Efficient adsorption of anionic azo dyes on porous heterostructured MXene/biomass activated carbon composites: Experiments, characterization, and theoretical analysis via advanced statistical physics models

Mesoporous activated carbon from mangosteen (Garcinia mangostana) peels by H3PO4 assisted microwave: Optimization, characterization, and adsorption mechanism for methylene blue dye removal

Abstract The jeopardy of the synthetic dyes effluents on human health and the environment has swiftly aggravated, threatening human survival. Hence, sustained studies have figured out the most acceptable way to eliminate this poisonous contaminant. Thereby, our investigation aimed to fabricate montmorillonite/magnetic NiFe 2 O 4 @amine-functionalized chitosan (MMT-mAmCs) composite as a promising green adsorbent to remove the cationic methylene blue (MB) and crystal violet (CV) dyes from the wastewater in neutral conditions. Interestingly, MMT-mAmCs composite carries high negative charges at a wide pH range from 4 to 11 as clarified from zeta potential measurements, asserting its suitability to adsorb the cationic contaminants. In addition, the experimental study confirmed that the optimum pH to adsorb both MB and CV was pH 7, inferring the ability of MMT-mAmCs to adsorb both cationic dyes in simple process conditions. Furthermore, the ferromagnetic behavior of the MMT-mAmCs composite is additional merit to our adsorbent that provides facile, fast, and flawless separation. Notably, the as-fabricated composite revealed an auspicious adsorbability towards the adsorptive removal of MB and CV, since the maximum adsorption capacity of MB and CV were 137 and 118 mg/g, respectively. Moreover, the isotherm and kinetic investigatins depicted that the adsorption of both cationic dyes fitted Langmuir and Pseudo 2nd order models, respectively. Besides, the advanced adsorbent preserved satisfactory adsorption characteristics with maximal removal efficacy exceeding 87% after reuse for ten consecutive cycles. More importantly, MMT-mAmCs efficiently adsorbed MB and CV from real agricultural water, Nile river water and wastewater samples at the neutral pH medium, reflecting its potentiality to be a superb reusable candidate for adsorptive removal cationic pollutants from their aquatic media. 

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Efficient removal of noxious methylene blue and crystal violet dyes at neutral conditions by reusable montmorillonite/NiFe2O4@amine-functionalized chitosan composite

Biochar was produced from the sawdust of the wood forest species Cedrella fissilis and later used as an adsorbent to remove atrazine herbicide from aqueous media. Biochar showed high thermal stability, an amorphous structure, and a highly irregular surface, mainly composed of carbon-containing bonds. The isothermal curves confirmed that the increase in temperature favored the adsorption of the herbicide. The Langmuir model best suited the experimental equilibrium data, with the maximum adsorption capacity of 7.68 mg g-1 at 328 K. The thermodynamic parameters confirmed a spontaneous process of an endothermic nature governed by physical interactions (interactions of van der Waals and hydrogen bonds). Kinetic studies showed that equilibrium was reached within 180 min. The linear driving force model (LDF) showed good statistical adjustment to the experimental data, where it was observed that the diffusion coefficient increased with the concentration of adsorbate. Biochar can be reused in up to three cycles. Finally, the adsorbent showed good efficiency in real water samples from rivers contaminated with atrazine, with 76.58% and 71.29% removal. 

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Investigation of biochar from Cedrella fissilis applied to the adsorption of atrazine herbicide from an aqueous medium

Abstract In this investigation, new porous adsorbent beads were formulated via the incorporation of graphene oxide (GO) into cellulose acetate beads (CA) for the adsorptive removal of methylene blue (MB) dye. The experimental results signified that the adsorption of MB dye increased with the increase in the GO ratio from 10 to 25%. In addition, the adsorption process obeyed PSO kinetic model and Langmuir isotherm model with a maximum adsorption capacity reaching 369.85 mg/g. More importantly, it was proposed that the adsorption mechanism of MB dye onto GO@CA proceeded via electrostatic interactions, H-bonding, van der Waals forces, n-π and π -π interactions. Besides, the fabricated beads exhibited an excellent ability to recycle and reuse after five successive cycles. In addition, there was a high selectivity of GO@CA beads towards MB molecules in the presence of co-existing cations such as Fe 2+ , Zn 2+ , Cu 2+ and Ni 2+ . 

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Graphene oxide incorporated cellulose acetate beads for efficient removal of methylene blue dye; isotherms, kinetic, mechanism and co-existing ions studies

Adsorption of methylene blue from aqueous solution on activated carbons and composite prepared from an agricultural waste biomass: A comparative study by experimental and advanced modeling analysis

Aiming to improve the thermal stability and flame retardant properties of calcium alginate, calcium alginate (CaAlg)/hydroxyapatite (HAP) hybrid material was synthesized in situ by the sol–gel method at room temperature. It was found that the HAP particles were generated from nanospheres to urchin-like microspheres, finally to wrinkled sponge microspheres with the two-dimensional nanostructured surface. The results showed that the thermal stability and flame retardancy of the hybrid material were significantly improved, and its mechanism was proposed as HAP promoted the decarboxylation of alginate resulting in carbonization of CaAlg/HAP, and it was the function of solid phase before 350 °C, while the synergistic effects of gas phase and solid phase after 350 °C that led to the high flame retardancy of CaAlg/HAP. 

https://www.researchsquare.com/article/rs-875067/latest.pdf

Meng Yu

Papers

Adsorption of methylene blue from aqueous solution on activated carbons and composite prepared from an agricultural waste biomass: A comparative study by experimental and advanced modeling analysis

Adsorption of methylene blue from aqueous solution on activated carbons and composite prepared from an agricultural waste biomass: A comparative study by experimental and advanced modeling analysis

Simple and green synthesis of calcium alginate/hydroxyapatite hybrid material without high temperature treatment and its flame retardancy