Fabrication and Application of the NaOH-activated Sorbent from Gayo Arabica Coffee Shells for Adsorption of Lead Metal (Pb) in Liquid Waste

Indonesia is a developing country with a high level of environmental pollution, especially heavy metal pollution from industrial waste such as Pb(II). One of several environmentally-friendly separation methods that can be used to reduce levels of Pb(II) is adsorption by using waste-based biosorbent. In this study, we report the fabrication of low-cost and green adsorbent from Gayo Arabica coffee shell waste. The fabricated adsorbent is activated by NaOH to further improve its performance and is applied for the removal of Pb(II) in liquid waste. The resulting adsorbents are characterized using Scanning Electron Microscopy (SEM) to determine the morphological structure, Fourier Transform Infra-Red Spectrophotometer (FTIR) to determine the functional groups, and X-Ray Diffraction, (XRD) to determine the crystalline structure. The results show that the characterization of the two types of adsorbents meet the quality requirements according to SNI 06-3730-1995. The initial concentration of Pb(II) solution used is 300 mg/L, contact time (0, 30, 60, 90, 120 and 150 minutes) and type of activator (0.5 M NaOH and without activator). The initial concentration of Pb(II) before and after adsorption is tested using AAS. The analysis results obtained show that the maximum absorption capacity that can be carried out by the adsorbent is 271,577 mg/g and an efficiency of 90% at the equilibrium time of 120 minutes using an adsorbent NaOH 0.5 M. It is also revealed that the adsorption process of Pb(II) by coffee shell sorbent follows isotherm Langmuir model.