Low-cost Limoniastrum monopetalum fruits as efficient biosorbent of methylene blue from aqueous suspension

The present paper underlines the chemical analysis and the valorization of Limoniastrum monopetalum fruits as a low-cost adsorbent. The characterization and the investigation of the adsorption capacity of this new bio-adsorbent are among the novelty of the present paper. Several characterization techniques have been used. The effect of some experimental parameters on the biosorption of methylene blue has been quantified. Indeed, the experiments were performed at different pH values, initial dye concentrations, temperatures, and contact times. The second step consists to fit the kinetic data using several kinetic models. Bangham model and pseudo-first-order model satisfactory fit the experimental data. In the third step, four advanced models obtained from statistical physics are tested to describe the adsorption isotherms. These models are powerful since a physical meaning may be easily attributed to all their adjustable parameters. The use of these models is among the novelty of the study. The monolayer model with one energy seems to be the more suitable to fit the data. The half-saturation concentration and the number n of anchored molecules per site were evaluated. It appears that the investigated fruit could be anchored by one or two dye molecules per site. The adsorption energy varies in the range of 15 to 20 kJ mol(-1) depending on the temperature. This confirms that the adsorption proves to be a physisorption process. The maximum biosorption capacity of methylene blue was about 142 mg g(-1) for a temperature of 22 degrees C. It decreases slightly with temperature. The results revealed that Limoniastrum monopetalum fruit is a potential candidate for eliminating cationic dyes from polluted water.

Automated summary

This paper focuses on the chemical analysis and valorization of Limoniastrum monopetalum fruits as a low-cost adsorbent. The characterization and investigation of the adsorption capacity of this new bio-adsorbent are novel. Experimental parameters were varied to quantify the effect on the biosorption of methylene blue. Various kinetic and isotherm models were used to fit the data, with the monolayer model showing the best fit. The results indicate that Limoniastrum monopetalum fruit is a potential candidate for removing cationic dyes from polluted water.