An adsorbent called chitosan coated magnetic hydroxyapatite nanoparticles (CS-MHAP) was prepared with the purpose of improvement for the removal of Ni2+ ions and textile dye by coprecipitation. Structure and properties of CS-MHAP were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and vibrating sample magnetometer (VSM). Weight percent of chitosan was investigated by thermal gravimetric analysis (TGA). The prepared CS-MHAP presents a significant improvement on the removal efficiency of Ni2+ ions and reactive blue 19 dye (RB19) in comparison with chitosan and magnetic hydroxyapatite nanoparticles. Moreover, the adsorption capacities were affected by several parameters such as contact time, initial concentration, adsorbent dosage, and initial pH. Interestingly, the prepared adsorbent could be easily recycled from an aqueous solution by an external magnet and reused for adsorption with high removal efficiency.
Abstract:Acne is the over growth of the commensal bacteria Propionibacterium acnes (P. acnes) on human skin. Lauric acid (LA) has been investigated as an effective candidate to suppress the activity of P. acnes. Although LA is nearly insoluble in water, dimethyl sulfoxide (DMSO) has been reported to effectively solubilize LA. However, the toxicity of DMSO can limit the use of LA on the skin. In this study, LA-loaded poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) micelles (PCL-PEG-PCL) were developed to improve the bactericidal effect of free LA on P. acnes. The block copolymers mPEG-PCL and PCL-PEG-PCL with different molecular weights were synthesized and characterized using 1 H Nuclear Magnetic Resonance spectroscopy ( 1 H NMR), Fourier-transform infrared spectroscopy (FT-IR), Gel Permeation Chromatography (GPC), and Differential Scanning Calorimetry (DSC). In the presence of LA, mPEG-PCL diblock copolymers did not self-assemble into nano-sized micelles. On the contrary, the average particle sizes of the PCL-PEG-PCL micelles ranged from 50-198 nm for blank micelles and 27-89 nm for LA-loaded micelles. The drug loading content increased as the molecular weight of PCL-PEG-PCL polymer increased. Additionally, the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of free LA were 20 and 80 µg/mL, respectively. The MICs and MBCs of the micelles decreased to 10 and 40 µg/mL, respectively. This study demonstrated that the LA-loaded micelles are a potential treatment for acne.
In this study a novel magnetic composite used as a photocatalyst with combination of zinc oxide nanoparticles and chitosan (ZnO/Fe 3 O 4 /CS) was synthesized by a simple co-precipitation method. The role of the prepared magnetic nanocomposite is to improve the removal efficiency of textile dye due to the photocatalytic activity of zinc oxide nanoparticles and reusable capacity of Fe 3 O 4 magnetic nanoparticles. Constituents and structure properties of ZnO/Fe 3 O 4 /CS were investigated by scanning electron microscopy (SEM), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Magnetic property of the prepared composite was determined by vibrating sample magnetometer (VSM). The results demonstrated that ZnO/Fe 3 O 4 /CS nanocomposite dramatically improved the removal efficiency of reactive blue 198 dye (RB198) with high photocatalytic activity and easy separation by a permanent magnet. In addition, the photocatalytic activity of the prepared composite was also performed under different parameters such as contact time, initial pH, the amount of composite and initial concentration of RB198. Interestingly, ZnO/Fe 3 O 4 /CS nanocomposite still showed high removal efficiency after recycling three times and performed in a real textile dyeing wastewater.
Six
of the most promising lab-scale synthesis process methodologies
for N-doped carbon dots (NCDs) are selected and compared in terms
of green chemistry and circular and EcoScale/Good-Manufacturing-Practice
metrics. We compare a new innovative route, the low-temperature plasma-enabled
synthesis of carbon dots, e.g., from citric acid and monoethanolamine,
to more-established literature processes, such as thermochemical processes,
from the same or other materials. Along with this study, the advantages
and disadvantages of each method are depicted in manifold sustainability
facets. It is shown how recycling/reuse of nonconverted starting materials
and solvents can improve the sustainability profile. In addition,
safety constraints, cost analysis, and energy consumption are considered.
The analysis showed that the thermal process from citric acid and
monoethanolamine gives the best performance with regard to the sustainability
assessment chosen here. It has a material circularity indicator of
0.971, with an EcoScale factor of 56% and an E-factor of 5.56. In
continuation of those results, the paper shows how the low-temperature
plasma using the same materials and the same recycling strategy can
be improved to come closer to the performance of its thermal counterpart.
It has the best energy efficiency, while lacking so far in mass efficiency.
From this study, we learned more about which of these methods are
most promising for scaling-up and industrial manufacturing of N-doped
carbon dots.
Removal of heavy metals in wastewater treatment is crucial to protect the environment, wildlife, and human health. Various techniques have been developed focusing on removal of heavy metal ions, pharmaceuticals, and other contaminants from different wastewater sources. The main methods include adsorption, filtration, ion exchange, electrochemical, reverse osmosis, precipitation, flotation/coagulation/ flocculation, and photocatalytic-based treatments. This paper comprehensively assesses the sustainability of those common technologies used for wastewater process treatment. The sustainability profile depends mostly on the exact approach followed for each technology, including its energy consumption, type of radiation (where appropriate), auxiliary materials used (e.g., catalysts, adsorbents), and further specific experimental process settings. Thus, while sustainability inevitably provides a multifaceted answer, the review finally aims for sustainability benchmarking of all technologies, by compressing the manifold outcomes toward a compact information set, such as a table and radar plot.
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