Facile synthesis of biopolymer decorated magnetic coreshells for enhanced removal of xenobiotic azo dyes through experimental modelling

Design of cross-linked chitosan-adipic acid/Al2O3 nanoparticles for highly efficient removal of bromothymol blue dye: Physicochemical properties, isotherms, and adsorption kinetics

In the present work, an eco-friendly cross-linked chitosan-adipic acid/Al2O3 nanoparticles (CTS-ADP/Al2O3) nanocomposite was designed for the highly efficient removal of bromothymol blue (BTB) dye from an aquatic medium. Several analytical approaches including Zeta potential, BET, XRD, FTIR, pHpzc, and FESEM-EDX were adopted to investigate the CTS-ADP/Al2O3's physicochemical properties. The response surface methodology approach was used to conduct a comprehensive study on the capability of CTS-ADP/Al2O3 to remove BTB dye. This research took into account the factors that impact adsorption, including the CTS-ADP/Al2O3 dosage (0.02-0.08 g), the duration (10-50 min), and the pH (4-10). The BTB equilibrium data fitted well with the Freundlich isotherm. A reasonable agreement of the kinetics data of BTB adsorption by CTS-ADP/Al2O3 was provided using a pseudo-first-order model. The adsorption capability of CTS-ADP/Al2O3 was outstanding (527.3 mg/g). It is possible to attribute the effective adsorption of BTB on the positively charged CTS-ADP/Al2O3 to the electrostatic attraction between the BTB anions and the positively charged CTS-ADP/Al2O3, as well as to n-π, and H-bond interactions. This work reveals that CTS-ADP/Al2O3 has a surprising potential as an effective bio-adsorbent to treat industrial wastewater.

Abatement of methylene blue and diazinon pesticide from synthetic solutions using magnetic biochar from pistachio shells modified with MOF-808

This study develops a magnetic composite from pistachio shell biochar (PSBC/CoFe₂O₄) modified with MOF-808 for removing methylene blue (MB) dye and diazinon (DA) pesticide from water. The composite, with a surface area of 151.53 m2/g and magnetic saturation of 19.653 emu/g, allowed easy separation from solutions. Key adsorption factors such as pH, temperature, contact time, adsorbent dosage, and initial pollutant concentration were optimized. Maximum removal efficiencies of 99.32% for MB and 99.14% for DA were achieved at adsorbent dosages of 1 g/L for MB and 1.5 g/L for DA, initial concentrations of 5 mg/L, temperatures of 55 °C, contact times of 60 min for MB and 80 min for DA, and pH levels of 9 for MB and 6 for DA. Thermodynamic analysis confirmed that the adsorption process is spontaneous and endothermic, with enthalpy values of 55.091 kJ/mol for MB and 42.028 kJ/mol for DA, while entropy values indicated increased randomness during adsorption. Kinetic studies revealed that adsorption involved both physical and chemical interactions, with intraparticle diffusion not being the rate-limiting step. The Freundlich isotherm model provided the best fit (R2 = 0.971 for MB and 0.988 for DA), highlighting heterogeneous surface interactions. The composite showed higher adsorption capacities for MB (31.44 mg/g) than for DA (21.49 mg/g) and exhibited excellent regeneration potential, performing better in deionized water due to the inhibitory effects of salts in non-deionized water.

Enhanced fluoride removal using montmorillonite clay modified with CoFe2O4 and metal-organic frameworks

The use of modified clays can play an effective role as an effective adsorbent in removing fluoride (Flu) ions from water and aqueous solutions. In the present research, montmorillonite clay (MMt) was modified using CoFe2O4 magnetic particles and Al-Fe fumarate metal-organic framework (Al-Fe Fum) and was utilized as an efficient adsorbent for removing Flu from aqueous solution. The properties of MMt and MMt/CoFe2O4/Al-Fe Fum samples were investigated using different techniques. The results showed that with the modification of MMt using CoFe2O4 magnetic particles and the metal-organic framework of Al-Fe Fum, the BET surface has increased notably from 13.217 to 365.80 m2/g. To investigate the effect of independent variables and their interaction on the efficiency of the Flu adsorption, response surface method-central compound design (RSM-CCD) was served. Based on the results of ANOVA, the F-value and p-value parameters for the desired model were determined to be 783.09 and < 0.0001, respectively, which confirms the success and high ability of the model. The number of R2, adjusted R2, and Predicted R2 for adsorption of Flu ion was determined to be 0.998, 0.997, and 0.995, respectively, which shows that the proposed regression model can describe the process of adsorption and interaction between variables well. Compared to other kinetic models, the pseudo 2nd order kinetic model has a greater ability to describe the Flu adsorption behavior. The R2 parameter value determined that the Freundlich isotherm model has a suitable ability to investigate the isotherm behavior and confirms the effect of heterogeneous surfaces in the process. Generally, the outcomes signified that the MMt and MMt/CoFe2O4/Al-Fe Fum samples can be reused several times in the process of Flu adsorption, while the efficiency is more than 90%.

Hydrogels Based on Chitosan and Nanoparticles and Their Suitability for Dyes Adsorption from Aqueous Media: Assessment of the Last-Decade Progresses

Water is one of the fundamental resources for the existence of humans and the environment. Throughout time, due to urbanization, expanding population, increased agricultural production, and intense industrialization, significant pollution with persistent contaminants has been noted, placing the water quality in danger. As a consequence, different procedures and various technologies have been tested and used in order to ensure that water sources are safe for use. The adsorption process is often considered for wastewater treatment due to its straightforward design, low investment cost, availability, avoidance of additional chemicals, lack of undesirable byproducts, and demonstrated significant efficacious potential for treating and eliminating organic contaminants. To accomplish its application, the need to develop innovative materials has become an essential goal. In this context, an overview of recent advances in hydrogels based on chitosan and nanocomposites and their application for the depollution of wastewater contaminated with dyes is reported herein. The present review focuses on (i) the challenges raised by the synthesis process and characterization of the different hydrogels; (ii) the discussion of the impact of the main parameters affecting the adsorption process; (iii) the understanding of the adsorption isotherms, kinetics, and thermodynamic behavior; and (iv) the examination of the possibility of recycling and reusing the hydrogels.

Chitosan anchored nZVI bionanocomposites for treatment of textile wastewater: Optimization, mechanism, and phytotoxic assessment

In recent years, there has been a growing focus on treating textile wastewater due to its escalating threat to aquatic ecosystems and exposed communities. The present study investigates the adsorption efficacy of biopolymer functionalized nanoscale zero-valent iron (CS@nZVI) composite for the treatment of textile wastewater using the RSM-CCD model. The structure and morphology of CS@nZVI were characterized using XRD, FTIR, FESEM, and EDX. CS@nZVI was then evaluated for its adsorption potential in removing COD, color, and other physico-chemical parameters from textile wastewater. The results showed the high efficacy of CS@nZVI for COD and color removal from textile wastewater. Under optimal conditions (pH 6, contact time 60 min, and 1.84 g CS@nZVI), COD removal reached a maximum of 85.53%, and decolorization efficiency was found to be 89.73%. The coefficient of determination R2 (0.98) and AIC (269.75) values suggested quadratic model as the best-fitted model for optimizing the process parameters for COD removal. Additionally, the physico-chemical parameters were found to be within permissible limits after treatment with CS@nZVI. The influence of coexisting ions on COD removal followed the order PO43- > SO42- > Cl- >Na+ > Ca2+. The kinetics data fitted well with the pseudo-first-order reaction, indicating physisorption as the primary mechanism. The thermodynamic study revealed the endothermic nature of the removal process. Reusability tests demonstrated that great regeneration capacity of spent CS@nZVIafter five consecutive cycles. Furthermore, toxicological studies showed reduced toxicity in treated samples, leading to improved growth of Vigna radiata L. These findings suggest that CS@nZVI bionanocomposites could serve as an efficient, cost-effective, and eco-friendly remediation agent for the treatment of textile effluents, presenting significant prospects for commercial applications.

Zero-valent Iron Nanoparticles: Biogenic Synthesis and their Medical Applications; Existing Challenges and Future Prospects

OBJECTIVES

In the last decade, nanobiotechnology is emerging as a keen prudence area owing to its widespread applications in the medical field. In this context, zero-valent iron nanoparticles (nZVI) have garnered tremendous attention attributed to their cheap, non-toxic, excellent paramagnetic nature, extremely reactive surface, and dual oxidation state that makes them excellent antioxidants and free-radical scavengers. Facile biogenic synthesis, in which a biological source is used as a template for the synthesis of NPs, is presumably dominant among other physical and chemical synthetic procedures. The purpose of this review is to elucidate plant-mediated synthesis of nZVI, although they have been successfully fabricated by microbes and other biological entities (such as starch, chitosan, alginate, cashew nut shell, etc.) as well.

METHODS

The methodology of the study involved keyword searches of electronic databases, including ScienceDirect, NCBI, and Google Scholar (2008-2023). Search terms of the review included 'biogenic synthesis of nZVI', 'plant-mediated synthesis of nZVI', 'medical applications of nZVI', and 'Recent advancements and future prospects of nZVI'.

RESULTS

Various articles were identified and reviewed for biogenic fabrication of stable nZVI with the vast majority of studies reporting positive findings. The resultant nanomaterial found great interest for biomedical purposes such as their use as biocompatible anticancer, antimicrobial, antioxidant, and albumin binding agents that have not been adequately accessed in previous studies.

CONCLUSION

This review shows that there are potential cost savings applications to be made when using biogenic nZVI for medical purposes. However, the encountering challenges concluded later, along with the prospects for sustainable future development.