Effect of inorganic salt ions on the adsorption of quinoline using coal powder

In this study, coal powder was used as an adsorbent for quinoline pollutant. The effect of inorganic salt ions on the adsorption was mainly explored. Results suggest the addition of inorganic salt ions can enhance both the removal rate and the adsorbed amount of quinoline. The removal rate and adsorbed amount of quinoline were 83.87% and 1.26 mg/g without inorganic salt ions. Under the same adsorption conditions, the removal rate and adsorbed amount of quinoline could reach 90.21% and 1.35 mg/g when Na + was present in the solution, and 94.47% and 1.42 mg/g with the presence of Ca 2+ . In addition, the adsorption of quinoline using coal was fitted to the Freundlich isothermal adsorption model. Changes in the Gibbs free energy, entropy and heat of adsorption were all negative, indicating that the adsorption was spontaneous and exothermic. The changes in the absolute value of Gibbs free energy under both Na + and Ca 2+ were higher than that of the blank condition. Pseudo-second-order kinetic model was found to fit the adsorption kinetic data well, and the activation energy of adsorption under Na + and Ca 2+ were lower than that of the blank. These indicate that the addition of inorganic salt ions was beneficial to the adsorption process.