Preparation of Chitosan Poly(methacrylate) Composites for Adsorption of Bromocresol Green

Experimental and Theoretical Studies on the Adsorption of Bromocresol Green from Aqueous Solution Using Cucumber Straw Biochar

Biochar prepared from crop straw is an economical method for adsorbing bromocresol green (BCG) from textile industrial wastewater. However, there is limited research on the adsorption mechanism of biochar for the removal of BCG. This study utilized cucumber straw as raw material to prepare biochar with good adsorption potential and characterized its physicochemical properties. Through adsorption experiments, the effects of solution pH, biochar dosage, and initial dye concentration on adsorption performance were examined. The adsorption mechanism of cucumber straw biochar (CBC) for BCG was elucidated at the molecular level using adsorption kinetics, adsorption isotherm models, and density functional theory (DFT) calculations. Results show that the specific surface area of the CBC is 101.58 m2/g, and it has a high degree of carbonization, similar to the structure of graphite crystals. The presence of aromatic rings, -OH groups, and -COOH groups in CBC provides abundant adsorption sites for BCG. The adsorption process of CBC for BCG is influenced by both physical and chemical adsorption, and can be described by the Langmuir isotherm model, indicating a monolayer adsorption process. The theoretical maximum monolayer adsorption capacity (qm) of BCG at 298 K was calculated to be 99.18 mg/g. DFT calculations reveal interactions between BCG and CBC involving electrostatic interactions, van der Waals forces, halogen-π interactions, π-π interactions, and hydrogen bonds. Additionally, the interaction of hydrogen bonds between BCG and the -COOH group of biochar is stronger than that between BCG and the -OH group. These findings provide valuable insights into the preparation and application of efficient organic dye adsorbents.

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 Nanoparticles Loaded with Quercetin and Valproic Acid: A Novel Approach for Enhancing Antioxidant Activity against Oxidative Stress in the SH-SY5Y Human Neuroblastoma Cell Line

BACKGROUND

Multiple drug-delivery systems obtained by loading nanoparticles (NPs) with different drugs that have different physicochemical properties present a promising strategy to achieve synergistic effects between drugs or overcome undesired effects. This study aims to develop a new NP by loading quercetin (Que) and valproic acid (VPA) into chitosan. In this context, our study investigated the antioxidant activities of chitosan NPs loaded with single and dual drugs containing Que against oxidative stress.

METHOD

The synthesis of chitosan NPs loaded with a single (Que or VPA) and dual drug (Que and VPA), the characterization of the NPs, the conducting of in vitro antioxidant activity studies, and the analysis of the cytotoxicity and antioxidant activity of the NPs in human neuroblastoma SH-SY5Y cell lines were performed.

RESULT

The NP applications that protected cell viability to the greatest extent against H2O2-induced cell damage were, in order, 96 µg/mL of Que-loaded chitosan NP (77.30%, 48 h), 2 µg/mL of VPA-loaded chitosan NP (70.06%, 24 h), 96 µg/mL of blank chitosan NP (68.31%, 48 h), and 2 µg/mL of Que- and VPA-loaded chitosan NP (66.03%, 24 h).

CONCLUSION

Our study establishes a successful paradigm for developing drug-loaded NPs with a uniform and homogeneous distribution of drugs into NPs. Chitosan NPs loaded with both single and dual drugs possessing antioxidant activity were successfully developed. The capability of chitosan NPs developed at the nanometer scale to sustain cell viability in SH-SY5Y cell lines implies the potential of intranasal administration of chitosan NPs for future studies, offering protective effects in central nervous system diseases.

Removal of bromophenol blue from polluted water using a novel azo-functionalized magnetic nano-adsorbent

Water pollution from organic dyes poses a serious danger to the environment. In the present work, we report a novel adsorbent (ADFS) based on azo-dye-functionalized superparamagnetic iron oxide nanoparticles (SPIONs) for the removal of the anionic dye bromophenol blue (BPB) from contaminated water. The fabricated SPIONs, azo dye, and ADFS adsorbent were characterized with FTIR and UV-vis absorption spectroscopy, 1HNMR spectroscopy, mass spectrometry, SEM imaging, dynamic light scattering (DLS), zeta potential measurements, vibrating sample magnetometry, thermogravimetric analysis, differential thermal analysis, and X-ray diffraction analysis. DLS measurements showed a particle size of 46.1 and 176.5 nm for the SPIONs and the ADFS, respectively. The adsorbent exhibited an adsorption capacity of 7.43 mg g-1 and followed the pseudo-second-order kinetics model (r2 = 0.9981). The ADFS could efficiently remove BPB from water after stirring for 120 minutes at room temperature and pH 2. The adsorption process was proved to occur via physisorption, as revealed by the Freundlich isotherm (n = 1.82 and KF = 11.5). Thermodynamic studies implied that the adsorption is spontaneous (-8.03 ≤ ΔG ≤ -0.58 kJ mol-1) and enthalpy-driven might take place via van der Waals interactions and/or hydrogen bonding (ΔH = -82.19 kJ mol-1 and ΔS = -0.24 kJ mol-1 K-1).

The Evaluation of Cellulose Acetate Capsules Functionalized for the Removal of Cd(II)

Cellulose acetate is derived from cellulose and has the characteristics of biodegradability and reusability. So, it has been used for the elimination of toxic compounds capable of producing different diseases, such as cadmium, that result from human and industrial activity. For this reason, capsules functionalized with Cyanex 923 were prepared and characterized by FTIR spectroscopy, Energy Dispersive X-ray Spectroscopy (EDX), and SEM. The functionalized capsules were used for removing and recovering Cd(II) by modifying variables such as HCl concentration in the extraction medium and carrier content in the capsules, among others. The extraction of cadmium from battery leachates and the three isotherm models, Langmuir, Freundlich, and Dubinin Radushkevich, were also tested to model the cadmium removal process. The results showed a favorable physical sorption with a good capacity for extraction and the possibility of reusing the capsules for up to seven cycles without a decrease in the percentage of cadmium recovery.

Correlation between cocoa shell modifications by CTAB and its dye adsorption properties

Cocoa shell was modified whit sodium hydroxide (NaOH) and cationic surfactant cetyltrimethylammonium bromide (CTAB) to increase surface functionality, surface area, and positive charge density. The prepared adsorbent CC-OH-CTAB was used to remove indigo carmine (IC) and bromocresol green (BCG) dyes from water. The optimal pH for IC and BCG adsorption were 2 and 4, respectively. The equilibrium was attained after a contact time of 30 min for IC and 120 min for BCG. The maximum adsorption capacity (Qmax) of IC and BCG obtained was 85.1 mg g-1 and 192.7 mg g-1, respectively. The Liu isotherm model best described the equilibrium results. The adsorption kinetics model showed that IC and BCG adsorption onto CC-OH-CTAB followed the pseudo-first-order and pseudo-second-order model, respectively. The regeneration and reusability experiments indicated that CC-OH-CTAB had much stability and excellent performance meanwhile repeatedly used. Finally, the insertion of CTAB on the CC-OH surface proved to be an excellent way to improve the adsorption performance of this material concerning dyes.

Biosynthesized silver nanoparticles for electrochemical detection of bromocresol green in river water

In this study, silver nanoparticles (AgNPs)-based electrochemical sensor has been reported for assessing bromocresol green (BG) in river water. Firstly, AgNPs were greenly produced using the aqueous extract of Ficus sycomorus leaves. Then, the AgNP-modified glassy carbon (GC) electrode was prepared using the sticking method. AgNPs were characterized using transmission electron microscope (TEM), X-ray diffraction (XRD), square wave voltammetry (SWV) and scanning electron microscope (SEM). TEM and SEM were used for determining the size of AgNPs before and after adsorption, respectively. The results show that there was an increase in AgNP size from 20 to 30 nm. Additionally, XRD was used for characterizing the crystal nature of AgNPs, while SWV exhibited a characteristic oxidation peak of AgNPs at 0.06 V. Moreover, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used for characterizing the catalytic effect of AgNPs. BG as a targeted pollutant was detected at AgNPs/GC based on its oxidation through proton and electron transfer. Two peaks corresponding to the monomer and polymer oxidation were detected. The monomer- and polymer-based sensors have revealed a linear range of 2.9 × 10-5 to 2.1 × 10-4 mole l-1 and low detection limits (LODs) of 1.5 × 10-5 and 1.3 × 10-5 mole l-1, respectively.

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

Since contamination of xenobiotics in water bodies has become a global issue, their removal is gaining ample attention lately. In the present study, nZVI was synthesized using chitosan for removal of two such xenobitic dyes, Bromocresol green and (BCG) and Brilliant blue (BB), which have high prevalence in freshwater and wastewater matrices. nZVI functionalization prevents nanoparticle aggregation and oxidation, enhancing the removal of BCG and BB with an efficiency of 84.96% and 86.21%, respectively. XRD, FESEM, EDS, and FTIR have been employed to investigate the morphology, elemental composition, and functional groups of chitosan-modified nanoscale-zerovalent iron (CS@nZVI). RSM-CCD model was utilized to assess the combined effect of five independent variables and determine the best condition for maximum dye removal. The interactions between adsorbent dose (2-4 mg), pH (4-8), time (20-40 min), temperature (35-65 0C), and initial dye concentration (40-60 mg/L) was modeled to study the response, i.e., dye removal percentage. The reaction fitted well with Langmuir isotherm and pseudo-first-order kinetics, with a maximum qe value of 426.97 and 452.4 mg/g for BCG and BB, respectively. Thermodynamic analysis revealed the adsorption was spontaneous, and endothermic in nature. Moreover, CS@nZVI could be used up to five cycles of dye removal with remarkable potential for real water samples.

Artificial Intelligence-Based Tools for Process Optimization: Case Study—Bromocresol Green Decolorization with Active Carbon

This study highlights the benefits of optimizing the decolorization of bromocresol green (a colorant/pH indicator widely used in the industry, whose degradation produces toxic byproducts) by adsorption on active carbon. A set of experiments were planned and performed based on the design of experiments methodology for the following parameters: the colorant concentration (0.009-0.045 g/L), the amount of adsorbent (0.5-3 g/L), and the contact time (60-240 min). Modeling and optimization strategies were employed to determine the working conditions leading to efficiency maximization. Using the response surface methodology, the optimum values of the primary process parameters were established. In addition, a modified bacterial foraging optimization algorithm was applied as an alternative optimizer in combination with artificial neural networks in order to determine multiple combinations of parameters that can lead to maximum process efficiency. Different solutions were obtained with the considered strategies, and the maximum efficiency obtained was >99%. The study emphasizes that adsorption on active carbon is an effective method for bromocresol green decolorization in wastewater that can be further improved using advanced optimization methods.

Azo-functionalized superparamagnetic Fe3O4 nanoparticles: an efficient adsorbent for the removal of bromocresol green from contaminated water

Water contamination is regarded as one of the world's worst tragedies owing to the continual depletion of water resources suitable for drinking and agriculture. Researchers have recently been interested in developing novel and more effective adsorbents for wastewater purification. We report herein a magnetic adsorbent nanomaterial for the removal of the anionic dye bromocresol green (BCG) from wastewater. The adsorbent is based on superparamagnetic iron oxide (cubic Fe₃O₄) nanoparticles (SPIONs) coated with a high-molecular-weight azo dye synthesized via diazo coupling of vitamin B1 with a trisubstituted benzene derivative. The proposed adsorbent was characterized using scanning electron microscopy, FTIR and ¹H-NMR spectroscopy, mass spectrometry, dynamic light scattering, vibrating sample magnetometry, thermal analysis, and X-ray diffraction crystallography. At room temperature and pH 2.0, the synthesized adsorbent showed an average particle size of 65.9 ± 8.0 nm, a high magnetization saturation (65.58 emu g⁻¹), a high equilibrium adsorption capacity (36.91 mg g⁻¹). Adsorption of BCG was found to take place via a physisorption mechanism and followed a pseudo-second-order rate kinetics. Thermodynamic studies revealed that the adsorption process is enthalpy driven by hydrogen bonding and/or van der Waals interactions. After treating water samples with the suggested adsorbent, it can be easily removed from water using a strong external magnetic field.

An efficient adsorbent based on azo-dye-coated superparamagnetic Fe₃O₄ nanoparticles was synthesized for the removal of the anionic dye, bromocresol green, from wastewater.

Acrylate and Methacrylate Polymers' Applications: Second Life with Inexpensive and Sustainable Recycling Approaches

Polymers are widely employed in several fields thanks to their wide versatility and the easy derivatization routes. However, a wide range of commercial polymers suffer from limited use on a large scale due to their inert nature. Nowadays, acrylate and methacrylate polymers, which are respectively derivatives of acrylic or methacrylic acid, are among the most proposed materials for their useful characteristics like good biocompatibility, capping ability toward metal clusters, low price, potentially recyclability and reusability. Here, we discuss the advantages and challenges of this class of smart polymers focusing our attention on their current technological applications in medical, electronic, food packaging and environmental remediation fields. Furthermore, we deal with the main issue of their recyclability, considering that the current commercial bioplastics are not yet able to meet the global needs as much as to totally replace fossil-fuel-based products. Finally, the most accredited strategies to reach recyclable composites based on acrylic polymers are described.

Enhanced adsorption of acid Blue-25 dye onto chitosan/porous carbon composite modified in 1-allyl-3-methyl imidazolium bromide ionic liquid

In this study, chitosan/porous carbon composite (C-PC) modified in 1-Allyl-3-methyl imidazolium bromide [AMIM][Br] under airtight condition was prepared for the removal of Acid Blue-25 dye (AB-25) from aqueous medium. For comparison of adsorption efficiency of C-PC, chitosan-activated carbon composite (C-AC) was also prepared in 1% acetic acid. The adsorbents were characterised using SEM, EDX, XRD, BET, TGA and FTIR. The micrograph of C-PC revealed cavities and slightly rough surfaces dominated with similar sized and irregular shaped stone-like materials which differ from the precursors' micrograph. BET analysis revealed the domination of mesopores on the C-PC and C-AC surfaces, as the hydroxyl and amino group on C-PC are the main active sites for AB-25 dye uptake. The dye was better adsorbed onto C-PC at pH 2 and C-AC at pH 4. The adsorption capacity obtained for C-PC, C-AC, activated carbon (AC) and chitosan (CH) using Langmuir isotherm model are 3333.33 mg/g, 909.90 mg/g, 909.09 mg/g and 833.33 mg/g, respectively. The experimental data are well described by Langmuir and Fruendlich isotherms for adsorption of the dye onto C-PC, AC and CH. C-AC fitted into Langmuir isotherm only. The kinetics of the adsorption fitted into pseudo-second order indicating the possibility of chemical interactions in the adsorption process.

Chitosan modifications for adsorption of pollutants - A review

In recent times, research interest into the development of biodegradable, cost-effective and environmental friendly adsorbents with favourable properties for adsorption of pollutants is a challenge. Modification of chitosan via different physical and chemical methods have gained attention as a promising approach for removing organic (such as dyes and pharmaceuticals) and inorganic (such as metal/metal ions) pollutants from aqueous medium. In this regard, researchers have reported grafting and cross-linking approach among others as a potentially useful method for chitosan's modification for improved adsorption efficiency with respect to pollutant uptake. This article reviews the trend in chitosan modification, with regards to the summary of some recently published works on modification of chitosan and their adsorption application in pollutants (metal ion, dyes and pharmaceuticals) removal from aqueous medium. The review uniquely highlights some common cross-linkers and grafting procedures for chitosan modification, their influence on structure and adsorption capacity of modified-chitosan with respect to pollutants removal. Findings revealed that the performance of modified chitosan for adsorption of pollutants depends largely on the modification method adopted, materials used for the modification and adsorption experimental conditions. Cross-linking is commonly utilized for improving the chemical and mechanical stabilities of chitosan but usually decreases adsorption capacity of chitosan/modified-chitosan for adsorption of pollutants. However, literature survey revealed that adsorption capacity of cross-linked chitosan based materials have been enhanced in recently published works either by grafting, incorporation of solid adsorbents (e.g metals, clays and activated carbon) or combination of both prior to cross-linking.

Osteoblast cell viability over ultra-long tricalcium phosphate nanocrystal-based methacrylate chitosan composite for bone regeneration

Bio-ceramic morphology plays a crucial role in bone repair and regeneration. It is extensively utilized in bone scaffold synthesis due to its better biological system activity and biocompatibility. Here, the ultra-long tricalcium phosphate (UTCP) was synthesized with the assistance of the ultrasonication method. The UTCP is modified as a scaffold by the reinforcement of methacrylate chitosan (MAC) polymer. The functionality of UTCP, UTCP combined MAC, methotrexate (MTX) loaded composites was characterized through FTIR (Fourier transform infrared spectroscopy). The crystalline natures are investigated by the XRD (X-ray diffraction), and results shows the ultra-long tricalcium phosphate crystalline phase is not altered after the reinforcement of MAC polymer and loading of MTX drugs. The morphological analyses were observed through electron microscopic analysis, and rod, polymer-coated rod structures were observed. The UTCP/MAC composite mechanical stress was increased from 1813 Pa of UTCP to 4272 Pa. The MTX loading and release was achieved 79.0 % within 3 h and 76.15 % at 20 h respectively. The UTCP/MAC and UTCP/MAC/MTX's viability investigated osteoblast like the cells (MG-63), and the MTX loaded UTCP/MAC composite exhibits good viability behaviors up to 96.0 % in 14 days. The results confirm the higher compatibility of the composite and profitable cell growth. It may be suitable for bone implantation preparation and it helps in faster regeneration of bone tissue after the in-vivo and clinical evaluation.

Modification of epoxy groups of poly(hydroxylmethyl methacrylate-co-glycidyl methacrylate) cryogel with H3PO4 as adsorbent for removal of hazardous pollutants

Poly(hydroxylmethyl methacrylate-co-glycidyl methacrylate) (p(HEMA-GMA)) macroporous cryogel with high density of epoxy groups was synthesized, and the epoxy groups of the cryogel were modified into phosphonate groups. The effects of dye concentrations, adsorption time, pH, salt concentration, and adsorption temperature on the adsorption of Direct Blue-53 (DB-53) and Reactive Blue-160 (RB-160) dyes were studied. The maximum adsorption capacity was found to be 245.3 and 155.8 mg/g (0.255 or 0.119 mmol/g) for the DB-53 and RB-160 dyes, respectively. The higher adsorption capacity achieved for the DB-53 compared with the RB-160 dye can result from the pendant primary amino groups of the DB-53 dye as well as the smaller size of the dye molecule. The Langmuir isotherm model and the pseudo-second-order kinetic model well described the experimental data. The p(HEMA-GMA)-PO₄^2- adsorbent has many operational advantages for the removal of pollutants. It could be a promising adsorbent to be used in industrial wastewater treatment.