Sequential adsorptive removal of phosphate, nitrate and chromate from polluted water using active carbon derived from stems of Carissa carandas plant
Abstract Sulphuric acid-generated active carbon from stems of Carissa carandas plant is investigated successfully as an adsorbent for the sequential removal of phosphate, nitrate and chromate from polluted water. Controlling parameters are investigated and optimized for the maximum removal of the pollutants. At pH: 7, phosphate and nitrate can be simultaneously removed, while at pH: 2, chromate can be sequentially removed from the admixtures of the three pollutants. The active carbon is characterized using FTIR, FESEM and EDX. Sorption mechanisms are investigated using various adsorption isotherms and kinetic models. Thermodynamics parameters are evaluated. The data reveal the Langmuir isotherm model of adsorption, pseudo-second-order kinetics and spontaneity of sorption processes. Langmuir individual maximum adsorption capacity is: 72.75 mg/g for chromate; 63.40 mg/g for phosphate; and 49.15 mg/g for nitrate. The active carbon can be regenerated and reused. The method is used for the removal of all three pollutant ions from polluted water. The merit of this investigation is that an active carbon is identified with good adsorption capacities for the successful sequential removal of phosphate, nitrate and chromate ions from polluted water.