DISSOLVED ORGANIC CARBON REMOVAL IN WATER BY ADSORPTION PROCESS USING ARCAMANIK SOIL AND KARANG NUNGGAL BENTONITE

• Main Author: Diani Nur Muflihah, Astri
• Format: Theses
• Language: Indonesia
• Subjects: Teknik saniter dan perkotaan; teknik perlindungan lingkungan
• Online Access: https://digilib.itb.ac.id/gdl/view/67393
• Institution: Institut Teknologi Bandung

Dissolved organic carbon (DOC) can form carcinogenic disinfection by-products (DBP), such as trihalomethane (THM) and haloacetic acid (HAA), during the chlorination process. Chlorination is the most common disinfection method used in water treatment plant in Indonesia. The average DOC concentrations of surface water that contain peat water in Central Kalimantan Province (rivers and lakes) and Riau Province (Tapung Kanan River, Tapung Kiri River, Mandau River, and Siak River) were 12.28 mg/L and 12.04 mg/L, respectively, while the recommended concentration of DOC in drinking water is <4 mg/L in raw water and <2 mg/L in processed water. Adsorption is an advanced technology that is affordable and has the potential to remove DOC in water. Bentonite and soil are materials that are widely available in nature and have the potential to become adsorbents. Both have different characteristics so that the adsorption efficiency is expected to be different as well. This research was conducted to observe the characteristics of soil and bentonite that affect its performance in adsorption of DOC. The characteristics of the adsorbent tested were surface charge, surface area, functional group, mineral species, organic content, surface morphology, and surface constituent elements. The adsorption experiment was carried out by varying the dose, initial concentration, and contact time. The analysis carried out were effect of dose, effect of initial concentration, effect of contact time, adsorption isotherm, adsorption kinetics, thermodynamic parameter analysis, and analysis of adsorption mechanism. The results of the adsorbent characteristics show that, at the operating pH, the surface charge of bentonite is negative while the surface charge of the soil is positive; soil surface area (37.865 m2/g) is larger than that of bentonite (34.912 m2/g); bentonite showed peaks at similar wavenumber to that of the soil but lower peak height; the soil is dominated by labradorite 46% and bentonite is dominated by cristobalite 57% which is suspected to be caused by the transformation of montmorillonite; soil has higher organic content (0.288%) compared to bentonite (0.086%); The morphology of the soil surface is observed to be rough while bentonite is smoother with a layered structure; and the mass percentage of Al, Si, and Fe elements in the soil are greater than that of bentonite. The results of the adsorption analysis showed that the dose was directly proportional to the DOC removal but inversely proportional to the adsorption capacity; initial concentration is directly proportional to the adsorption capacity and inversely proportional to the DOC removal; contact time variation is directly proportional to the adsorption capacity and the DOC removal; the best fitted isotherm model is the Langmuir isotherm model; and the best fitted kinetic model is pseudo-second order. Langmuir and pseudo-second order model showed the application of chemical adsorption mechanism assumptions. Analysis of thermodynamic parameters showed the tendency of physical adsorption mechanism. The post-adsorption analysis of adsorbents results showed that the FTIR test showed a more significant decrease in peaks on bentonite, this indicated that more functional groups played a role in DOC removal using bentonite and SEM results showed that the surface of the post- adsorption adsorbents were rougher than that of pre-adsorption. Analysis of the pre-adsorption and post-adsorption characteristics of adsorbents concluded that the soil has the characteristics of electrostatic forces and van der Waals forces; bentonite has a surface functional groups, Al-O-Si and C-N; both have a hydroxyl group but the group plays a more important role in the adsorption process using bentonite. The experments showed that the soil removed DOC better than bentonite. For that reason, it can be said that soil characteristics make the soil more effective in removing DOC and has a better affinity of DOC. Therefore, it can be concluded that the mechanisms in the adsorption process are physisorption and chemosorption, however the electrostatic bond and the van der Waals force, which are physisorption, are the dominant mechanism. Respectively, electrostatic bond and van der Waals force are described by pzc value and organic content.