Removal of arsenic from water using pine leaves

The present study proposed the use of Chir pine leaves (Pinus roxburghii) to remove As(V) ions from aqueous solutions. The influence of different sorption parameters such as the adsorbent dose, solution pH, contact time, agitation speed, and initial arsenic concentration were studied thoroughly to evaluate optimum conditions. Maximum adsorption has taken place at pH 4.0 while equilibrium was achieved in 35 min. Langmuir, Freundlich, Temkin, Elovich, Dubinin–Radushkevich and Flory–Huggins isotherm models were used to explain the phenomenon. Maximum adsorption capacity of P. roxburghii was 3.27 mg/g that was compared with the capacities of some previous adsorbents used for arsenic removal. Heat of sorption was close to 50 kJ/mol. Adsorption mechanism was explored by Pseudo first- and second-order kinetic models, and it was found that the process followed second order kinetics. The study concluded that the Chir pine leaves can be a good adsorbent for removing As(V) from water owing to the fine adsorption capacity.

► Chir pine leaves (Pinus roxburghii) have been used as adsorbent to remove As(V) ions from aqueous solutions.
► Maximum adsorption has taken place at pH 4.0, adsorbent dose 1 g for 50 mL of 10 mg/L arsenic solution, contact time 35 min and agitation speed 100 rpm.
► The order of fit in relation to coefficient of correlation was Langmuir Flory–Huggins > Freundlich > Dubinin–Radushkevich > Temkin > Elovich.
► Maximum adsorption capacity was 3.37 mg of As(V) per gram of P. roxburghii leaves.
► Interaction between adsorbate and adsorbent was chemical in nature and followed second-order kinetics.