Effect of lignin contents in raw lignocellulosic materials on the efficiency of modification process and the removal of Fe³⁺, Ca²⁺, and Mg²⁺ in aqueous solution

The different chemical agents such as ethanol, NaOH/water, and NaOH/ethanol-water were investigated to separate the lignin component in the three kinds of raw lignocellulosic materials (cotton fiber, acacia auriculiformis sawdust, coconut shell powder) in the Souther Vietnam. The lignin contents were evaluated based on the Kappa number. The obtained results revealed that the 0.2 mol/L (M) solution of NaOH in the ethanol:water v/v ratio of 7:3 was the good delignified agent and the lignin contents reduced in the sequence as follow: coconut shell powder > acacia auriculiformis sawdust > cotton fiber. The lignin contents in raw materials have significant influence on the efficiency of modification process by using citric acid (CA) in the sequence as follow: modified cotton fiber > modified acacia auriculiformis sawdust > modified coconut shell powder. When using a fixed-bed column, the obtained results showed that modified materials could remove Fe 3+ , Ca 2+ , and Mg 2+ with the good efficiency in some specific conditions.