Comparing low-cost activated carbon made from coffee waste and bagasse to remove heavy metals and methylene blue dye

Abstract

Heavy metal contamination from wastewater, mainly iron (Fe), copper (Cu), and methylene blue (MB) dye, presents a substantial risk to both human health and the environment. Biomass-sourced activated carbon, with its porous structure and environmentally friendly adsorption properties, offers a sustainable method for removing these metals. This study investigated the cost-effective removal of Fe, Cu, and MB dye from wastewater by utilizing sugarcane bagasse activated carbon (SCBAC) and espresso coffee waste activated carbon (ECWAC). The study then compared the adsorbents’ effectiveness based on variables, for instance, initial concentration, contact duration, pH, and adsorbent dosage. Batch experiments were conducted to assess the adsorption efficiency of SCBAC and ECWAC. The results showed that SCBAC outperformed ECWAC in pollutant removal. Removal efficiencies ranged from 4.8 % to 100 %. Various adsorbent ratios (0.2, 0.4, 0.6, 0.8, and 1) and contact times ranging from 10 to 240 min were investigated. The findings showed that a higher adsorbent dose led to the removal of large amounts of heavy metals and MB dye, with efficiencies reaching 100 %. Kinetic studies were assessed using pseudo-first-order and pseudo-second-order models to clarify the potential copper adsorption mechanism, which indicated a more rapid adsorption rate on the adsorbent, with the pseudo-second-order model exhibiting an acceptable fit for all samples. SCBAC and ECWAC had irregular, cavity-filled surfaces with BET surface areas of 403.1 and 359.1 m²/g, respectively. The FTIR spectra of SCBAC and ECWAC exhibit unique chemical compositions and functional groups, such as aromatic structures elucidating their structural characteristics and possible applications. SEM images showed that the activated carbon’s upper surface was not smooth and had many holes of different sizes and shapes.