Activated carbon derived from sugarcane and modified with natural zeolite for efficient adsorption of methylene blue dye: experimentally and theoretically approaches

Fabrication of 3D Graphene-Silk Elastic Aerogels for Sustainable and Efficient Removal of Organic Dyes from an Aqueous Medium

Water pollution by dyes is a serious environmental issue of modern society that needs to be addressed effectively. Herein, a promising adsorbent, i.e., 3D composite aerogel, was developed by using reduced graphene oxide and silk fibroin (rGO-SF) via hydrothermal and freeze-drying techniques. The efficiency of the prepared aerogel toward methylene blue (MB) dye adsorption was explored in batch adsorption experiments. A study revealed the adsorption capacity of rGO-SF120 as 249.89 mg/g toward methylene blue (MB) dye. The aerogel also selectively adsorbs MB over other dyes, such as rhodamine B (RhB) and methylene orange (MO). The adsorption process was mainly chemical (as data fitted well to both pseudo-second-order and Elovich kinetic models) and followed the Langmuir model, indicating that it formed a single layer of dye on its surface. Overall, the rGO-SF120 aerogel is an effective and potential candidate for treating dye-loaded water with high efficiency.

Preparation of Alumina Oxo-Cluster/Cellulose Polymers and Dye Adsorption Application

Aluminum oxide clusters (AlOCs) possess high surface areas and customizable pore structures, making them applicable in the field of environmental remediation. However, their practical use is hindered by stability issues, aggregation tendencies, and recycling challenges. This study presents an in -situ synthesis of AlOCs on cellulose using a solvent thermal method. The resulting adsorbent's structural and property profiles were thoroughly characterized using multiple analytical techniques. Batch adsorption experiments were performed to assess the adsorbent's capacity and kinetics in removing selected dyes from aqueous solutions. Additionally, both real-environment simulation and regeneration experiments have been conducted to thoroughly assess the adsorbent's reliability, stability, and practical applicability. The aim was to engineer an effective and recyclable adsorbent specifically tailored for dye-contaminated wastewater treatment.

Selective adsorption of cationic dye by κ-carrageenan-potato starch bio-hydrogel: Kinetics, isotherm, and thermodynamic studies

An eco-friendly κ-carrageenan/potato starch bio-hydrogel is designed for the efficient removal of methylene blue (MB) dye from water. The incorporation of potato starch was successfully confirmed through XRD, FT-IR, and SEM analysis, while TGA highlighted the hydrogel's thermal stability. Batch adsorption experiments demonstrated excellent MB removal efficiency, with a maximum adsorption capacity of 116.1 mg/g under optimal conditions (initial dye concentration: 100 mg/L, contact time: 180 min, temperature: 20 °C, adsorbent dosage: 1.6 g/L, and pH: 11). FT-IR analysis indicated that electrostatic interactions and hydrogen bonding primarily govern the adsorption process. The adsorption followed pseudo-second-order kinetics and fitted well with the Langmuir isotherm model. Thermodynamic studies revealed that the adsorption was exothermic and spontaneous. A key feature of this bio hydrogel is its selective affinity for the cationic dye MB, in a mixture with Acid Orange (AO) and other cationic dyes (Rhodamine B (Rh B) and crystal violet (CV)). The adsorbent also demonstrated impressive reusability, maintaining 93 % of its efficiency after five cycles, highlighting its potential for sustainable and cost-effective water treatment.

Cellulose Acetate Supported MOF-5/Crystalline Nanocellulose Composite Film as an Adsorbent Material for Methylene Blue Removal from Aqueous Solutions

In this study, a novel, low-cost, and efficient adsorbent film was fabricated by a solvothermal method. The adsorbent film was developed to be hydrolytically stable, not vulnerable to aggregation in aqueous environments, and not prone to secondary contamination. The adsorbent consists of cellulose acetate (CA) as a support embedded with a MOF-5/crystalline nanocellulose (CNC) composite material. The CA-supported MOF-5/CNC film was characterized using a variety of techniques, including X-ray diffraction, thermal gravimetric analysis, scanning electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy, which revealed hydroxyl and carbonyl functional groups on the adsorbent film. The film was evaluated for the adsorptive removal of methylene blue (MB) from an aqueous solution. Adsorption was characterized by a rapid increase in MB adsorption during the first hour with equilibrium achieved within 4-5 h into the adsorption process. The maximum adsorption capacity was determined to be 4.29 mg/g and the maximum dye removal efficiency was 77%. The MB adsorption process best fitted the Freundlich isotherm and pseudo-second-order kinetic models. Thermodynamic studies showed that the adsorption was exothermic and feasible. The adsorbent film showed admirable regeneration ability, demonstrating its cost-effectiveness and its potential as a promising material for wastewater treatment.

Synergistic adsorption of methylene blue using ternary composite of phosphoric acid geopolymer, calcium alginate, and sodium lauryl sulfate

The removal of dyes from the aquatic ecosystem is necessary being a major threat to life. For enhanced remediation of methylene blue (MB) dye, a new ternary biopolymer-geopolymer-surfactant composite adsorbent is synthesized by combining phosphoric acid geopolymer (PAGP), calcium alginate (Alg), and sodium lauryl sulfate (SLS). During the synthesis of the composites, PAGP and SLS were mixed with the alginate matrix, producing porous hybrid beads. The PAGP-SLS-alginate (PSA) beads prepared were characterized using different analytical tools, i.e., scanning electron microscopy (SEM), Fourier transform infrared spectrophotometry (FTIR), X-ray diffractometry (XRD), surface area and porosimetery (SAP), and thermogravimetric analysis (TGA). To ascertain the ideal conditions for the adsorption process, a batch reactor procedure was used to investigate the effects of several parameters on MB adsorption, including pH (2, 4, 6, 8, 10), PSA adsorbent dosage (0.06-0.12 g), MB concentration (50-500 mg/L), contact time (15 to 300 min), and temperature (25, 35, and 45 °C). The SEM investigation indicated that ~ 1860 μm-sized PSA beads with 6-8 μm voids are generated. Based on XRD, FTIR, and SAP examinations, the material is amorphous, having numerous functional groups and an average pore size of 6.42 nm. Variation of pH has a little effect on the adsorption process, and the pH of 7.44 was found to be the pHpzc of the PSA beads. According to the findings of the batch study, equilibrium adsorption was obtained in 270-300 min, showing that the adsorption process was moderately slow-moving and effective. The dye adsorption linearly increased with initial dye concentration over concentration range of 50-500 mg/L and reciprocally decreased with rise in temperature. 0.06 g adsorbent dose, 25 °C, pH10, and 270 min were found to be the better conditions for adsorption experiments. Langmuir isotherm fitted well compared to Freundlich, Temkin, and Dubinin-Radushkevich (DR) isotherm models on the experimental data, and the maximum adsorption capacity(qmax) calculated was 1666.6 mg. g-1. Pseudo-second-order (PSO) kinetics model and multi steps (two) intra particle diffusion (IPD) model fitted well on the adsorption kinetics data. The system's entropy, Gibbs free energy, and change in enthalpy were measured and found to be -109.171 J. mol-1. K-1, - 8.198 to - 6.014 kJ. mol-1, and - 40.747 kJ. mol-1. Thermodynamics study revealed that adsorption process is exothermic, energetically favorable and resulting in the decrease in randomness. Chemisorption is found to be the dominant mechanism as confirmed by pH effect, Langmuir isotherm, PSO kinetics, IPD model, and thermodynamics parameters. PSA beads were successfully regenerated using ethanol in a course of 120 min and re-used for five times. To sum up, the PSA adsorbent's impressive adsorption capability of 1666.66 mg/g highlights its potential as a successful solution for methylene blue removal. The results of this study add to the expanding corpus of information on sophisticated adsorption materials and demonstrate PSA's potential for real-world uses in wastewater treatment and environmental clean-up.

Advancements in Olive-derived Carbon: Preparation Methods and Sustainable Applications

In the realm of material science, carbon materials, especially olive-derived carbon (ODC), have become vital due to their sustainability and diverse properties. This review examines the sustainable extraction and use of ODC, a carbohydrate-rich by-product of olive biomass. We focus on innovative preparation techniques like pyrolysis, which are crucial forenhancing ODC's microstructure and surface properties. Variables such as activating agents, impregnation ratios, and pyrolysis conditions significantly influence these properties. ODC's high specific surface area renders it invaluable for applications in energy storage (batteries and supercapacitors) and environmental sectors (water purification, hydrogen storage). Its versatility and accessibility underscore its potential for broad industrial use, makingit as a key element in sustainable development. This review provides a detailed analysis of ODC preparation methodologies, its various applications, and its role in advancing sustainable energy solutions. We highlight the novelty of ODC research and its impact on future studies, establishing this review as a crucial resource for researchers and practitioners in sustainable carbon materials. As global focus shifts towards eco-friendly solutions, ODC emerges as a critical component in shaping a sustainable, innovation-driven future.

Bioinspired High-Magnesium Calcite for Efficiently Reducing Chemical Oxygen Demand in Lake Water

Organic matter accumulation in water can cause serious problems such as oxygen depletion and quality deterioration of waters. While calcium carbonate has been used as green and low-cost adsorbent for water treatment, its efficiency in reducing the chemical oxygen demand (COD) of water, which is a measure of organic pollution, is restrained by the limited specific surface area and chemical activity. Herein, inspired by the high-magnesium calcite (HMC) found in biological materials, a feasible method to synthesize fluffy dumbbell-like HMC with large specific surface area is reported. The magnesium inserting increases the chemical activity of the HMC moderately but without lowering its stability too much. Therefore, the crystalline HMC can retain its phase and morphology in aqueous environment for hours, which allows the establishment of adsorption equilibrium between the solution and the adsorbent that retains its initial large specific surface area and improved chemical activity. Consequently, the HMC exhibits notably enhanced capability in reducing the COD of lake water polluted by organics. This work provides a synergistic strategy to rationally design high-performance adsorbents by simultaneously optimizing the surface area and steering the chemical activity.

Removal of direct dyes from wastewater using chitosan and polyacrylamide blends

This study investigated the feasibility of employing neat chitosan powder, polyacrylamide, and chitosan micro-beads as adsorbents for the rapid and efficient removal of Direct Blue 78 dye from textile industrial wastewater. A series of batch experiments were conducted to examine the impact of adsorbent dose, contact time, and pH on the adsorption process. The physicochemical analysis, including FTIR, zeta potential analysis, and SEM were performed to identify the adsorption mechanism of chitosan powder and micro-beads. It was found that increasing the powder chitosan dose to 4.5 g/L and contact time up to 40 min resulted in achieving a significant increase in dye removal efficiency up to 94%. The highest removal efficiency of 94.2% was achieved at an initial dye concentration of 50 mg/L, a chitosan dosage of 4.5 g/L, and an optimized contact time of 60 min. Utilizing a polyacrylamide gel dose of 45 mL/L reduced the sedimentation time of chitosan from 8 h to 5 min. Equilibrium studies showed an initial L-shaped equilibrium curve, indicating that the adsorption process primarily arises from electrostatic interactions between dye molecules and adsorbent particles (physical forces). The Langmuir isothermal model demonstrated the best fit to the equilibrium data. Combining chitosan powder with polyacrylamide gel emerges as an economically viable choice for dye removal in industrial wastewater effluents, offering a cost-effective alternative to pricey commercial adsorbents. The results of the study revealed that the presence of polyacrylamide dye enhanced the removal efficiency and settling time of DB78 dye using chitosan.

Synthesis and Characterization of Zeolite NaY Dispersed on Bamboo Wood

Zeolites in powder form have the potential to agglomerate, lowering access to active sites. Furthermore, a suspension of fine zeolite powder in liquid media is difficult to separate. Such drawbacks could be improved by dispersing zeolite crystals on support materials. This work demonstrates the dispersion of zeolite NaY crystals on bamboo wood by mixing the wood with zeolite gel before hydrothermal treatment. The syntheses were performed with acid-refluxed and non-refluxed wood. The phase of zeolites, particle distribution and morphology, zeolite content in the wood, and zeolite-wood interaction were investigated using X-ray diffraction, X-ray tomography, scanning electron microscopy, thermogravimetric analysis, nitrogen sorption analysis, and X-ray photoelectron spectroscopy. Higher zeolite content and better particle dispersion were obtained in the synthesis with the acid-refluxed wood. The composite of NaY on the acid-refluxed wood was demonstrated to be an effective adsorbent for Ni(II) ions in aqueous solutions, providing a higher adsorbed amount of Ni(II) per weight of NaY.

Comprehensive evaluation of zeolite/marine alga nanocomposite in the removal of waste dye from industrial wastewater

A systematic study integrating laboratory, analytical, and case study field trial was conducted to figure out the effective adsorbent that could be used for the removal of Congo red (CR) dye from industrial wastewater effluent. The ability of the zeolite (Z) to adsorb CR dye from aqueous solutions was evaluated after it was modified by the Cystoseira compressa algae (CC) (Egyptian marine algae). Zeolite, CC algae were combined together in order to form the new composite zeolite/algae composite (ZCC) using wet impregnation technique and then characterized by the aid of different techniques. A noticeable enhancement in the adsorption capacity of newly synthesized ZCC was observed if compared to Z and CC, particularly at low CR concentrations. The batch style experiment was selected to figure out the impact of various experimental conditions on the adsorption behavior of different adsorbents. Moreover, isotherms and kinetics were estimated. According to the experimental results, the newly synthesized ZCC composite might be applied optimistically as an adsorbent for eliminating anionic dye molecules from industrial wastewater at low dye concentration. The dye adsorption on Z and ZCC followed the Langmuir isotherm, while that of CC followed the Freundlich isotherm. The dye adsorption kinetics on ZCC, CC, and Z were agreed with Elovich, intra-particle, and pseudo-second-order kinetic models, correspondingly. Adsorption mechanisms were also assessed using Weber's intraparticle diffusion model. Finally, field tests showed that the newly synthesized sorbent has a 98.5% efficient in eliminating dyes from industrial wastewater, authorizing the foundation for a recent eco-friendly adsorbent that facilitate industrial wastewater reuse.

Removal of anthraquinone dye from wastewaters by hybrid modified activated carbons

Dyes are among the main environmental pollutants, due to the high amount of discharge of wastewater, lost in the dyeing process, without any further treatment. Anthraquinone dyes are stable and resistant in the aquatic system. Among the methods that have been applied to remove these dyes from wastewaters, adsorption on activated carbon has been reported as a very effective technique, and its modification with oxides and hydroxides of metals have been used to increase its surface area. In the present study, the production of activated carbon was originated by coconut shells, and a mixture of metals and metalloids, such as magnesium, silicate, lanthanum, and aluminum (AC-Mg-Si-La-Al), was used for its subsequent modification and applied to Remazol Brilliant Blue R (RBBR) removal. AC-Mg-Si-La-Al surface morphology was studied by BET, FTIR, and SEM methods. For the evaluation of AC-Mg-Si-La-Al, several parameters, such as dosage, pH, contact time, and initial RBBR concentration were studied. According to the results, in pH 5.0 ± 0.1, the dye percentage rate reached 100% by applying 0.5 g/L. Therefore, the optimal dose of 0.4 g/L and pH 5.0 ± 0.1 are selected, which leads to 99% removal of RBBR. The experimental data found to better fit to Freundlich isotherm (R² = 0.9189) and pseudo-second-order kinetic (R² = 0.9291) models and 4 h were the sufficient time for adsorption. According to thermodynamics, a positive value of ∆H⁰ (19.661 kJ/mol) suggests the endothermic nature of the process. The AC-Mg-Si-La-Al adsorbent was able to regenerate after 5 cycles of use, showing only a 17% decrease in its efficiency. Because of its effectiveness in full RBBR removal, AC-Mg-Si-La-Al could be further examined for the removal of several other dyes, even anionic or cationic.

Solvatochromism as a Novel Tool to Enumerate the Optical and Luminescence Properties of Plastic Waste Derived Carbon Nanodots and Their Activated Counterparts

Herein, we have developed a one-pot methodology to synthesise three types of C-dots and their activated counterparts from three different types of waste plastic precursors such as poly-bags, cups and bottles. The optical studies have shown the significant change in the absorption edge in case of C-dots in comparison to their activated counterparts. The respective variation in the sizes is correlated with the change in electronic band gap values of formed particles. The changes in the luminescence behaviour are also correlated with transitions from the edge of the core of formed particles. The obtained variations in the Stokes shift values of C-dots, and their ACs were used to explore the types of surface states and their related transitions in particles. The mode of interaction between C-dots and their ACs was also determined using solvent-dependent fluorescence spectroscopy. This detailed investigation could provide significant insight on the emission behaviour and the potential usage of formed particles as an effective fluorescent probe in sensing applications.

An Investigation of a Natural Biosorbent for Removing Methylene Blue Dye from Aqueous Solution

T he current study reports the use of zeolite prepared from a kaolin composite via physical mixing with different ratios from fiber of palm tree (Zeo-FPT) as a sustainable solid sorbent for the removal of methylene blue (MB) dye from aqueous solutions. The prepared biosorbent was fully characterized using XRD, TGA, SEM, and FTIR. The impacts of various analytical parameters, for example, contact time, dosage, MB dye concentration, and the pH of the solution, on the dye adsorption process were determined. After a contact time of 40 min, the capacity to remove MB dye was 0.438 mg g−1 at a Zeo-FPT composition ratio of 1F:1Z. At pH 8, Zeo-FPT (1F:1Z) had a removal efficiency of 87% at a sorbent dosage of 0.5 g for a concentration of MB dye in an aqueous phase of 10 mg L−1. The experimental data were also analyzed using the kinetic and adsorption isotherm models. The retention process fitted well with the pseudo-second-order model (R2 0.998), where the Qe,calc of 0.353 mg g−1 was in acceptable agreement with the Qe,exp of 0.438 mg g−1. The data also fitted well with the Freundlich isotherm model, as indicated by the correlation coefficient value (R2 0.969). The Zeo-FPT attained a high percentage (99%) in the removal of MB dye from environmental water samples (tap water, bottled water, and well water). Thus, it can be concluded that the proposed zeolite composite with fiber of palm tree (Zeo-FPT) is a suitable, environmentally friendly, and low-cost adsorbent for removing dyes from wastewater.