Used coffee/PCL composite filter for Cu(II) removal from wastewater

A coffee ground composite membrane for copper adsorption was prepared using used coffee grounds and polycaprolactone, a biodegradable polymer. The prepared sample shows a removal efficiency of 90 % or more in 4 h at a concentration of 100 μM (= 13.45 ppm), which satisfies the drinking water acceptance criteria of 1.5 mg L⁻¹ set by the World Health Organization. The functional groups of the coffee composite filter were analyzed with X-ray photoelectron spectroscopy, and the surface of the filter membrane was analyzed using scanning electron microscope. UV–vis spectrophotometry confirmed the adsorption capacity and amount of Cu(II) adsorption of the filter or coffee grounds, and Langmuir, Freundlich, Redlich-Peterson, and Fritz-Schlunder isotherms were used to investigate the removal mechanism. The kinetic studies were also performed to clearly demonstrate the adsorption process.