Development of Ni(II) resistant S. cerevisiae and its application: Adsorption study and modeling

The study aims to develop Ni(II) resistant Saccharomyces cerevisiae to decontaminate high Ni(II) concentrations from an aqueous system. Initially, two different microorganisms were taken: Bacillus circulans MTCC 3161, Saccharomyces cerevisiae. For these two strains, the experiments were carried out for successive screening for survival/tolerance, minimum inhibitory concentration (MIC), and biosorption capacity for Ni(II) from an aqueous solution. Ni(II) resistant Saccharomyces cerevisiae AJ208 showed a MIC of 5500 mg/L for Ni(II). Nucleotide sequences of Saccharomyces cerevisiae AJ208 were deposited in the Gene bank. All experiments were conducted to determine the effects of various physical conditions, such as pH, age and volume of inoculum, temperature, and incubation time, the volume of fermentation medium. The characterization of the Saccharomyces cerevisiae AJ208 was carried out using SEM-EDAX, FTIR. The Langmuir isotherm and pseudo-second-order kinetic models are well fitted with the experimental data. The Langmuir maximum adsorption capacity is 170.06 mg/g. The thermodynamic studies showed the mechanism of Ni(II) removal is an endothermic and spontaneous reaction. The experimental data have been analyzed using statistical method (MLR) and Genetic algorithm (GA). This study reports the highest Ni(II) resistant Saccharomyces cerevisiae AJ208 (5000 mg/L) and also the feasibility of Ni(II) removal from 3000 mg/L initial Ni(II) concentration into an aqueous solution, which could be of great interest as a potential reference strain for Ni(II) removal.

A comprehensive assessment of Yarrowia lipolytica and its interactions with metals: Current updates and future prospective

The non-conventional yeast Yarrowia lipolytica has been popular as a model system for understanding biological processes such as dimorphism and lipid accumulation. The organism can efficiently utilize hydrophobic substrates (hydrocarbons and triglycerides) thereby rendering it relevant in bioremediation of oil polluted environments. The current review focuses on the interactions of this fungus with metal pollutants and its potential application in bioremediation of metal contaminated locales. This fungus is intrinsically equipped with a variety of physiological and biochemical features that enable it to tide over stress conditions induced by the presence of metals. Production of enzymes such as phosphatases, reductases and superoxide dismutases are worth a special mention. In the presence of metals, levels of inherently produced metal binding proteins (metallothioneins) and the pigment melanin are seen to be elevated. Morphological alterations with respect to biofilm formation and dimorphic transition from yeast to mycelial form are also induced by certain metals. The biomass of Y. lipolytica is inherently important as a biosorbent and cell surface modification, process optimization or whole cell immobilization techniques have aided in improving this capability. In the presence of metals such as mercury, cadmium, copper and uranium, the culture forms nanoparticulate deposits. In addition, on account of its intrinsic reductive ability, Y. lipolytica is being exploited for synthesizing nanoparticles of gold, silver, cadmium and selenium with applications as antimicrobial compounds, location agents for bioimaging and as feed supplements. This versatile organism thus has great potential in interacting with various metals and addressing problems related to their pollutant status.

Sustainable and efficient technologies for removal and recovery of toxic and valuable metals from wastewater: Recent progress, challenges, and future perspectives

Due to their numerous effects on human health and the natural environment, water contamination with heavy metals and metalloids, caused by their extensive use in various technologies and industrial applications, continues to be a huge ecological issue that needs to be urgently tackled. Additionally, within the circular economy management framework, the recovery and recycling of metals-based waste as high value-added products (VAPs) is of great interest, owing to their high cost and the continuous depletion of their reserves and natural sources. This paper reviews the state-of-the-art technologies developed for the removal and recovery of metal pollutants from wastewater by providing an in-depth understanding of their remediation mechanisms, while analyzing and critically discussing the recent key advances regarding these treatment methods, their practical implementation and integration, as well as evaluating their advantages and remaining limitations. Herein, various treatment techniques are covered, including adsorption, reduction/oxidation, ion exchange, membrane separation technologies, solvents extraction, chemical precipitation/co-precipitation, coagulation-flocculation, flotation, and bioremediation. A particular emphasis is placed on full recovery of the captured metal pollutants in various reusable forms as metal-based VAPs, mainly as solid precipitates, which is a powerful tool that offers substantial enhancement of the remediation processes' sustainability and cost-effectiveness. At the end, we have identified some prospective research directions for future work on this topic, while presenting some recommendations that can promote sustainability and economic feasibility of the existing treatment technologies.

Utility of 5-(2',4'-dimethylphenylazo)-6-hydroxy-pyrimidine-2,4-dione in PVC membrane for a novel green optical chemical sensor to detect zinc ion in environmental samples

In plasticized (2-nitro-phenyloctyl ether (o-NPOE)) and polyvinyl chloride (PVC) membrane incorporating (N,N-diethyl-5-(octadecanoylimino)-5H-benzo[a] phenolxazine-9-amine (ETH 5294) and sodium tetraphenyl borate (NaTPB), an ionophore 5-(2',4'-dimethylphenylazo)-6-hydroxy-pyrimidine-2,4-dione (DMPAHPD) form an optical chemical sensor for zinc determination is ascribed. The sensor response is based on selective complexation of Zn²⁺ with DMPAHPD in the designed membrane phase, resulting in an ion exchange process between H⁺ in the membrane and Zn²⁺ in the sample solution. The influences of several experimental parameters, as membrane composition, pH, and type and concentration of the regenerating reagent, were demonstrated. The sensor has a response range of 5.0 × 10^-9 to 2.5 × 10^-5 M Zn²⁺ with detection and quantification limits of 1.6 × 10^-9 and 4.9 × 10^-9 M, respectively. The response time of 1 min at 0.1 M phosphate buffer solution of pH 5.0 with recording repeatability and sensor-to sensor reproducibility is reported. The proposed sensor signifies high selectivity for Zn²⁺ over various transition metal ions, alkali, and alkaline earth ions. The sensor membrane can be simply regenerated with 0.5 M HNO₃. The sensor has been used to assess Zn²⁺ in river, waste, tap, sea, well, and spring waters samples, serum of diabetic patients, powdered milk, hair, red meat, pharmaceutical formulations, and talc powder samples.

A novel artificial intelligent model for predicting water treatment efficiency of various biochar systems based on artificial neural network and queuing search algorithm

This study aims at providing a robust artificial intelligent model for predicting the efficiency of heavy metal removal from aqueous solutions of biochar systems with high accuracy and reliability. Not only is it environmentally significant, but it is also a powerful tool for improving biochar adsorption efficiency, reducing the risk of a global water shortage. Accordingly, 22 types of biomass feedstock with a total of 44 biochar systems and 353 experiments, aiming to remove six heavy metal ions (i.e., Cu²⁺, Pb²⁺, Zn²⁺, As³⁺, Cd²⁺, and Ni²⁺) from water were considered and evaluated. Subsequently, an artificial neural network (ANN) model was designed for predicting the heavy metal adsorption efficiency onto these biochar systems. To improve the accuracy of the ANN model, the queuing search algorithm (QSA), a human activities-based algorithm, was applied, aiming to optimize the parameters of the developed ANN model, called the QSA-ANN model. The results showed that the proposed optimization QSA-ANN model provided high accuracy with a root-mean-squared error (RMSE) of 0.051 and 0.074; determination coefficient (R²) of 0.978 and 0.960; variance accounted for (VAF) of 97.707 and 95.882, for the training and testing phases, respectively. Compared to the traditional ANN model, the accuracy of the proposed optimization QSA-ANN model was improved 2.7% on the training dataset and 2.9% on the testing dataset. With an accuracy of 96% in practice, the proposed optimization QSA-ANN model was recommended for practical engineering to predict and improve heavy metal adsorption efficiency onto biochar systems.

Application of neural network in metal adsorption using biomaterials (BMs): a review

ANN models for predicting wastewater treatment efficacy of biomaterial adsorbents.

High Catalytic Activity of Fluorophore-Labeled Y-Shaped DNAzyme/3D MOF-MoS2NBs as a Versatile Biosensing Platform for the Simultaneous Detection of Hg2+, Ni2+, and Ag+ Ions

In this study, we have designed a three-fluorophore-labeled Y-shaped DNAzyme with a high catalytic cleavage activity and a three-dimensional (3D) MOF-MoS₂NB (metal-organic framework fused with molybdenum disulfide nanobox), which was synthesized as an efficient quencher of the fluorescent biosensor. The synthesized porous 3D MOF-MoS₂NBs and Y-shaped DNAzyme exhibited a good analytical response toward the simultaneous multiple detections of Hg²⁺, Ni²⁺, and Ag⁺ ions over the other coexisting metal ions. More specifically, the three kinds of enzyme aptamer and substrate aptamer (SA) were hybridized and annealed to form the Y-shaped DNAzyme structure and labeled with three different fluorophores such as FAM, TAMRA, and ROX over the 3'-end of SA. When the targets were induced, the DNAzyme was triggered to cleave the fluorophore-labeled SAs. Then, the cleaved SAs (FAM-SA, TAMRA-SA, and ROX-SA) were adsorbed on the 3D MOF-MoS₂NB surface to quench the fluorescence signal due to a noncovalent interaction (van der Waals and π-π stacking interaction), which transmuted the fluorescence on-state to off-state. As a result, the fluorescence assay confiscated the high selectivity and sensitivity for the target analytes of Hg²⁺, Ni²⁺, and Ag⁺ ions achieved for the detection limits of 0.11 nM, 7.8 μM, and 0.25 nM, respectively. Accordingly, the sensitivity of the developed sensor was explored with a better lower detection limit than the previously reported biosensors. The utility of the designed Y-shaped DNAzyme may find a broad field of application in real water sample analysis with interfering contaminants.

Potentiality of living Bacillus pumilus SWU7-1 in biosorption of strontium radionuclide

Bacillus pumilus SWU7-1 was isolated from strontium ion (Sr(II))-uncontaminated soil, its biosorption potential was evaluated, and the effect of γ-ray radiation treatment on its biosorption was discussed. Domesticated under Sr(II) stress promoted the biosorption ability of B. pumilus to Sr(II), and the biosorption efficiency increased from 46.09% to 94.69%. At a lower initial concentration, the living bacteria had the ability to resist the biosorption of Sr(II). The optimal initial concentration range was 54-130 mg/L. The biosorption profile was better matched by Langmuir than Freundlich model, showing that the biosorption process of Sr(II) by the experimental strain was closer to the surface adsorption. According to Langmuir model, the maximum biosorption capacity of B. pumilus on Sr (II) was 299.4 mg/g. During the bacterial growth in the biosorption process, the changes in biosorption capacity and efficiency can be divided into two phases, and a pseudo-second-order model is followed in each phase. There was no significant difference in the biosorption efficiency of bacteria with different culture time after γ-ray radiation, and all of them were above 90%, which showed that B. pumilus had significant radiation resistance under experimental conditions. This study emphasized the potential application of B. pumilus in the treatment of radioactive Sr(II) pollution by biosorption.

Optimization and Experimental Design of the Pb2+ Adsorption Process on a Nano-Fe3O4-Based Adsorbent Using the Response Surface Methodology

Magnetic Fe3O4 nanoparticles have been used as adsorbents for the removal of heavy-metal ions. In this study, optimization of the Pb2+ adsorption process using Fe3O4 has been investigated. The adsorbent was characterized by various techniques such as transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and Brunauer-Emmett-Teller (BET) analysis. The influence of process variables on adsorption of Pb2+ ions in accordance with p < 0.05 was investigated and analyzed by the Box-Behnken design (BBD) matrix with five variables (pH, adsorbent dose, initial Pb2+ ion concentration, contact time, and temperature). The pH and temperature were observed to be the most significant parameters that affected the Pb2+ ion adsorption capacity from the analysis of variance (ANOVA). Conduction of 46 experiments according to BBD and a subsequent analysis of variance (ANOVA) provide information in an empirical equation for the expected response. However, a quadratic correlation was established to calculate the optimum conditions, and it was found that the R 2 value (0.99) is in good agreement with adjusted R 2 (0.98). The optimum process value of variables obtained by numerical optimization corresponds to pH 6, an adsorbent dose of 10 mg, and an initial Pb2+ ion concentration of 110 mg L-1 in 40 min at 40 °C adsorption temperature. A maximum of 98.4% adsorption efficiency was achieved under optimum conditions. Furthermore, the presented model with an F value of 176.7 could adequately predict the response and give appropriate information to scale up the process.

The sorbed mechanisms of engineering magnetic biochar composites on arsenic in aqueous solution

The aim of this study was to produce magnetic biochar for the removal of As (III) from the aquatic environment. Magnetic biochar (MBC) was prepared from corn straw‑derived biochar. Pristine biochar (BC) was impregnated with iron oxide and relative analyses were performed on the adsorption capacity of BC's and MBC's. After impregnation, the specific surface area of MBC800-0.6₃₀₀ increased from 79.66 to 309.7 m² g^-1 and superparamagnetic magnetization was about 9.75 emu g^-1 contributed by the contained Fe₃O₄. Results of MBC800-0.6₃₀₀ showed maximum adsorption capacity (Q_max) 22.94 mg g^-1 for As (III) based on Langmuir model which is 5.71 times higher than the adsorption capacity of BC800 (4.02 mg g^-1). The adsorption of As (III) increased significantly due to the successful loading of iron oxide and the increased oxygen functional groups that were confirmed by XPS and FTIR results. The removal of As (III) followed Langmuir isotherm model and pseudo-second-order (R² ≥ 0.99), indicated that the adsorption rate was monolayer and depended on the chemical adsorption process, respectively. Consequently, the simple preparation procedure and high adsorption performance suggest that MBC800-0.6₃₀₀ could be used as an environment-friendly and extremely effective adsorbent for As (III) removal from aqueous environment.

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.

Adsorption of low concentrations of bromide ions from water by cellulose-based beads modified with TEMPO-mediated oxidation and Fe(III) complexation

Due to strong activity, it is very difficult to remove low concentrations of bromide in medical wastewater by traditional method, thus highly effective and greener adsorbents should be utilized to design. In this work, the cellulose beads (CBs) were modified by the TEMPO-mediated oxidation and then bonded with Fe³⁺ to fabricate Fe(III)-complexed carboxylated cellulose beads (Fe-CCBs) adsorbents. Structure and properties of Fe-CCBs were analyzed using Energy dispersive spectrum (EDS), Scanning electron microscopy (SEM), Fourier transform infrared spectrum (FT-IR), total acidity and basicity groups, X-ray diffraction (XRD), N₂ adsorption-desorption and Thermogravimetric (TGA). Moreover, batch adsorption experiments showed that the adsorption of Br^- was better consistent with general-order kinetic model and Liu isotherm model, which could also further clarify the adsorption process mechanism. Meanwhile, the results revealed that removal of Br- was a spontaneous exothermic process and was more suitable to be carried out under neutral or acidic conditions. Furthermore, the mechanism of adsorption behavior of bromide ions on Fe-CCBs was based on a combination of electrostatic attraction and outer-sphere complexation. The results of this study can provide guidance for the design of novel material adsorbents and the removal of harmful anions from aqueous solutions.

Iron oxide Permeated Mesoporous rice-husk nanobiochar (IPMN) mediated removal of dissolved arsenic (As): Chemometric modelling and adsorption dynamics

Adsorption based technologies are most widely used to mitigate the global predominance of heavy-metal groundwater contaminants like Arsenic (As), owing to their high efficiency and economic operation. The current study involves the optimization of Iron oxide Permeated Mesoporous rice-husk nanobiochars (IPMN) for As removal, which were synthesized through a chemically amended pyrolytic approach. The IPMN variants were screened based on preliminary OVAT (one-variable-at-a-time) studies for As removal. Chemometric investigations employing a central composite design matrix of Response surface methodology was further used to understand the influence of the process parameters on the adsorption of As on the most efficient IPMN variant. A Multi-Layered-Perceptron based artificial neural network was further used to confirm the veracity of the experimental and predictive conditions, to derive the optimal condition for the best adsorption efficiency. In addition, the dynamics of As adsorption by the optimal IPMN variant was modelled using pseudo-first-order (Lagergren) and pseudo-second-order (Ho) rate kinetic equations followed by isotherm studies using non-linear regression of Langmuir, Freundlich and Sips adsorption isotherms. The IPMNs have an appreciably higher uptake capacity (>90%) for dissolved As, as compared to the native milled rice husk (∼20%), alongside a substantial recyclability, thereby establishing their potential as a highly efficient, economical and sustainable nanobiochar for As removal.

Development of Two novel silica based symmetric triazine-ring opening N-donor ligands functional adsorbents for highly efficient separation of palladium from HNO3 solution

The synthesis and characterization of two novel symmetric triazine-ring opening ligands CA-MP (pyridine derivative)/CA-BOPhen (1,10-phenanthroline derivative) functionalized SiO₂-P (P = Polymer) adsorbents for separation of Pd(II) from HNO₃ solutions are presented. SEM, N₂ adsorption/desorption isotherms, TGA and EDS spectroscopy characterization results showed that CA-MP and CA-BOPhen were successfully introduced into the pores of SiO₂-P carrier via physical intermolecular interactions. CA-MP@SiO₂-P and CA-BOPhen@SiO₂-P show high efficiency, high selectivity, extremely fast adsorption rates towards Pd(II) over 19 typical fission or corrosion products in HNO₃ solution. The distribution coefficient K_d values of CA-MP@SiO₂-P and CA-BOPhen@SiO₂-P are up to 206.5 and 205.7 cm³/g, respectively, within 10-15 min of contact time in 0.4 M HNO₃. The adsorption capacities of them to Pd(II) were determined to be 0.36 mmol/g and 0.23 mmol/g, respectively. The fast adsorption rates and high selectivity of two adsorbents towards Pd(II) were related to the formation of the highly preorganized complex [Pd(NO₃)(L)]⁺ (L = CA-MP or CA-BOPhen). These results demonstrate that CA-MP@SiO₂-P and CA-BOPhen@SiO₂-P possess great potential for highly efficient removal of Pd(II) from highly active liquid waste (HLW).

Preconcentration of morphine and codeine using a magnetite/reduced graphene oxide/silver nano-composite and their determination by high-performance liquid chromatography

A novel magnetic solid-phase extraction technique based on a ternary nano-composite, magnetite/reduced graphene oxide/silver, as a nano-sorbent was developed for simultaneous extraction/preconcentration and measurement of morphine and codeine in biological samples by high-performance liquid chromatography. The magnetic ternary nano-composite was synthesized and its functional groups, morphological structure, and magnetic properties were characterized by field emission scanning electron microscopy, vibrating sample magnetometer, powder X-ray diffraction, energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. The optimizing of the significant variables affecting the extraction process was evaluated by a response surface methodology. In the optimized conditions, the constructed calibration curves for morphine and codeine are linear in the range of 0.01-10 μg L^-1 with correlation coefficients of 0.9983 and 0.9976, respectively. The detection limit and enrichment factor for morphine and codeine are 1.8 ng L^-1, 1000 and 2.1 ng L^-1, 1000, respectively. The presented technique was employed for the monitoring of morphine and codeine in numerous blood and urine samples with relative recoveries between 97.0 and 102.5%, and relative standard deviations of 1.02-5.10% for the spiked samples.

Biosorption Potential of Phanerochaete chrysosporium for Arsenic, Cadmium, and Chromium Removal from Aqueous Solutions

Efficient degradation of hazardous contaminants from contaminated water is the major challenge for researchers, wherein heavy metals are the prominent contaminants. Consequently, the assessment of multimetal removal is necessary using efficient biosorbant. In this work, the capability of Phanerochaete chrysosporium is evaluated for the individual and simultaneous removal of heavy metals. Individual and simultaneous removal of As, Cd, and Cr is optimized using response surface methodology based on the central composite design by changing the variables, i.e., pH, fungal biomass, and metal concentration. Optimization of the individual metal removal study reveals that fungus effectively absorbs As (29.95 mg L-1), Cd (18.1 mg L-1), and Cr (26.34 mg L-1) at 6.1, 5.64, and 4.15 of pH, respectively. Similarly, As (14.18 mg L-1), Cd (4.53 mg L-1), and Cr (9.28 mg L-1) are absorbed by fungal hyphae simultaneously within 1 h. Changes in the morphology of fungal hyphae are detected in metal absorbed samples as compared to the control hyphae. Interaction of metal-absorbed fungal hyphae is analyzed using FTIR spectroscopy, revealing that the proteins, carbohydrates, and fatty acids present in the fungal cell are interacted with metals. The model white rot fungi used in the present study can be applied efficiently for the multimetal removal in effluent treatment plants.

High efficiency removal of As(III) from waters using a new and friendly adsorbent based on sugarcane bagasse and corncob husk Fe-coated biochars

Water contamination of As is a big issue in many areas around the globe. Therefore, cheap and efficient techniques are essential facing traditional treatment methods. Then, biochars (BC) emerged recently as material that can be used for As removal. However, research about efficiency of BC produced from local feedstock is still needed. The purpose of this study is to assess the efficiency of BC produced from sugarcane bagasse (SB) together with corncob husk (CH) with and without Fe(III) (BC_Fe) modification to be used for removal of As(III) from waters. The BC and BC_Fe produced at different pyrolysis temperatures were characterised using FTIR and SEM/EDS. Adsorption capacities of BC and BC_Fe were evaluated via batch adsorption, desorption and column tests and their performance was compared with adsorption using activated carbon. The results showed that Fe modification improve substantially the As(III) adsorption in a way that both BC_Fe-SB and BC_Fe-CH removed from 85% to 99.9% from 1000 µg/L As(III) solutions. Both materials fitted well in Langmuir model and the maximum adsorption capacity was 20 mg/g for BC_Fe-SB and 50 mg/g for BC_Fe-CH. The adsorption kinetics of BC_Fe was fast (≤ 30 min) and it had a better performance than activated carbon. The column tests showed that the process is efficient even at high As(III) concentrations. The fast removal process and good removal results make the BC_Fe-SB and BC_Fe-CH attractive for in situ and commercial (filters) use, since time and efficiency are required in new technologies.

Ultrasonic-assisted manufacturing of new hydrogel nanocomposite biosorbent containing calcium carbonate nanoparticles and tragacanth gum for removal of heavy metal

This article reports the first incorporation of calcium carbonate nanoparticles (CC NPs) into tragacanth gum (TG) to prepare a new hydrogel nanocomposite (HNC) system using a green, safe, and eco-friendly method, ultrasound irradiation as an efficient biosorbent of heavy metal ions from wastewater. Morphological studies revealed that the surface of obtained HNCs is rough, homogeneous, and porous-like due to the embedding of CC NPs as well as sonication in comparison to the neat TG which has a smooth surface. The particle size reduction was observed for CC NPs in the matrix (from 57 to 10 nm), which is owing to the extraordinary effect of sonication on this process. Thermal stability of HNCs has been increased after using CC NPs from 8.5 wt% for TG to about 22 wt% for HNCs. The optical band gap of TG/CC HNC 5 wt% calculated to be 4.46 eV which is less than that of CC NPs (5.58 eV) and even TG (6.28 eV) and this result indicated that TG/CC HNC 5 wt% is relatively more conductive than CC NPs and TG. The nitrogen adsorption-desorption disclosed an isotherm type III of Brunauer classification for TG/CC HNC 5 wt% and the surface area has been increased from 0.7 m².g^-1 for TG to 2.3 m².g^-1 for TG/CC HNC 5 wt%. Also, the BET surface area for TG/CC HNC 5 wt% calculated to be 7.8 nm which is classified into mesoporous materials. The Pb²⁺ ions were significantly removed from water using TG/CC HNC 5 wt% and the removal efficiency was determined as 83% at optimized conditions (pH = 5, adsorbent dosage = 0.015 g, time = 3 h, and Pb²⁺ concentration = 70 mg.L^-1).

Facile preparation of a tetraethylenepentamine-functionalized nano magnetic composite material and its adsorption mechanism to anions: competition or cooperation

A tetraethylenepentamine (TEPA)-functionalized nano-Fe₃O₄ magnetic composite material (nFe₃O₄@TEPA) was synthesized by a facile one-pot solvothermal method. It was characterized by elementary analysis (EA), powder X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). The results show that the nFe₃O₄@TEPA has an average size of ∼20 nm, with a saturation magnetization intensity of 48.2 emu g⁻¹. Its adsorption properties were investigated by adsorbing fluorine ions, phosphate, Cr(vi) and their co-existing water system. The adsorption performance was studied as a function of solution pH, initial concentration of ions, contact time and temperature for each ion. The adsorption of the multi-ion co-existing system was studied via batch tests, XPS and FTIR analyses. The effect of co-existing ions was studied through Box-Behnken Design (BBD) and response surface methodology (RSM). It can be deducted that the adsorption mechanism of an individual fluorine ion or phosphate was mainly related to electrostatic attraction, while that of Cr(vi) might be mainly related to electrostatic attraction and coordination interactions. For the fluorine ion and phosphate bi-component system, their adsorption was competitive via ion exchange. For the Cr(vi), fluorine ion and phosphate tri-component co-existing system, Cr(vi) took priority for adsorption and could replace the absorbed fluorine ion or phosphate by competitive reaction, but not vice versa.

A tetraethylenepentamine (TEPA)-functionalized nano-Fe₃O₄ magnetic composite material (nFe₃O₄@TEPA) was synthesized by a facile one-pot solvothermal method.

Ultrasonic-assisted synthesis of superabsorbent hydrogels based on sodium lignosulfonate and their adsorption properties for Ni2

Nowadays, the attention of both academic and industrial research is paid to the novel materials based on renewable organic resources. Sodium lignosulphonate (SLS) is selected in this study to synthesize novel superabsorbent hydrogels by ultrasonic polymerization. The structure, morphology and stability of SLS-based hydrogel were confirmed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Under the optimal condition, SLS-based hydrogel possesses the water absorbency of 1328g·g^-1 in distilled water and 110g·g^-1 in 0.9wt% NaCl solution. In addition, the prepared SLS-hydrogel as an adsorbent was applied to remove Ni²⁺ from an aqueous solution in virtue of its low cost and favorable adsorption capacity. The various experimental conditions that influence the adsorption capacity were investigated such as temperature (20-60°C), pH (2.0-7.0), contact time (0-360min) and initial concentration of the Ni²⁺ solution (100-600mg·L^-1). Then the adsorption capability could reach 293mg·g^-1 under optimal conditions. The results revealed that the adsorption behavior is spontaneous and endothermic. Furthermore, it was observed that the adsorption mechanism and adsorption equilibrium data obeyed pseudo-second-order kinetic and Freundlich models.

Isotherms and kinetic study of ultrasound-assisted adsorption of malachite green and Pb2+ ions from aqueous samples by copper sulfide nanorods loaded on activated carbon: Experimental design optimization

Copper sulfide nanorods loaded on activated carbon (CuS-NRs-AC) was synthesized and used for simultaneous ultrasound-assisted adsorption of malachite green (MG) and Pb²⁺ ions from aqueous solution. Following characterization of CuS-NRs-AC were investigated by SEM, EDX, TEM and XRD, the effects of pH (2.0-10), amount of adsorbent (0.003-0.011g), MG concentration (5-25mgL^-1), Pb²⁺ concentration (3-15mgL^-1) and sonication time (1.5-7.5min) and their interactions on responses were investigated by central composite design (CCD) and response surface methodology. According to desirability function on the Design Expert optimum removal (99.4%±1.0 for MG and 68.3±1.8 for Pb²⁺ions) was obtained at pH 6.0, 0.009g CuS-NRs-AC, 6.0min mixing by sonication and 15 and 6mgL^-1 for MG and Pb²⁺ ions, respectively. High determination coefficient (R²>0.995), Pred-R²-value (>0.920) and Adju-R²-value (>0.985) all are good indication of best agreement between the experimental and design modelling. The adsorption kinetics follows the pseudo-second order model and adsorption isotherm follows the Langmuir model with maximum adsorption capacity of 145.98 and 47.892mgg^-1 for MG and Pb²⁺ ions, respectively. This adsorbent over short contact time is good choice for simultaneous removal of large content of both MG and Pb²⁺ ions from wastewater sample.

Preparation and characterization of a novel macroporous silica-bipyridine asymmetric multidentate functional adsorbent and its application for heavy metal palladium removal

The effective removal of heavy metal ¹⁰⁷Pd(II) from highly active liquid waste (HLW) is very valuable for reducing its hazardous and risk to public health and environment. For this purpose, a novel silica-bipyridine multidentate functional adsorbent was synthesized by vacuum infusing a new asymmetric N-donor ligand CA-MTBP (bipyridine derivative) into the macroporous SiO₂-P support. SEM, N₂ adsorption-desorption isotherms, TGA, XRD, FT-IR, ²⁹Si solid-state NMR and XPS spectroscopy were utilized to systematically characterize the physicochemical properties of the adsorbent. The characterization results indicated that CA-MTBP was successfully immobilized onto the pores of SiO₂-P by intermolecular interaction. Strong hydrogen-bonding interactions identified by single crystal structure of the ligand and ²⁹Si NMR may play a key role in achieving this immobilization. TGA and TOC studies showed that CA-MTBP/SiO₂-P had excellent thermal stability and highly HNO₃ resistance. EDS and XPS investigations provided directly evidences for Pd(II) being selectively adsorbed onto the adsorbent. The adsorbent had excellent adsorption capability, fast adsorption kinetics and high selectivity for Pd(II) over other typical tested metals in HNO₃ media.

Biosorption of nickel (II) and zinc (II) from aqueous solutions by the biomass of yeast Yarrowia lipolytica

This study examined the biosorption process of Ni(II) and Zn(II) from an aqueous solution by dead biomass of Yarrowia lipolytica. Optimum biosorption conditions were determined as a function of pH, biomass dosage, contact time, and temperature. The biosorbent was characterized by FTIR, which indicated the participation of hydroxyl, carboxyl, amide and amine groups in the process of binding the metal ions. The results showed that the biosorption processes of both metal ions closely followed pseudo-second order kinetics. The equilibrium data of Ni(II) and Zn(II) ions at 20, 30 and 40°C fitted the Langmuir and Freundlich isotherm models. Langmuir isotherm provided a better fit to the equilibrium data, with a maximum biosorption capacity of the Y. lipolytica biomass for Ni(II) and Zn(II) of 30.12 and 44.44 mg/g respectively. The calculated thermodynamic parameters demonstrated that the biosorption of Ni(II) and Zn(II) ions onto the Y. lipolytica was feasible, spontaneous and endothermic.

Multi-responses optimization of simultaneous biosorption of cationic dyes by live yeast Yarrowia lipolytica 70562 from binary solution: Application of first order derivative spectrophotometry

Present study is based on application of live yeast Yarrowia lipolytica 70562 as new biosorbent was investigated for the simultaneous biosorption of Crystal Violet (CV) and Brilliant Green (BG) from wastewater. The effect of operating parameters such as initial dye concentrations (6-14mgL^-1), solution pH (4.0-8.0) and contact time (4-20h) was investigated by response surface methodology (RSM) for modeling and optimization of biosorption process and accordingly the best operational conditions was set as: initial CV and BG concentration of 8.0, and 10mgL^-1, pH of 7.0 and contact time of 16h. Above specified conditions lead to achievement of maximum biosorption of 98.823% and 99.927% for CV and BG dyes, respectively. The experimental equilibrium data well explained according to Langmuir isotherm model with maximum biosorption capacity of 65.359 and 56.497mgg^-1 for BG and CV, respectively. The second order and intraparticle diffusion models as cooperative mechanism has high efficiency and performance for interpretation of real data.

Application of experimental design and derivative spectrophotometry methods in optimization and analysis of biosorption of binary mixtures of basic dyes from aqueous solutions

Simultaneous biosorption of malachite green (MG) and crystal violet (CV) on biosorbent Yarrowia lipolytica ISF7 was studied. An appropriate derivative spectrophotometry technique was used to evaluate the concentration of each dye in binary solutions, despite significant interferences in visible light absorbances. The effects of pH, temperature, growth time, initial MG and CV concentration in batch experiments were assessed using Design of Experiment (DOE) according to central composite second order response surface methodology (RSM). The analysis showed that the greatest biosorption efficiency (>99% for both dyes) can be obtained at pH 7.0, T=28°C, 24h mixing and 20mgL^-1 initial concentrations for both MG and CV dyes. The quadratic constructed equation ability for fitting experimental data is judged based on criterions like R² values, significant p and lack-of-fit value strongly confirm its high adequacy and applicability for prediction of revel behavior of the system under study. The proposed model showed very high correlation coefficients (R²=0.9997 for CV and R²=0.9989 for MG), while supported by closeness of predicted and experimental value. A kinetic analysis was carried out, showing that for both dyes a pseudo-second order kinetic model adequately describes the available data. The Langmuir isotherm model in single and binary components has better performance for description of dyes biosorption with maximum monolayer biosorption capacity of 59.4 and 62.7mgg^-1 in single component and 46.4 and 50.0mgg^-1 for CV and MB in binary components, respectively. The surface structure of biosorbents and the possible biosorbents-dyes interactions between were also evaluated by Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The values of thermodynamic parameters including ΔG° and ΔH° strongly confirm which method is spontaneous and endothermic.

Application of modificated magnetic nanomaterial for optimization of ultrasound-enhanced removal of Pb2+ ions from aqueous solution under experimental design: Investigation of kinetic and isotherm

Magnetic γ-Fe₂O₃ nanoparticles modificated by bis(5-bromosalicylidene)-1,3-propandiamine (M-γ-Fe₂O₃-NPs-BBSPN) and characterized by field emission scanning electron microscopy (FE-SEM), Fourier transforms infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). This modified compound as novel adsorbent was applied for the ultrasound-assisted removal of Pb²⁺ ion in combination with flame atomic absorption spectroscopy (FAAS). The influences of the effective parameters including initial Pb²⁺ ion concentration, pH, adsorbent mass and ultrasound time were optimized by central composite design (CCD). Maximum removal percentage of Pb²⁺ ion which obtained at 25mgL^-1 of Pb²⁺, 25mg of adsorbent and 4min mixing with sonication at pH 6.0. The precision of the equation obtained by CCD was confirmed by the analysis of variance and calculation of correlation coefficient relating the predicted and the experimental values of removal percentage of Pb²⁺ ion. The kinetic and isotherm of ultrasound-assisted removal of Pb²⁺ ion was well described by second-order kinetic and Langmuir isotherm model with maximum adsorption capacity of 163.57mgg^-1.

Limnothrix sp. KO05: A newly characterized cyanobacterial biosorbent for cadmium removal: the enzymatic and non-enzymatic antioxidant reactions to cadmium toxicity

In this study, we isolated five indigenous cyanobacterial strains from different aqueous environments, with heavy metals contamination, in East Azerbaijan Province (northwest portion of Iran). A strain was identified by morphological and 16S rRNA sequence analysis as Limnothrix sp. KO05 and selected for further studies as having the greatest potential for cadmium uptake. Scanning electron microscopy (SEM) demonstrated cyanobacterium Limnothrix sp. KO05 forms filamentous structures and is straight or curved to some extent. The utmost biosorption capacity was found to be 82.18±1.22mgg^-1 at a Cd (II) concentration level of 150mgL^-1. Langmuir adsorption isotherm indicated a better fit to the experimental data. Response surface methodology (RSM) on the basis of four independent variables and the predicted maximum biosorption efficiency was 98.7% under the optimum condition. FT-IR spectroscopy profile of the Cd treated sample as demonstrated in confirmation of the benefits of various functional groups of proteins and polysaccharides of cyanobacterial biomass, involved in surface binding of Cd. The determination of catalase (CAT) activity in strain KO05 exposed to Cd (II) concentrations of 2, 5 and 10mgL^-1 showed an increase in enzyme activity after 24h exposure compared to unexposed cells. Correspondingly, CAT activity showed a significant decrease after 48h of treatment with Cd (II) concentrations of 5 and 10mgL^-1. CAT activity was decreased significantly at all concentrations within 72h after exposure to Cd. On the contrary, while ascorbate peroxidase (APX) gave the expected lower activity compared to the CAT within 24h after Cd treatment, its activity lasted up to 72h. Limnothrix sp. KO05 cells treated with 5 and 10mgL^-1 Cd (II) over 72h exposure showed a reduction in chlorophyll a contents compared to the controls. However, following exposure to Cd, chlorophyll a and carotenoid contents is reduced and after overcoming stress and deployment of an adaptation mechanism, the amounts of these pigments is gradually increased in the cells. The reduction was slower for chlorophyll a pigment compared to carotenoids that may be an indication of the physiological importance of chlorophyll pigment for the phtosynthetic cells. Results related to lipid peroxidation in Limnothrix sp. KO05 represent a significant increase of MDA in the first 24h after exposure to the different concentrations of Cd (2, 5 and 10mgL^-1). However, the MDA levels were decreased over time and no significant difference attained after 72h exposure to Cd concentrations of 2 and 10mgL^-1 compared to control.

Design and construction of nanoscale material for ultrasonic assisted adsorption of dyes: Application of derivative spectrophotometry and experimental design methodology

Response surface methodology (RSM) based on central rotatable experimental design was used to investigate the effect of ultrasound assisted simultaneous adsorption process variables on Cu: ZnS-NPs-AC from aqueous solution. Cu: ZnS-NPs-AC was characterized using field emission scanning electron microscopy (FE-SEM), Energy Dispersive X-ray Spectroscopy (EDX) and X-ray diffraction (XRD). To overcome the severe methylene blue (MB) and brilliant green (BG) dyes spectral overlapping, derivative spectrophotometric method were successfully applied for the simultaneous determination of dyes in their binary solutions. Simultaneous determination of the dyes can be carried out using the first-order and second order derivative signal at 664 and 663nm for BG and MB, respectively. The factors investigated were pH (2.5-8.5), adsorbent mass (0.006-0.030g), sonication time (1-5min) and initial MB and BG concentration (3-15mgL^-1). Five levels, which were low level, center point, upper level and two axillar points, were considered for each of the factors. The desirability function (DF: 0.9853) on the STATISTICA version 10.0 software showed that the optimum removal (99.832 and 99.423% for MB and BG, respectively) was obtained at pH 8.0, adsorbent mass 0.024g, sonication time 4min and 9mgL^-1 initial concentration for each dye. Besides, the results show that obtained data were adequately fitted into the second-order polynomial model, since the calculated model F value (172.96 and 96.35 for MB and BG, respectively) is higher than the critical F value. The values of coefficient of determination (0.9968 and 0.9943 for MB and BG, respectively) and adjusted coefficient of determination (0.9911 and 0.9840 for MB and BG, respectively) are close to 1, indicating a high correlation between the observed and the predicted values. The ultrasonic amplitude and adsorbent mass were found to be the most effective variable influencing the adsorption process. The adsorption equilibrium was well described by the Langmuir isotherm model with maximum adsorption capacity of 185.2 and 151.5mgg^-1 for MB and BG respectively on adsorbent. The results indicate that pseudo-second-order kinetic equation and intra-particle diffusion model can better describe the adsorption kinetics.

Treatment of Pb ion contaminated wastewater using hazardous parthenium (P. hysterophorus L.) weed

In this study, a low-cost, sustainable biosorbent parthenium (P. hysterophorus L.) weed powder was investigated for the treatment of Pb contaminated wastewater. Physicochemical characteristics of the biosorbent were measured, namely, bulk density as 0.42 g cm^-3, porosity as 45%, BET surface area as 20.79 m² g^-1, particle size as <125 μm, moisture content as 68% and point of zero charge as 5.6. The various parameters of biosorption process were examined. The maximum percentage removal of Pb ion achieved was 98.3% with 1.0 g L^-1 of biosorbent dose for 50 mg L^-1 initial Pb ion concentration at process condition of pH 4, temperature 30 °C (303 K), agitation speed 200 rpm and 150 min of equilibrium contact time. The equilibrium data were examined by various rate kinetics models and adsorption isotherm models. Sorption of Pb ion onto biosorbent was confirmed by Fourier transform infrared spectroscopy (FTIR) transmittance spectra and field-emission scanning electron microscopy and energy-dispersive X-ray (FESEM-EDX) analysis of native as well as Pb ion adsorbed biosorbent. The change in thermodynamic parameters, such as Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) was calculated. The results suggest that biosorption process using parthenium (P. hysterophorus L.) weed powder as biosorbent was a spontaneous, feasible and efficient method for treatment of Pb-bearing wastewater.

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

The present research is focused on the synthesis and characterization of zinc (II) oxide nanorods loaded on activated carbon (ZnO-NRs-AC) to prepare an outstanding adsorbent for the simultaneous adsorption of heavy metals and dyes as hazardous pollutant using ultrasound energy. The adsorbent was identified by Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analysis. The individual effects and possible interactions between the most effective variables including initial metal ions (Cd²⁺ and Co²⁺) and azo dyes (methylene blue (MB) and crystal violet (CV)) concentration, adsorbent dosage and ultrasonic time on the responses were investigated by response surface methodology (RSM) and optimum conditions was fixed at Cd²⁺, Co²⁺, MB and CV concentrations were 25, 24, 18 and 14mgL^-1, respectively, 0.025g of ZnO-NRs-AC and 5.1min sonication to achieve maximum removal percentage (>97.0%) for targets compounds. The artificial neural network (ANN) model was applied for prediction of data with Levenberg-Marquardt algorithm (LMA), a linear transfer function (purelin) at output layer and a tangent sigmoid transfer function (tansig) in the hidden layer with 14 neurons. The minimum mean squared error (MSE) of 0.9646, 0.0402 and 0.0753 with high determination coefficient (R²) of 0.9996, 0.9991 and 0.9999 for train, test and validation, respectively, were able to predict and model the adsorption process. The results of examination of the time on experimental adsorption data and their subsequent fitting reveal applicability of pseudo-second-order and intraparticle diffusion model. The experimental equilibrium data was analyzed by Langmuir, Freundlich, Temkin and D-R isotherm models and explored that the data well presented by Langmuir model with maximum adsorption capacity of 97.1, 92.6, 83.9 and 81.6mgg^-1 for Cd⁺², Co⁺² ions, MB and CV dyes, respectively.

Synthesis of Iron Doped Zeolite Imidazolate Framework-8 and Its Remazol Deep Black RGB Dye Adsorption Ability

Zeolite imidazole framework-8 (ZIF-8) and the iron doped ZIF-8 (Fe-ZIF-8) were synthesized by the hydrothermal process. The obtained materials were characteristic of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), nitrogen adsorption/desorption isotherms, and atomic absorption spectroscopy (AAS). The results showed that the obtained Fe-ZIF-8 possessed the ZIF-8 structure with a large specific area. ZIF-8 and Fe-ZIF-8 were used for the removal of Remazol Deep Black (RDB) RGB dye from aqueous solutions. The various factors affecting adsorption such as pH, initial concentration, contact time, and temperature were investigated. The results showed that the introduction of iron into ZIF-8 provided a much larger adsorption capacity and faster adsorption kinetics than ZIF-8 without iron. The electrostatic interaction and π-π interaction between the aromatic rings of the RDB dye and the aromatic imidazolate rings of the adsorbent were responsible for the RDB adsorption. Moreover, the coordination of the nitrogen atoms and oxygen in carboxyl group in RDB molecules with the Fe2+ ions in the ZIF-8 framework played a vital role for the effective removal of RDB from aqueous solution.

Predictive modeling and validation of arsenite removal by a one pot synthesized bioceramic buttressed manganese doped iron oxide nanoplatform

Arsenite removal by a one pot synthesized bioceramic buttressed manganese doped iron oxide nanoplatform.

Preparation of nanomaterials for the ultrasound-enhanced removal of Pb2+ ions and malachite green dye: Chemometric optimization and modeling

Copper oxide nanoparticle-loaded activated carbon (CuO-NP-AC) was synthesized and characterized using different techniques such as FE-SEM, XRD and FT-IR. It was successfully applied for the ultrasound-assisted simultaneous removal of Pb²⁺ ions and malachite green (MG) dye in binary system from aqueous solution. The effect of important parameters was modeled and optimized by artificial neural network (ANN) and response surface methodology (RSM). Maximum simultaneous removal percentages (>99.0%) were found at 25mgL^-1, 20mgL^-1, 0.02g, 5min and 6.0 corresponding to initial Pb²⁺ concentration, initial MG concentration, CuO-NP-AC amount, ultrasonication time and pH, respectively. The precision of the equation obtained by RSM was confirmed by the analysis of variance and calculation of correlation coefficient relating the predicted and the experimental values of ultrasound-assisted simultaneous removal of the analytes. A good agreement between experimental and predicted values was observed. A feed-forward neural network with a topology optimized by response surface methodology was successfully applied for the prediction of ultrasound-assisted simultaneous removal of Pb²⁺ ions and MG dye in binary system by CuO-NPs-AC. The number of hidden neurons, MSE, R², number of epochs and error histogram were chosen for ANN modeling. Then, Langmuir, Freundlich, Temkin and D-R isothermal models were applied for fitting the experimental data. It was found that the Langmuir model well describes the isotherm data with a maximum adsorption capacity of 98.328 and 87.719mgg^-1 for Pb²⁺ and MG, respectively. Kinetic studies at optimum condition showed that maximum Pb²⁺ and MG adsorption is achieved within 5min of the start of most experiments. The combination of pseudo-second-order rate equation and intraparticle diffusion model was applicable to explain the experimental data of ultrasound-assisted simultaneous removal of Pb²⁺ and MG at optimum condition obtained from RSM.