Biogas is a renewable fuel source of methane (CH4), and its utilization as a natural gas substitute or transport fuel has received much interest. However, apart from CH4, biogas also contains carbon dioxide (CO2) which is noncombustible, thus reducing the biogas heating value. Therefore, upgrading biogas by removing CO2 is needed for most biogas applications. In this study, an amine-functionalized adsorbent for CO2 capture from biogas was developed. Mesoporous MgO was synthesized and functionalized with different tetraethylenepentamine (TEPA) loadings by wet impregnation technique. The prepared adsorbents (MgO-TEPA) were characterized by X-ray diffraction (XRD) and N2 adsorption-desorption. The CO2 adsorption performance of the prepared MgO-TEPA was tested using simulated biogas as feed gas stream. The results show that the CO2 adsorption capacities of the adsorbents increase with increasing TEPA loading. The optimum TEPA loading is 40 wt.%, which gives the highest CO2 adsorption capacity of 4.98 mmol/g. A further increase in TEPA loading to 50 wt.% significantly reduces the CO2 adsorption capacity. Furthermore, the stability and regenerability of the adsorbent with 40% TEPA loading (MgO-TEPA-40) were studied by performing ten adsorption-desorption cycles under simulated biogas and real biogas conditions. After ten adsorption-desorption cycles, MgO-TEPA-40 shows slight decreases of only 5.42 and 5.75% of CO2 adsorption capacity for the simulated biogas and biogas, respectively. The results demonstrate that MgO-TEPA-40 possesses good stability and regenerability which are important for the potential application of this amine-based adsorbent.

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The treatment of NH3 releasing concentrated rubber latex to air was studied using skim serum in laboratory scale of bubble absorption reactor. The skim serum (pH 2.5 to 3) is a liquid waste from concentrated rubber latex. The concentration of NH3 in air (300 to 1500 ppmv) and air flow rate (0.5 to 1.5 l/min) feeding into the reactor were measured for the effect of the treatment efficiency. At lower NH3 concentration and air flow rate have resulted to higher NH3 removal efficiency. Bubble absorption reactor can be effectively used and applied to remove NH3 releasing from the concentrated rubber latex process to the air without any plugging of the skim rubber in the system. Skim serum waste liquid has the result in higher efficiency in NH3 removal comparing to pure water usage. This study would be practically used as a guidance for the further design and operate to minimize waste and emission control in rubber industrial-scale system.