The water-intensive textile industry releases dye-laden effluent into aquatic habitats, creating environmental and public health problems. Innovative and sustainable water treatment solutions are needed because textile dyes, particularly Orange G (OG), are poisonous and pathogenic. Therefore, in this work we synthesized a composite adsorbent chitosan (CS), bentonite (Bnt) crosslinked with glutaraldehyde (GLD) named as (CS/Bnt@GLD) for the removal of Orange G (OG) dye from aqueous solutions. The composite was analyzed using SEM, EDS, FTIR, XRD, and pH at zero-point charge (pHzpc = 7.72), validating the effective incorporation of components and functional groups pertinent to dye adsorption. The influence of factors, including initial dye concentration, pH, adsorbent dosage, temperature, and contact time was examined throughout extensive ranges. Batch adsorption tests indicated that the optimal dye removal effectiveness (96.18%) was attained at a pH of 7, a temperature of 25 °C, a dose of 0.75 g/L, and an initial OG concentration of 10 mg/L. The adsorption capacity escalated with dye concentration, with a peak of 52.63 mg/g at 50 mg/L, as shown by the Langmuir isotherm model (R2 = 0.9983). Kinetic analyses revealed that the adsorption conformed to a pseudo-second-order model (R2 = 0.9999), indicating chemisorption with multilayer interactions. Thermodynamic studies indicated that the reaction is spontaneous (ΔG° = –5.16 to –1.86 kJ/mol) and exothermic (ΔH° = –38.00 kJ/mol). The composite demonstrated efficient performance in actual water matrices (adsorption > 69.56% for OG concentrations > 50 mg/L) and shown commendable reusability, maintaining 74.65% efficiency after five cycles. These findings illustrate the prospective capability of CS/Bnt@GLD for economical and effective dye elimination in wastewater treatment applications.Highlights<UnorderedList Mark="Bullet"> <ItemContent> The study focused on the removal of Orange G (OG) dye from textile wastewater, a harmful azo dye. </ItemContent> <ItemContent> A chitosan-bentonite composite crosslinked by glutaraldehyde (CS/Bnt@GLD) based adsorbent was synthesized. </ItemContent> <ItemContent> Synthesized CS/Bnt@GLD composite is recyclable revealing high removal percentage (95%) and adsorption capacity (52.63 mg/g) for OG dye. </ItemContent> <ItemContent> The CS/Bnt@GLD composite reveal excellent potential for removal of OG dye under real conditions. </ItemContent> </UnorderedList>

Efficient Adsorption of Orange G (OG) Dye From Aqueous Solution by Using Chitosan-Bentonite Crosslinked by Glutaraldehyde (CS/Bnt@GLD) Composite: Synthesis, Characterization, Experimental Studies, and Mechanism

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发表日期：

2025年7月13日

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Devesh Vishwakarma,
Deepa Kannaujiya,
Shivangi Awasthi,
Shikha

摘要

The water-intensive textile industry releases dye-laden effluent into aquatic habitats, creating environmental and public health problems. Innovative and sustainable water treatment solutions are needed because textile dyes, particularly Orange G (OG), are poisonous and pathogenic. Therefore, in this work we synthesized a composite adsorbent chitosan (CS), bentonite (Bnt) crosslinked with glutaraldehyde (GLD) named as (CS/Bnt@GLD) for the removal of Orange G (OG) dye from aqueous solutions. The composite was analyzed using SEM, EDS, FTIR, XRD, and pH at zero-point charge (pHzpc = 7.72), validating the effective incorporation of components and functional groups pertinent to dye adsorption. The influence of factors, including initial dye concentration, pH, adsorbent dosage, temperature, and contact time was examined throughout extensive ranges. Batch adsorption tests indicated that the optimal dye removal effectiveness (96.18%) was attained at a pH of 7, a temperature of 25 °C, a dose of 0.75 g/L, and an initial OG concentration of 10 mg/L. The adsorption capacity escalated with dye concentration, with a peak of 52.63 mg/g at 50 mg/L, as shown by the Langmuir isotherm model (R² = 0.9983). Kinetic analyses revealed that the adsorption conformed to a pseudo-second-order model (R² = 0.9999), indicating chemisorption with multilayer interactions. Thermodynamic studies indicated that the reaction is spontaneous (ΔG° = –5.16 to –1.86 kJ/mol) and exothermic (ΔH° = –38.00 kJ/mol). The composite demonstrated efficient performance in actual water matrices (adsorption > 69.56% for OG concentrations > 50 mg/L) and shown commendable reusability, maintaining 74.65% efficiency after five cycles. These findings illustrate the prospective capability of CS/Bnt@GLD for economical and effective dye elimination in wastewater treatment applications.

Highlights

The study focused on the removal of Orange G (OG) dye from textile wastewater, a harmful azo dye.

A chitosan-bentonite composite crosslinked by glutaraldehyde (CS/Bnt@GLD) based adsorbent was synthesized.

Synthesized CS/Bnt@GLD composite is recyclable revealing high removal percentage (95%) and adsorption capacity (52.63 mg/g) for OG dye.

The CS/Bnt@GLD composite reveal excellent potential for removal of OG dye under real conditions.