The performance of nanorods material as adsorbent for removal of azo dyes and heavy metal ions: Application of ultrasound wave, optimization and modeling

Evaluating the efficacy of recyclable nanostructured adsorbents for rapid removal of methylparaben from aqueous solutions

In this study, we evaluate the efficiency of two novel nanostructured adsorbents - chitosan-graphitic carbon nitride@magnetite (CS-g-CN@Fe3O4) and graphitic carbon nitride@copper/zinc nanocomposite (g-CN@Cu/Zn NC) - for the rapid removal of methylparaben (MPB) from water. Our characterization methods, aimed at understanding the adsorbents' structures and surface areas, informed our systematic examination of influential parameters including sonication time, adsorbent dosage, initial MPB concentration, and temperature. We applied advanced modeling techniques, such as response surface methodology (RSM), generalized regression neural network (GRNN), and radial basis function neural network (RBFNN), to evaluate the adsorption process. The adsorbents proved highly effective, achieving maximum adsorption capacities of 255 mg g-1 for CS-g-CN@Fe3O4 and 218 mg g-1 for g-CN@Cu/Zn NC. Through genetic algorithm (GA) optimization, we identified the optimal conditions for the highest MPB removal efficiency: a sonication period of 12.00 min and an adsorbent dose of 0.010 g for CS-g-CN@Fe3O4 NC, with an MPB concentration of 17.20 mg L-1 at 42.85 °C; and a sonication time of 10.25 min and a 0.011 g dose for g-CN@Cu/Zn NC, with an MPB concentration of 13.45 mg L-1 at 36.50 °C. The predictive accuracy of the RBFNN and GRNN models was confirmed to be satisfactory. Our findings demonstrate the significant capabilities of these synthesized adsorbents in effectively removing MPB from water, paving the way for optimized applications in water purification.

Application of Taguchi method, response surface methodology, DFT calculation and molecular dynamics simulation into the removal of orange G and crystal violet by treated biomass

In this work, the efficiency of the treated plant Carpobrotus edulis (TPCE) as an effective biosorbent for removing the orange G (OG) and crystal violet (CV) dyes from aqueous solution was investigated. TPCE was characterized by FT-IR, Ss, pHz and SEM-EDX. The influence of parameters such as bioadsorbent dose, contact time, initial concentration, temperature and pH was tested using Taguchi experimental design (TED) with L8 orthogonal array (five parameters in two levels). The initial concentration, bioadsorbent dose and contact time are the main parameters for the removal of CV and OG dyes, while the effects of pH and temperature are minimal. The maximum removal efficiency of dyes under optimal operating conditions was 97.93 % and 92.68 %, respectively. which at the optimal conditions of 3 g/L, pH 10, 20 mg/L, 35 °C, 5 min and 15 g/L, pH 4, 20 mg/L, 35 °C, 60 min for CV and OG dyes, respectively. The results of response surface methodology (RSM) and analysis of variance (ANOVA) showed that the initial concentration Ci of CV dye was the most significant factor in the adsorption efficiency with a contribution of 51.56 %. On the other hand, the OG bioadsorbent dose is the most important factor in adsorption efficiency with a percentage contribution of 56.41 %. The Density Functional Tight Binding (DFTB) method shows that dyes strongly bind the adsorbent surface. Monte Carlo and molecular dynamics simulations show significant interactions between dye and adsorbent surface. The reusability of biomaterial indicated that the adsorption performance dropped very slightly up to five cycles.

Sonoactivated Nanomaterials: A potent armament for wastewater treatment

The world is currently facing a critical issue of water pollution, with wastewater being a major contributor. It comes from different types of pollutants, including industrial, medical, agricultural, and domestic. Effective treatment of wastewater requires efficient degradation of pollutants and carcinogens prior to discharge. Commonly used methods for wastewater treatment include filtration, adsorption, biodegradation, advanced oxidation processes, and Fenton oxidation, among others.The sonochemical effect refers to the decomposition, oxidation, reduction, and other reactions of pollutant molecules in wastewater upon ultrasound activation, achieving pollutants removal. Furthermore, the micro-flow effect generated by ultrasonic waves creates tiny bubbles and eddies. This significantly increases the contact area and exchange speed of pollutants and dissolved oxygen, thereby accelerating pollutant degradation. Currently, ultrasonic-assisted technology has emerged as a promising approach due to its strong oxidation ability, simple and cheap equipments, and minimal secondary pollution. However, the use of ultrasound in wastewater treatment has some limitations, such as high energy consumption, lengthy treatment time, limited water treatment capacity, stringent water quality requirements, and unstable treatment effects. To address these issues, the combination of enhanced ultrasound with nanotechnology is proposed and has shown great potential in wastewater treatment. Such a combination can greatly improve the efficiency of ultrasonic oxidation, resulting in an improved performance of wastewater purification. This article presents recent progress in the development of sonoactivated nanomaterials for enhanced wastewater disposal. Such nanomaterials are systematically classified and discussed. Potential challenges and future prospects of this emerging technology are also highlighted.

A review on the green synthesis of nanoparticles, their biological applications, and photocatalytic efficiency against environmental toxins

Green synthesis of nanoparticles (NPs) using plant materials and microorganisms has evolved as a sustainable alternative to conventional techniques that rely on toxic chemicals. Recently, green-synthesized eco-friendly NPs have attracted interest for their potential use in various biological applications. Several studies have demonstrated that green-synthesized NPs are beneficial in multiple medicinal applications, including cancer treatment, targeted drug delivery, and wound healing. Additionally, due to their photodegradation activity, green-synthesized NPs are a promising tool in environmental remediation. Photodegradation is a process that uses light and a photocatalyst to turn a pollutant into a harmless product. Green NPs have been found efficient in degrading pollutants such as dyes, herbicides, and heavy metals. The use of microbes and flora in green synthesis technology for nanoparticle synthesis is biologically safe, cost-effective, and eco-friendly. Plants and microbes can now use and accumulate inorganic metallic ions in the environment. Various NPs have been synthesized via the bio-reduction of biological entities or their extracts. There are several biological and environmental uses for biologically synthesized metallic NPs, such as photocatalysis, adsorption, and water purification. Since the last decade, the green synthesis of NPs has gained significant interest in the scientific community. Therefore, there is a need for a review that serves as a one-stop resource that points to relevant and recent studies on the green synthesis of NPs and their biological and photocatalytic efficiency. This review focuses on the green fabrication of NPs utilizing diverse biological systems and their applications in biological and photodegradation processes.

Application of physical vapor deposition technology for practical utilization of nano-size copper oxide for lead uptake from solution: kinetics, equilibrium, and recycling studies

For the first time, copper oxide-coated glass beads (CuO-GBs) were fabricated using physical vapor deposition (PVD) technology for sequestrating Pb²⁺ ions from solution is addressed. Compared to other coating procedures, PVD offered high-stability uniform CuO nano-layers attached with 3.0-mm glass beads. Heating of copper oxide-coated glass beads after deposition was rather necessary to achieve the best stability of the nano-adsorbent. Detection of nano-size copper oxide on the beads was made by FTIR (intense peak at 655 cm^-1 for CuO bond stretching) and XRF (Cu peak at 8.0 keV). Scanning electron micrographs taken at high magnification power indicated the presence of CuO in nano-range deposited over glass beads. The maximum deposited amount of CuO on the beads was 1.1% and accomplished at the following operational conditions: internal pressure 10^-5 mmHg, Ar flow rate 8.0 mL/min, voltage 84 V, pre-sputtering time 20 s, total sputtering time 10.0 min, and post-heating temperature 150 °C for 3 h. A univariate analysis indicated that the optimum Pb²⁺ uptake by CuO-GBs from solution was achieved at pH 7.0-8.0, 7 beads/50 mL, 120-min contact time, and 15-mg/L initial concentration. Kinetic data for Pb²⁺ uptake was best presented by a pseudo-second-order model with a relative prediction error of 3.2 and 5.1% for GBs and CuO-GBs, respectively. On the other hand, Pb²⁺ equilibrium isotherms at 25 °C were fairly presented by the Langmuir model, and the predicted saturation values were 5.48 and 15.69 mg/g for GBs and CuO-GBs, respectively. CuO and CuO-GBs had similar Pb²⁺ saturation values (~ 16 mg/g), although the latter demonstrated 4 times faster kinetic, thanks to fixation CuO on glass beads. Moreover, the chemical stability of copper oxide-coated glass beads was tested under different conditions. Recycling of copper oxide-coated glass beads was also investigated, and 90% of the surface was recovered using 0.01-M HNO₃.

Effective removal of Pb(II) and Ni(II) ions by Bacillus cereus and Bacillus pumilus: An experimental and mechanistic approach

Herein, we report a bacteria-based strategy as an efficient, reasonable, benign, and promising methodology for remediating heavy metals fed waterbodies. The contemporary study deals with isolating, screening, and characterizing heavy metal resistive bacteria from metal-rich sites. The transcriptome analysis reveals the identity of the isolated species as Bacillus pumilus and Bacillus cereus. Batch studies put forth the bioremoval results in designed conditions of different pH, concentration, dose, and time. The mechanistic actions are drawn using complementary techniques such as Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The theory of surface adsorption of lead (Pb(II)) and nickel (Ni(II)) is further fostered by the application of adsorption isotherms. The conducted studies establish the bacterial morphological stratagems and multifarious biochemical approaches for countering metallic ions of Pb(II) and Ni(II). The exhibition of significant removal results by the isolated bacterial strains in simulated water samples with remarkable proliferation rates has opened up its favorability for industrial platforms.

Neural-based modeling adsorption capacity of metal organic framework materials with application in wastewater treatment

We developed a computational-based model for simulating adsorption capacity of a novel layered double hydroxide (LDH) and metal organic framework (MOF) nanocomposite in separation of ions including Pb(II) and Cd(II) from aqueous solutions. The simulated adsorbent was a composite of UiO-66-(Zr)-(COOH)2 MOF grown onto the surface of functionalized Ni50-Co50-LDH sheets. This novel adsorbent showed high surface area for adsorption capacity, and was chosen to develop the model for study of ions removal using this adsorbent. A number of measured data was collected and used in the simulations via the artificial intelligence technique. Artificial neural network (ANN) technique was used for simulation of the data in which ion type and initial concentration of the ions in the feed was selected as the input variables to the neural network. The neural network was trained using the input data for simulation of the adsorption capacity. Two hidden layers with activation functions in form of linear and non-linear were designed for the construction of artificial neural network. The model's training and validation revealed high accuracy with statistical parameters of R2 equal to 0.99 for the fitting data. The trained ANN modeling showed that increasing the initial content of Pb(II) and Cd(II) ions led to a significant increment in the adsorption capacity (Qe) and Cd(II) had higher adsorption due to its strong interaction with the adsorbent surface. The neural model indicated superior predictive capability in simulation of the obtained data for removal of Pb(II) and Cd(II) from an aqueous solution.

Highly enhanced dye adsorption of MoO3 nanoplates fabricated by hydrothermal-calcination approach in presence of chitosan and thiourea

Water pollution by organic dyes poses great challenge to the environment and living organism. Hence effective removal of organic dyes by cost effective methods have received significant attention in recent years. Herein, we report the complete removal of organic dyes (rhodamine B), methylene blue) and eosin yellow) from water via effective adsorption by MoO₃ catalyst. Hydrothermally synthesised MoO₂ (1) and amorphous MoS_x (2) using ammonium molybdate without and with thiourea exhibited low dye adsorption. In contrast, crystalline micro/nanoplates of MoO₃ (3 and 4) obtained from calcination of 1 and 2 showed highly enhanced dye adsorption. Particularly 4 showed higher dye adsorption compared to 3. UV-Visible absorption studies confirmed complete removal of organic dyes upon stirring with MoO₃ catalyst. Dye removal studies further revealed that cationic dyes are adsorbed faster than anionic dye that could be attributed to the surface charge of MoO₃. Interestingly, the adsorbed dyes were not released from MoO₃ for more than 50 days. The exhausted MoO₃ catalyst can be recovered by annealing at 400 °C. MoO₃ catalyst has also been used as packing materials in dropper column and demonstrated effective removal of dyes by passing through dyes separately as well as mixture.

Ultrasonic Dyeing of Polyester Fabric with Azo Disperse Dyes Clubbed with Pyridonones and Its UV Protection Performance

The textile sector is closely linked to environmental pollution as a result of the use of toxic chemicals and their disposal in liquid waste, which negatively affects for the environment. Moreover, textile industries, especially wet processing, consume a large amount of energy, water, and chemical auxiliaries. Therefore, there is an urgent need to find a solution that takes the problem of environmental pollution into account. Considering ultrasound as an environmentally safe alternative for dyeing polyester fabrics with the disperse dyes that we have prepared before, the comparison between the ultrasonic dyeing method and conventional dyeing at low temperatures was investigated. Dye exhaustion on polyester fabrics and fastness properties such as the washing, rubbing, light, and perspiration of all of the dyed fabrics were performed by two dyeing methods. Additionally, the ultraviolet protection factors (UPF) for dyed polyester fabrics were evaluated.

Green Synthesis of Metallic Nanoparticles: Applications and Limitations

The past decade has witnessed a phenomenal rise in nanotechnology research due to its broad range of applications in diverse fields including food safety, transportation, sustainable energy, environmental science, catalysis, and medicine. The distinctive properties of nanomaterials (nano-sized particles in the range of 1 to 100 nm) make them uniquely suitable for such wide range of functions. The nanoparticles when manufactured using green synthesis methods are especially desirable being devoid of harsh operating conditions (high temperature and pressure), hazardous chemicals, or addition of external stabilizing or capping agents. Numerous plants and microorganisms are being experimented upon for an eco–friendly, cost–effective, and biologically safe process optimization. This review provides a comprehensive overview on the green synthesis of metallic NPs using plants and microorganisms, factors affecting the synthesis, and characterization of synthesized NPs. The potential applications of metal NPs in various sectors have also been highlighted along with the major challenges involved with respect to toxicity and translational research.

Adsorption of Crystal Violet Dye Using Activated Carbon of Lemon Wood and Activated Carbon/Fe3O4 Magnetic Nanocomposite from Aqueous Solutions: A Kinetic, Equilibrium and Thermodynamic Study

Activated carbon prepared from lemon (Citrus limon) wood (ACL) and ACL/Fe₃O₄ magnetic nanocomposite were effectively used to remove the cationic dye of crystal violet (CV) from aqueous solutions. The results showed that Fe₃O₄ nanoparticles were successfully placed in the structure of ACL and the produced nanocomposites showed superior magnetic properties. It was found that pH was the most effective parameter in the CV dye adsorption and pH of 9 gave the maximum adsorption efficiency of 93.5% and 98.3% for ACL and ACL/Fe₃O₄, respectively. The Dubinin–Radushkevich (D-R) and Langmuir models were selected to investigate the CV dye adsorption equilibrium behavior for ACL and ACL/Fe₃O₄, respectively. A maximum adsorption capacity of 23.6 and 35.3 mg/g was obtained for ACL and ACL/Fe₃O₄, respectively indicating superior adsorption capacity of Fe₃O₄ nanoparticles. The kinetic data of the adsorption process followed the pseudo-second order (PSO) kinetic model, indicating that chemical mechanisms may have an effect on the CV dye adsorption. The negative values obtained for Gibb’s free energy parameter (−20 < ΔG < 0 kJ/mol) showed that the adsorption process using both types of the adsorbents was physical. Moreover, the CV dye adsorption enthalpy (ΔH) values of −45.4 for ACL and −56.9 kJ/mol for ACL/Fe₃O₄ were obtained indicating that the adsorption process was exothermic. Overall, ACL and ACL/Fe₃O₄ magnetic nanocomposites provide a novel and effective type of adsorbents to remove CV dye from the aqueous solutions.

Ultrasound wave assisted removal of Ceftriaxone sodium in aqueous media with novel nano composite g-C3N4/MWCNT/Bi2WO6 based on CCD-RSM model

The aim of this study was ultrasound assisted removal of Ceftriaxone sodium (CS) based on CCD model. Using sonochemical synthesized Bi₂WO₆ implanted on graphitic carbon nitride/Multiwall carbon nanotube (g-C₃N₄/MWCNT/Bi₂WO₆). For this purpose g-C₃N₄/MWCNT/Bi₂WO₆ was synthesized and characterized using diverse approaches including XRD, FE-SEM, XPS, EDS, HRTEM, FT-IR. Then, the contribution of conventional variables including pH, CS concentration, adsorbent dosage and ultrasound contact time were studied by central composite design (CCD) under response surface methodology (RSM). ANOVA was employed to the variable factors, and the most desirable operational conditions mass provided. Drug adsorption yield of 98.85% obtained under these defined conditions. Through conducting five experiments, the proper prediction of the optimum point were examined. The respective results showed that RSD% was lower than 5% while the t-test confirmed the high quality of fitting. Langmuir isotherm equation fits the experimental data best and the removal followed pseudo-second order kinetics. The estimation of the experimentally obtained maximum adsorption capacities was 19.57 mg.g^- of g-C₃N₄/MWCNT/Bi₂WO₆ for CS. Boundary layer diffusion explained the mechanism of removal via intraparticle diffusion.

Mitigation of environmentally-related hazardous pollutants from water matrices using nanostructured materials - A review

An unprecedented rise in population growth and rapid worldwide industrial development are associated with the increasing discharge of a range of toxic and baleful compounds. These toxic pollutants including dyes, endocrine-disrupters, heavy metals, personal care products, and pharmaceuticals are destructing nature's balance and intensifying environmental toxicity at a disquieting rate. Therefore, finding better, novel and more environmentally sound approaches for wastewater remediation are of great importance. Nanoscale materials have opened up some new horizons in various fields of science and technology. Among a range of treatment technologies, nanostructured materials have recently received incredible interest as an emerging platform for wastewater remediation owing to their exceptional surface-area-to-volume ratio, unique electrical and chemical properties, quantum size effects, high scalability, and tunable surface functionalities. An array of nanomaterials including noble metal-based nanostructures, transition metal oxide nanomaterials, carbon-based nanomaterials, carbon nanotubes, and graphene/graphene oxide nanomaterials to their novel nanocomposites and nanoconjugates have been attempted as the promising catalysts to overcome environmental dilemmas. In this review, we summarized recent advances in nanostructured materials that are particularly engineered for the remediation of environmental contaminants. The toxicity of various classes of relevant tailored nanomaterials towards human health and the ecosystem along with perspectives is also presented. In our opinion, an overview of the up-to-date advancements on this emerging topic may provide new ideas and thoughts for engineering low-cost and highly-efficient nanostructured materials for the abatement of recalcitrant pollutants for a sustainable environment.

Adsorption onto MWCNTs Coupled with Cloud Point Extraction for Dye Removal from Aqueous Solutions: Optimization by Experimental Design

AIMS

The main aim of the study was to examine the feasibility and benefits of adsorption onto multi-walled carbon nanotubes (MWCNTs) coupled with cloud point extraction (CPE) for the removal of Rhodamine B (RB) from aqueous solutions.

BACKGROUND

MWCNTs offer the particular features of the ideal adsorbents for the organic dyes such as hollow tubular structure and specific surface area. Nevertheless, they suffer from the drawbacks of low dispersion in the aqueous solutions and separation inconvenience from the media. Cloud point extraction, combined with the adsorption onto MWCNTs can be a promising method to overcome the problems.

OBJECTIVE

In the study, adsorption onto MWCNTs coupled with CPE was applied for RB removal from aqueous solutions. The process was optimized by the response surface modeling method. Moreover, the applicability of the proposed method in the real sample analyses was investigated.

METHODS

MWCNTs were used as adsorbent and Triton X-100 (TX-100) as the nonionic surfactant for CPE process. The experiments were carried out based on a Box-Behnken design (BBD) with the input variables of MWCNTs dosage (0.6-1.2 mg), solution pH (3-9), clouding time (20-40 min) and TX-100 concentration (10-20 v/v%) using 5 mg L-1 RB solutions.

RESULT

Regression analyses resulted in a statistically significant quadratic model (R2=0.9718, F=24.96, p<0.0001) by which the optimum levels of the variables were predicted as: MWCNTs dosage of 0.7 mg, pH=3, clouding time of 39.9 minutes and TX-100 concentration of 19.91% (v/v). The predicted conditions were experimentally validated by achieving an RB removal of 94.24%.

CONCLUSION

Based on the results, the combination of the environmentally friendly technique of CPE with adsorption onto MWCNTs allows the efficient removal of RB from water samples and the method can be effectively optimized by the response surface modeling.

Capture of I131 from medical-based wastewater using the highly effective and recyclable adsorbent of g-C3N4 assembled with Mg-Co-Al-layered double hydroxide

This paper reports a very high capacity and recyclable Mg-Co-Al-layered double hydroxide@ g-C₃N₄ nanocomposite as the new adsorbent for remediation of radioisotope-containing medical-based solutions. In this work, a convenient solvothermal method was employed to synthesize a new nano-adsorbent, whose features were determined by energy dispersive X-ray (EDS/EDX), XRD, FESEM, TEM, TGA, BET, and FT-IR spectroscopy. The as-prepared nano-adsorbent was applied to capture the radioisotope iodine-131 mainly from the medical-based wastewater under different conditions of main influential parameters, (i.e. adsorbent dose, initial I₂ concentration, sonication time, and temperature). The process was evaluated by three models of RSM, CCD-ANFIS, and CCD-GRNN. Furthermore, comprehensive kinetic, isotherm, thermodynamic, reusability cycles and optimization (by GA and DF) studies were conducted to evaluate the behavior and adsorption mechanism of I₂ on the surface of Mg-Co-Al-LDH@ g-C₃N₄ nanocomposite. High removal efficiency (95.25%) of ¹³¹I in only 30 min (i.e. during 1/384 its half-life), along with an excellent capacity that has ever been reported (2200.70 mg/g) and recyclability (seven times without breakthrough in the efficiency), turns the nanocomposite to a very promising option in remediation of ¹³¹I-containing solutions. Besides, from the models studied, ANFIS described the process with the highest accuracy and reliability with R² > 0.999.

Ultrasonic-assisted recycling of Nile tilapia fish scale biowaste into low-cost nano-hydroxyapatite: Ultrasonic-assisted adsorption for Hg2+ removal from aqueous solution followed by "turn-off" fluorescent sensor based on Hg2+-graphene quantum dots

This study was planned to recycle calcium and the phosphorus-rich Nile tilapia fish scale biowaste into nano-hydroxyapatite (FHAP), using ultrasonic-assisted extraction of calcium and phosphorus from fish scales, which was optimized in term of extraction time, acid concentration, extraction temperature, and ultrasonic power. These two elements were determined simultaneously by inductively coupled plasma atomic emission spectrometry and the FHAP phase was formed upon addition of the extracted element solution in alkaline medium using homogenous precipitation assisted with ultrasound energy. The FHAP adsorbent was characterized by x-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller. A combination of FHAP and the ultrasonic method was then used to remove Hg²⁺ from aqueous solution. Four significant variables affecting Hg²⁺ removal, namely, adsorbent dosage, pH, ultrasonic power, and adsorption time, were studied. The results exhibited that the optimal conditions for maximizing the removal of Hg²⁺ were 0.02 g adsorbent dosage, pH 8, 0.4 kW ultrasonic power, 20 min adsorption time, and 30 °C adsorption temperature. The sorption mechanism of Hg²⁺ was revealed by isotherm modeling, indicating that FHAP adsorbent has a potential for Hg²⁺ removal in aqueous media with the maximum adsorption capacity being 227.27 mg g^-1. This adsorption behavior is in agreement with the Langmuir model as reflected by a satisfactory R² value of 0.9967, when the kinetics data were fitted with pseudo-second-order. Therefore, the FHAP could be an alternative adsorbent for the ultrasonic-assisted removal of Hg²⁺ at very high efficiency and within a very short period of time.

Trimethyl chitosan nanoparticles for ocular baicalein delivery: Preparation, optimization, in vitro evaluation, in vivo pharmacokinetic study and molecular dynamics simulation

To improve ocular bioavailability of baicalein (BAI), trimethyl chitosan coated lipid nanoparticles of baicalein (TMC-BAI-LNPs) were prepared, optimized and characterized. The properties of TMC-BAI-LNPs such as morphology, particle size, zeta potential and fourier transform infrared spectroscopy were investigated. Additionally, molecular dynamics simulation was applied as a new method to evaluate drug-biological membrane interactions. Transmission electron microscopy showed that the LNPs were approximately spherical in shape with a smooth surface. TMC-BAI-LNPs had a particle size of 162.8 nm, a positive surface charge with a zeta potential of 26.6 mV. The entrapment efficiency and drug loading values of BAI in the formulation were 90.65% and 2.04%, respectively. Moreover, in vitro drug release revealed that TMC-BAI-LNPs had a sustained release effect. In vivo studies indicated TMC-BAI-LNPs had no ocular irritation and the AUC of TMC-BAI-LNPs was 3.17-fold than that of the control (p < 0.01). Molecular dynamics simulation data showed that BAI had a poor membrane permeability, which limited the ocular bioavailability. The results indicated that TMC-BAI-LNPs might open up a new avenue for ocular administration. Furthermore, molecular dynamics simulation could predict permeability of drugs.

Synthesis of sewage sludge-based carbon/TiO2 /ZnO nanocomposite adsorbent for the removal of Ni(II), Cu(II), and chemical oxygen demands from aqueous solutions and industrial wastewater

The removal of heavy metal ions and organic materials from wastewater due to their toxicity is necessary. In the present study, the titanium dioxide/zinc oxide (TiO₂ /ZnO) nanocomposite has been coated on the sewage sludge carbon (SSC) surface and its application was investigated for the adsorption of Ni(II), Cu(II), and chemical oxygen demands (COD) reduction from aqueous solutions and industrial wastewaters in Eshtehard, Iran. The effect of adsorption parameters in a single system such as TiO₂ /ZnO ratio, TiO₂ /ZnO concentration, pH, adsorbent dosage, contact time, ionic strength, temperature, and initial concentrations of Ni(II), Cu(II), and COD was investigated on the adsorption capacity of synthesized SSC/TiO₂ /ZnO adsorbent. The pseudo-second order and Redlich-Peterson isotherm models were best described the kinetic and equilibrium data of Ni(II), Cu(II), and COD sorption. The maximum monolayer sorption capacities of Ni(II), Cu(II), and COD were found to be 62.3, 75.1, and 1,120.3 mg/g, respectively. The central composite design was used to investigate the interaction effects of pH and initial concentrations of Ni(II), Cu(II), and COD on the simultaneous removal of Ni(II), Cu(II), and COD from aqueous solutions in a ternary system. The potential of synthesized SSC/TiO₂ /ZnO adsorbent was investigated for Ni(II), Cu(II), and COD adsorption from industrial wastewaters of Iran. PRACTITIONER POINTS: The novel sewage sludge carbon/TiO₂ /ZnO adsorbent was synthesized. Adsorption of Ni(II), Cu(II), and chemical oxygen demands (COD) from industrial wastewaters was investigated. Maximum Ni(II), Cu(II), and COD sorption capacities were 62.3, 75.1, and 1,120.3 mg/g. Simultaneous removal of Ni(II), Cu(II), and COD was investigated in a ternary system.

Synthesis and application of hydrazono-imidazoline modified cellulose for selective separation of precious metals from geological samples

A new hydrazono-imidazoline modified cellulose (HIMC) was synthesized for selective recovery of Pt(IV), Pd(II) and Au(III) from geological samples. Cellulose was oxidized by periodate and was further functionalized with hydrazono-imidazoline moieties to afford N-donor chelating fibers. Scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), N₂ physisorption, elemental analysis, and energy-dispersive X-ray spectroscopy (EDX) were used for characterization. Introducing the hydrazono-imidazoline groups at the surface of cellulose fibers did not alert their ordered structure and crystallinity, as indicated by XRD and SEM results. Factors affecting the adsorption were systematically investigated. Under the optimized conditions, the HIMC sorbent exhibited high adsorption capacities of 105, 88 and 75 mg g^-1 for Pt(IV), Pd(II) and Au(III), respectively. Besides, the metal ion adsorption process fitted by pseudo-second-order kinetic model and Langmuir adsorption isotherm. These results highlight the applicability of this carbohydrate-based sorbent for the selective recovery of precious metals from various matrices.

Purification of Forest Clear-Cut Runoff Water Using Biochar: A Meso-Scale Laboratory Column Experiment

Biochar can be an effective sorbent material for removal of nutrients from water due to its high specific surface area, porous structure, and high cation and anion exchange capacity. The aim of this study was to test a biochar reactor and to evaluate its efficiency in runoff water purification and consecutive nutrient recycling in clear-cut peatland forests. The goodness of the method was tested in a meso-scale (water volume thousands of liters) reactor experiment by circulating runoff water through wood biochar-filled columns and by determining water nutrient concentrations in the column inlet and outlet. The pseudo-first and second order kinetic models were fitted to the experimental data and the adsorption rate (Kad) and maximum adsorption capacity (Qmax) of the biochar reactor were quantified. The concentration of total nitrogen (TN) decreased by 58% during the 8-week experiment; the majority of TN adsorption occurred within the first 3 days. In addition, NO3-N and NH4-N concentrations decreased below the detection limit in 5 days after the beginning of the experiment. The maximum adsorption capacity of the biochar reactor varied between 0.03–0.04 mg g−1 biochar for NH4-N, and was equal to 0.02 mg g−1 biochar for TN. The results demonstrated that the biochar reactor was not able to adsorb TN when the water TN concentration was below 0.4 mg L−1. These results suggest that a biochar reactor can be a useful and effective method for runoff water purification in clear-cut forests and further development and testing is warranted. Unlike traditional water protection methods in peatland forestry, the biochar reactor can effectively remove NO3-N from water. This makes the biochar reactor a promising water protection tool to be tested in sites where there is the risk of a high rate of nutrient export after forest harvesting or drainage.

Nano-engineered Adsorbent for the Removal of Dyes from Water: A Review

Background:

The huge quantity of wastewater, containing poisonous and hazardous dyes, is released by various industries which pollute water in direct and indirect ways. Most of the dyes are a dangerous class of water contaminants which have affected the environment drastically. Some dyes such as congo red, rhodamine B, methylene blue, methyl violet, and crystal violet are a serious threat to human beings.

Remediation Method:

Numerous methods are available for the removal of dyes from water. Adsorption, being a superior and eco-friendly technique, has advantage of eliminating organic dyes because of the availability of materials as adsorbents. The inexpensive nanomaterials are a more attractive choice for remediation of various dyes due to their unique properties and offer an adequate pathway to adsorb any organic dye from water to overcome its hazardous effects on human health.

Results:

In this review, we have discussed the latest literature related to various types of synthesis, characterization and uses as adsorbent for highly adsorptive removal capacity of nanoparticles for organic dyes.

Conclusion:

Adsorption technology provides an attractive pathway for further research and improvement in more efficient nanoparticles, with higher adsorption capacity, for numerous dyes to eliminate the dyes discharged from various industries and thus reduce the contamination of water. Therefore, nanocomposites may contribute to future prospective water treatment process.

Synthesis and application of Ce-doped TiO2 nanoparticles loaded on activated carbon for ultrasound-assisted adsorption of Basic Red 46 dye

Ce was doped on TiO₂ nanoparticles (NPs), and this association was loaded on activated carbon (Ce-TiO₂-NPs-AC). The characterization was completed by FE-SEM, TEM, and XRD, and finally these NPs were used for the ultrasonic-assisted adsorption of Basic Red 46 (BR 46) from aqueous solution. An experimental model suggested by the central composite design (CCD)-as a branch of response surface methodology (RSM)-provides insight into the influence of variables, such as BR 46 concentration, pH, adsorbent mass, and sonication time, on BR 46 removal. Experimental results revealed that setting conditions at 25 mg L^-1 of BR 46, pH 5.0, 0.02 g of Ce-TiO₂-NPs-AC and 4 min sonication resulted in a high coefficient of determination (R² > 0.99) and low probability values. The difference in the values is likely due to the accumulation of more than 99% of BR 46, while equilibrium data described by Langmuir isotherm model with a high adsorption capacity of 58.61 mg g^-1 and adsorption process were successfully correlated with pseudo-second-order kinetics model.

Advanced TiO2-SiO2-Sulfur (Ti-Si-S) Nanohybrid Materials: Potential Adsorbent for the Remediation of Contaminated Wastewater

In this present work, TiO₂-SiO₂-sulfur (Ti-Si-S) nanohybrid material was successfully prepared using TiO₂ nano powder, TEOS sol-gel precursor, and elemental sulfur as raw material by sol-gel process and hydrothermal method at 120 °C temperature. Raman spectroscopy, XRD, SEM, TEM, and N₂ absorption-desorption characterized the synthesized nanohybrid material. The characterization results confirmed the homogeneous distribution of sulfur in the nanohybrid material. The size of the Ti-Si-S nanohybrid material is vary between 20 and 40 nm and the surface areas of the nanohybrid material was measured using N₂ absorption-desorption, which showed value of 57.2 m² g^-1. The potential of Ti-Si-S nanohybrid material as an adsorbent was further tested to adsorb methylene blue (MB) from aqueous solution. Adsorption performance of hybrid material was highly influenced by the solution pH and mass of adsorbent. The adsorption of MB using Ti-Si-S nanohybrid material was homogeneous monolayer adsorption, which followed the Langmuir adsorption isotherm with a q_e,max value of 804.80 mg g^-1 and pseudo-second-order rate equation. The dye diffusion mechanism partially followed both intraparticle and liquid film diffusion mechanisms. Thermodynamics studies predicted the spontaneous and endothermic nature of the whole adsorption process. The Ti-Si-S nanohybrid material was used for six repeated cycles of MB dye adsorption-desorption.

Enhancement of organic pollutants bio-decontamination from aqueous solution using newly-designed Pseudomonas putida-GA/MIL-100(Fe) bio-nanocomposites

As a natural adsorption material, graphene has become a hot research topic in water treatment due to its unique framework, large surface area, low cost, and simple preparation. Here, a series of composite material aerogels (GA/MIL-100(Fe)) consisting of Fe metal-organic frameworks (MIL-100 (Fe)) and graphene-based aerogel (GA) were prepared through a hydrothermal and step-by-step strategy and used for the adsorption of an azo dye in wastewater, scilicet acid orange 10 (AO10). The adsorption equilibrium of AO10 solutions with concentrations of 50 and 100 mg/L was reached within 45 min but the dye could not be fully removed. Besides, the synthesized composite material (GA/MIL-100(Fe)) was a good carrier for immobilized Pseudomonas putida cells due to its good biocompatibility and non-toxicity. A new, environmentally friendly adsorption and biodegradation process has been exploited here, which was to immobilize bacterial cells to the surface of GA/MIL-100(Fe) by a covalent bonding method to form a novel biocomposite material. The material could be used to completely remove AO10 dyes in 14 and 26 h from solutions with initial AO10 concentrations of 50 and 100 mg/L, respectively. This way of combining biological and physical adsorption has a higher processing efficiency and shows huge potential for the treatment of industrial wastewater.

Modeling and optimization of V2O5/TiO2 nanocatalysts for NH3-Selective catalytic reduction (SCR) of NOx by RSM and ANN techniques

In the present study, two statistical methods including the response surface method (RSM) and artificial neural network (ANN), were employed for modeling and optimization of selective catalytic reduction of NOx with NH₃ (NH₃-SCR) over V₂O₅/TiO₂ nanocatalysts. The relationship between catalyst preparation variables, such as metal loading, impregnation temperature, and calcination temperature on NO conversion were investigated. The R² value of 0.9898 was obtained for quadratic a RSM model, which proves the high agreement of the model with the experimental data. The results of Pareto analysis revealed that three factors including calcination temperature, V loading, and impregnation temperature have a considerable impact on the response. Deduced from the established RSM model, the order of influence on the NO conversion was as follows: calcination followed by V loading and impregnation temperature. The optimum condition of catalyst preparation for maximum NO conversion over V₂O₅/TiO₂ nanocatalysts was predicted to be at 0.0051 mol of V loading, an impregnation temperature of 50 °C and a calcination temperature of 491 °C. Moreover, an ANN model was created by a feed-forward back propagation network (with the topology 4, 12 and 1) to model the relation between the selected catalyst preparation variables and NH₃-SCR process temperature. The R² values for training, validation as well as test sets, were 0.99, 0.9810 and 0.9733. These high values proved the accuracy of the AAN model in modeling and estimating the NO conversion over V₂O₅/TiO₂ nanocatalysts. According to the ANN model, the relative significance of each variable on NO conversion is calcination temperature, process temperature loading, and impregnation temperature from high to low importance, respectively, corroborating the obtained results from RSM.

Modified Leach Residues from Processing Deep-Sea Nodules as Effective Heavy Metals Adsorbents

The possible use of leaching residue from leaching deep-sea nodules in SO2/H2SO4/H2O medium as a low-cost adsorbent of heavy metals (Pb(II), Cd(II), Cu(II), Ni(II), Co(II), As(V)) was studied. The leaching residue was found to be an effective adsorbent for all of the tested elements; however, it was inactive in the solution containing As(V). The chemical activation of adsorbent in 10 vol. % HCl resulted in the greatest improvement of adsorption properties, while the activation in 10 vol. % HNO3 and heat treatment at 250 °C did not significantly affect the sorption characteristics of treated adsorbents compared with the original leaching residue. After HCl activation, the maximal adsorption capacities for lead (12.0 mg/g at pH 5.0 after 1 h), nickel (3.1 mg/g at pH 5.5 after 4 h) and cobalt (2.0 mg/g at pH 5.0 after 2 h) were achieved. Additional mechanical treatment connected with HCl activation provided the highest adsorption capacities for cadmium (11.5 mg/g at pH 4.0) and copper (5.7 mg/g at pH 4.5). Coprecipitation of Fe/Al-based particles on the surface of the leaching residue increased As(V) removal of the adsorbent. Surface coating based on AlIII was extremely effective, causing the increase of the adsorption capacity from 0 with the original leaching residue, to 28.1 mg/g (pH 7.0, 24 min). Kinetics studies showed the rapid progress of adsorption for Pb(II), Cd(II), and As(V) in tens of minutes, while the adsorption of Cu(II), Ni(II) and Co(II) approached a steady state after 2 h.

Adsorption of Congo Red (Acid Red 28) Azodye on Biosynthesized Copper Oxide Nanoparticles

A green synthesis of copper oxide nanoparticles and its removal efficiency of azodye were studied. Biosynthesis of stable copper oxide nanoparticles were preformed using Aloe barbadensis leaf extract as a size and shape-directing agent for preparing of spherical copper oxide nanoparticles by calcination at 400 °C. The leaf extract of Aloe barbadensis was prepared in deionized water. The produced copper particles were calcined at 400 °C to produce copper oxide nanoparticles. The characterization of copper oxide nanoparticles was performed by XRD, SEM, FTIR, UV spectroscopy. The XRD analysis showed that the average particle size was between 5-30 nm. The shape of the copper oxide nanoparticles was spherical and cubic. EDX of the synthesized nanoparticles showed the composition consists of 68 % copper. The UV-visible spectrum analysis confirms an absorption peak at 200-400 nm of the produced CuO nanoparticles. The FTIR analysis of the copper oxide particles indicate the presence of the organometallic Cu-O bond between Cu and O. The obtained copper oxide was used as a removing agent of Congo red dye. The effect of variables like concentration, time, pH, adsorbent dosage were studied. It was observed from the results that the maximum dye removal occurs at pH of 4, the concentration of nanoparticles was 1 mg/L and the maximum time for dye removal was 120 min. The Langmuir isotherm model was calculated to study the adsorption efficiency of the Congo red dye on the produced copper oxide nanoparticles. The kinetics of pseudo second order is followed by adsorption. The calculated sum of square was 0.012 and r2 = 0.98. it was observed that the model fit the best and straight line with r2 value of 0.991 and probability value of 1.6E-5. The nanoparticles remove 70 % of the Congo red dye from its solution. This showed that the copper oxide nanoparticles has efficient capacity of azodye degradation.

Synthesis of Poly(AN-co-VP)/Zeolite Composite and Its Application for the Removal of Brilliant Green by Adsorption Process: Kinetics, Isotherms, and Experimental Design

In this study, a poly(acrylonitrile-co-N-vinyl pyrrolidone)/zeolite (poly(AN-co-VP)/zeolite) composite was synthesized by in situ free radical polymerization (FRP). The structural properties of the composite were analyzed by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The characterization results indicated that the composite had a homogeneous and 3-dimensional (3D) structure. The decomposition temperature and glass transition temperature (Tg) were found as 410°C and 152°C, respectively. A poly(AN-co-VP)/zeolite composite was used to investigate the adsorption of brilliant green (BG) which is a water-soluble cationic dye. The kinetics, isotherms, and thermodynamics of adsorption were examined, and results showed that equilibrium data fitted the Langmuir isotherm model, and the adsorption kinetics of BG followed pseudo-second-order model. According to the thermodynamic properties, the adsorption process was endothermic and spontaneous. Response surface methodology (RSM), which was improved by the application of the quadratic model associated with the central composite design, was employed for the optimization of the study conditions such as adsorbent mass, time, and initial dye concentration. The RSM indicated that maximum BG removal (99.91%) was achieved at the adsorbent mass of 0.20 g/50 mL, an initial BG concentration of 40.20 mg/L, and a contact time of 121.60 minutes.

Ultrasound combined with manganese-oxide nanoparticles loaded on activated carbon for extraction and pre-concentration of thymol and carvacrol in methanolic extracts of Thymus daenensis, Salvia officinalis, Stachys pilifera, Satureja khuzistanica, and mentha, and water samples

A dispersive micro solid-phase extraction (DMSPE) technique was developed using manganese-oxide nanoparticles loaded on activated carbon (Mn₃O₄-NPs-AC) as an effective sorbent combined with ultrasound for the extraction and determination of a trace amount of thymol and carvacrol in methanolic extracts of Thymus daenensis, Salvia officinalis, Stachys pilifera, Satureja khuzistanica and mentha, and water samples.

β-Cyclodextrin modified electrospinning fibers with good regeneration for efficient temperature-enhanced adsorption of crystal violet

Novel β-cyclodextrin modified fibers with highly insoluble infraction and temperature enhanced adsorption performance were fabricated via electrospinning technology and followed thermo-crosslinking. The fabricated fibers were characterized by FT-IR, ¹H NMR, TGA and SEM. In the fibers, β-CD was crosslinked with methacrylic acid (MAA) units to maintain morphologies of fibers and further be utilized for the adsorption of Crystal Violet through complex and electrostatic interaction. In particular, N-isopropyl acrylamide (NIPAM) units were introduced to create thermo-responsively hydrophobic internal cavity within the swelling fibers at high temperatures. Benefiting from that, the maximum adsorption amount could reach to 1253.78 mg g^-1, enhanced by 20% than that at low temperatures. The adsorption data of the fibers fit well the pseudo-second-order model and Langmuir isotherm model. Moreover, the fibers could maintain high regeneration efficiency even after four adsorption-desorption cycles. These results indicated the practical application values of the β-cyclodextrin modified fibers in the dye wastewater treatment field.

Decolorization of crystal violet from aqueous solutions by a novel adsorbent chitosan/nanodiopside using response surface methodology and artificial neural network-genetic algorithm

A novel adsorbent of chitosan/nanodiopside nanocomposite (CS-NDIO) was synthesized as a green composite for the removal of crystal violet (CV) and characterized by techniques like XRD, FT-IR, BET, and FESEM analysis. The influence of parameters like molar ratios of CS to NDIO, initial pH of the solution, dosage of adsorbent, initial concentration of CV and contact time was investigated and evaluated by central composite design (CCD; 5 levels and 4 factors). Also, Hybrid model of (ANN) model with genetic algorithm (GA) optimization was applied to the experimental data get through CCD. The optimized molar ratio of CS-NDIO was found: 20/80. Optimal parameter choice for maximum CV adsorption process using CCD and ANN-GA were as follows: pH = 7.50 and 7.499, adsorbent mass: 0.0077 and 0.0077 g, CV concentration: 20.000 and 20.002 mg/L, and contact time: 25.00 and 25.00 min, respectively. The evaluation adsorption equilibrium and kinetic data were fitted with the Langmuir monolayer isotherm model (q_max: 104.66 mg g^-1 and R²: 0.9937) and pseudo-second order kinetics mechanism (R²: 0.9978). Thermodynamic parameters (R²: 0.9180, ΔH°: -74.93 kJ mol^-1, ΔG°: -12.89 kJ mol^-1, and ΔS°: 0.93 kJ mol^-1 K^-1) were calculated and indicating adsorption to be an exothermic and spontaneous process.

Cavitation-Dispersion Method for Copper Cementation from Wastewater by Iron Powder

The circular economy for sustainable economic deployment is strongly based on the re-use of secondary products and waste utilization. In the present study, a new effective cementation method for recovering valuable metallic copper from industrial wastewater using Fe0 powders is reported. A high-speed mixer-disperser (HSMD) capable of providing a cavitation effect was used for the rapid intake, dispersion, and mixing of Fe0 powder in an acidic wastewater solution (pH ≈ 2.9) containing copper ions mainly in the form of CuSO4. Three iron powders/particles were tested as the cementation agent: particles collected from industrial dust filters (CMS), water-atomized iron-based powder AHC100.29, and sponge-iron powder NC100.24. The effects of mixing regimes and related mixing conditions on the effectiveness of the Cu cementation process were evaluated by comparison between the HSMD and a laboratory paddle mixer. It was observed that the use of cavitation provided more efficient copper removal during the copper cementation process in comparison to the standard experiments with the propeller mixer. Under the cavitation regime, about 90% of copper was cemented in the first five minutes and the final copper removal of 95% was achieved using all three Fe0 powders after seven minutes of cementation. In comparison, only around 55% of copper was cemented in the first seven minutes of cementation using the traditional mixing method.