Removal of Pb ions using green Co3O4 nanoparticles: Simulation, modeling, adsorption, and biological studies

Polyurethane sponges bearing cucurbituril adsorb Cr(III) and Pb(II) ions from contaminated water samples

Water contamination with toxic metals causes harmful effects on the environment and to human health. Although cucurbiturils have carboxyl groups in their portal that can interact with metal ions, there is a lack of studies about their use as metal adsorbent. This scenario has motivated conduction of the present study, which addresses the use of cucurbit[6]uril (CB[6]) and cucurbit[8]uril (CB[8]) for adsorbing Pb and Cr from water samples, in free forms and immobilized in poly(urethane) sponges. The adsorption kinetics revealed that CB[8] leads to faster adsorption compared to CB[6], with equilibrium achieved in 8 h for CB[8] and 48 h for CB[6] for both metals, and achieved up to 80% of decrease in metal concentration. The Langmuir isotherm model provided a better description of adsorption for Cr and Pb in CB[6] and Pb in CB[8] with a maximum concentration adsorbed of 32.47 mg g-1 for Pb in CB[6], while the Dubinin-Radushkevich model was more suitable for Cr adsorption in CB[8]. Sponges containing CB[6] and CB[8] have proven to be efficient for Pb and Cr remediation in tannery effluent samples, reducing Cr and Pb concentration by 42 and 33%, respectively. The results indicate that CB[6] and CB[8], whether used in their pure form or integrated into sponges, exhibit promising potential for efficiently adsorbing metals in aqueous contaminated environments.

Preconcentration and selective extraction of trace Hg(ii) by polymeric g-C3N4 nanosheet-packed SPE column

In this study, we successfully synthesized polymeric graphitic carbon nitride (g-C3N4) nanosheets through thermal means and proposed their application in solid-phase extraction (SPE) for the enrichment of trace Hg(ii). The nanosheets underwent characterization using scanning electron microscopy, tunnelling electron microscopy, and energy-dispersive X-ray spectroscopy. The column packed with polymeric carbon nitride nanosheets demonstrated effective extraction of trace Hg(ii) ions from complex samples. The g-C3N4 nanosheets possess a zeta potential value of -20 mV, enabling strong interaction with positively charged divalent Hg(ii) ions. This interaction leads to the formation of stable chelates with the nitrogen atoms present in the polytriazine and heptazine units of the material. The proposed method exhibited a high preconcentration limit of 0.33 μg L-1, making it suitable for analysing trace amounts of Hg(ii) ions. Moreover, the method's applicability was confirmed through successful analysis of real samples, achieving an impressive preconcentration factor of 200. The detection limit for trace Hg(ii) ions was determined to be 0.6 μg L-1. To assess the accuracy of the method, we evaluated its performance by recovering spiked amounts of Hg(ii) and by analysing certified reference materials. The results indicated excellent precision, with RSD consistently below 5% for all the analyses conducted. In conclusion, the thermally synthesized polymeric carbon nitride nanosheets present a promising approach for solid-phase extraction and preconcentration of trace Hg(ii) from real samples. The method showcases high efficiency, sensitivity, and accuracy, making it a valuable tool for environmental and analytical applications.

A state-of-art-review on emerging contaminants: Environmental chemistry, health effect, and modern treatment methods

Pollution problems are increasingly becoming e a priority issue from both scientific and technological points of view. The dispersion and frequency of pollutants in the environment are on the rise, leading to the emergence have been increasing, including of a new class of contaminants that not only impact the environment but also pose risks to people's health. Therefore, developing new methods for identifying and quantifying these pollutants classified as emerging contaminants is imperative. These methods enable regulatory actions that effectively minimize their adverse effects to take steps to regulate and reduce their impact. On the other hand, these new contaminants represent a challenge for current technologies to be adapted to control and remove emerging contaminants and involve innovative, eco-friendly, and sustainable remediation technologies. There is a vast amount of information collected in this review on emerging pollutants, comparing the identification and quantification methods, the technologies applied for their control and remediation, and the policies and regulations necessary for their operation and application. In addition, This review will deal with different aspects of emerging contaminants, their origin, nature, detection, and treatment concerning water and wastewater.

Green synthesis of nickel-doped magnesium ferrite nanoparticles via combustion for facile microwave-assisted optical and photocatalytic applications

NixMg1-xFe2O4(x = 0, 0.2, 0.4, 0.6) nanoparticles were symphonized via combustion with microwave assistance in the presence of Tamarindus indica seeds extract as fuel. Nanoparticles nature, size, morphology, oxidation state, elemental composition, and optical and luminescence properties were analysed using PXRD, FTIR, SEM, EDX, and HRTEM with SAED, XPS, UV-Visible and photoluminescence spectroscopy. PXRD analysis confirms that synthesized nanoparticles are spinel cubic and have a 17-18 nm average crystalline size. Tetrahedral and octahedral sites regarding stretching vibrations were confirmed by FTIR analysis. SEM and HRTEM data it is disclosed that the morphology of synthesized nanoparticles has nano flakes-like structure with sponge-like agglomeration. Elemental compositions of prepared nanoparticles were confirmed through EDX spectroscopy. XPS Spectroscopy confirmed and revealed transition, oxidation states, and elemental composition. The band gap and absorption phenomenon were disclosed using UV-visible spectroscopy, where the band gap declines (2.1, 2, 1.6, 1.8 eV), with increase in nickel NixMg1-xFe2O4(x = 0, 0.2, 0.4, 0.6) doping. Photoluminescence intensity reduces with an incline in nickel doping, was confirmed and disclosed using photoluminescence spectroscopy. Dyes (Methylene blue and Rhodamine B) degradation activity was performed in the presence of NDMF nanoparticles as a photocatalyst, which disclosed that 98.1% of MB dye and 97.9% of RB dye were degraded in 0-120 min. Regarding initial dye concentration and catalyst load, 5 ppm was initiated as the ideal initial concentration for both RB and MB dyes. 50 mg catalyst dosage was found to be most effective for the degradation of MB and RB dyes. In comparison, pH studies revealed that photodegradation efficiency was higher in neutral (MB-98.1%, RB-97.9%) and basic (MB-99.6%, RB-99.3%) conditions than in acidic (MB-61.8%, RB-60.4%) conditions.

Novel and sustainable green sulfur-doped carbon nanospheres via hydrothermal process for Cd (II) ion removal

Herein, the synthesis, characterization, and adsorption performance of a novel green sulfur-doped carbon nanosphere (S-CNs) is studied to eliminate Cd (II) ions from water effectively. S-CNs were characterized using different techniques including Raman spectroscopy, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), , Brunauer-Emmett-Teller (BET) specific surface area analysis and Fourier transform infrared spectrophotometry (FT-IR), were performed. The efficient adsorption of the Cd (II) ions onto S-CNs strongly depended on pH, initial concentration of Cd (II) ions, S-CNs dosage, and temperature. Four isotherm models (Langmuir, Freundlich, Temkin & Redlich Peterson) were tested for modeling. Out of four, Langmuir showed more applicability than the other three models, with a Q_max value of 242.72 mg/g. Kinetic modeling studies suggest a superior fit of the obtained experimental data with the Elovich equation (linear) and pseudo-second-order (non-linear) rather than other linear and non-linear models. Data obtained from thermodynamic modeling indicates that using S-CNs for Cd (II) ions adsorption is a spontaneous and endothermic . The current work recommends using better and recyclable S-CNs to uptake excess Cd (II) ions.

Aqueous Pb(II) Removal Using ZIF-60: Adsorption Studies, Response Surface Methodology and Machine Learning Predictions

Zeolitic imidazolate frameworks (ZIFs) are increasingly gaining attention in many application fields due to their outstanding porosity and thermal stability, among other exceptional characteristics. However, in the domain of water purification via adsorption, scientists have mainly focused on ZIF-8 and, to a lesser extent, ZIF-67. The performance of other ZIFs as water decontaminants is yet to be explored. Hence, this study applied ZIF-60 for the removal of lead from aqueous solutions; this is the first time ZIF-60 has been used in any water treatment adsorption study. The synthesized ZIF-60 was subjected to characterization using FTIR, XRD and TGA. A multivariate approach was used to investigate the effect of adsorption parameters on lead removal and the findings revealed that ZIF-60 dose and lead concentration are the most significant factors affecting the response (i.e., lead removal efficiency). Further, response surface methodology-based regression models were generated. To further explore the adsorption performance of ZIF-60 in removing lead from contaminated water samples, adsorption kinetics, isotherm and thermodynamic investigations were conducted. The findings revealed that the obtained data were well-fitted by the Avrami and pseudo-first-order kinetic models, suggesting that the process is complex. The maximum adsorption capacity (q_max) was predicted to be 1905 mg/g. Thermodynamic studies revealed an endothermic and spontaneous adsorption process. Finally, the experimental data were aggregated and used for machine learning predictions using several algorithms. The model generated by the random forest algorithm proved to be the most effective on the basis of its significant correlation coefficient and minimal root mean square error (RMSE).