CaCl2 and MgCl2 can affect the adsorption of natural zeolite and modified zeolite to Pb2 +. When the concentrations of CaCl2 and MgCl2 were both 10mmol · -1, the amount of Pb2 + adsorbed by natural zeolite increased by 66.% and 54.%, respectively, compared with the control treatment. Addition of 2-10mmol.L-1 CaCl2 and MgCl2 resulted in increased Pb2 + adsorption of the ammonium chloride modified zeolite by 16.%-18.% and 16, respectively, compared to the control treatment. 8%-19.%. The results show that the influence of different factors must be considered when using zeolite to remove Pb in wastewater, so as to maximize the removal efficiency of heavy metals.

With the continuous development of human society, economic development has brought benefits, but also produced a lot of pollution. With the sharp increase of industrial "three wastes" and the increase of automobile exhaust emissions, the pollution of heavy metals in soil, water and plants in human living environment is becoming more and more serious, which has become an ecological problem in the coordinated development of economy, society and environment. Heavy metals are generally not biodegradable, and once they enter the water or soil, they are difficult to remove. They can enter the human body through the food chain and cause many diseases (such as cancer). Among the many heavy metal elements, lead (Pb) is a common pollutant in the environment. It not only has strong toxicity, but also can cause toxicity to the nervous and hematopoietic system, causing spasm, nerve retardation, anemia and other symptoms, especially for children. Health poses a major threat. Therefore, it is very important to study the removal of Pb2 in solution. Adsorption is an effective physical and chemical water treatment method, which is often used to purify heavy metal contaminated wastewater. Zeolite is composed of Si, Al, O3 elements of tetrahedron, due to the silicon oxygen tetrahedron and aluminum oxygen tetrahedron can construct an infinite expansion of the three-dimensional space frame, so the zeolite has a strong adsorption and ion exchange capacity. Because of the unique spatial structure of zeolite, it can adsorb or exchange heavy metal ions in water, so scholars at home and abroad have done a lot of research on zeolite. Studies have shown that the ability of zeolite to adsorb Pb2 is stronger than other heavy metals.