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Despite being a promising biomass source for gasification, the practical use of rice straw in Vietnam is hindered by its low gasification efficiency. This study introduces an innovative approach by integrating the production of syngas and CO 2 adsorbent during the gasification process of rice straw, departing from the conventional focus solely on improving gasification efficiency. Results showed that the gasification of rice straw, conducted in the 20 kWe commercial gasification system (PP20 All Power Lab), attained a thermal conversion efficiency of 58.7%. Syngas produced exhibited consistent composition, with CO and H 2 content ranging from 12.1% to 15%, CO ranging from 16.9% to 22.1%, and CH 4 ranging from 1.9% to 3.9% throughout the operation, demonstrating relative stability. Notably, a considerable amount of residual char, accounting for 22.1 wt% of the initial feedstock, was generated. Characterized by notable traits such as high surface basicity, aromaticity, and a dense concentration of (ultra-)micropores, the residual char demonstrates suitability for applications in CO 2 adsorption. In controlled laboratory conditions (25 °C, 1 atm, without heat-mass transfer limitations), the adsorption capacity reached 1.2 mmol g−1. Transitioning to more practical conditions (40 °C, 1 atm, within a 2-cm adsorbent bed subject to diffusion constraints), the CO 2 adsorption capacity of the residual char ranged between 2% and 4.8% of the adsorbent's weight, while the CO 2 /N 2 selectivity measured between 25.5 and 29.7. These findings underscore the significant potential of integrating syngas and CO 2 adsorbent production through rice straw gasification, indicating a promising avenue for sustainable energy and carbon capture technologies. [Display omitted] • Stable syngas quality obtained throughout rice straw gasificatiom. • Use of residual char after gasification as cost-effective and scalable CO 2 adsorbents. • CO 2 capture capacities reached up to 1.2 mmol g−1 at 25 °C, 1 atm. • Potential for cascading use of rice straw for energy and adsorbent production. [ABSTRACT FROM AUTHOR]

In this work, alginate-modified biochar derived from rice husk waste was synthesized using a simple process. The modified biochar (MBC) and rice husk biochar (RhBC) were investigated for removing Pb (II) ions in wastewater. The BET result displayed significantly improved specific surface area of MBC up to 120 m2/g along with a total pore volume of 0.653 cm3/g. FTIR spectrums presented the higher oxygen-contained functional groups of MBC as compared to RhBC, resulting in increasing adsorption capacity of Pb (II). MBC had higher adsorption capacity (112.3 mg/g) and faster removal rate (0.0081 g mg−1 min−1) than those of RhBC (41.2 mg/g and 0.00025 g mg−1 min−1). Modified RhBC can remove more than 99% of Pb (II) from wastewater and it could be utilized for three cycles with a removal performance of over 90%. In addition, the Pb adsorption mechanism by using MBC was proposed and the practical application of MBC for the treatment of wastewater in Vietnam was discussed. [Display omitted] • Alginate modified rice husk biochar (MBC) was used for Pb (II) removal in wastewater. • MBC had higher adsorption capacity (112.3 mg/g) as compared to others adsorbents. • More than 99% of Pb (II) in wastewater sample was removed by MBC. • MBC still has high efficiency of Pb (over 90%) after 3 times reused. [ABSTRACT FROM AUTHOR]