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Abstract. Presently, biomass is mostly utilized as co-fuel in coal combustion in view of energy diversification and emission reduction. However, since the coal content of bio-briquettes is high (up to 80% in this study), gas emissions such as those of SO x still occur. Therefore, the introduction of SO 2 adsorbent is common in coal briquette or bio-briquette combustion. A calcium-based material is usually used for this goal. The aim of this study was to observe the effects of desulfurization temperature and Ca/S ratio (Ca = calcium content in adsorbent; S = sulfur content in coal and biomass) on desulfurization efficiency and kinetics. The ratio of coal to biomass (palm kernel shell/PKS) was fixed at 90:10 (wt/wt) and the ratios of Ca to S were varied at 1:1, 1.25:1, 1.5:1, 1.75:1 and 2:1. The mixtures of coal, PKS and adsorbent were briquetted at a molding pressure of 6 ton/cm 2 with Jatropha curcas seeds and starch mixture as binding agents. Desulfurization was performed within a temperature range of 300 to 500°C for 720 seconds at an airflow rate of 1.2 L/min. The results showed that the highest desulfurization efficiency (90.6%) was associated with the Ca/S ratio of 2:1 and temperature of 400°C. Moreover, the highest reaction rate constant of desulfurization was 0.280 min -1 .

Abstract. Adsorption of Cu(II) ions from aqueous solution onto activated carbon (AC) prepared from Pithecellobium jiringa shell (PJS) waste was investigated by conducting batch mode adsorption experiments. The activation with ultrasound assistance removed almost all functional groups in the PJS-AC, while more cavities and pores on the PJS-AC were formed, which was confirmed by FTIR and SEM analyses. The Cu(II) ion adsorption isotherm fitted best to the Freundlich model with average R 2 at 0.941. It was also correlated to the Langmuir isotherm with average R 2 at 0.889. This indicates that physical sorption took place more than chemical sorption. The maximum Cu(II) ion adsorption capacity onto the PJS-AC for a dose of 1 g was 104.167 mg/g at 30 °C and pH 4.5, where the Langmuir constant was 0.523 L/mg, the Freundlich adsorption intensity was 0.523, and the Freundlich constant was 5.212 L/mg. Cu(II) adsorption followed the pseudo second-order kinetic (PSOKE) model with average R 2 at 0.998, maximum adsorption capacity at 96.154 mg/g, PSOKE adsorption rate constant at 0.200 g/mg.min, temperature at 30 °C and pH at 4.5. The changes in enthalpy, entropy, free energy and activation energy were determined, and the results confirmed that Cu(II) adsorption onto the PJS-AC was exothermic chemical adsorption in part. There was a decrease in the degree of freedom and the adsorption was non-spontaneous.

Pollution by mercury dissolved in aqueous media causes a crucial problem for health and environment. In this study, activated carbon from Bambusa vulgaris var. striata was produced by chemical activation using NaOH for mercury adsorption. The effects of mercury initial concentrations namely 50 and 100 mg/L on the breakthrough characteristics of the adsorption process were defined. The mechanism of the adsorption process through the fixed-bed column was fitted to the Thomas model. The activated carbon was characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The adsorption study with a continuous system and using the Thomas model showed that the highest adsorption capacity (q 0) of mercury ions is 218.08 mg/g. It can be concluded that activated carbon from Bambusa vulgaris var. striata has a great potential to act as an adsorbent to remove mercury from water.

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