We investigated the efficiency of in-situ formed magnesium hydroxide (Mg(OH)2) for the removal of sodium lignosulfonate (SLSN) from aqueous solution. Adsorption experiments considered the effects of various conditions such as pH, MgCl2 concentration, contact time, and temperature on SLSN removal efficiency. It was found that approximately 93%-99% SLSN was removed by in-situ formed Mg(OH)2. The adsorption was rapid, and the contact time required to reach complete adsorption equilibrium was less than 2min. Moreover, that the Mg(OH)2 lost about 0.5-3.0% adsorption capacity for SLSN when NO3-, HCO3-, H2PO4- and SO42- anions were simultaneously present with SLSN. The experimental data suggested that there was little competitive adsorption of SLSN with other coexisting anions on Mg(OH)2. The co-precipitation/adsorption process was exothermic and physical, involving weak interactions such as electrostatic attraction, hydrogen bonding, adhesive forces, and van der Waals forces between SLSN molecules and the binding sites on Mg(OH)2.
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