CoFe2O4@Methylcellulose/AC as a New, Green, and Eco-friendly Nano-magnetic Adsorbent for Removal of Reactive Red 198 from Aqueous Solution

Combining biological and chemical methods to disassemble of cellulose from corn straw for the preparation of porous carbons with enhanced adsorption performance.

The biochar adsorption process is very efficient in the treatment of wastewater treatment. In this study, Moringa oleifera seeds-derived biochar (B) was modified using chitosan-ZnO (CZ), denoted as CZ-B, applied for the removal of methylene blue (MB) dye in an aqueous solution. The biochars were characterized using spectroscopic, Scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques. Response surface methodology (RSM) was applied to explore the impact of time, concentration, and pH on the sorption of MB. The surface functional groups, e.g., hydroxyls, nitriles, carbonyls, carboxylic, ester, and phenol structures were enhanced as observed from spectroscopic results. The irregular porous surface of biochar, the uniform orientation of spherical-shaped CZ particles, and agglomerated chunks of porous rock in CZ-B particles were identified from SEM analysis. XRD patterns indicated a fully amorphous structure of biochar, whereas crystallinity introduced in the CZ-B structure by incorporating CZ was observed. At pH 8, the sorption of MB on all the sorbents was maximum. MB removal efficiency (% R) of biochar, CZ, and CZ-B were 44%, 47% and 89.7 %, respectively. The CZ incorporation has increased the MB removal efficiency by ∼104%. Biochar preferred pseudo-second-order and intraparticle diffusion models, indicating a dual mechanism of chemisorption and pore diffusion, whereas CZ-B followed the pseudo-2nd-order model. Biochar and CZ followed Langmuir isotherm with sorption capacity of 55.10 and 55.85 mg/g, respectively; the Freundlich model explained the sorption isotherm of CZ-B with 135.20 sorption capacity. RSM analysis for CZ-B revealed that experimental results were best fitted (R2 = 0.9729) into a quadratic second-order polynomial model. The correlation of the actual to the predicted value indicated a reasonable response estimation. Therefore, with the optimization of process parameters, CZ-B can be applied as an efficient sorbent to eliminate organic dyes. Main findings of the work: Modification of M. oleifera seed-originated biochar by chitosan-ZnO composite results in an excellent ternary composite with enhanced sorption properties against organic dye, methylene blue (MB). 

Chitosan-ZnO decorated Moringa oleifera seed biochar for sequestration of methylene blue: Isotherms, kinetics, and response surface analysis

Biochar is a promising engineering material to sequestrate organic pollutants from wastewater. In the current study, several surface-modified Moringa (M.) oleifera leaf biochars were prepared and utilized for the sorption of methyl orange (MO) dye from an aqueous solution. Raw biochar was produced by the carbonization of M. oleifera leaves at 350°C in a muffle furnace for 2 h. The surface-modified M. oleifera biochars were prepared at 400°C, 500°C, and 600°C using phosphoric acid (H3PO4) at different combinations to improve the biochar pore structure, surface functional groups, and biochar stability. The highest surface area (267.15 ± 42.40 m2/g) of the modified biochar was achieved at 500°C with H3PO4 to raw biochar ratio of 1.5. Surface morphological results revealed the formation of pores, troughs, and channels with the increasing activation temperature. The carbon (C) content (wt%) was maximum (79.61%) for activated biochar at 500°C. The presence of enhanced functional groups, e.g., hydroxyl, aliphatic carbon-hydrogen, carbonyl, ester, and phenol structures in surface-modified biochars was observed from FT-IR results. The Langmuir isotherm model was fitted to better describe the adsorption phenomenon for both surface-modified biochars and raw biochar compared to the Freundlich isotherm model. The highest adsorption capacity was 175 mg MO dye/g of activated biochar prepared at 500°C with an H3PO4 impregnation ratio of 1.5. Pseudo-1st order model fitted the best for raw biochars whereas pseudo-2nd order and intraparticle diffusion models better describe the sorption of MO onto activated biochar. The results anticipated M. oleifera leaf-activated biochar as an efficient tool for the treatment of MO contaminated wastewater. 

Phosphoric acid surface modified
 Moringa oleifera
 leaves biochar for the sequestration of methyl orange from aqueous solution: Characterizations, isotherm, and kinetics analysis

Industrial effluents contaminated with different types of organic dyes have become a major concern to environmentalists due to the carcinogenic nature of the dyes, which are harmful to human and aquatic life. In recent years, the treatment of contaminated effluents by natural resources has been proposed as the most sustainable solution for this problem. In this work, Moringa oleifera (M. oleifera) seed-derived biochar composites, e.g., Biochar-Chitosan (BC), Biochar-ZnO (BZ), and Chitosan-ZnO (CZ) were produced and characterized. The synthesized materials were then utilized to adsorb a cationic dye, methylene blue. Spectroscopic analysis of the biochar-based composites revealed that the modification of biochar by chitosan and ZnO introduced different functional and active groups in the biochar surface. Pore development in the structure of biochar nanocomposites was visible in surface morphological images. The derived biochar was fully amorphous and increased crystallinity by the ZnO modification. The obtained surface area varied from 0.90 ± 0.00 to 14.48 ± 1.13 m2 g−1 for prepared sorbents, where BZ corresponds to the highest and BC corresponds to the lowest surface area, respectively. The basic pH (9) was the most favorable condition for sorption. The sorption reached equilibrium at 90 min. Isotherm revealed the favorability of the Langmuir model over the Freundlich and Temkin models. The highest sorption capacity (~170 mg/g) was found for BC. The BC and BZ showed a 75% increase and 16% decrease in removal due to the chitosan and ZnO modification, respectively. Response surface methodology (RSM) optimization for BC showed similar results to the analytical experiments. The characterization and experimental results prefigure the chemical functionalities as the critical parameter over the surface area for the adsorption process.

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Synthesis, Characterization and Sorption Properties of Biochar, Chitosan and ZnO-Based Binary Composites towards a Cationic Dye

Highly removal of anionic dye from aqueous medium using a promising biochar derived from date palm petioles: Characterization, adsorption properties and reuse studies

Hakim Djafer Khodja

Papers

Highly removal of anionic dye from aqueous medium using a promising biochar derived from date palm petioles: Characterization, adsorption properties and reuse studies