A green chemistry-based classification model for the synthesis of silver nanoparticles

The assessment of the implementation of green chemistry principles in the syntheses of nanomaterials is a complex decision-making problem that necessitates the integration of several evaluation criteria. Multiple Criteria Decision Aiding (MCDA) provides support for such a challenge. One of its methods – Dominance-based Rough Set Approach (DRSA) – was used in this research to develop a model for the green chemistry-based classification of silver nanoparticle synthesis protocols into preference-ordered performance classes. DRSA allowed integration of knowledge from both peer-reviewed literature and experts (decision makers, DMs) in the field, resulting in a model composed of decision rules that are logical statements in the form: “if conditions, then decision”. The approach provides the basis for the design of rules for the greener synthesis of silver nanoparticles. Decision rules are supported by synthesis protocols that enforce the principles of green chemistry to various extents, resulting in robust recommendations for the development and assessment of silver nanoparticle synthesis that perform at one of five pre-determined levels. The DRSA-based approach is transparent and structured and can be easily updated. New perspectives and criteria could be added into the model if relevant data were available and domain-specific experts could collaborate through the MCDA procedure

Co-constructive development of a green chemistry-based model for the assessment of nanoparticles synthesis

Nanomaterials (materials at the nanoscale, 10−9m) are extensively used in several industry sectors due to the improved properties they empower commercial products with. There is a pressing need to produce these materials more sustainably. This paper proposes a Multiple Criteria Decision Aiding (MCDA) approach to assess the implementation of green chemistry principles as applied to the protocols for nanoparticles synthesis. In the presence of multiple green and environmentally oriented criteria, decision aiding is performed with a synergy of ordinal regression methods; preference information in the form of desired assignment for a subset of reference protocols is accepted. The classification models, indirectly derived from such information, are composed of an additive value function and a vector of thresholds separating the pre-defined and ordered classes. The method delivers a single representative model that is used to assess the relative importance of the criteria, identify the possible gains with improvement of the protocol’s evaluations and classify the non-reference protocols. Such precise recommendation is validated against the outcomes of robustness analysis exploiting the sets of all classification models compatible with all maximal subsets of consistent assignment examples. The introduced approach is used with real-world data concerning silver nanoparticles. It is proven to effectively resolve inconsistency in the assignment examples, tolerate ordinal and cardinal measurement scales, differentiate between inter- and intra-criteria attractiveness and deliver easily interpretable scores and class assignments. This work thoroughly discusses the learning insights that MCDA provided during the co-constructive development of the classification model, distinguishing between problem structuring, preference elicitation, learning, modeling and problem-solving stages

Environmentally friendly synthesized and magnetically recoverable designed ferrite photo-catalysts for wastewater treatment applications

Fenton processes are promising wastewater treatment alternatives for bio-recalcitrant compounds. Three different methods (i.e., reverse microemulsion, sol-gel, and combustion) were designed to synthesize environmentally friendly ferrites as magnetically recoverable catalysts to be applied for the decomposition of two pharmaceuticals (ciprofloxacin and carbamazepine) that are frequently detected in water bodies. The catalysts were used in a heterogeneous solar photo-Fenton treatment to save the cost of applying high-energy UV radiation sources, and was performed under a slightly basic pH to avoid metal leaching and adding salts for pH adjustment. All the developed catalysts resulted in the effective treatment of ciprofloxacin and carbamazepine in both synthetic and real domestic wastewater. In particular, the sol-gel synthesized ferrite was more magnetic and more suitable for reuse. The degradation pathways of both compounds were elucidated for this treatment. The degradation of ciprofloxacin involved attacks to the quinolone and piperazine rings. The degradation pathway of carbamazepine involved the formation of hydroxyl carbamazepine and dihydroxy carbamazepine before yielding acridine by hydrogen abstraction, decarboxylation, and amine cleavage, which would be further oxidized

Influence of operating parameters on surface properties of RF glow discharge oxygen plasma treated TiO2/PET film for biomedical application

In this paper, a thin transparent titania (TiO2) film was coated on the surface of flexible poly(ethylene terephthalate) (PET) film using the sol–gel method. The surface properties of the obtained TiO2/PET film were further improved by RF glow discharge oxygen plasma as a function of exposure time and discharge power. The changes in hydrophilicity of TiO2/PET films were analyzed by contact angle measurements and surface energy. The influence of plasma on the surface of the TiO2/PET films was analyzed by atomic force microscopy (AFM) as well as the change in chemical state and composition that were investigated by X-ray photo electron spectroscopy (XPS). The cytotoxicity of the TiO2/PET films was analyzed using human osteoblast cells and the bacterial eradication behaviors of TiO2/PET films were also evaluated against Staphylococcus bacteria. It was found that the surface roughness and incorporation of oxygen containing polar functional groups of the plasma treated TiO2/PET films increased substantially as compared to the untreated one. Moreover the increased concentration of Ti3 + on the surface of plasma treated TiO2/PET films was due to the transformation of chemical states (Ti4 + → Ti3 +). These morphological and chemical changes are responsible for enhanced hydrophilicity of the TiO2/PET films. Furthermore, the plasma treated TiO2/PET film exhibited no citotoxicity against osteoblast cells and antibacterial activity against Staphylococcus bacteria which can find application in manufacturing of biomedical devices

Barium-Encapsulated Biodegradable Polycaprolactone for Sulfate Removal

Various compositions of barium carbonate (BaCO3) loaded polycaprolactone (PCL) composites were prepared, including 2.5/97.5, 10/90, 30/70, 50/50 and 90/10 (PCL/BaCO3), via re-precipitation technique. Small-scale column tests were conducted to study the efficiency of sulfate removal using the PCL/BaCO3 composites. The composites before and after their use to remove sulfate were extensively characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), and thermogravimetric analysis (TGA). As PCL is a biodegradable polymer, these composites are environmentally friendly and have several advantages over barium sulfate precipitation in overcoming clogging issues in filters or resins due to collection of natural organic matter (NOM). The media used in this study exhibited high capacity and was able to remove more than 90% sulfate from synthetic sulfate containing waters and NOM samples collected from the Ohio River

Editorial for Special Issue “Multifunctional Nanomaterials and Hybrid Structures for Sensors, Actuators and Smart Technologies”

Advanced materials related to sensing, actuation, catalysis, and other functionalities for interactive devices depend on surface interactions and quantum effects in solids [...

Green Synthesis of Ag and Pd Nanospheres, Nanowires, and Nanorods Using Vitamin B2: Catalytic Polymerisation of Aniline and Pyrrole

For the first time, we report green chemistry approach using vitamin B2 in the synthesis of silver (Ag) and palladium (Pd), nanospheres, nanowires, and nanorods at room temperature without using any harmful reducing agents, such as sodium borohydride (NaBH4) or hydroxylamine hydrochloride and any special capping or dispersing agent. Vitamin B2 was used as reducing agent as well as capping agent due to its high-water solubility, biodegradability, and low-toxicity compared with other reducing agents. The average particle size of nanoprticle was found to be Ag (average size 6.1±0.1 nm) and Pd (average size 4.1±0.1 nm) nanoparticles in ethylene glycol and Ag (average size 5.9±0.1 nm, and average size 6.1±0.1) nanoparticles in acetic acid and NMP, respectively. The formation of noble multiple shape nanostructures and their self assembly were dependent on the solvent employed for the preparation. When water was used as solvent media, Ag and Pd nanoparticles started to self-assemble into rod-like structures and in isopropanol Ag and Pd nanoparticles yielded wire-like structures with a thickness in the range of 10 to 20 nm and several hundred microns in length. In acetone and acetonitrile medium, the Ag and Pd nanoparticles are self-assembled into a regular pattern making nanorod structures with thicknesses ranging from 100 to 200 nm and lengths of a few microns. The so-synthesized nanostructures were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, and UV spectroscopy. The ensuing Ag and Pd nanoparticles catalyzed the reactions of aniline and pyrrole to generate polyaniline and polypyrrole nanofibers and may find various technological and biological applications. This single-step greener approach is general and can be extended to other noble metals and transition metal oxides

Adsorption Of Ammonium Ions Onto Multi-Walled Carbon Nanotubes

Multi-walled carbon nanotubes (MWCNTs) surfaces have been characterized by FTIR and SEM techniques. The adsorption performance of MWCNTs was investigated for the removal of ammonium ions from wastewater. The effect of contact time, temperature and initial ions concentration on the adsorption of ammonium ions by MWCNTs were studied and optimized. The results showed a high adsorption capacity of 129 mg/g according to Langmuir isotherm model and removal efficiency of 95%. In addition, the adsorption kinetic and equilibrium data were fitted to the pseudo–second–order model. The potential application of MWCNTs for adsorption of ammonium ions from wastewater was successfully accomplished using a batch adsorption technique