Development Of A New Type Of Acidulous Water Material With Alpha Hydroxy Acid And Granular Activated Carbon

In this paper, alpha hydroxy acid modified granular activated carbon was prepared as a a new type of acidulous water material (the pH value is in the range of 4.0 to 6.5) by wet and dry method, respectively. Granular activated carbon and different alpha hydroxy acids were used as main raw materials and modifying agents, respectively. The effects of material formula, reaction temperature and heating time on producing volume of acidulous water were discussed. The optimal formula and preparation process of acidulous water material were then decided. BET, SEM and other analytical methods were used to characterize the microstructures of materials. At the same time, the removal efficiency of Cu2+ onto materials were investigated recycled after desorption.The results showed that the acidulous water material prepared from malic acid and citric acid modified granular activated carbon have many excellent properties, such as long-life, high yield, superior recycling. As compared with unmodified granular activated carbon, the granular activated carbon that were recycled after desorption exhibited better biosorption ability for Cu2+ because some organic functional groups were introduced. The acidulous water material can be prepared by wet and dry methods successfully. The alpha hydroxy acid modified granular activated carbon prepared by wet method has more yeild than that by dry method, while dry method preparation process was much simpler, cleaner and more environmental than wet method. Malic acid modified granular activated carbon produced much more acidulous water than critic acid modified granular activated carbon by using wet method, while citric acid modified granular activated carbon produced much more acidulous water than malic acid modified granular activated carbon by using dry method. The optimum processes of wet and dry method were as follows:20 g activated carbon was mixed with malic acid (0.6 mol/L,0.2 L) at 60℃ for 8 h and 5g malic acid at 110℃ for 6 h, respectively. The yield of acidulous water material prepared by wet method and dry method were 250.5 L and 159 L, respectively.The BET showed that specific surface of modified granular activated carbon was greatly reduced. Specific surface area of granular activated carbon is 701.65 m2/g, average pore size is 1.74 nm and pore volume is 0.31 m3/g; specific surface area of malic acid modified granular activated carbon after desorption is 459.37 m2/g, average pore size is 1.18 nm and pore volume is 0.26 m3/g; specific surface area of citic acid modified granular activated carbon after desorption is 453.17 m2/g, average pore size is 1.87 nm and pore volume is 0.21 m3/g. Acidulous water material after desorption have a large of specific surface area. Surface of acidulous water material after desorption contained some functional groups, such as -COOH,-OH,-COOC-, etc., The organic functional group improved removal efficiency of Cu2+ and the adsorption time was reduced.