Lignin based microspheres for effective dyes removal: Design, synthesis and adsorption mechanism supported with theoretical study

• Published in: Journal of environmental management Vol. 326; p. 116838
• Main Authors: Salih, Rabab, Veličković, Zlate, Milošević, Milena, Pavlović, Vera P., Cvijetić, Ilija, Sofrenić, Ivana V., Gržetić, Jelena D., Marinković, Aleksandar
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15-01-2023
• Subjects: Adsorbent/adsorbate interactions; Batch and flow mode; Charged/neutral dyes; Competitive dye removal; Mass transport; Sulfated microsphere; Charged/neutral dyes; Mass transport; Sulfated microsphere; Competitive dye removal; Batch and flow mode; Adsorbent/adsorbate interactions
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2022.116838

Multifunctional lignin bio-based adsorbent, b-LMS, was obtained via inverse copolymerization in the suspension of acryloyl modified kraft lignin (KfL-AA) and bio-based trimethylolpropane triacrylate (bio-TMPTA). Morphological and structural characterization of KfL-AA and b-LMS was performed using BET, FTIR, Raman, NMR, TGA, SEM, and XPS techniques. The b-LMS microspheres with 253 ± 42 μm diameters, 69.4 m2 g−1 surface area, and 59% porosity efficiently adsorb Malachite Green (MG), Tartrazine (T), and Methyl Red (MR) dye. The influence of pH, pollutant concentration, temperature, and time on the removal efficiency was studied in a batch mode. Favorable and spontaneous processes with high adsorption capacities e.g. 116.8 mg g−1 for MG, 86.8 mg g−1 for T, and 68.6 mg g−1 for MR indicate the significant adsorptive potential of b-LMS. Results from diffusional and single mass transfer resistance studies indicate that pore diffusion is a rate-limiting step. Theoretical calculations confirmed a higher affinity of b-LMS to cationic dye MG compared with an anionic and neutral one, i.e. T and MR, respectively. The data fitting from a flow system, using semi-empirical equations and Pore Surface Diffusion Modelling (PSDM) provided breakthrough point determination. The results from the desorption and competitive adsorption study proved the exceptional performance of b-LMS. Moreover, sulfation of b-LMS, i.e.production of b-LMS-OSO3H, introduced high-affinity sulfate groups with respect to cationic dye and cations. Developed methodology implements the principle of sustainable development and offers concept whose results contribute to the minimization of environmental pollution.
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•Synthesis of multifunctional fully bio-based lignin microspheres (b-LMS) has been optimized.•Boosted adsorption efficiency of cationic and anionic dyes onto b-LMS has been achieved.•Exceptional b-LMS performances were confirmed in both batch and column system.•Rate limiting step and adsorption mechanism was assessed from mass transfer and theoretical studies.•Sulfation of b-LMS improves cation and positively charged dye removal capability.