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Magnetic chitosan nanoparticles, synthesized by in situ precipitation, have been used as adsorbents to remove sulfamethoxazole (SMX), a sulfonamide antibiotic dangerous due to its capacity to enter ecosystems. The adsorption of SMX has been carried out in the presence of tertiary wastewaters from a depuration plant to obtain more realistic results. The effect of pH on the adsorption capacity significantly changed when carrying out the experiments in the presence of wastewater. This change has been explained while taking into account the charge properties of both the antibiotic and the magnetic chitosan. The composition of wastewaters has been characterized and discussed as regards its effect on the adsorption capacity of the magnetic chitosan. The models of Elovich and Freundlich have been selected to describe the adsorption kinetics and the adsorption isotherms, respectively. The analysis of these models has suggested that the adsorption mechanism is based on strong chemical interactions between the SMX and the magnetic chitosan, leading to the formation of an SMX multilayer. [ABSTRACT FROM AUTHOR]

Methanol is expected to be a possible solution for reducing global greenhouse gas emissions and minimizing the dependency on fossil fuels. This paper presents a systematic approach of methanol (MeOH) production from industrial waste gases including flue gas (FG) and coke oven gas (COG) that are considered an important threat to the environment. The impact of process parameters, including dimensional parameters (length, diameter, and number of tubes) and operational parameters (reactor temperature, pressure, and thermal fluid temperature) over the MeOH synthesis, are investigated by Aspen Plus. Firstly, the synthesis process is designed and optimized using syngas (SG) as a feed material. Secondly, by replacing the feed material with FG and COG, methanol production variability is investigated and demonstrated for the same optimized process. Afterward, an efficient heat exchange network system is developed for all three different processes using Aspen Energy Analyzer. The optimized dimensional parameters of the MeOH synthesis reactor are determined to be a length of 12 m, a diameter of 0.06 m, and 5000 tubes for achieving a conversion rate of 75%. Meanwhile, the optimized operational parameters are identified as a reactor temperature of 209   ° C , reactor pressure of 70 bar, and thermal fluid temperature of 196   ° C . Furthermore, the influence of the stoichiometric number (SN) on the process was observed with higher SN values resulting in increased hydrogen (H2) concentration and an improved forward reaction of MeOH synthesis, leading to higher conversion rates. The findings and insights gained from this study can serve further improvements and advancements in MeOH synthesis processes. [ABSTRACT FROM AUTHOR]

Bubbling fluidized bed (BFB) reactor is advantageous for synthesis gas or syngas production among other available gasifiers. In this study, a BFB gasifier has been designed, utilizing non-woody biomass (rice straw) and air as gasifying medium, to investigate the effect of equivalence ratio (ER), static bed height, and operating temperature on synthesis gas yield and gasification efficiency. To calculate various structural and operating parameters, a reaction chamber with a diameter of 10 cm and a bed material of 400-500 pm has been studied. Considering the minimum fluidization velocity, slugging velocity, and terminal velocity, the optimum operating velocity has been taken as 17.25 cm/s. The calculated optimum transport disengagement height (TDH) is 86 cm, and the freeboard height is approximately 116 cm. Thus, the overall height of the reactor has come up as 202 cm. Almost 80% carbon conversion efficiency (CCE) was achieved from this BFB reactor with an optimum ER value of 0.35 during rice straw gasification. The same gasifier results in a synthesis gas yield of 3.6 Nm³/kg with a lower heating value (LHV) of about 3.5 MJ/Nm³ at optimum ER value. Further scaling up this process based on the findings of this study for industrial-scale synthesis gas production can pave a way for bioenergy generation from non-woody biomass. [ABSTRACT FROM AUTHOR]