Green synthesis of bio-functionalized nano-particles for the application of copper removal - characterization and modeling studies

Uptake and accumulation mechanisms of hexachloroplatinate(IV) ions in the unicellular alga, Pseudococcomyxa simplex

Platinum uptake was examined by adding hexachloroplatinate(IV) solution to the unicellular alga Pseudococcomyxa simplex. After the addition of platinum solution ([Pt] = 100 mg/kg, pH 3.2-3.2) for a certain time, the cells were quickly frozen and subjected to μ-XRF (X-ray fluorescence) analysis using synchrotron X-rays. The beam size of approximately 1 micrometer allowed visualization of the platinum distribution within a single cell. On the other hand, we examined platinum uptake in enzyme-treated protoplasts and lyophilized cells and found that the platinum uptake concentrations in these samples were higher than in living in-vivo cells. Cell wall and cell metabolism were presumed to interfere with the uptake of hexachloroplatinate(IV) ions. All platinum ions taken up by the cells were reduced to divalent form. The effect of light on platinum addition was also investigated. When platinum was added under light conditions, some samples showed higher platinum accumulation than under shade conditions.

Identifying global status and research hotspots of heavy metal remediation: A phase upgrade study

Impact of heavy metal (HM) pollution and its understanding on environment as well as human beings has grown a lot during the last few decades. The goal of this study is to create a scientometric study on heavy metal contamination, in the period 1989 to 2020, in order to provide futuristic goals for the new researchers on wastewater treatment. For this, a search was conducted in the Web of Science (WoS) and Scopus databases, related to heavy metal pollution. Totally, 37,154 records were collected during the study period from 1989 to 2020. The findings revealed that China, the United States, and India has most referenced papers across a wide range of trans disciplinary issues such as toxicity, technology, and pollution. As a result, this study concludes that more research on various treatment methods is required in order to obtain high-quality water for consumption and routine activities, with the incorporation of various treatment tasks poses various challenges for the upcoming future studies.

Facile synthesis of biogenic palladium nanoparticles using biomass strategy and application as photocatalyst degradation for textile dye pollutants and their in-vitro antimicrobial activity

Among biological applications, plant-mediated Pd NPs for multi-drug resistance (MDR) developed in pathogenic bacteria were synthesized with the help of biomass of lemon peel, a biological material, with a non-toxic, environmentally friendly, human-nature green synthesis method. Characterization of synthesized Pd NPs was carried out by UV-Vis spectrometry, Transmissive Electron Microscopy (TEM), X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) techniques. According to TEM analysis, Pd NPs were confirmed to be in a spherical shape and the mean particle size was determined to be 4.11 nm. The crystal structure of Pd NPs was checked using XRD analysis and the mean particle size was observed to be 6.72 nm. Besides, the antibacterial activity of Pd NPs was determined against Escherichia coli (E. coli) (ATCC 8739), Bacillus subtilis (B. subtilis ATCC 6633), Staphylococcus aureus (S. aureus ATCC 6538), Klebsiella pneumoniae (K. pneumoniae ATCC 11296) and Serratia marcescens (S. marcescens ATCC) bacteria. Antibacterial activity was determined to be high in Pd NPs which is in conformance with the results acquired. The Pd NPs showed good photocatalytic activity, after 90 min illumination, about 81.55% and 68.45% of MB and MO respectively were catalysed by the Pd NPs catalyst, and 74.50% of RhB dyes were removed at 120 min of illumination. Within the scope of this project, it is recommended to use Pd NPs obtained by the green synthesis in the future as an antibacterial agent in biomedical use and for the cleaning of polluted waters.

Comparative study of effective antibiofilm activity of beneficial microbes-mediated zirconia nanoparticles

In the present study, beneficial microbes-mediated zirconia nanoparticles were prepared using endophytic bacteria isolated from the seed of Terminalia chebula which were evaluated on inhibition of bacterial adherence and promotion to exhibit antibiofilm properties. The structure and distribution of the zirconia nanoparticles were examined through SEM (Scanning Electron Microscopy), EDS (Energy-Dispersive X-Ray spectroscopy), and XRD (X-ray diffraction analysis), which reveal the distribution of the particles. The morphology of biogenic zirconia nanoparticles was monoclinic and cubic. The formation of zirconia particle was confirmed using UV spectrum and the functional groups were intensified in FTIR (Fourier-transform infrared spectroscopy). The antibiofilm activity of the synthesized nanoparticles was tested in oral pathogens that cause biofilm by membrane integrity and leads to periodontal associated disease. The results showed that the particles had a significant effect on biofilm removal caused by oral pathogens. For determined concentration, the cytotoxicity of the endophytic bacterial facilitated zirconia nanoparticle (Zr NPs) was examined in HGF (Human gingival fibroblast cell line).

Synthesis of magnesium nanocomposites decked with multilayer graphene (MG) and its application for the adsorptive removal of pollutant

Fossil fuel burning is the exclusive of key causes for greenhouse fume Carbon dioxide (CO₂). Magnesium nanocomposites synthesized in combination with graphene were characterized and their performance in adsorbing CO₂ is validated. The novelty of this work is the use of magnesium oxide decked MG to capture CO₂. The magnesium nanocomposites decked with multilayer graphene (MG) were prepared using a simple combustion process. BET surface area of 1480 m²g^-1 makes it desirable for adsorbing CO₂ molecules. FTIR analysis after adsorption of CO₂ shows peak mid position at 3470.45 cm^-1, 1300-1000 cm^-1, 1603 cm^-1, and 1114.30 cm^-1 corresponding to the functional groups R-C-O, R-OH, R-COOH, -alkyne, Si-O-Si, and R-C-O-H shifted, signifying that chemisorption has taken place. The effect of many experimental parameters like adsorbent mass, period, and concentration of CO₂ was optimized during the experiments. A maximum of 92.2% of CO₂ was adsorbed at a concentration of 5 × 10^{- 4} M at the optimum contact of 70 min. During the experiment, the saturation point was attained at 70 min. Experiment results were best fitting to Langmuir adsorption isotherm; the maximum monolayer adsorption capacity of MG was 7.067 × 10^-3 mol/g/min. The kinetics of CO₂ on MG was labeled by Pseudo-second-order and R² value nearly 0.988.

Application of a polymer-magnetic-algae based nano-composite for the removal of methylene blue - Characterization, parametric and kinetic studies

The potential ability of synthesized PPy-Fe₃O₄-SW nano-composite to remove Methylene Blue (MB) from synthetic textile dye solution was investigated under batch conditions. Through parametric studies, the influence of process parameters namely solution pH, on the effective performance of nano-composite was studied. PPy - Fe₃O₄- SW nano-composite removed 99.14% of MB at the optimized conditions of pH-10, temperature - 25 °C, initial MB concentration - 50 mg/L, nano-composite dosage - 20 mg and contact time - 20 min. PPy - Fe₃O₄- SW nano-composite has a maximum sorption capacity of 666.66 mg/g. The kinetics and isotherm study revealed that the chromium adsorption obeys pseudo second order (PSO) model (R² = 0.9941) and Freundlich isotherm (R² = 0.9910) respectively. The PSO kinetic constant (K₂) was found to be 0.000442 (g/mg) min. The thermodynamic feasibility was confirmed through negative values of standard free energy at all tested conditions. The characteristics of adsorption study were analyzed and the results of FTIR, SEM and EDS confirmed the uptake of MB by PPy-Fe₃O₄-SW nano-composite.

A review on recent trends in the removal of emerging contaminants from aquatic environment using low-cost adsorbents

Emerging contaminants (ECs), a class of contaminants with low concentrations but significant harm, have received a lot of attention in recent times. ECs comprises of various chemicals that enter the environment every day. In today's modern lifestyle, we use many chemical-based products. These persist in wastewater and ultimately enter the water bodies, causing serious problems to the human and aquatic ecosystem. This is because the conventional wastewater treatment methods are inefficient in identifying and removing such contaminants. Aiming for a long-term, effective solution to this issue, Adsorption was proposed. Although several adsorbents are already present in the market, which have proved beneficial in removing such ECs, not all are affordable. This article reviews replacing costly adsorbents with agriculture-based biomass that are abundant, inexpensive, and biodegradable and possess excellent adsorption capacity. The objectives of this article is to look at adsorption as a viable treatment option for emerging pollutants, as well as sophisticated and cost-effective emerging contaminants treatment options.

Efficient and fast degradation of 4-nitrophenol and detection of Fe(III) ions by Poria cocos extract stabilized silver nanoparticles

In this study, a simple and environment-friendly method has been successfully applied for the production of silver nanoparticles (AgNPs) using Poria cocos extract. The reaction time of 60 min, the temperature of 90 °C, and silver ion concentration of 2.0 mM were identified as the best condition for the PC-AgNPs fabrication. The XRD analysis confirmed a highly crystalline face-centered cubic structure of the biosynthesized material. The PC-AgNPs were presented separately in a spherical shape with an average crystal size of 20 nm, as endorsed by the TEM and FE-SEM measurements. The presence and crucial role of biomolecules in stabilizing the nanoparticles were elucidated by FTIR, EDX, and DLS techniques. The prepared biogenic nanoparticles were further applied for the reduction of 4-nitrophenol (4-NP) and colorimetric detection of Fe³⁺ ions. The study results proved that PC-AgNPs exhibited superior catalytic activity and reusability in the conversion of 4-NP by NaBH₄. The complete reduction of 4-NP could be achieved in 10 min with the pseudo-first-order rate constant of 0.466 min^-1, and no significant performance loss was found when the material was reused five times. The colorimetric probe based on PC-AgNPs displayed outstanding sensitivity and selectivity towards Fe³⁺ ions with a detection limit of 1.5 μM in a linear range of 0-250 μM. Additionally, the applicability of the developed assay was explored for testing Fe³⁺ ions in tap water. PC-AgNPs have a great potential for further applications as a promising catalyst for reducing nitrophenols and biosensors for the routine monitoring of Fe³⁺ in water.

Adsorptive potential of iron oxide based nanocomposite for the sequestration of Congo red from aqueous solution

The ability of polypyrrole-Iron oxide-seaweed nanocomposite has been tested for the removal of congo red from aqueous solution. The characteristics of nanocomposite after adsorption of Congo red (CR) have been analyzed. FTIR results authorized the involvement of various functional groups in the adsorption of CR. The change in morphology of nanocomposite was analyzed using scanning electron microscope (SEM). TEM and BET analysis were performed to characterize the nanocomposite. The effect of various parameters namely pH, adsorbent dosage, initial dye concentration, adsorption time and temperature are studied. The optimum condition for the effective removal of CR are: pH-3, initial CR concentration- 40 mg/L, nanocomposite dosage- 20 mg, contact time-40 min and temperature-40^οC. Adsorption isotherm studies and kinetic studies were done. Langmuir isotherm fits with the experimental data very well with high coefficient of determination (R² = 0.98) and maximum dye uptake of 500 mg/g is reported. In kinetic studies, pseudo second order model was obeyed (R² = 0.994). Thermodynamic properties were determined and found that the nature of process is spontaneous, endothermic and increased in randomness. The mechanism of sorption was proposed. Desorption studies were carried out and showed that the nanocomposite could be effectively reused up to five cycles. Thus the outcomes proved that the polypyrrole-iron oxide-seaweed nanocomposite to be an operative, recyclable and low-cost adsorbent for the treatment of dye bearing water.