Fast decolorization of cationic dyes by nano-scale zero valent iron immobilized in sycamore tree seed pod fibers: kinetics and modelling study

Methylene blue removal using nano-TiO2/MWCNT/Chitosan hydrogel composite beads in aqueous medium

Dyestuff, one of the most hazardous compounds in terms of threats to people and the environment, is found in wastewater from industrial usage. The removal of Methylene Blue (MB) from a water-based medium has been studied by numerous researchers using a variety of adsorbents. To remove MB from aqueous solution, nano-TiO2/MWCNT/Chitosan hydrogel composite beads (n-TiO2/MWCNT/Cht) were developed in this study using a sol-gel method. This research discusses the characterisation of a new adsorbent substance using Infrared Spectroscopy (FT-IR) analysis and scanning electron microscopy (SEM). The optimal pH, adsorbent dosage, duration, and starting concentration were ascertained by analyzing the removal efficiencies of MB using the batch adsorption method. Adsorption behaviour at the equilibrium state has been investigated using a variety of adsorption isotherms, including Freundlich, Langmuir, and Dubinin-Radushkevich. The Langmuir adsorption isotherm has been useful to clarify adsorption behaviors. nTiO2-Cht/MWCNT had an adsorption capacity of 80.65 mg/g for MB. The pseudo-second-order kinetic model offered the best agreement to the experimental data for the adsorption of MB. Kinetic models of pseudo-first-order and pseudo-second-order were employed to explore the adsorption processes of MB on the n-TiO2/MWCNT/Cht. This study demonstrated the efficiency of n-TiO2/MWCNT/Cht for the removal of MB from a water-based solution.

Chitosan coated biomass waste-based magnetic hydrogel beads for the removal of methylene blue

Due to developing technology and increasing population, human needs have increased, and textile activities have gained momentum. Many synthetic dyestuffs are used to meet the needs in this field. In this study, a cheap, useful, innovative, environmentally friendly and sustainable adsorbent was developed for the removal of Methylene Blue(MB), which is one of the dyes that is harmful to the environment. In the cultivation of fruit trees, in addition to the product, very high amounts of by-products/waste (garbage, branches, bark, leaves, etc.) are produced. In this direction, fig tree wastes were immobilized with chitosan, made magnetic, and MB adsorption on the developed adsorbent was examined in a batch system. Glutaraldehyde was used as crosslinker. Characterization of synthesized glutaraldehyde cross-linked chitosan-coated magnetic vegetable waste composite beads (g-CMBW) was carried out by SEM, EDX, FTIR and XRD. In the study, the effects of temperature (25-55 °C), pH (3.0-8.0), initial MB concentration (10-250mg/L), contact time (5-360min) and the amount of adsorbent (2-10 g/L) on MB adsorption with g-CMBW were examined. The optimum conditions obtained were determined as pH 6.0, temperature 25 °C, adsorbent amount 6 g/L, and contact time 120 min. The maximum adsorption capacity in MB removal using g-CMBW composite beads was calculated as 103.1 mg/g according to the Langmuir isotherm model. The temperature studies showed that the adsorption capacity decreased with increasing temperature, showing that the system was exothermic. In light of these results, it was determined that there are new promising adsorbents of natural origin, with higher adsorption capacity, lower cost, and alternatives to commercially used adsorbents in the removal of MB from aqueous media.

Extraction of Lightweight Platanus orientalis L. Fruit's Stem Fiber and Determination of Its Mechanical and Physico-Chemical Properties and Potential of Its Use in Composites

Natural fibers extracted from plants are preferred as an alternative to synthetic products. The main reasons for this preference are their affordable cost, light weight and good mechanical properties. However, finding new natural raw materials is challenging due to growth limitations in different geographical areas. Platanus orientalis L. (Eastern plane tree) is a tree with abundant fruits that can grow in many regions of the world. The aim of this study was to determine the mechanical (tensile strength, tensile modulus, elongation), physical (density, fiber diameter) and chemical (cellulose, hemicellulose and lignin) properties of Platanus orientalis L. fruit's stem by fiber extraction from the stems of the tree. It was determined that the extracted fiber had good mechanical properties and cellulose content of 42.03%. As a result of thermogravimetric analysis, it was determined that the plane tree fruit's stem fiber had thermal resistance of up to 299 °C. The tensile strength value was 157.76 MPa, the tensile modulus value was 1.39 GPa and the elongation value was 22.01%. It was determined that it is suitable for use in fiber reinforcement in thermoplastic-based composites at temperatures below 299 °C. According to the results obtained by the mechanical, chemical and physical analysis of Platanus orientalis L. fruit's stem fiber (PoLfs), it could be recommended as a suitable alternative as a reinforcing fiber in thermoplastic and thermoset composites.

Removal of water pollutants using plant-based nanoscale zero-valent iron: A review

Nanotechnology has been increasingly explored for the treatment of various waste streams. Among different nanoparticles, nanoscale zerovalent iron (nZVI) has been extensively investigated due to its high reactivity and strong reducing power. However, conventional methods for the synthesis of nZVI particles have several limitations and led to the green synthesis of nZVI using plant-based materials. Plant extracts contain various reducing agents that can be used for nZVI synthesis, eliminating the need for toxic chemicals, and reducing energy consumption. Additionally, each plant species used for nZVI synthesis results in unique physicochemical properties of the nanoparticles. This review paper provides an overview of plant-based nZVI particle synthesis, its characteristics, and its application for the removal of different classes of pollutants such as dyes, heavy metals, nutrients, and trace organic pollutants from water. The review shows that continued research on plant-based nZVI particles to fully understand its potential in wastewater treatment, especially for the removal of a wider variety of pollutants, and for improving sustainability and reducing the cost and environmental impact of the process, is necessary.

Green Synthesis of Nano-Zero-Valent Iron Using Ricinus Communis Seeds Extract: Characterization and Application in the Treatment of Methylene Blue-Polluted Water

In this study, the removal of methylene blue dye (MB) from aqueous solution was examined using a novel green adsorbent to overcome the obstacles encountered in chemical methods. Ricinus communis (RC) aqueous seeds extract was herein used as a reducing and capping agent to synthesize a novel nano-zero-valent iron (RC-nZVI) for the adsorption of harmful MB. Structural and morphological characterization of the synthesized RC-nZVI were performed using several techniques, e.g., steady-state absorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and zeta potential. The maximum efficiency of the removal was 96.8% at pH 6 and 25 °C. According to the kinetics study results, the adsorption process obeys the pseudo-first-order model. The experimental equilibrium data were fitted to the Freundlich isotherm model, the maximum adsorption capacity reached was 61.37 mg·g-1, and the equilibrium parameters were determined. The synthesized RC-nZVI possesses good reusability and can be considered as a potential economic and environmentally friendly adsorbent.

Decolorization of water through removal of methylene blue and malachite green on biodegradable magnetic Bauhinia variagata fruits

Batch sorption experiments were performed to investigate the potential of Bauhinia variagata fruit (BVf) and nano-magnetic Bauhinia variagata fruit (nM-BVf) to remove methylene blue (MB) and malachite green (MG). Equilibrium studies have been carried out using various experimental parameters such as the amount of biosorbent, initial solution concentration, contact time, pH, and temperature. The Langmuir, Freundlich, Scatchard, D-R and Temkin adsorption models were applied for the experimental information of MB and MG. The Freundlich model fits better than the Langmuir model. Freundlich model confirmed the magnificent dye sorption ability; 19.3 mg/g for BVf/MB, 21.2 mg/g for nM-BVf/MB, 19.7 mg/g for BVf/MG, and 30.1 mg/g for nM-BVf/MG. The pseudo-second-order kinetic model displayed a more suitable behavior to the experimental result for the removal of MG and MB. Thermodynamic parameters such as changes in Gibbs free energy (ΔG^o), enthalpy (ΔH^o), and entropy (ΔS^o) were investigated and the fine details in the adsorption system were completed. The conclusion from this study is that the prepared nano biosorbent can be efficient for the removal of cationic dyes from wastewater.

Elimination of basic blue 9 by electrocoagulation coupled with pelletized natural dead leaves (Sapindus mukorossi) biosorption

Elimination of basic blue 9 (BB-9), a cationic textile dye, by electrocoagulation coupled with biosorption exploiting pelletized natural dead leaves (PNDL) of Sapindus mukorossi, an economic alternative biosorbent, was investigated. The experimental runs were conducted in a laboratory-scale hybrid reactor loaded with Al electrodes, aeration spargers and PNDL packed twin suspended buckets. The pelletized adsorbents offer key advantages of good mechanical stability, lesser clogging risk, and easy disengagement as compared to powdered adsorbents. The parameters of current density, pH, PNDL dose, and initial dye concentration were studied for the decolorization and COD removal efficiency. The experimental results revealed that up to 99.9% decolorization and 90.01% COD removal efficiency achieved after 8 min at optimum condition of current density (j)=20.27 mA/cm², pH = 9, PNDL dose = 6 g/L, and initial dye concentration = 50 mg/L. The BB-9 elimination followed the first-order kinetics with K₁=0.318 min^-1 and R²=0.997. The results revealed the potential of PNDL as a feasible biosorbent with the effective performance of the coupled process.

Biosorption of methylene blue and malachite green on biodegradable magnetic Cortaderia selloana flower spikes: modeling and equilibrium study

This study involves the production of a novel biosorbent obtained from Cortaderia selloana flower spikes (CSFs). Magnetic C. selloana flower spikes (nM∞CSFs) was applied as an ideal biosorbent for the elimination of dyes from water. They were utilized for the removal from aqueous solutions of malachite green (MG) and methylene blue (MB) dyes. The analyses of the equilibrium were done under certain experimental parameters such as contact time, initial dye concentration, pH, and quantity of biosorbent. The rapid intake of dyes to reach the equilibrium in a short period time showed the effectiveness of nM∞CSFs to adsorb MG and MB. The experimental information of MB and MG was obtained from the Langmuir model and it confirmed the magnificent dye biosorption ability; 72.99 mg/g for CSFs/MB, 119.05 mg/g for nM∞CSFs/MB, 31.06 mg/g for CSFs/MG, and 56.50 mg/g for nM∞CSFs/MG. Langmuir's model affirmed the excellent dye biosorption ability. The pseudo-second-order kinetic model displayed a great fit to the experimental result for the removal of MG and MB. The nM∞CSFs compared with raw biosorbent affirmed that the magnetic form of the biosorbent has a greater removal ability for MB and MG. nM∞CSFs is a noteworthy biosorbent for MB and MG removal from wastewater. [Figure: see text] HIGHLIGHTS Magnetic Cortaderia selloana flower spikes (nM∞CSFs) was synthesized for the biosorption of dyes FT-IR and SEM analysis were used for characterization. The Langmuir isotherm model fitted the data of the adsorption for nM∞CSFs nM∞CSFs is a noteworthy biosorbent for MB and MG removal from wastewater. A NOVELTY STATEMENT   This novel biodegradable biosorbent (magnetic-C. selloana flower spikes-(nM∞CSFs)) has many different functional groups to bind MG and MB from aqueous medium. The method to bring the magnetic form was well described and gives an astronomically immense capacity for the abstraction of the dyes. It resists in acidic or basic medium and has a vigorous structure. It has an immense capacity for the dyes compared to other biosorbents. It can be cited by a sizably voluminous number of investigators or researchers when it is published because it is incipient biosorbent in the literature and can be utilized as a novel biosorbent for the removal of dyes.

Synthesis and Application of Zero-Valent Iron Nanoparticles in Water Treatment, Environmental Remediation, Catalysis, and Their Biological Effects

Present and past anthropogenic pollution of the hydrosphere and lithosphere is a growing concern around the world for sustainable development and human health. Current industrial activity, abandoned contaminated plants and mining sites, and even everyday life is a pollution source for our environment. There is therefore a crucial need to clean industrial and municipal effluents and remediate contaminated soil and groundwater. Nanosized zero-valent iron (nZVI) is an emerging material in these fields due to its high reactivity and expected low impact on the environment due to iron's high abundance in the earth crust. Currently, there is an intensive research to test the effectiveness of nZVI in contaminant removal processes from water and soil and to modify properties of this material in order to fulfill specific application requirements. The number of laboratory tests, field applications, and investigations for the environmental impact are strongly increasing. The aim of the present review is to provide an overview of the current knowledge about the catalytic activity, reactivity and efficiency of nZVI in removing toxic organic and inorganic materials from water, wastewater, and soil and groundwater, as well as its toxic effect for microorganisms and plants.