Facile Synthesis of Polyethylenimine-modified Sugarcane Bagasse Adsorbent for Removal of Anionic Dye in Aqueous Solution

Polyethyleneimine-functionalized magnetic sugarcane bagasse cellulose film for the efficient adsorption of ibuprofen

Polyethyleneimine-modified magnetic sugarcane bagasse cellulose film (P-SBC/Fe3O4 film) was simply fabricated for the removal of ibuprofen (IBP), a typical emerging organic contaminant. The P-SBC/Fe3O4 film exhibited an equilibrium adsorption amount of 370.52 mg/g for IBP and a corresponding removal efficiency of 92.63 % under following adsorption conditions: 318 K, pH 4, and 0.25 mg/mL dosage. Thermodynamic studies indicated that adsorption of IBP on the P-SBC/Fe3O4 film was spontaneous (∆G < 0) and endothermic (∆H > 0). The adsorption data conformed to the Freundlich isotherm model and multilayer adsorption model (two layers), and an average of 3-4 active sites on the P-SBC/Fe3O4 film share an IBP molecule. Both the EDR-IDR and AOAS models vividly described the dynamic characteristics of adsorption process. Model fitting results, theoretical calculations, and comprehensive characterization revealed that adsorption is driven by electrostatic interactions between the primary amine of P-SBC/Fe3O4 film and the carboxyl group of IBP molecule, while other weak interactions are also non-ignorable. Furthermore, quantitative calculations based on density functional theory (DFT) underscored the importance of PEI functionalization. In conclusion, P-SBC/Fe3O4 film is an environmentally friendly and cost-effective adsorbent with significant potential for effectively removing IBP, while maintaining its efficacy over multiple cycles.

Development and optimization of geopolymer adsorbent for water treatment: Application of mixture design approach

The current paper refers to the study of a new approach to optimizing the adsorptive properties of geopolymers by varying the aluminosilicate precursors from kaolin (K), metakaolin (MK), and coal fly ash (CFA) as internal synthesis factors. The simplex-augmented-centroid mixture design was applied to identify the optimal formulation from the three aluminosilicate precursors to develop a geopolymer (GP) with a distinctive structure that positively affects its dye adsorption efficiency. The variously formulated GP samples were tested for the removal of both methylene blue (MB-dye) and crystal violet dye (CV-dye) from an aqueous solution. The mathematical-statistical analysis of the experimental readings suggested that the generated special cubic models were significant, and thus the chosen approach was adequate for determining the optimum blending proportion. The optimization tools indicated that the optimal mixture from the three aluminosilicate precursors for developing a GP with high adsorption efficiency was 58% MK, 42% K, and 0% CFA. The optimized geopolymer (GP_O) was synthesized and then analyzed using a variety of physicochemical techniques, which revealed the presence of an amorphous N-A-S-H gel-rich porous structure as an influencing property on the geopolymer's organic dye adsorption efficiency. The dependence of the adsorption mechanism of both MB-dye and CV-dye by GP_O on the adsorbent dosage, contact time, initial dye concentration, temperature, and solution pH was evaluated. The isothermic and kinetic experimental readings for MB and CV-dyes adsorption by GP_O were well fitted to the pseudo-second-order and Freundlich models, with an exothermic, favorable, and spontaneous adsorption reaction thermodynamically. The experimental studies in the lab scale on GP_O produce comparable results. From these results, it has been concluded that the accuracy and feasibility of the mixture design simulation succeeded in optimizing and developing a geopolymeric sorbent material with great potential as an excellent economical agent for removing cationic dyes from aqueous media. This point represents an added value compared to traditional non-optimized geopolymer absorbents. Besides, this geopolymer material represents a significant application possibility for water treatment and remediation of hazardous dye pollutants.

Secondary bond interface assembly of polyethyleneimine on zein microparticles for rapid adsorption of Reactive Black 5

Textile dye wastewater has the characteristics of high concentration, complex composition and changeable color degree and pH, which is difficult to be effectively and completely treated, and easy to cause environmental pollution. Here, a strategy of secondary bond interface assembly of polyethyleneimine on zein microparticles (PEI) (PEI@zein) was constructed to achieve rapid and efficient removal of Reactive Black 5 (RB5), which is one of the most widely used reactive dyes in the textile industry. Structural analysis indicated that the as-prepared PEI layer immobilized on zein microparticles was constructed based on the interface assembly dominated by hydrophobic interactions and electrostatic attraction between PEI molecules and zein chains. The novel interface showed excellent absorption performance for RB5 with an absorption capacity of 631.0 mg·g^-1, rapid adsorption in 2 min, wide pH range of 4-10. Mechanism analysis suggested the effective adsorption of RB5 by PEI@zein microparticles was mainly attributed to secondary bond interface such as electrostatic interaction and hydrogen bond between RB5 and PEI immobilized on the surface of zein microparticles. Moreover, due to the presence of secondary bond interface, RB5 adsorbed on microparticles can be easily desorbed by using 0.01 M NaOH. Therefore, the strategy of secondary bond interface assembly with polyethyleneimine on zein microparticles has high potential for practical application in the treatment of dye-containing wastewater.

Modified Beaded Materials from Recycled Wastes of Bagasse and Bagasse Fly Ash with Iron(III) Oxide-Hydroxide and Zinc Oxide for the Removal of Reactive Blue 4 Dye in Aqueous Solution

Dye contamination in wastewater affects the photosynthesis of aquatic plants and algae by blocking the sunlight, and it induces toxicity to aquatic organisms, which might result in human health effects. Thus, the treatment of dyes in wastewater is required before discharging into the receiving water for safety purposes. Six dye adsorbent materials bagasse beads (BB), bagasse fly ash beads (BFB), bagasse beads with mixed iron(III) oxide-hydroxide (BBF), bagasse fly ash beads with mixed iron(III) oxide-hydroxide (BFBF), bagasse beads with mixed zinc oxide (BBZ), and bagasse fly ash beads with mixed zinc oxide (BFBZ) were synthesized and investigated using various characterization techniques such as X-ray diffractometry (XRD), field emission scanning electron microscopy with focused ion beam (FESEM-FIB), energy dispersive X-ray spectrometry (EDX), and Fourier transform infrared spectroscopy (FTIR). A series of batch experiments on the effects of dosage (0.5-3 g), contact time (3-18 h), temperature (30-80°C), pH (3-11), and initial concentration (30-90 mg/L) were used to investigate reactive blue 4 (RB4) dye removal efficiencies in aqueous solution, and their adsorption isotherms and kinetics were studied for explaining their adsorption patterns and mechanisms. All dye adsorbent materials demonstrated semicrystalline structures, and their surface morphologies had a spherical shape with coarse surfaces. Five main elements of oxygen, carbon, calcium, chlorine, and sodium and six main functional groups of alcohol and carboxylic acid (O-H), carbon dioxide (O=C=O), aromatic groups (C=O and N=O), alkene (C-H), and sodium alginate (C-O-C) were detected in all dye adsorbent materials. For batch tests, they could remove RB4 dye by more than 90%, and BFBF exhibited the highest RB4 dye removal efficiency at 99.36%. Freundlich and pseudo-second-order kinetic models well explained their adsorption patterns and mechanisms, in which BFBF demonstrated a higher maximum adsorption capacity (q _m) of 10.277 mg/g than that of other dye adsorbent materials. Therefore, all dye adsorbent materials offer good potential for further industrial applications.