A comparative study of aerobically digested and undigested sludge in preparation of magnetic chars and their application in 1-diazo-2-naphthol-4-sulfonic acid adsorption
• Magnetic chars are prepared and characterized using aerobically digested and undigested sewage sludge. • Langmuir–Freundlich model is used to simulate their adsorption isotherm of 1,2,4-Acid. • Different adsorption mechanism may be correlated with their chemical composition and textural properties.