Synthesis and characterization of egg-albumen-formaldehyde based magnetic polymeric resin (MPR): Highly efficient adsorbent for Cd(II) ion removal from aqueous medium

Myrica esculenta Leaf Extract-Assisted Green Synthesis of Porous Magnetic Chitosan Composites for Fast Removal of Cd (II) from Water: Kinetics and Thermodynamics of Adsorption

Heavy metal contamination in water resources is a major issue worldwide. Metals released into the environment endanger human health, owing to their persistence and absorption into the food chain. Cadmium is a highly toxic heavy metal, which causes severe health hazards in human beings as well as in animals. To overcome the issue, current research focused on cadmium ion removal from the polluted water by using porous magnetic chitosan composite produced from Kaphal (Myrica esculenta) leaves. The synthesized composite was characterized by BET, XRD, FT-IR, FE-SEM with EDX, and VSM to understand the structural, textural, surface functional, morphological-compositional, and magnetic properties, respectively, that contributed to the adsorption of Cd. The maximum Cd adsorption capacities observed for the Fe3O4 nanoparticles (MNPs) and porous magnetic chitosan (MCS) composite were 290 mg/g and 426 mg/g, respectively. Both the adsorption processes followed second-order kinetics. Batch adsorption studies were carried out to understand the optimum conditions for the fast adsorption process. Both the adsorbents could be regenerated for up to seven cycles without appreciable loss in adsorption capacity. The porous magnetic chitosan composite showed improved adsorption compared to MNPs. The mechanism for cadmium ion adsorption by MNPs and MCS has been postulated. Magnetic-modified chitosan-based composites that exhibit high adsorption efficiency, regeneration, and easy separation from a solution have broad development prospects in various industrial sewage and wastewater treatment fields.

Nanotechnology- A ray of hope for heavy metals removal

Environmental effects of heavy metal pollution are considered as a widespread problem throughout the world, as it jeopardizes human health and also reduces the sustainability of a cleaner environment. Removal of such noxious pollutants from wastewater is pivotal because it provides a propitious solution for a cleaner environment and water scarcity. Adsorption treatment plays a significant role in water remediation due to its potent treatment and low cost of adsorbents. In the last two decades, researchers have been highly focused on the modification of adsorption treatment by functionalized and surface-modified nanomaterials which has spurred intense research. The characteristics of nano adsorbents attract global scientists as it is also economically viable. This review shines its light on the functionalized nanomaterials application for heavy metals removal from wastewater and also highlights the importance of regeneration of nanomaterials in the view of visualizing the economic aspects along with a cleaner environment. The review also focused on the proper disposal of nanomaterials with crucial issues that persist in the adsorption process and also emphasize future research modification at a large-scale application in industries.

Engineered Magnetic Carbon-Based Adsorbents for the Removal of Water Priority Pollutants: An Overview

This review covers the preparation, characterization, and application of magnetic adsorbents obtained from carbon-based sources and their application in the adsorption of both inorganic and organic pollutants from water. Different preparation routes to obtain magnetic adsorbents from activated carbon, biochar, hydrochar, graphene, carbon dots, carbon nanotubes, and carbon nanocages, including the magnetic phase incorporated on the solid surface, are described and discussed. The performance of these adsorbents is analyzed for the removal of fluoride, arsenic, heavy metals, dyes, pesticides, pharmaceuticals, and other emerging and relevant water pollutants. Properties of these adsorbents and the corresponding adsorption mechanisms have been included in this review. Overall, this type of magnetic adsorbents offers an alternative for facing the operational problems associated to adsorption process in water treatment. However, some gaps have been identified in the proper physicochemical characterization of these adsorbents, the development of green and low-cost preparation methods for their industrial production and commercialization, the regeneration and final disposal of spent adsorbents, and their application in the multicomponent adsorption of water pollutants.

Fabrication of Highly Porous Polymeric Nanocomposite for the Removal of Radioactive U(VI) and Eu(III) Ions from Aqueous Solution

In the present study, a polymeric nanocomposite, CoFe2O4@DHBF, was fabricated using 2,4 dihydroxybenzaldehyde and formaldehyde in basic medium with CoFe2O4 nanoparticles. The fabricated nanocomposite was characterized using FTIR, TGA, XRD, SEM, TEM, and XPS analyses. The analytical results revealed that the magnetic nanocomposite was fabricated successfully with high surface area 370.24 m2/g. The fabricated CoFe2O4@DHBF was used as an efficient adsorbent for the adsorption of U(VI) and Eu(III) ions from contaminated water. pH, initial concentration, adsorption time, and the temperature of the contaminated water solution affecting the adsorption ability of the nanocomposites were studied. The batch adsorption results exposed that the adsorption capacity for the removal of U(VI) and Eu(III) was found to be 237.5 and 225.5 mg/g. The adsorption kinetics support that both the metal ions follow second order adsorption kinetics. The adsorption isotherm well fits with the Langmuir adsorption isotherm and the correlation coefficient (R2) values were found to be 0.9920 and 0.9913 for the adsorption of U(VI) and Eu(III), respectively. It was noticed that the fabricated nanocomposites show excellent regeneration ability and about 220.1 and 211.3 mg/g adsorption capacity remains with U(VI) and Eu(III) under optimum conditions.

Amine functionalized egg albumin hydrogel with enhanced adsorption potential for diclofenac sodium in water

The removal of diclofenac sodium (DFS) from wastewater has attracted increasing attention because it is within the extensively prescribed nonsteroidal anti-inflammatory drugs and pose ecotoxicity. Therefore, fabrication of versatile adsorbents of low-cost, higher-effectiveness and excellent recyclability is significant for the treatment of DFS contaminated wastewater. This work reports a promising biobased egg albumin (ALB) hydrogel functionalized with a large density of adsorptive amine sites via polyethyleneimine (PEI). The composite ALB/PEI hydrogel demonstrated an excellent DFS removal capacity, i.e. 232.5 mg/g, in an optimum experimental condition (pH∼6; contact time∼180 min; adsorbent dosage∼0.5 g/L) which revealed to be considerably higher or competitive than many reported adsorbents. The adsorption isotherms better accorded with the Langmuir model and the kinetics with the pseudo second-order model, indicating the mono-layer chemisorption process. Besides, the regeneration steps up to four sequential adsorption/desorption cycles demonstrated an excellent reusability. The Fourier-transform infrared spectrometry (FTIR), and X-ray photoelectron spectroscopy (XPS) results implied that the adsorption process followed via the electrostatic interactions, hydrogen bonding, and π-π stacking between the functionality of hydrogel and aromatic rings of DFS. Considering the low-cost, and an excellent DFS removal capacity, the natural composite ALB/PEI hydrogel could be a promising adsorbent for the treatment of DFS contaminated wastewater.

Multifunctional magnetic MgMn-oxide composite for efficient purification of Cd2+ and paracetamol pollution: Synergetic effect and stability

A multifunctional magnetic composite (0.3Ma-MgMnLDO-a) with the function of Cd²⁺ adsorption and paracetamol (PAM) degradation was successfully fabricated. Surface morphology showed that Fe₃O₄ agglomeration was overcome on composite. The composite had high specific surface area of 105.32 m² g^-1 and saturation magnetization of 40 emu∙g^-1. 0.3Ma-MgMnLDO-a could reach Cd²⁺ adsorption equilibrium within 5 min with 99 % removal rate. The maximum adsorption capacity was 3.76 mmol·g^-1 (422.62 mg g^-1), which apparently higher than that of Fe₃O₄-a and MgMnLDO-a, indicating that the Fe/Mn synergism results in excellent ability for Cd²⁺ adsorption. Moreover, the composite could efficiently activate peroxymonosulfate (PMS) to rapid degrade PAM with the highest first-order rate constants (k_obs = 0.116 min^-1) and total organic carbon (TOC) removal rate (67.7 %), which also due to the contribution of Fe/Mn synergism in PMS activation. The cycling of Mn^III/Mn^IV and Fe^II/Fe^III played an important role in activating PMS to generateO₂^-•, ¹O₂ and OH for degradation. The composite exhibited both stable adsorption and catalytic performance on wide pH (3-9) and five reuse cycles. Notably, there was mutual promotion between Cd²⁺ and PAM adsorption, while the coexistence of Cd²⁺ had slight inhibition on PAM degradation. Overall, the magnetic composite had promising application for purifying heavy metals and pharmaceuticals.

Preparation of chitosan based magnetic nanocomposite for tetracycline adsorption: Kinetic and thermodynamic studies

In the present study, the magnetic nanocomposite is fabricated using chitosan, thiobarbituric acid, malondialdehyde and Fe₃O₄ nanoparticles (CTM@Fe₃O₄). The fabricated nanocomposite (CTM@Fe₃O₄) is characterized using FTIR, TGA, BET, XRD, Raman, XPS, FESEM, and HRTEM techniques. The results of BET analysis confirmed that the nanocomposite has a mesoporous structure with high surface area of 376 m² g^-1 and high pore volume 0.3828 cm³ g^-1. The adsorption of tetracycline (TC) onto CTM@Fe₃O₄ adsorbent is carried out using batch technique by changing several factors such as pH, concentration, contact time, and temperature. Langmuir and pseudo-second-order nonlinear models were found to be the best-fit models to predict isotherms and kinetics of adsorption, respectively. The highest adsorption capacity of 215.31mg/g was achieved at the optimum conditions of 0.05g adsorbent dosage, 60mg/L TC concentration. Overall, results demonstrated that CTM@Fe₃O₄ nanocomposite was an excellent adsorbent material with superparamagnetic properties, which allowed the separation as well as recovery of the adsorbent from aqueous solution using external magnet for effective industrial applications.