Preparation Of Four Biomass Carbon Adsorbents And Their Adsorption Performance Of Cadmium And Lead From Aqueous Solution

Heavy metals are the key pollutants for water prevention and control.They exist in complex and diverse forms with significant toxicity to animals and plants and cannot be removed by water self-purification,posing a great threat to ecological balance and human health.Although there have been no large-scale heavy metal pollution incidents in China in recent years,water,soil,crops and other related tests in various regions have repeatedly found excessive heavy metal content,especially lead and cadmium pollution.Therefore,it is urgent to seek effective,economical and practical methods to remove lead and cadmium from water.In this paper,the water samples of five typical traffic locations in Wuxi Huishan section of Xicheng Canal were taken as the research object,and the content of lead and cadmium in the water samples was determined by inductively coupled plasma emission spectrometry.Four kinds of adsorbents including acrylic acid modified corn husk biomass adsorbents（CHF@AA）,Mn O₂ modified corn husk biomass adsorbent（CHF@Mn O₂）,eggplant biomass adsorbent（Eggplant biomass）and polyethyleneimine modified eggplant biomass adsorbent（PEI-Eggplant biomass）,and their adsorption properties towards lead and cadmium in water were studied and analyzed.The main research contents are as follows:1.Preparation of acrylic acid modified corn husk fiber adsorbent and its removal performance for cadmium in waterBiomass fibers were extracted from discarded corn husks,and acrylic modified corn husk biomass adsorbent was prepared using acrylic acid（AA）as a modifier.The adsorption removal performance for cadmium in water was investigated.The results showed that the optimal conditions for Cd²⁺adsorption were as follows:the dosage of adsorbent was 0.25g/L,the adsorption time was 90 min,the p H was 6.0,and the temperature was 40℃.The kinetic fitting results showed that the specific adsorption process of the modified corn husk fiber adsorbent was dominated by chemical adsorption,and the removal rate remained above70.10%after 5 cycles,showing good cycling performance and stability.The average removal rates of Cd²⁺were 27.45%,22.15%,35.77%,37.45%and 23.31%,respectively,when acrylic modified corn husk fiber was used to remove Cd²⁺from water samples taken from five typical traffic locations in Wuxi Huishan section of Xicheng Canal.2.Preparation of Mn O2 modified corn husk fiber adsorbent and its removal performance for cadmium in waterBiomass fibers were extracted from discarded corn husks,and Mn O₂ was loaded on their surfaces.The Mn O₂ modified corn husk fiber adsorbent was prepared by in situ growth and hydrothermal technologies;and its adsorption removal performance for cadmium in water was investigated.The adsorption experiments results showed that the optimal conditions for Cd²⁺adsorption by Mn O₂ modified corn husk biomass adsorbent were as follows:the adsorbent dosage was 0.2 g/L,the adsorption time was 600 min,p H was 6.0,and the temperature was 40℃.The kinetic fitting results showed that the specific adsorption process of Mn O₂ modified corn husk fiber adsorbent for Cd²⁺was dominated by chemical adsorption,and the removal rate remained above 83.17%after 5 cycles,showing good cycling performance and stability.The Mn O₂ modified corn husk fiber was used to remove Cd²⁺from water samples taken from five typical traffic locations in Wuxi Huishan section of Xicheng Canal,and the average removal rates were 39.81%,29.13%,42.13%,55.44%and45.58%,respectively.3.Preparation of eggplant biomass adsorbent and its removal performance for lead in waterThe eggplant biomass adsorbent was prepared from waste eggplant using freeze-drying and high-temperature carbonization technology and its adsorption removal performance for lead in water was investigated.The results showed that the optimal conditions for Pb²⁺adsorption by eggplant biomass adsorbent were as follows:the dosage of adsorbent was 0.3g/L,the adsorption time was 120 min,the p H was 5.0,and the temperature was 20℃.The kinetic fitting results showed that the specific adsorption process of Pb²⁺was dominated by chemical adsorption,and the removal rate remained above 59.06%after 5 cycles,which had good recycle performance and stability.The average removal rates of Pb²⁺were 35.94%,40.06%,40.72%,39.00%and 41.55%,respectively,when eggplant biomass adsorbents were used to remove Pb²⁺from water samples taken from five typical traffic locations in Wuxi Huishan section of Xicheng Canal.4.Preparation of polyethyleneimine modified eggplant biomass adsorbent and its removal performance for lead in waterBiomass fibers were extracted from waste eggplant,and polyethyleneimine（PEI）modified eggplant biomass adsorbent was prepared using PEI as a modifier and by surface chemical bond technology to modify amino groups.The adsorption removal performance for lead in water was investigated.The adsorption experiments results showed that the optimal conditions for Pb²⁺adsorption of polyethyleneimine modified eggplant biomass were as follows:the dosage of the adsorbent was 0.2 g/L,the adsorption time was 90 min,the p H was 6.0,and the temperature was 20℃.The kinetic fitting results showed that the specific adsorption process of Pb²⁺by polyethyleneimine modified eggplant biomass adsorbent was dominated by chemical adsorption,and the removal rate remained above 79.98%after 5cycles,showing good cycling performance and stability.The Pb²⁺removal rates were52.50%,53.10%,51.87%,53.31%and 54.72%,respectively,when polyvinylimine modified eggplant biomass was used to remove water samples from five typical traffic locations in Wuxi Huishan section of Xicheng Canal.