Bio-based Adsorbent Research Articles

Fruit peel incorporated alginate based magnetic hydrogel bio-composite beads for removal of hexavalent chromium

High adsorption capacity, reusability and sustainability are the most important features sought in the adsorbent preferences to be used in wastewater treatment. In this research work, magnetic composite beads prepared from fruit peels (nectarine and orange) and alginate (ALG) as biopolymers (NAF and OAF) were synthesized by dropping and pH-precipitation method as alternative adsorbents. By encapsulating the adsorbent using alginate and imparting magnetic properties, the separation of the adsorbent from water after the adsorption process has been simplified. Fourier transform infrared spectroscopy analysis (FTIR), scanning electron microscopy (SEM) analysis, energy-dispersive X-ray (EDX)-mapping and X-ray diffraction (XRD) analyses were performed to examine the surface chemical structure and surface morphological structure of these new synthesized biosorbents. The calculated maximum adsorption capacities were 224.3 mg/g for OAF and 256.5 mg/g for NAF at 298 K and pH =2.0. It was observed that the adsorption process for both adsorbents was endothermic and spontaneous. Moreover, the adsorptions of Cr (VI) onto both adsorbents followed the pseudo-second order model and fit the Langmuir isotherm model better. OAF and NAF were found to be reusable with stable adsorption capacity for at least five cycles. Overall, this study demonstrates the performance of OAF and NAF in the removal of Cr (VI) ions from aqueous solutions, thus highlighting the promising potential of these magnetic bio-based adsorbents for sustainable water treatment.

Macroscopic and Microscopic Levels of Methylene Blue Adsorption on a Magnetic Bio-Based Adsorbent: In-Depth Study Using Experiments, Advanced Modeling, and Statistical Thermodynamic Analysis

A magnetic bio-based adsorbent derived from H2O2-activated zeolite and turmeric carbohydrate polymer was fabricated, characterized, and utilized in removing methylene blue (MB) dye at pH 8.0 and temperatures between 25 and 55 °C. To understand the molecular-scale adsorption mechanism, a range of advanced statistical physics models were employed in conjunction with conventional equilibrium models. The as-synthesized biosorbent presented high maximum capacities according to the Langmuir model, with values ranging from 268.67 to 307.73 mg/g. The double-layer equation yielded the best-fitting results to the MB experimental data among the applied statistical physics models. The number of MB molecules ranged from 1.14 to 1.97, suggesting a multi-molecular mechanism with a non-parallel orientation. The main factor affecting the effectiveness of this adsorbent was the density of its functional groups, which varied from 27.7 to 142.1 mg/g. Adsorption energies in the range of 19.22–21.69 kJ/mol were obtained, representing the existence of physical forces like hydrogen bonds and electrostatic interactions. To complete the macroscopic examination of the MB adsorption mechanism, thermodynamic parameters such as entropy, Gibbs free energy, and internal energy were considered. The adsorption/desorption outcomes up to five cycles displayed the stability of the magnetic biosorbent and its potential for decontaminating industrial effluents. Overall, this work increases our understanding of the MB adsorption mechanism onto the produced biosorbent at the molecular level.

Ionic liquids-assisted integration of biobased materials for sustainable elaboration of nanocomposites using hydroxyethyl cellulose and interlayered clay for efficient separation of Co(II) from multi-component mixtures

This study focuses on the development of eco-friendly biobased adsorbents through a sustainable hydrothermal and freeze-drying synthesis process, utilizing cost-effective bio-sourced materials to minimize energy consumption and waste. The biobased adsorbents were elaborated using hydroxyethyl cellulose-ionic liquids and bentonite clay. The elaborated biocomposites were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy/attenuated total reflection (FTIR/ATR), thermogravimetric analysis (TGA), and electron microscopy-energy dispersive X-ray (SEM–EDX), Brunauer–Emmett–Teller (BET) and zeta potential (ZP). Structural analysis confirms the intercalation and incorporation of HEC-ILs polymeric chains into Be-Na matrix and the formation of biocomposites. The [HEC-ILs/Be-Na] composite was subsequently employed for solid-phase extraction of Co(II) by investigating the effect of pH, initial Co(II) concentrations, time, temperature, and the presence of co-existing ions (Na(I), Li(I), Mn(II), Ni(II), and Al(III)). The adsorption kinetics of Co(II) metal ions were suitably characterized using the pseudo-second-order model (with R2 > 0.99). Furthermore, the adsorption isotherms conformed to the Langmuir model (with R2 > 0.97), suggesting a chemisorption process with an adsorption capacity of 69.8 mg/g. The thermodynamic study reveals that the adsorption process exhibits characteristics of spontaneity and endothermicity (ΔH° = 74.197 kJ mol−1, ΔG° < 0 kJ mol−1). The proposed mechanism for Co(II) adsorption on the developed biocomposite involves electrostatic interactions, ion exchange, and anion-π interactions. The biobased composite exhibited remarkable selectivity for Co(II) and demonstrated great potential as an adsorbent for industrial applications.Graphical abstract

Machine learning prediction of dye adsorption by hydrochar: Parameter optimization and experimental validation

In response to escalating global wastewater issues, particularly from dye contaminants, many studies have begun using hydrochar to adsorb dye from wastewater. However, the relationship between the preparation conditions of hydrochar, the properties of hydrochar, experimental conditions, types of dyes, and equilibrium adsorption capacity (Q) has not yet been fully explored. This study conducted a comprehensive assessment using twelve distinct ML models. The Gradient Boosting Regressor (GBR) model exhibited superior performance with R² (0.9629) and RMSE (0.1166) in the test dataset, marking it as the most effective among the evaluated models. Moreover, this study also proved the feasibility of the GBR model through stability testing and residual analysis. A feature importance analysis prioritized the variables as follows: experimental conditions (41.5 %), properties of hydrochar (26.0 %), preparation conditions (18.1 %), and type of dye (14.4 %). Meanwhile, experimental conditions (C0 > 30 mmol/g, pH > 8, and higher solvent temperatures) and hydrochar properties (the BET surface area > 2000 m²/g, an (O+N)/C molar ratio < 0.6, and an H/C molar ratio of approximately 0.06) show higher Q for dyes. Experimental validation of the GBR model confirmed its practical utility with a suitable predictive accuracy (R² = 0.8704). Moreover, the study developed a Python-based GUI that has integrated the best GBR models to facilitate researchers' ongoing application and improvement of this predictive model. This study not only underscores the efficacy of ML in enhancing the understanding of dye adsorption by hydrochar but also sets a precedent for future research on sustainable contaminants removal through bio-based adsorbents.

Adsorption Properties and Mechanisms of Methylene Blue by Modified Sphagnum Moss Bio-Based Adsorbents.

The abundant pore structure and carbon composition of sphagnum peat moss render it a bio-based adsorbent for efficient methylene blue removal from wastewater. By utilizing sphagnum moss sourced from Guizhou, China, as raw material, a cost-effective and highly efficient bio-based adsorbent material was prepared through chemical modification. The structure and performance of the modified sphagnum moss were characterized using SEM, EDS, FTIR, and TGA techniques. Batch adsorption experiments explored the effects of contact time, adsorbent dosage, pH, initial dye concentration, and temperature on adsorption performance. Kinetics, isotherm models, and thermodynamics elucidated the adsorption behavior and mechanism. The modified sphagnum moss exhibited increased surface roughness and uniform surface modification, enhancing active site availability for improved adsorption. Experimental data aligned well with the Freundlich isotherm model and pseudo-second-order kinetic model, indicating efficient adsorption. The study elucidated the adsorption mechanism, laying a foundation for effective methylene blue removal. The utilization of modified sphagnum moss demonstrates significant potential in effectively removing MB from contaminated solutions due to its robust adsorption capability and efficient reusability.

Efficient adsorption of Congo red (CR) dye onto novel lignin-based magnetic core-shell adsorbent: Synthesis, characterization and experimental studies

BackgroundFurfural residue is a by-product in the furfural production from the biomass, and enriched in cellulose and lignin. Lignin is considered efficient candidates for the preparation of bio-based adsorbents because of a variety of functional groups and reactive sites involved. MethodsIn this study, we prepared the tunable covalent binding of the aldehyde-based furfural residue lignin onto amine-functionalized Fe3O4 magnetic nanoparticles using cyanuric chloride as a chemoselective cross-linker. The novel lignin-based magnetic adsorbent in core-shell structure was reported for the first time to remove Congo red from aqueous solution. Significant FindingsA distinct core-shell structure is formed, according to the SEM, TEM, FTIR, BET, XPS, and VSM techniques. Adsorption studies suggested that endothermic processes occured for CR adsorption onto AFRL@AMNP, and both pseudo-first and pseudo-second order models could provide a good description of the adsorption kinetics. The Langmuir model estimated the qmax of CR by AFRL@AMNP were 218.2 mg/g at 290 K. According to FTIR, XPS, and DFT calculations, electrostatic interactions, hydrogen bonds, and π-π interactions were identified as main mechanisms for CR onto AFRL@AMNP. More importantly, due to the incorporation of Fe3O4 magnetic nanoparticle, AFRL@AMNP can be easier to separate from the aqueous solutions and be reused.

Exploring the circular prospects of cashew nutshells and avocado seeds as potential adsorbents for onboard natural gas storage

Natural gas (NG), known for its eco-friendly energy attributes, faces challenges such as low volumetric density, leakage susceptibility, and explosion risks during storage and transport. To narrow this gap, this study reports on the potential of bio-based adsorbents from cashew nut shells (CNS) and avocado seeds (AVS) as an alternative approach for the onboard storage of NG. CNS and AVS were characterized to determine moisture content, volatile matter content, ash content, and fixed carbon content. Additionally, the study determined the optimal loading of activating agents to produce activated carbons (ACs). ACs were produced through a dual process involving simultaneous chemical activation and carbonization. In the chemical activation phase, a sample of either cashew nut shells (CNS) or avocado seeds (AVS) was impregnated with phosphoric acid at various ratios. Subsequently, the properties of the ACs, including surface area, pore volume, and X-ray diffraction (XRD), were evaluated. The NG adsorption capacity of the ACs was assessed, and Freundlich and Langmuir isotherm adsorption equations were derived to elucidate the NG adsorption behavior on the ACs. The results revealed that the proximate analysis of CNS and AVS showed low moisture content (6.48% and 8.91%), high volatile matter (80.21% and 73.09%), low ash content (1.48% and 4.71%), and high fixed carbon (13.65% and 15.59%), indicating suitability for AC formulations. During synthesis, adding phosphoric acid to AVS or CNS in a 1:1 ratio resulted in significantly larger surface areas and pore volumes in the produced ACs. X-ray diffraction analysis of the ACs produced from CNS or AVS with phosphoric acid added at a 1:1 ratio indicated a broad diffraction background and a predominantly amorphous structure. The performance of the ACs in the adsorption of NG demonstrated that ACs produced from 1:1 mixtures of CNS with phosphoric acid and AVS with phosphoric acid exhibited higher adsorption capacities, 0.038 g/g and 0.031 g/g, respectively, at a low pressure of 5 bar, showcasing a novelty of this study. Furthermore, the Freundlich equation test yielded a constant R² exceeding 0.9, with positive adsorption intensity and adsorption capacity values, indicating a favorable fit for the model. In contrast, the Langmuir equation test resulted in a constant R² exceeding 0.9, but the adsorption capacity exhibited negative values, leading to inconclusive explanations. These findings affirm that bio-wastes can be an effective source of adsorbents for onboard natural gas storage , suggesting a means to reduce the take-dispose model and promote a circular economy in the energy sector.

Pilot-scale foam and cast-coated nanocellulose filters for water treatment

AbstractA large variety of substances, for instance heavy metal ions from different sources including mining, industry, and agricultural activities, pollute fresh water sources. Bio-based adsorbents, such as cellulose nanofibers (CNF), have recently been introduced in the process of treating water to remove hazardous pollutants primarily owing to their natural abundance, non-toxicity, and renewability. Surface modification of CNF, e.g. by catalytically oxidising the primary C6-OH groups of CNF selectively into carboxylic (COO−) groups with TEMPO, yields materials that are effective in adsorbing positively charged heavy metal ions, e.g. Cu ions. However, to utilise CNF in continuous processes beyond static, batch-wise adsorption, in particular on (pre-)industrial scale, they need to be immobilised on filter substrates in thin layers and an efficient manner. In this work, we report bio-adsorbent-based filters prepared by coating TEMPO-CNF on viscose filters using two different pilot-scale coating approaches, foam and cast coating. The performance of TEMPO-CNF filters was evaluated in terms of their water permeance as well as adsorption of metal ions including Cu(II) and Ca(II). By foam coating thin layers could be fabricated in a time efficient way facilitating high adsorption capacities (52 mg g−1), whilst by cast coating higher amounts of TEMPO-CNF could be deposited allowing for adsorbing higher absolute amounts (280 mg m−2) of heavy metal ions. Graphical abstract

Utilization and value-adding of waste: Fabrication of porous material from chitosan for phosphate capture and energy storage

Efficient removal and recycling of phosphorus from complex water matrices using environmentally friendly and sustainable materials is essential yet challenging. To this end, a novel bio-based adsorbent (DX-FcA-CS) was developed by coupling oxidized dextran-crosslinked chitosan with ferrocene carboxylic acid (FcA). Detailed characterization revealed that the incorporation of FcA reduced the total pore area of DX-FcA-CS to 7.21 m2·g−1, one-third of ferrocene-free DX-CS (21.71 m2·g−1), while enhancing thermal stability and PO43− adsorption performance. Adsorption kinetics and isotherm studies demonstrated that the interaction between DX-FcA-CS and PO43− followed a pseudo-second-order kinetic model and Langmuir model, indicating chemical and monolayered adsorption mechanisms, respectively. Moreover, DX-FcA-CS exhibited excellent anti-interference properties against concentrated co-existing inorganic ions and humic acid, along with high recyclability. The maximum adsorption capacity reached 1285.35 mg·g−1 (∼428.45 mg P g−1), three times that of DX-CS and surpassing many other adsorbents. PO43−-loaded DX-FcA-CS could be further carbonized into electrode material due to its rich content of phosphorus and nitrogen, transforming waste into a valuable resource. These outstanding characteristics position DX-FcA-CS as a promising alternative for phosphate capture and recycling. Overall, this study presents a viable approach to designing environmentally friendly, recyclable, and cost-effective biomaterial for wastewater phosphate removal and value-added applications.

Techno-Economic analysis of an efficient anthocyanin extraction process from grape pomace using eutectic solvents ─ A critical panorama regarding drying techniques and reusability of solvents

A techno-economic analysis of a novel eutectic solvent-based platform useful to recover anthocyanins from grape pomace was performed. The study addressed the economic impact of conventional drying methods and explored the economic implications of purification strategies to separate the extract from the eutectic solvent. This was exemplified by employing solid-phase extraction (SPE) with C18-based adsorbent material. An alternative low-energy demanding approach using SiO2 particles was also assessed for profitability as a freeze-drying replacement strategy. The results highlighted challenges in the economic feasibility of eutectic solvent reusability when conventional SPE is applied, highlighting the need to obtain new and inexpensive bio-based adsorbents. Moreover, it was uncovered that the SiO2-based drying strategy presents itself as a financially viable alternative, effectively addressing the elevated energy requirements associated with conventional drying methods. The findings highlight the potential of alternative solvents-based processes, particularly towards challenges related to the circularity of raw materials.

Biomass derived porous carbon for efficient iodine adsorption from vapor and solution

The efficient adsorption and storage of radioactive iodine from uranium fission reactions is essential for safe nuclear energy. Bio-based adsorption materials have gained significant attention in the field of radioactive contaminants removal. This is primarily due to their numerous advantages, including a wide range of raw material sources, low cost, ease of preparation, low toxicity, high removal efficiency and stable storage. In this study, rape pollen was chosen as sources of biomass porous carbon, which possesses a micron-sized ellipsoidal shape, homogeneous size, porous structure with sparsely linked network inside, and high carbon content. A biomass derived porous carbon (K-RPC) was synthesized by pretreatment, heat treatment, and advanced treatment techniques. The results indicate that the K-RPC exhibited a hierarchical porous structure with homogeneous and wormhole-like micro- or nanopores, and high specific surface area. The K-RPC demonstrates exceptional iodine capture performance, the capacity surpasses that of most bio-based adsorbents. Remarkably, the maximum adsorption capacity of iodine vapor is approximately fifteen times higher than that of commercial silver exchanged zeolite. The adsorption mechanism, primarily characterized by chemisorption. This study is the first attempt to apply pollen in the field of iodine capture, and the biomass porous carbon extracted from rape pollen has the potential to be a cost-effective iodine adsorption material.

Sustainable Bio-Based Adsorbents for Simultaneous and Efficient Removal of Hazardous Dyes from Aqueous Solutions.

Dyes provide a notable environmental issue as a result of their intrinsic poisonous and carcinogenic characteristics. An estimated 60,000 metric tons of dyes has been discharged into the environment, leading to a substantial increase in water pollution. The mitigation of these dyes is a substantial and intricate challenge. The primary objective of this research is to conduct a comprehensive analysis of the adsorption of cationic dyes containing positively charged groups such as sulphonates, amines, and triphenylmethanes. The adsorption study was carried out using four different low-cost adsorbents derived from biowaste, specifically Groundnut Shell (GS), Mosambi Peel (MP), Mango Bark (MBARK), and Mango Leaves (ML). The adsorbent materials were characterized using FTIR, UV-Vis spectroscopy, scanning electron microscopy (SEM), point-of-zero charge (PZC), and BET techniques. The adsorption capacity was found to be between 1.5 and 2.2 mg/gm for Groundnut Shell, Mosambi Peel, Mango Bark, and Mango Leaves for individual dye removal (Crystal violet, Methylene blue, Rhodamine B, and Malachite green). It was observed that adsorbent derived from mango bark showed excellent adsorption (%) in a mono-component dye system and, thus, was explored for the simultaneous removal of a mixture of the same dyes. MBARK exhibited an excellent overall dye removal efficiency of 94.44% (Qe = 2.7 mg/g) for the dye mixture in 60 min. From a detailed kinetic investigation, it was concluded that the adsorption followed the pseudo-second-order model (R2= 0.99963 to 1 for different dyes and adsorbents) hinting at chemisorption. The effect of the pH of the analyte solution and the dosage of adsorbent was also studied for simultaneous removal. The isothermal studies demonstrated that the Langmuir adsorption model (R2 = 0.99416) was the best-fitted model, suggesting monolayer adsorption. The adsorption process was predicted to be governed by ion exchange, electrostatic interaction, hydrogen bonding, pi-pi interaction, etc., based on charge, functional groups, and pH of dyes and adsorbent. Thus, this study highlights the application of low-cost biowaste as a potential adsorbent for the mitigation of toxic industrial dyes present in wastewater.

Enzymatic crosslinking of lignin nanoparticles and nanocellulose in cryogels improves adsorption of pharmaceutical pollutants

Pharmaceuticals, designed for treating diseases, ironically endanger humans and aquatic ecosystems as pollutants. Adsorption-based wastewater treatment could address this problem, however, creating efficient adsorbents remains a challenge. Recent efforts have shifted towards sustainable bio-based adsorbents. Here, cryogels from lignin-containing cellulose nanofibrils (LCNF) and lignin nanoparticles (LNPs) were explored as pharmaceuticals adsorbents. An enzyme-based approach using laccase was used for crosslinking instead of fossil-based chemical modification. The impact of laccase treatment on LNPs alone produced surface-crosslinked water-insoluble LNPs with preserved morphology and a hemicellulose-rich, water-soluble LNP fraction. The water-insoluble LNPs displayed a significant increase in adsorption capacity, up to 140 % and 400 % for neutral and cationic drugs, respectively. The crosslinked cryogel prepared by one-pot incubation of LNPs, LCNF and laccase showed significantly higher adsorption capacities for various pharmaceuticals in a multi-component system than pure LCNF or unmodified cryogels. The crosslinking minimized the leaching of LNPs in water, signifying enhanced binding between LNPs and LCNF. In real wastewater, the laccase-modified cryogel displayed 8–44 % removal for cationic pharmaceuticals. Overall, laccase treatment facilitated the production of bio-based adsorbents by improving the deposition of LNPs to LCNF. Finally, this work introduces a sustainable approach for engineering adsorbents, while aligning with global sustainability goals.

Fabrication of a bio-based polymer adsorbent and its application for extraction and determination of glycosides from Huangqi Liuyi Decoction

Huangqi Liuyi Decoction, a famous classical Chinese prescription, shows significant curative effect on diabetes and its complications, in which calycosin-7-glucoside, liquiritin and glycyrrhizic acid are the main components that playing these mentioned pharmacological activity, under the synergistic action of various other ingredients in the decoction. However, there are significant differences in the content of active compounds in Chinese medicinal materials, which mainly due to origin, picking seasons, and processing methods. Hence, the accurate content of the glycosides is the prerequisite for ensuring the pharmacological efficacy. Aiming at establishing an efficient extraction and determination method for accurate quantitative analysis of calycosin-7-glucoside, liquiritin and glycyrrhizic acid in Huangqi Liuyi Decoction, an on line solid-phase extraction-high-performance liquid chromatography method was developed, using a homemade bio-based monolithic adsorbent. The bio-based adsorbent was prepared in a stainless steel tube, using bio-monomers of methyleugenol and S-allyl-L-cysteine, which effectively reduced the dependence of the polymer field on non-renewable fossil resources and reduced carbon emissions. Furthermore, the prepared adsorbent owned abundant chemical groups, which can produce interactions of hydrogen bond, dipole-dipole, π-π and hydrophobic force with the target glycosides, thus improving the specific recognition ability of the adsorbent. The experiments were carried out on an LC-3000 HPLC instrument with a six-way valve. Methodology validation indicates that the recovery is in the range of 97.0%-103.4% with the RSD in the range of 1.6%-4.0%, due to the specific selectivity of the bio-based monolithic adsorbent for these three glycosides, and good matrix-removal ability for Huangqi Liuyi decoction. The limit of detection is 0.17, 0.50 and 0.33μg/mL for calycosin-7-glucoside, liquiritin and glycyrrhizic acid, respectively, and the limit of quantitation is 0.50, 1.50 and 1.00μg/mL, respectively, with the linear range of 2-200μg/mL for calycosin-7-glucoside, and 5-500μg/mL for liquiritin and glycyrrhizic acid. The present work provided a simple and efficient method for the extraction and determination of glycosides in complex medicinal plants.

In situ synthesis of ZIF-8 on lignosulfonate functionalized polyethyleneimine/carboxymethyl chitosan hybrid aerogels for efficient tetracycline removal

The alarming overuse of antibiotics poses a serious threat to the environmental security. Herein, a hybrid aerogel adsorbent, sodium lignosulfonate functionalized polyethyleneimine/carboxymethyl chitosan@ZIF-8 (CCSL@ZIF-8), was fabricated by introducing sodium lignosulfonate into polyethyleneimine/carboxymethyl chitosan (CSSL) and then in situ uniformly anchoring of ZIF-8 on CSSL aerogel. The incorporation of sodium lignosulfonate not only enhanced the mechanical properties of CCSL, but also provided a large number of chelating sites for Zn2+ and promoted the formation of ZIF-8. The sorption behavior and mechanism were studied by batch adsorption experiments and characterization analysis. The experimental results demonstrated that the maximum adsorption capacity of CCSL-1.0@ZIF-8 was 231.36 mg/g with a tetracycline (TC) concentration of 200 mg/L at 303 K, which was 7 times higher than that of CCSL-1.0 (30.73 mg/g). The absorption process followed the pseudo-second-order kinetic model and Freundlich isothermal model, and the process of adsorbing TC was dominated by multilayer chemisorption. The adsorption mechanism included pore filling, coordination bonds, hydrogen bonding, electrostatic interactions and π-π interactions. Moreover, the removal efficiency of TC by CCSL-1.0@ZIF-8 was maintained above 78 % after 6 cycles. Overall, this work presents a potential bio-based adsorbent for the effective removal of tetracycline from wastewater and provides a novel, facile, and green chemical technique for high-value utilization of lignin. Furthermore, the prepared biomass-based hybrid adsorbent has outstanding reusability and water stability, which has broad practical application prospects in antibiotic wastewater treatment.

Biosorption of Hexavalent Chromium by Freshwater Microalgae Craticula subminuscula from Aqueous Solutions

Recently, microalgae have tended to be used as a biological treatment for wastewater decontamination. The present study aimed to investigate the Cr(VI) removal using the freshwater microalgae ‘Craticula subminuscula’ and their biobased adsorbant, isolated from a Moroccan river in the High Atlas Mountain. The optimum operational conditions for maximum Cr(VI) biosorption by the biobased adsorbent form (95.32%) were determined at (pH = 1.09, adsorbent dose = 10.91 mg L−1, and treatment duration = 129.47 min) using response surface methodology (RSM). Under those optimal conditions, the biosorption process of Cr(VI) by C. subminuscula is endothermic, spontaneous and follows Langmuir and a pseudo-second-order model with a constant rate; the theoretical and experimental biosorption capacity of 0.0004 g/mg/min was 289.01 mg g−1 and 277.57 mg g−1, respectively. Fourier Transform Infrared Spectroscopy (FTIR) analyses of the biomass and scanning electron microscopy (SEM) revealed that the principal mechanism to remove Cr(VI) by C. subminuscula was the affinity of Cr(VI) by the cell walls of microalgae. Thus, the positive results of desorption cycles promise increased potential utilization of these algae in continuous systems within industrial processes. The findings contribute valuable insights into the effectiveness of C. subminuscula as a biobased remediation agent for Cr(VI) in wastewater treatment.

Adsorptive removal of reactive yellow 145 dye from textile industry effluents using teff straw-activated carbon: RSM-based process optimization

Abstract The study was focused on preparing activated carbon from one of the predominant agro-wastes, teff straw (TS), through chemical activation and investigating the optimum process condition for removing the reactive yellow 145 dye (RY 145) from simulated textile effluent and chemical oxygen demand (COD) from textile industry effluent. The prepared activated carbon (TSAC) was characterized using Fourier transform infrared (FTIR), scanning electron microscopy (SEM), point of zero charge (pHpzc), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) surface area. Response surface methodology (RSM) was adopted to optimize the process variables. Optimum parameters for the removal of RY 145 dye were contact time, pH, adsorbent dose, and initial dye concentration of 120 min, 2, 0.4 g, and 0.3 g/L, respectively, and 97% removal efficiency was achieved. The experimental data that well-fitted with the pseudo-second-order kinetic model, while examining isotherms, was the Langmuir model. Furthermore, the TSAC reusability study confirmed that TSAC can be used multiple times in dye removal from wastewater. These results suggested that a low-cost and eco-friendly bio-based adsorbent, TSAC, could be a promising and reusable adsorbent that could be an alternative for commercial activated carbon to be applied in polluted wastewater treatment.

A magnetic bio-based adsorbent prepared from Fe3O4 nanoparticles impregnated with diatom frustules and sodium alginate for methylene blue uptake: advanced modeling and mechanism

ABSTRACT Herein, magnetic iron oxide nanoparticles (MNPs) were impregnated with diatom frustules (DF) and sodium alginate (SA) to fabricate a magnetic bio-based adsorbent for the removal of methylene blue (MB) dye. The developed MNPs@DF/SA was characterized by XRD, TGA, DSC, FTIR, FESEM-EDX, TEM, and zeta potential techniques. Methylene blue (MB) adsorption was theoretically assessed at solution pH 8.0, adsorbent mass (50 mg), shaking time (4 h), MB concentration (100–400 mg/L), and different temperatures of 25, 40, and 50°C. A multilayer statistical model was the best in fitting the MB adsorption experiments at all solution temperatures. The number of MB molecules at each functional group (the steric n parameter) was between 1.16–1.33, which suggesting vertical geometry and multi-molecular mechanism. The adsorption capacity at saturation (Q sat) increased from 647.42 to 779.45 mg/g with increasing temperature from 25 to 50°C signifying an endothermic adsorption system. Extending the adsorption energies from 31.90 to 37.47 kJ/mol indicated that the MNPs@DF/SA – MB interactions were controlled by physical forces as electrostatic interactions. The fabricated MNPs@DF/SA reserved more than 79% of MB capture after five regeneration cycles, which recommended the suitability of this adsorbent in the removal of MB at an industrial level.

Adsorption Removal of Azo Dye (Methylene Blue) From Wastewater Using Biomaterials with Kinetic Modeling

Industrial wastewater containing dyes poses a significant environmental threat due to their persistence and potential toxicity. Adsorption using bio-based materials offers a promising and sustainable approach for dye removal. This study investigates the effectiveness of bio-based adsorbents derived from coconut husk, banana peels, and orange peels (pretreated with formaldehyde and sulfuric acid) for methylene blue (MB) removal. The adsorbents were characterized using SEM and FTIR. Batch adsorption experiments were conducted to evaluate the MB removal efficiency under various conditions (pH, dosage, temperature, agitation, and contact time). The results showed that the Freundlich isotherm model best described the equilibrium adsorption data, indicating favorable multilayer adsorption. Kinetic studies revealed a pseudo-first-order reaction with an exceptional removal efficiency of 99.94%. Notably, the R-squared value of 0.99992 signifies an excellent fit of the model to the experimental data. These findings demonstrate the remarkable potential of bio-based materials for MB removal from wastewater. This approach offers an eco-friendly and cost-effective solution for dye remediation in the textile and dyeing industries, contributing to cleaner water resources.

Design of a novel green bio-based organic–inorganic hybrid material for cost-effective and sustainable monitoring of antibiotic residues

An economical bio-based adsorbent was prepared by loading HA on silicon substrate using abandoned PVA as a physical crosslinking material. The adsorbent can achieve sustainable and simultaneous detection of multiple trace MACs in complex matrices.