Bio-based Adsorbent Research Articles

Carboxymethyl cellulose/sugarcane bagasse/polydopamine adsorbents for efficient removal of Pb2+ ions from synthetic and undergraduate laboratory wastes

Low-cost eco-friendly adsorbents are important as sustainable alternatives for water treatment. Carboxymethyl cellulose (CMC), polydopamine (PDA) and sugarcane bagasse microparticles (BG) were combined to create new biobased adsorbents that can be molded into desirable shapes and sizes, facilitating their application as filters for the treatment of wastewater. Their efficiency was evaluated towards the removal of Pb2+ ions from synthetic solutions and from an undergraduate laboratory waste containing other 16 metal ions, a case study within a real-world context. The adsorption isotherms of Pb2+ ions on CMC/BG/PDA in the absence and in the presence of Ca2+ and Mg2+ ions fitted better to Langmuir models, yielding maximal adsorption capacity values of 27.4 ± 2.8 mg/g and 25.9 ± 1.8 mg/g, respectively. The ΔHads and ΔSads values of +5.7 kJ/mol and +48.3 J/(K.mol), respectively, indicated interactions between Pb2+ ions and CMC/BG/PDA hydroxyl groups, which were confirmed by XPS spectra. The fixed bed column adsorption studies indicated the highest adsorption capacity (qTh) for Pb2+ ions (20 mg/L) as 70.3 mg/g, which would correspond to the purification of 3.5 L of water by 1.0 g of adsorbent. In the presence of Mg2+ and Ca2+ ions, the qTh for Pb2+ ions (20 mg/L) decreased to 28.3 mg/g due to the competitive adsorption. In the column, CMC/BG/PDA removed 80% of Pb2+ ions from the undergraduate laboratory waste at pH 1.0. The simultaneous removal of the other 16 metal ions from the laboratory waste was larger than 50%. The subsequent flocculation with a polycation removed 98.7% of Pb2+ ions and 90% of other metal ions, disclosing the potential of combining biobased CMC/BG/PDA adsorbents adsorption and flocculation to treat complex wastewater from undergraduate laboratories.

CO2 capture from biogas by biomass-based adsorbents: A review

• Recent advances in biogas upgrading by biomass-based adsorbents are reviewed. • An overview of the production process through activation, and characteristics of adsorbent. • Recyclability and selectivity of biomass-based adsorbents for CO 2 capture have been studied. • Selection of appropriate chemical additives can be considerably enhanced the CO 2 adsorption capacities. Biogas is one of the most important renewable energy sources containing methane, carbon dioxide, and small amounts of other gases and water. Raw biogas cannot be used because CO 2 and other inert gases reduce the energy content of biogas and calorific value. Biogas upgrading significantly improves the quality of biogas by removing CO 2 . One of the leading technologies of biogas enrichment is using an adsorption method on activated carbons due to their high selectivity for removing CO 2 . Activated carbon is a good choice due to its high adsorption capacity at atmospheric pressure, lower cost, hydrophobic properties, high surface area, and the ability to modify pore structure and surface performance. On the other hand, the massive production of agricultural waste and biomass negatively affects the environment, so recycling biowaste into valuable materials is essential economically and environmentally. To recycle and convert biowaste, activated carbon is simply made through carbonization and can be used as suitable adsorbents for separating gaseous mixtures, including CH 4 /CO 2 . In this review, bio-based adsorbents were investigated in porosity, morphology, composition, selectivity, and CO 2 capture to upgrade biogas.

The application of wasteLeucaena leucocephalaseed pods as a bio-based adsorbent for decolourization of solution

AbstractThe adsorption method is widely used in water and wastewater treatment; however, most industrial adsorbents are expensive, limiting the use of the adsorption method in developing countries. Therefore, this study aims at developing a biosorbent from waste Leucaena leucocephala seed pods (LLSP) and apply it (as a cost-effective bio-adsorbent) to remove Janus Green B dye (JGBD) from solutions at different values of pH, agitation time, LLSP dose and JGBD concentration. Different techniques were used to characterize LLSP before and after JGBD removal, including pore size distribution, surface area (SBET) analysis, FTIR, SEM, SPM and the point of zero charges (pHpzc) of the LLSP surface. The results proved that LLSP could remove up to 95% of JGBD at pH, LLSP dose, JGBD concentration and agitation time of 9, 0.08 g/100 ml, 50 mg/l and 30 min, respectively. Langmuir and Freundlich analyses were applied to fit the data for equilibrium biosorption, and it was noticed that the Langmuir isotherm model fits the data, and the full monolayer biosorption ability for JGBD was 142.85 mg/g.

Adsorption of Methylene Blue Dye Using Raw and Carbonized Peanut Shell

The menace of the disposal of agricultural wastes and water contamination is on the increase. Thus, the need to find a way to recycle these agriculture wastes and make water safe for use. In this study, raw Peanut shell (PSH) and Carbonized Peanut Shell (CPSH) were used as biobased adsorbents in the decontamination of methylene blue (MB) dye from solution. The prepared materials were characterized by SEM, FTIR, XRD, and BET surface area analysis. The batch adsorption method was selected in the MB removal process to maintain adsorbent dosage and dye concentration. The surface area was increased from 1.03 to 34.96 m2/g. also the pore diameter reduced form macropore (93 nm) to micropores (2.39 nm) after carbonization. The CPSH has an adsorption capacity of 104 mgg-1 and about 90% removal of the 50 mg/L MB with 40 mins at a pH of 6.5. The pseudo-second-order kinetic model best suits the adsorption performance of the CPSH adsorbent. Also, the dye adsorption procedure onto the PSH corresponds to the Langmuir isotherm while the CPSH best fitted with the Freundlich isotherm. This study presents PSH as an alternative resource for the preparation of a cheap and efficient adsorbent from agricultural waste for the removal of laden dye.

Ecofriendly Removal of Aluminum and Cadmium Sulfate Pollution by Adsorption on Hexanoyl-Modified Chitosan

The purity and safety of water as a finite resource is highly important in order to meet current and future human needs. To address this issue, the usage of environmentally friendly and biodegradable adsorbers and flocculants is essential. Chitosan, as a biopolymer, features tremendous properties as an adsorber and flocculant for water treatment. For the application of chitosan as an adsorber under acidic aqueous conditions, such as acid mine drainage, chitosan has been modified with hydrophobic hexanoyl chloride (H-chitosan) to reduce the solubility at a lower pH. In order to investigate the influence of the substitution of the hexanoyl chloride on the adsorption properties of chitosan, two chitosans of different molecular weights and of three different functionalization degrees were analyzed for the adsorption of CdSO4(aq) and Al2(SO4)3(aq). Among biobased adsorbents, H-chitosan derived from the shorter Chitosan exhibited extraordinarily high maximum adsorption capacities of 1.74 mmol/g and 2.06 mmol/g for Cd2+ and sulfate, and 1.76 mmol/g and 2.60 mmol/g for Al3+ and sulfate, respectively.

Facile Synthesis of Sustainable Tannin/Sodium Alginate Composite Hydrogel Beads for Efficient Removal of Methylene Blue.

To meet the requirement of sustainable development, bio-based adsorbents were developed for the removal of dye contaminant. To improve the adsorption capacity of pure sodium alginate (SA) adsorbent for the removal of methylene blue (MB), aromatic bio-based tannin (Tan) was incorporated through the cross-linking with calcium ion. The obtained Tan/SA composite hydrogel beads were characterized with SEM, FTIR and TG, demonstrating that millimeter-sized beads were obtained through calcium cross-linking with enhanced thermal stability. The maximum capacity (247.2 mg/g) at optimal condition (pH = 12, T = 45 °C) was obtained for the 40%Tan/SA adsorbents, with a removal efficiency of 82.4%. This can be ascribed to the electrostatic attraction between SA and MB, as well as the formation of π–π stacking between Tan and MB. The adsorption process for MB is endothermic, and chemical adsorption, the removal efficiency was exceeded 90% after five cycles.

Biodiesel from high‐acid‐value grease trap waste: process optimization and purification using bio‐based adsorbent

AbstractMaterial with negative value such as grease trap waste appears to be a cost‐effective feedstock for biodiesel production since it can be collected at little to no charge. Owing to its high lipid content, fatty acid methyl ester can be produced from grease trap waste via a two‐step production process with methanol, using potassium hydroxide as the catalyst. However, there are several process parameters that could affect the yield of the fatty acid methyl ester produced. In this study, the optimum conditions for biodiesel production were 6:1 methanol‐to‐oil molar ratio, 1.5 wt% potassium hydroxide loadings, a 40 °C reaction temperature and a 2 h reaction time, resulting in a fatty acid methyl ester yield of 87%. Further purification using 0.05 g L−1 of biobased adsorbent from woodchip biomass for a 1 h residence time at 25 °C yielded the highest removal of free fatty acid and soap at 98.2 and 67.9%, respectively. This study not only demonstrates the potential of grease trap waste as a bioresource for the production of biodiesel, but also proves an interesting and additional use of bio‐based adsorbent from woodchip biomass as an effective tool in biodiesel purification since the quality of biodiesel produced within the standard EN14214. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.

Efficient Removal of Methylene Blue by Bio-Based Sodium Alginate/Lignin Composite Hydrogel Beads.

Dye pollution is a serious issue in current environment protection, and bio-based adsorbents have been receiving much attention in wastewater treatment, due to their low cost, renewable, and environmentally friendly characteristics. Bio-based sodium alginate/lignin composite (SA/Lig) hydrogel beads were fabricated by a facile cross-linking with calcium ion and used for the removal of methylene blue (MB). The obtained SA/Lig microbeads were characterized with SEM, FTIR, and TG, and the effect of lignin content, pH, and temperature on the MB adsorption was investigated. The results indicated that the introduction of aromatic lignin can not only enhance thermal stability but also can improve the adsorption performance. Under optimal conditions, the maximum adsorption capacity (254.3 mg/g) was obtained for the SA/Lig-20% beads, with a removal efficiency of 84.8%. The adsorption process for MB is endothermic, and the rate-limiting step is chemical adsorption. The removal efficiency is higher than 90% after five cycles, revealing that the prepared beads show good regeneration ability.

Limonene‐derived hollow polymer particles: Preparation and application for the removal of dyes and heavy metal ions

AbstractHerein, a unique kind of sustainable limonene‐derived hollow polymeric particles (LHPPs) were synthesized based on a widely available biomass monocyclic terpene limonene, which could act as efficient adsorption material to remove cationic dyes (methylene blue, MB) and heavy metal ions (Ni2+). Benefiting from the hollow structure/porous shell layer and abundant carboxylic groups, LHPPs exhibit outstanding sorption ability, quick sorption velocity, and excellent regeneration. The adsorption results of MB and Ni2+ onto LHPPs were analyzed by utilizing two most common models, and the adsorption isotherms were better simulated by Langmuir equation, showing maximum sorption capacities of 909 and 75.8 mg/g. Furthermore, the sorption processes were better described with pseudo‐second order equation. Besides, the LHPPs exhibit a remarkable pH‐sensitive adsorption property because of the existence of carboxylic groups. When the pH value changed from 2 to 10, the sorption capacity for MB increased sharply from 226 to 829 mg/g, and the sorption capacity for Ni2+ enhanced remarkably from 6 to 74.9 mg/g with pH value increased in the range of 2–6. Moreover, these biobased adsorbents show high reusability over five adsorption/desorption cycles, making LHPPs promising sustainable absorbents for practical application in water treatment.

Modified os sepiae of Sepiella inermis as a low cost, sustainable, bio-based adsorbent for the effective remediation of boron from aqueous solution

The occurrence of boron in low concentration is essential; however, a higher concentration of boron source in water has a toxic effect on humans as well as have retard effect on agricultural plant growth. Thus, the affordable and facile method to remediate water from higher boron concentrations is highly demanded. This report explores the ability of naturally occurring sustainable bio-waste os sepiae (cuttlefish bone, CFB) as an effective adsorbent for the removal of boron from water. Chemical activation of the os sepiae powder was examined to improve the efficiency of boron adsorption. A batch adsorption study for boron considering various parameters such as chemical modification of os sepiae, pH, initial boron concentration, and the temperature was scrutinized. Untreated (CFB), alkali-treated (CFB-D) and acid-treated (CFB-A) os sepiae powders were investigated and the adsorption capacities reached up to 53.8 ± 0.04 mg/g, 66.4 ± 0.02 mg/g and 69.8 ± 0.02 mg/g, respectively, at optimal pH 8 and 25 °C. Boron adsorption by CFB, CFB-D, and CFB-A were well fitted with the linear Freundlich adsorption isotherm model with a correlation coefficient of 99.4%, 99.8%, and 99.7% respectively. Thermodynamic parameters indicated that the adsorption of boron by CFB is an exothermic process and more feasible at a lower temperature around 25 °C. Moreover, detailed morphological and chemical characterization of the influence of adsorbed boron on adsorbents was conducted and discussed. The Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis spectra confirms the involvement of various functional groups including amino, carbonate (CO3)2−, and hydroxyl groups on the adsorbent in the adsorption mechanisms for boron removal. The results indicate that CFB can be an excellent example for the recycling and reuse of biowaste for water remediation.

Unary and binary adsorption of anionic dye and toxic metal from wastewater using 3-aminopropyltriethoxysilane functionalized porous cellulose acetate microspheres

Recent industrial development raised a great concern for human health and environmental protection due to the generation of toxic wastewater. The present study aims to prepare a new low-cost bio-based adsorbent for the effective simultaneous removal of anionic dye and toxic metal. Porous cellulose acetate (CA) microspheres were synthesized using a double emulsion (W/O/W)–solvents evaporation technique then modified using 3-aminopropyltriethoxysilane (APTES-CA). SEM, FTIR and XRD results emphasized the successful preparation of APTES-CA microspheres with average diameter size around 380–430 μm. Porosity analysis announced the mesoporous structure of the CA microspheres and the meso-microporous structure of APTES-CA microspheres. Also, EDX elemental analysis confirmed the presence of Si and N of APTES indicating the successful modification of CA surface. Further to this, the adsorption study showed that APTES modification improved the adsorption efficacy toward RB19 and Pb2+. Where, in unary solution, almost complete removal of 10 mg/L Pb2+ was achieved using 1.00 g/L of APTES-CA after 30 min at pHo 5. On the other hand, 91% of 20 mg/L RB19 preadjusted to pHo 2 can be removed by 1.00 g/L of APTES-CA after 90 min. The kinetic study indicated that APTES-CA adsorbs RB19 and Pb2+ via different mechanisms, specifically, chemisorption for RB19 and physisorption for Pb2+. The theoretical Langmuir monolayer saturation capacity (180 mg/g) manifested a good efficiency of APTES-CA towards Pb2+. In the binary solution, Pb2+ does not affect RB19 adsorption while RB19 retards Pb2+ adsorption.

Lignin-based electrospinning nanofibers for reversible iodine capture and potential applications

The capture of radioactive iodine has recently attracted much attention due to the release of radioactive iodine during nuclear waste disposal and disasters. Exploring highly efficient, sustainable, and eco-friendly materials for capturing radioactive iodine has great significance in developing safe nuclear energy. We reported highly efficient, natural, lignin-based, electrospun nanofibers (LNFs) for reversible radioiodine capture. Abundant iodine adsorption sites, such as functional groups and the interaction between the intermolecular forces exist in LNFs. The capacity of the LNFs for the saturated adsorption of iodine was found to be 220 mg·g−1, which is higher than that of the majority of bio-based adsorbents studied. Moreover, the LNFs exhibited an excellent recycling behavior, and their absorption capacity remained at 84.72% after 10 recycles. Therefore, the results imply that the lignin-based nanofibers can act as a natural, sustainable and eco-friendly packed material for the purification columns in industrial applications. The results demonstrate that the novel, nanostructured, natural biomass, as an ideal candidate has the potential for practical nuclear wastewater purification.

Eco-friendly ferrocene-functionalized chitosan aerogel for efficient dye degradation and phosphate adsorption from wastewater

Developing highly efficient, biodegradable and eco-friendly adsorbents to remove pollutants from wastewater has been a significant and long-term global challenge. Herein, a novel aerogel (Fc-CS) has been developed through the functionalization of glutaraldehyde-crosslinked chitosan with ferrocene groups. Methylene blue (MB) and eutrophication ions (PO43−) have been chosen as model pollutants to evaluate the adsorption efficiency of Fc-CS aerogel. The results demonstrated that Fc-CS aerogel possessed high specific surface area and good thermal stability. Freundlich model fitting revealed that both PO43− and MB were adsorbed in a multilayered fashion on the Fc-CS aerogel through complex adsorption mechanisms, and pseudo-second-order kinetic model fitting confirmed the involvement of chemical adsorption. Benefiting from the appending of ferrocene groups, Fc-CS aerogel not only showed excellent PO43− adsorption performance, but also provided a Fenton-like active center to catalyze dyes degradation. According to the Langmuir isothermal model, the maximum adsorption capacity for PO43− was approximately 1141 mg·g−1, exceeding those of most previously reported bio-based adsorbents. The addition of H2O2 significantly enhanced the MB removal efficiency of Fc-CS aerogel from 8.20% to 92.79% by triggering a Fenton-like reaction. After five cycles, no significant attenuation in removal efficiency was observed for either MB or PO43−, with or without H2O2. This eco-friendly and recyclable biomaterial could be an attractive candidate for removing MB and PO43− from aquatic systems. The present work provided a feasible pathway to design and develop highly efficient bio-aerogel for wastewater treatment and environmental remediation.

Synthesis and Characterization of Dual-ion-Crosslinked Magnetic Sodium Alginate-Based Fe-SA-Y@Fe3O4 Biogel Composite with Ultrastrong Performance for Azo Dye Removal

Magnetic sodium alginate(SA)-based biogel composite Fe-SA-Y@Fe3O4 macroparticles were synthesized by co-crosslinking of Y(III) and Fe(III) ions according to the optimized preparation conditions and characterized by various modern analytical techniques. The results show that the macrogel beads have unique cauliflower-shaped surface and sensitive magnetic response. Fe-SA-Y@Fe3O4 composite was used for the removal of Direct Red 13 (DR 13) and Direct Black 19 (DB 19) dyes from water. The adsorption capacities and removal efficiency can reach 2487 mg/g and 99.5% for DR-13 and 2992 mg/g and 99.7% for DB-19 respectively within the equilibrium time of 60 min at 298 K and pH 2.0, and decrease slightly with pH up to 10.0. The kinetic and equilibrium adsorption data followed the Pseudo-second-order rate model and Langmuir isothermal model well, respectively. Electrostatic adsorption, various H-bonding and complexation were largely involved in dye adsorption processes with spontaneous and exothermic character by macrogel beads, which were explained by thermodynamic studies, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR), respectively. Fe-SA-Y@Fe3O4 composite with ultrahigh adsorption capacity and fast magnetic separation property will be a promising eco-friendly bio-based adsorbent for the superefficient purification of practical azo-dye effluents.

One-step foam assisted synthesis of robust superhydrophobic lignin-based magnetic foams for highly efficient oil-water separation and rapid solar-driven heavy oil removal

Taking effective measures to remove oil and organic pollutants from water has become a top priority. In this study, we developed a novel superhydrophobic and magnetic lignin-based polyurethane foam for highly efficient adsorption of organic pollutants and removal of viscous crude oil from water. The superhydrophobic bio-based magnetic foam was prepared by the addition of Fe3O4 nanoparticles during the foaming process followed by the immersion in an octadecyltrimethoxysilane (OTMS) solution. After modification by OTMS, the water contact angle (WCA) of the foam adsorbent was increased by 37.1°, exhibiting a high WCA of 156°. Fe3O4 nanoparticles endowed the foam with excellent photo-thermal performance, allowing the efficient adsorption of both crude oil and a wide range of organic solvents. The foam adsorbent had a high adsorption capacity up to 18.8 times of its own weight. The bio-based adsorbent could still retain a high adsorption capacity after over ten cycles. The magnetic property facilitated control and recycling of the foam adsorbent by using a magnetic field. Moreover, the bio-based foam adsorbent was fully degraded in a methanol/sodium hydroxide solution (0.5 mol/L) at 60 °C after 8 h. The outstanding mechanical stability, reusability, and environmental friendliness make these bio-based foam adsorbent highly promising for cleaning up pollutions in water.

Degradable Ti3C2Tx MXene Nanosheets Containing a Lignin Polyurethane Photothermal Foam (LPUF) for Rapid Crude Oil Cleanup

As two-dimensional (2D) nanomaterials with high photothermal conversion performance, MXenes have great potential for applications in photothermal-assisted crude oil recovery. In this study, MXene nanosheets modified a lignin-based polyurethane foam obtained with solar-to-heat conversion properties for heavy oil recovery. The adsorbent achieved a high solar absorption rate (>95%), and its surface maximum temperature reached up to 83.5 °C owing to the great solar-to-heat effect of MXenes. Due to the superb dispersibility of MXenes in polyol, the resulting bio-based foam adsorbent had a high thermal conductivity. Moreover, with the increase of temperature, the viscosity of the heavy crude oil decreases, which enables the adsorbent to adsorb more than seven times (7.6 ± 0.2 g/g) its weight of crude oil under 1 sun illumination (1.00 kW/m2) in 4 min. In addition, Ti3C2Tx MXene nanosheets containing lignin-based adsorbents readily degraded in alkaline solutions (degradation efficiency > 93%, in a methanol/0.5 mol/L NaOH aqueous solution mixture (1:1, v/v) for 8 h at 60 °C). The molecular dynamics simulation revealed that lignin had lower interaction energy with the solvent solutions when methanol was present, allowing the lignin molecules to unfold and make more contact with the solvent molecules. As a result, the β-O-4 bond of lignin is more likely to be exposed to accelerate the degradation process. The solid residues of degradation were only titanium dioxide (TiO2) nanoparticles, which were harmless to the environment. With their excellent rapid heavy oil removal performance, degradability, and environmental friendliness, these bio-based adsorbents pinpoint a promising solution to clean up high-viscous crude oil spills.

Tailoring a bio-based adsorbent for sequestration of late transition and rare earth elements.

The demand for new renewable energy sources, improved energy storage and exhaust-free transportation requires the use of large quantities of rare earth (REE) and late transition (LTM, group 8-12) elements. In order to achieve sustainability in their use, an efficient green recycling technology is required. Here, an approach, a synthetic route and an evaluation of the designed bio-based material are reported. Cotton-derived nano cellulose particles were functionalized with a polyamino ligand, tris(2-aminoethyl) amine (TAEA), achieving ligand content of up to ca. 0.8 mmol g-1. The morphology and structure of the produced adsorbent were revealed by PXRD, SEM-EDS, AFM and FTIR techniques. The adsorption capacity and kinetics of REE and LTM were investigated by conductometric photometric titrations, revealing quick uptake, high adsorption capacity and pronounced selectivity for LTM compared to REE. Molecular insights into the mode of action of the adsorbent were obtained via the investigation of the molecular structure of the Ni(II)-TAEA complex by an X-ray single crystal study. The bio-based adsorbent nanomaterial demonstrated in this work opens up a perspective for tailoring specific adsorbents in the sequestration of REE and LTM for their sustainable recycling.

Hydrothermal Carbonization of Residual Algal Biomass for Production of Hydrochar as a Biobased Metal Adsorbent

Conversion of residual algal biomass to value-added products is essential for enhancing the economics of algae cultivation. Algal hydrochar produced via hydrothermal carbonization of lipid-extracted Picochlorum oculatum is a material rich in oxygen functional groups and carbon (up to 67.3%) and hence a promising candidate for remediation of wastewaters. The hydrothermal carbonization conditions were optimized and the adsorption capacity of the hydrochar was tested for metal removal. By the end of the remediation process, cumulative removal of Al3+, Cu2+, Fe2+, Mg2+, Mn2+, and Pb2+ reached 89, 98, 75, 88, 75, and 100%, respectively. The adsorption of all metals was found to follow pseudo second-order kinetics and the Langmuir isotherm. Overall, when hydrothermal carbonization is applied to lipid-extracted algae, it generates a promising biobased adsorbent with value-added potential in metal remediation.

Study on the adsorption properties of multiple-generation hyperbranched collagen fibers towards isolan-series acid dyes.

In the present study, collagen fibers derived from leather solid wastes were used and modified as insoluble vectors and successfully employed as adsorbents for the removal of acid dyes. A “one-step” method was applied to synthesis effective adsorbents, which provided a sustainable way to reuse leather solid wastes via multifunctional modification. The adsorption properties of amino-terminated hyperbranched polymer (HBPN)-modified collagen fibers for the removal of different kinds of acid dyestuff from aqueous solutions were studied. The adsorption capacities of the second generation of modified collagen fibers (CF-HBPN-II) toward Isolan Black 2S-LD, Supralan Yellow, Isolan Grey K-PBL 02, Isolan Dark Blue 2S-GL 03, and Isolan Brown NHF-S were determined to be 224.87, 340.14, 287.36, 317.80, and 251.25 mg g−1, respectively. Three kinetic models, namely, pseudo-first-order, pseudo-second-order and intraparticle diffusion, were used to analyze the kinetic data. The fitting result indicated that the adsorption process of Isolan Black 2S-LD on CF-HBPN-II followed a pseudo-second-order rate model. The adsorption equilibrium of amino-terminated hyperbranched polymer-modified collagen fibers (CF-HBPN) was analyzed using the Langmuir, Freundlich and Temkin isotherm models. The Langmuir isotherm was suitable to describe the adsorption process of Isolan Black 2S-LD. RL was observed to be in the range of 0–1. The values of ΔH, ΔS and ΔG suggest that adsorption is an endothermic and spontaneous process. The adsorbed dye from the modified collagen fiber was successfully desorbed by 0.1 M NaOH. This research provides theoretical guidance for the engineering and recycling application of bio-based adsorbents.

Mitigating Water Pollution Using a Sustainable Biobased Low-Cost Adsorbent Derived From Mustard Straw

The present work is focussed on treating dye-laden polluted water by using a mustard straw-based activated carbon prepared using ZnCl2 and H3PO4 activation methods. The activation conditions based on the parameters reported in the literature are taken as follows: 700 °C activation temperature, impregnation ratio 2.0, and heating time 2 h. The textural and surface properties of mustard stalk activated carbon (MSAC) were studied by using SEM, nitrogen adsorption, and FT-IR, whereas its adsorption capacity was obtained using the methylene blue (MB) adsorption method. Activation of ZnCl2 and H3PO4 resulted in a BET surface area of 402 and 496 m2/g, respectively. The average pore diameter of the MSAC was found to be 2.13 and 2.59 nm for ZnCl2 and H3PO4 activation respectively. The Langmuir and Freundlich models were applied to evaluate the equilibrium parameters of MB adsorption. The monolayer adsorption capacity of MSAC by ZnCl2 and H3PO4 for MB removal from the Langmuir model were 122.25 and 213.21 mg/g respectively. Activation with H3PO4 was found to be more effective in modifying the structure of the mustard straw when compared with ZnCl2 and also it resulted in a higher adsorption capacity of MB. The present work highlights that the MSAC produced using H3PO4 activation is a low-cost bio-based adsorbent using abundant agricultural by-product namely mustard straw, and this adsorbent can be used in numerous industrially important applications.