Effects of Various Precipitants on Iron Removal from a Zinc Concentrate Pressure Leaching Solution

Autoclave leaching of zinc concentrate (Sphalerite) is an environmentally friendly process compared to roasting, which discharges pollutants into the atmosphere. Due to the amount of iron in the final product, a study is proposed to evaluate different reagents for eliminating iron from the autoclave outcome, minimizing Zn losses. The colloid formation, zinc losses, iron removal, phase separation stage characteristics (sedimentation and filtering), and reagent costs were used to evaluate six-iron precipitating reagents: CaO, Na2CO3, CaCO3, NaOH, MgO, and Ca(OH)2. CaO shows 99.5% iron removal and 87% zinc recovery. Although CaO was one of the reagents with significant zinc recovery, it presented operational difficulties in the filtration stage due to the high viscosity of the mixtures. Finally, Ca(OH)2 is the reagent recommended due to its ease of use, zinc yield recovery, electrowinning efficiency, and iron precipitate filtration rate. Zinc recovery was above 80%, while the iron concentration in the solution was below 50 ppm.

A Novel Method For The Fibre-Based Conductive Ring Spun Yarn Production

To take the advantages of spun yarns such as porosity, softness, bending as well as usability as yarn/fabric forms, in this study, it was worked on an alternative conductive yarn production method. Different from other methods such as coating, core-spun, blending, a conductive nanosuspension was applied to viscose, cotton and polyester open fibre bundles with different feeding amounts during the ring spinning with a specially developed apparatus. Reduced graphene oxide (rGO) was used to impart conductivity. Different from literature, rGO was synthesized with a single step process instead of two-step processes to ensure simple, easy-to-apply process and industrial applicability. Following to yarn production, winding, knitting and washing processes were realized to evaluate the changes in yarn conductivity and the usability of the yarns in the post-spinning processes. In addition to tensile properties of the yarns and air permeability of the fabrics, electrical resistance and environmental impact of the method was compared with immersion&drying process. The results indicated that alternative method allows the production of conductive (lower resistance than 100 kΩ) but also stronger, flexible, washable and breathable electronic textile products with an environmentally friendly process. There has been no effort, as yet, to get conductivity in this manner. Therefore, the developed method can be considered to be a new application in the functional yarn production field. The produced conductive yarns can be converted into fabric form by weaving, knitting and embroidery. Therefore, they can also be seen as an ideal as the platforms for future wearable electronics.

Special Issue “Applications of Biosorption in Wastewater Treatment”

The interest in the use of biosorption for the elimination of pollutants is because this technique is an efficient and environmentally friendly process, constituting an alternative to the so-called conventional treatment processes [...]

Effects of Preparation Conditions on the Efficiency of Visible-Light-Driven Hydrogen Generation Based on Cd0.25Zn0.75S Photocatalysts

Photocatalytic H2 production utilizing H2S, an industrial side-product, is regarded as an environmentally friendly process to produce clean energy through direct solar energy conversion. For this purpose, sulfide-based materials, such as photocatalysts, have been widely used due to their good solar response and high photocatalytic activity. In this work, a ZnS–CdS composite was studied, and special attention was dedicated to the influence of the preparation parameters on its H2 production activity. The ZnS–CdS composite, with an enhanced photoactivity for H2 production, was synthesized both from ammine complexes and, in a conventional way, directly from acetates at various pH values. Deviating from the traditional method, the photoactivity of ZnS–CdS prepared from ammine complexes was not affected by the pH. Besides, the hydrothermal treatment and the ammonia content strongly influenced the rate of H2 production in this system. DRS, TEM, SEM, XRD, and quantum yield measurements prove the dependence of the photoactivity of these catalysts on the structural and morphological properties determined by the preparation conditions. The promising photocatalytic efficiency achieved with the application of these ZnS–CdS catalysts, prepared without any metal deposition, encourages further investigations to enhance the rate of hydrogen generation by optimization of the reaction conditions for practical utilization.

Techniques of Preparation of Thin Films: Catalytic Combustion

Over the past several decades, an increasing amount of attention has been given to catalytic combustion as an environmentally friendly process. However, major impediments to large-scale application still arise on the materials side. Here, we review catalytic combustion on thin film catalysts in view of highlighting some interesting features. Catalytic films open the way for new designs of structured catalysts and the construction of catalysts for catalytic combustion. A special place is occupied by materials in the form of very thin films that reveal catalytic activity for various chemical reactions. In this review, we demonstrate the high catalytic activity of thin film catalysts in these oxidation reactions.

Magnetic Pulse Hybrid Joining of Polymer Composites to Metals

To lighten their vehicles, car manufacturers are inclined to substitute steel structures with aluminum alloys or composites parts. They are then faced with the constraints inherent to dissimilar (galvanized steel/aluminum) or hybrid (metal/composite) assemblies. Recent developments in magnetic pulse welding seems to offer a viable route. Very fast, this process can be robotized and generates a very localized heating system which limits the formation of intermetallic and damage the composite. Low energy consumption, without filler metal or smoke it is recognized as an environmentally friendly process. In this paper, electromagnetic pulse welding is exploited to assemble polymer composite to metals. Two techniques, a metallic insert in polymer composite or an external patch, have been tested with possible design considerations.

In Situ Wood Fiber Dyeing Through Laccase Catalysis for Fiberboard Production

The aim of the present work was to develop an innovative and environmentally friendly process for wood fiber dyeing and to produce 3-dimensionally fully colored medium-density fiberboard (MDF). The potential of laccase-catalyzed polymerization of selected precursors to form dyes useful in fiberboard manufacturing, a technique used for the first time in this field, was demonstrated. Some of the 7 aromatic compounds tested yielded colored products after laccase treatment under both acid and alkaline conditions, and a good variety of colors was attained by using mixtures of two different monomers. To demonstrate the coloration and design potential of laccase conversion of aromatic compounds, MDFs were enzymatically dyed using an in situ one-step laccase-catalyzed coloration process, and the results were compared against commercial MDFs obtained by using organic coloring agents. Important advantages over conventional processing methods include good color fastness and, in some cases, new hydrophobic properties, allowing designers and woodworkers to explore the beauty of textures and the use of simpler and milder processing conditions that eliminate harsh chemical use and reduce energy consumption.

Hydrothermal Synthesis of Clove Buds-Derived Multifunctional Carbon Dots Passivated with PVP- Antioxidants, Catalysis, and Bioimaging Applications

The present study reports a one-step clean synthesis of carbon dots (CDs) using clove buds and polyvinylpyrrolidone (PVP) as the starting precursor via hydrothermal routes. The adopted technique is facile, reproducible, and cost-effective for the production of externally passivated carbon dots owing to an environmentally friendly process utilizing natural precursors. The study evidenced the synergetic effect of passivation on light absorption and fluorescence properties in comparison to non-passivated carbon dots (CCDs). The structural and morphological study revealed that the PVP-passivated clove-derived carbon dots (PPCCDs) were spherical with an average diameter of ~ 2 nm and crystalline with an interlayer spacing of 0.33 nm. The PPCCDs showed excellent antioxidant activity against DPPH free radicals and also showed good catalytic activity for the degradation of Rhodamine-B (Rh-B) dye under studied conditions. Synthesized PPCCDs showed dose-dependent toxicity in L929 (mouse fibroblast) cell lines, while the appropriate concentration used in biological studies was found to be biocompatible as evidenced by MTT assays and also revealed in bioimaging potential. To conclude, synthesised PPCCDs is an economically potent candidate with multifunctional aspects, which can serve as an excellent antioxidant, catalyst, and efficient multicolor bioimaging tool.

A Review of the Processes Associated with the Removal of Oil in Water Pollution

Water plays an essential role in production and refining processes. Many industries that use petrochemicals also require water, especially for cleaning purposes. The wastewaters released by these processes are often rich in petroleum pollutants, which requires significant treatment prior to disposal. The presence of petroleum contaminants in rivers and oceans is a significant threat to human health, as well as to many animal species. A current challenge for most industries and conventional effluent treatment plants is compliance with accepted disposal standards for oil-polluted wastewater. Of particular importance is the processing of dispersed oil in water, as well as oil in water emulsion. Conventional oil and water separation methods for processing oil in water contamination have several technology gaps in terms of applicability and efficiency. The removal and effective processing of dispersed oil and emulsions from oily wastewater is a costly and significant problem. The objective of this paper is to provide a review of the principles associated with oil in water emulsion separation, with the aim of providing a more definitive understanding of the terminology, processes, and methodologies, which will assist the development of a more efficient, innovative and environmentally friendly process for the separation of oily wastewater.

BIOPLASTIC MADE OF ORANGE PEELS

This study uses orange peel waste to create a biopolymer that can be used for different purposes. In order to achieve this, we evaluated various technologies for the production of the biopolymer, and tried to design the most environmentally friendly process possible. One of the reasons why this bioplastic should be manufactured is to participate in the replacement of common environmental hazardous plastic, which has been banned in many places. On the other hand, using orange peel as the main ingredient is an alternative and gives value to an organic waste that has limited use in circular economy solutions. In this research we present a methodology to create a bioplastic of orange peels. As a result, we obtained a biodegradable, flexible and resistant material to be used in the manufacture of containers, utensils, etc. In addition, it is a material that, given the raw materials used, is considered GRAS (Generally Recognized As Save), implying a non-toxic product that is safe for the consumer.