Design of sodium alginate/soybean extract beads loaded with hemp hurd and halloysite as novel and sustainable systems for methylene blue adsorption

Abstract

This work concerns the fabrication of a green, novel, and sustainable system for the efficient removal of methylene blue from aqueous solutions. The proposed system is obtained by using sodium alginate/soybean extract blend reinforced with hemp hurd from agro-waste resources and halloysite nanotubes (HNTs). The ionotropic gelation methodology, using calcium chloride as a crosslinking agent, was easily applied to obtain composite beads. The adsorption studies were carried out up to 24 h using methylene blue as model system. The effect of HNTs on adsorption capacity was investigated proving that an increase in inorganic filler determined an increase in adsorption capacity from 32 to 49 mg/g by adding 35% wt of HNTs. The experimental data were fitted through four different models, demonstrating that the adsorption phenomenon is described by second-order process. Film diffusion and pore diffusion values were evaluated to better investigate the rate controlling mechanisms. Isotherm studies were then carried out to extrapolate thermodynamic parameters. Finally, a possible mechanism of adsorption was proposed on the basis of chemisorption mechanism. Here, we demonstrate that the proposed novel, inexpensive, and sustainable composite material obtained from agro-waste resources has high efficiency in removing a cationic dye from wastewaters.

Efficient Removal of Methylene Blue by Bio-Based Sodium Alginate/Lignin Composite Hydrogel Beads

“…The maximum adsorption capacity, removal efficiency, and regeneration of the obtained SA/Lig beads were compared with bio-based materials in the literature [ 34 , 35 ]. As shown in Table 3 , there are almost no regeneration data for the reported adsorbents [ 7 , 8 , 9 , 10 , 11 ]. Though some of the adsorbents show a much high adsorption capacity at a high initial concentration, the removal efficiency is relatively low.…”

“…Marrakchi reported the adsorption of MB with a cross-linked chitosan/sepiolite composite film [ 8 ], where the maximum monolayer adsorption capacity is 40.986 mg/g, which was obtained for the CS50SP50 under optimal conditions. Bio-based sodium alginate/soybean extract beads reinforced with hemp hurd and halloysite were reported by Viscusi for the adsorption of MB [ 9 ], and the adsorption capacity reached 49 mg/g when adding 35 wt% halloysite. The results of kinetic fitting revealed that the adsorption was based on the chemisorption mechanism.…”

“…Based on these features of dyes, electrostatic attraction, π-π stacking, and a hydrogen bond can be designed in the construction of adsorbents. Due to its ionic characteristic, the electrostatic attraction was first taken into account in the adsorbents’ design, thus the bio-based positive chitosan and negative cellulose alginate are the most used polymer matrices [ 7 , 8 , 9 , 10 , 11 ]. As the dyes are aromatic molecules, bio-based aromatic tannin- and lignin-based adsorbents have also been developed based on the π-π stacking interaction [ 13 , 14 , 15 ].…”

Facile Synthesis of Sustainable Tannin/Sodium Alginate Composite Hydrogel Beads for Efficient Removal of Methylene Blue

“…Chitosan/sepiolite composite hydrogel were prepared with cross-linking using epichlorohydrin, the CS50SP50 was selected as the best adsorbent for the adsorption of MB, and the monolayer adsorption capacities of this composite is 40.986 mg/g [ 6 ]. Sodium alginate/soybean extract composite hydrogel beads were reported for the removal of MB by Viscusi et al [ 7 ], the adsorption data can be described with a second-order model, and the maximum adsorption capacity is 49 mg/g. Lu et al reported magnetic activated carbon/sodium alginate composite hydrogel beads for the adsorption of MB [ 8 ], and the maximum adsorption capacity is 222.3 mg/g with initial concentration of 700 mg/L, with a removal efficiency of 31.8%.…”

Sustainable food packaging films based on alginate and aloe vera

“…[14] Sodium alginate, a natural biopolymer extracted from brown seaweed, is mainly composed of alternate blocks of 1-4 linked α-L-guluronic and β-D-mannuronic acid residues. [15] Sodium alginate is a promising material in food, pharmaceutical, cosmetics, and other chemical industries as a stabilizing, thickening, and gelling agent due to its distinguishing properties like biocompatibility, biodegradability, non-toxic nature, and low cost. [16] Nonetheless, it has disadvantages like its strong hydrophilic nature as well as poor mechanical and thermal stability which have restricted its use in comparison to synthetic plastics.…”