Optimization of the removal efficiency of three biodegradable chelating agents for soil cadmium

Abstract

In recent years, there has been a significant increase in the release of cadmium-containing pollutants into the environment from mining, industrial emissions, wastewater irrigation and the use of chemical fertilizers and pesticides. This leads to the degradation of soil quality and poses a threat to human health. Chemical leaching remediation technology is an effective method for controlling Cd contamination in soil. However, the leaching agent has a low removal efficiency of heavy metals. In order to find more suitable environmentally friendly new leaching agents, this study investigates the effects of three biodegradable chelating agents PMAS, EDTMPS and GLDA on the removal of heavy metal Cd in soil in the single factor soil leaching experiment. The concentration of the chelating agents, the leaching time and the pH of the leaching solution were varied to study their effects. The Box-Behnken (BBD) effect based on RSM was used to design the experimental conditions to optimize the leaching process of three biodegradable chelating agents. The optimum conditions for Cd removal by PMAS, EDTMPS and GLDA were obtained as follows: concentration 7 %, pH = 3.61, reaction time 180 min; concentration 4.94 %, pH = 3.0, reaction time 180 min; and concentration 4.96 %, pH = 3.0, reaction time 180 min. The validation test results showed that the deviation from the experimental value is less than 3 % under the theoretically optimal washing conditions, confirming the reliability and accuracy of the response surface methodology optimization process, which provides a reference for the development of efficient, environmentally friendly and low-cost leaching agents.

Keywords

• Soil Cd pollution
• Biodegradable chelating agent
• Response surface method
• Chemical soil leaching