Modified Activated Carbon Treatment Of Waste-water Containing Chromium

The industrial production will emit large amounts of wastewater containing chromium, chromium as inorganic heavy metal toxic substances on the human body great harm. The adsorption method because of its good effect and is applied to the treatment of chromium containing wastewater, as people increasingly high requirements for water quality, also appeared a lot of methods modified absorption materials to improve the adsorption efficiency and achieve better effect. Study on the activated carbon modified with citric acid is still relatively rare, and then modified by microwave were combined into a new method of treating chromium containing wastewater. In this paper, by using citric acid microwave modification of activated carbon to improve the removal efficiency, the preparation of a greater amount of adsorption of activated carbon, its preparation process and study of chromium wastewater treatment effect.This paper selects well-developed pore structure, specific surface area, high thermal and chemical stability of activated carbon as an adsorption material, the use of citric acid, microwave, citric acid microwave modified activated carbon, respectively to study the best modified condition combination, combination of conditions and adsorption kinetics of adsorption. Using BET and SEM, the structure of activated carbon, surface morphology, surface functional groups, etc.. Experimental results show that:(1) The best conditions of natural active carbon adsorption of chromium six: chromium solution initial concentration is 50%, dosage is /0.3lg, reaction temperature is 25℃, pH=4, adsorption time is 12 h.(2) The optimum conditions of activated carbon modified by citric acid citric acid concentration is 50%, modification time is 4h, modification temperature is 25℃. The optimum adsorption conditions of modified activated carbon at room temperature for chromium ion initial concentration is 20mg/L, dosage is 30mg/L, reaction pH=3.0, adsorption time is 5h.(3) The optimum conditions of microwave modified activated carbon was C-1, the modified time is 2min, and quantity is 5g. The optimum adsorption conditions of modified activated carbon at room temperature is chromium ion initial concentration is 20mg/L, dosage is 10g/L, reaction pH=3.0, adsorption time is 2h.(4) The optimum conditions of activated carbon modified by Microwave- citric acid microwave combined C-1, 1min irradiation, the concentration of citric acid is 50%. The optimum adsorption conditions of modified activated carbon at room temperature: chromium ion solution initial concentration is 20mg/L, adsorption time is 1.0h, dosage is 10g/L.(5) Langmuir adsorption isotherm model is more fitting four activated carbon adsorption behavior of the process, but also to describe the adsorption process for a variety of factors conditions are secondary adsorption kinetics model is more appropriate.(6) The removal rates of GAC-N,GAC-W, and GAC-NW were 98.52%, 93.70% and 86.25%, respectively, and compared with the original carbon of GAC-k, 11.86%, 1.94% and 6.72% respectively.. The acidic functional groups of the surface of the activated carbon modified by citric acid were increased, the specific surface area decreased. The surface of the activated carbon modified by microwave is more than that of the surface, but the acid functional groups of the surface of the microwave is decreased, while the alkaline functional groups are improved.. The pore structure of the citric acid microwave modified activated carbon was not destroyed, but its specific surface area was increased.