Sustainable approaches for nickel removal from wastewater using bacterial biomass and nanocomposite adsorbents: A review

Sustainable fabrication of hybrid silver-copper nanocomposites (Ag-CuO NCs) using Ocimum americanum L. as an effective regime against antibacterial, anticancer, photocatalytic dye degradation and microalgae toxicity

In this study, a sustainable fabrication of hybrid silver-copper oxide nanocomposites (Ag-CuO NCs) was accomplished utilizing Ocimum americanum L. by one pot green chemistry method. The multifarious biological and environmental applications of the green fabricated Ag-CuO NCs were evaluated through their antibacterial, anticancer, dye degradation, and microalgae growth inhibition activities. The morphological features of the surface functionalized hybrid Ag-CuO NCs were confirmed by FE-SEM and HR-TEM techniques. The surface plasmon resonance λ_max peak appeared at 441.56 nm. The average hydrodynamic size distribution of synthesized nanocomposite was 69.80 nm. Zeta potential analysis of Ag-CuO NCs confirmed its remarkable stability at -21.5 mV. XRD and XPS techniques validated the crystalline structure and electron binding affinity of NCs, respectively. The Ag-CuO NCs demonstrated excellent inhibitory activity against Vibrio cholerae (19.93 ± 0.29 mm) at 100 μg/mL. Anticancer efficacy of Ag-CuO NCs was investigated against the A549 lung cancer cell line, and Ag-CuO NCs exhibited outstanding antiproliferative activity with a low IC₅₀ of 2.8 ± 0.05 μg/mL. Furthermore, staining and comet assays substantiated that the Ag-CuO NCs hindered the progression of the A549 cells and induced apoptosis as a result of cell cycle arrest at the G₀/G₁ phase. Concerning the environmental applications, the Ag-CuO NCs displayed efficient photocatalytic activity against eosin yellow degradation up to 80.94% under sunlight irradiation. Microalgae can be used as an early bio-indicator/prediction of environmental contaminants and toxic substances. The treatment of the Ag-CuO NCs on the growth of marine microalgae Tetraselmis suecica demonstrated the dose and time-dependent growth reduction and variations in the chlorophyll content. Therefore, the efficient multifunctional properties of hybrid Ag-CuO NCs could be exploited as a regime against infective diseases and cancer. Further, the findings of our investigation witness the remarkable scope and potency of Ag-CuO NCs for environmental applications.

A Mathematical Simulation of Copper and Nickel Ions Separation Using Prepared Nanocellulose Material

Environmental risks can arise from the existence of heavy metals in wastewater and their land disposal. To address this concern, a mathematical technique is introduced in this article that enables the anticipation of breakthrough curves and the imitation of copper and nickel ion separation onto nanocellulose in a fixed-bed system. The mathematical model is based on mass balances for copper and nickel and partial differential equations for pore diffusion in a fixed bed. The study evaluates the impact of experimental parameters such as bed height and initial concentration on the shape of the breakthrough curves. At 20 °C, the maximum adsorption capacities for copper and nickel ions on nanocellulose were 5.7 mg/g and 5 mg/g, respectively. The breakthrough point decreased with increasing solution concentration at higher bed heights, while at an initial concentration of 20 mg/L, the breakthrough point increased with bed height. The fixed-bed pore diffusion model showed excellent agreement with the experimental data. The use of this mathematical approach can help alleviate the environmental hazards that arise from the presence of heavy metals in wastewater. The study highlights the potential of nanocellulose as a material for membrane technology, which can effectively address these risks.

Sustainability and carbon neutralization trends in microalgae bioenergy production from wastewater treatment: A review

Reducing CO2 emissions using biomass is gaining popularity as an environmentally friendly strategy. Due to high growth rates, low production costs, and ability to withstand harsh conditions, microalgae have become quite popular. Microalgae may also undertake photosynthesis, converting CO2 and solar energy into sugar before becoming biomass, making them an excellent source of renewable and promising biofuels. CO2 sequestration and biofixation was utilized to compare the synthesis of biodiesel as a third-generation biofuel from various types of wastewater was also used as a source for the algal cultivation. This review article focuses on recent developments, research discoveries in the field of microalgal CO2 capture modification and the optimization of conversion efficiency. This review is intended to serve as a helpful and reference for the use of wastewater treatment with microalgae to collect CO2. The overarching objective of this study is to assist wastewater treatment systems in achieving carbon neutrality.

Nickel adsorption from waters onto Fe3O4/sugar beet pulp nanocomposite

In this study the magnetic nanocomposite material was synthesized with Fe₃O₄ impregnated to sugar beet pulp using chemical precipitation technique. Ni(II) removal performance of magnetic nanocomposite was investigated under different environmental conditions such as contact time, adsorbent dose, pH, initial heavy metal concentration, etc. The experimental studies have shown that, 81.2% Ni(II) removal efficiency was achieved at optimal conditions (25 mg/L initial Ni(II) concentration at 40 minute contact time, 200 rpm shaking speed, 5 g/L nanocomposite dose and pH 6.6). Freundlich and Langmuir isotherm experiments were performed and correlation coefficients were determined as 94.5% and 99.4%, respectively. The maximum adsorption capacity of material was achieved as 9.36 mg/g. These findings indicate that the adsorption that takes place is a monolayer process. The results of the pseudo-second order kinetic model (R² = 0.9947) indicate the chemisorptions process is used for Ni(II) removal using the electrostatic interaction. Thermodynamic studies illustrated that Ni(II) adsorption onto nanocomposite are exothermic and causes a decrease in the entropy. The adsorption of Ni(II) ions is non-spontaneous except for at low temperature and low initial concentrations. Nanocomposite characterization was illuminated with XRD, FT-IR, BET, TGA, TEM, SEM/EDX analysis.