Search results for "Chemical engineering"
showing 10 items of 5892 documents
Management of irrigation water and nutrient demands of tomato (Lycopersicon esculentum Mill.) using urban treated wastewater from a pilot-scale horiz…
2017
The reuse of treated wastewater (TWW) in crop irrigation is an advanced and rational approach to water resource management in agriculture. Results would seem to demonstrate that it could be an extremely important tool in the reduction of freshwater (FW) consumption in agriculture, at the same time helping to increase crop yields through the transfer of nutrients required for crop growth. In arid and semi-arid areas of the Mediterranean, constructed wetlands can play a key role in the treatment and reuse of wastewater due to their multifunctional nature. The aim of this study was to manage water and nutrient requirements of tomato (Lycopersicon esculentum Mill.) using TWW from a pilot-scale …
Nanoparticle-Directed Metal–Organic Framework/Porous Organic Polymer Monolithic Supports for Flow-Based Applications
2017
A two-step nanoparticle-directed route for the preparation of macroporous polymer monoliths for which the pore surface is covered with a metal–organic framework (MOF) coating has been developed to facilitate the use of MOFs in flow-based applications. The flow-through monolithic matrix was prepared in a column format from a polymerization mixture containing ZnO-nanoparticles. These nanoparticles embedded in the precursor monolith were converted to MOF coatings via the dissolution–precipitation equilibrium after filling the pores of the monolith with a solution of the organic linker. Pore surface coverage with the microporous zeolitic imidazolate framework ZIF-8 resulted in an increase in su…
Volcanic SiO2-cristobalite: A natural product of chemical vapor deposition
2020
Abstract Cristobalite is a low-pressure, high-temperature SiO2 polymorph that occurs as a metastable phase in many geologic settings, including as crystals deposited from vapor within the pores of volcanic rocks. Such vapor-phase cristobalite (VPC) has been inferred to result from silica redistribution by acidic volcanic gases but a precise mechanism for its formation has not been established. We address this by investigating the composition and structure of VPC deposited on plagioclase substrates within a rhyolite lava flow, at the micrometer to nanometer scale. The VPC contains impurities of the form [AlO4/Na+]0—coupled substitution of Al3+ charge-balanced by interstitial Na+—which are ty…
Methodologies for feasibility studies related to wastewater reclamation and reuse projects
2006
Abstract About 20% of the total surface water in Europe is strongly threatened due to pollution problems, and 60% of European cities over-exploit their groundwater resources. The European Framework Water Directive established that by the year 2015 “a good ecological state” of all European water resources and a sustainable use of water must be achieved. Wastewater reuse presents a promising solution to the growing pressure on Europe's water resources. However, wastewater reuse implementation in Europe faces obstacles that include insufficient public acceptance; technical, economic and hygienic risks; and lack of regulations. On the other hand, a very important aspect to implement a water reu…
Determination of Glyphosate and AMPA in Food Samples Using Membrane Extraction Technique for Analytes Preconcentration
2021
The method for determining glyphosate (NPG) and its metabolite AMPA (aminomethyl phosphonic acid) in solid food samples using UAE-SLM-HPLC–PDA technique was developed. Firstly, ultrasonic-assisted solvent extraction (UAE) and protein precipitation step were used for the analyte isolation. Then, the supernatant was evaporated to dryness and redissolved in distilled water (100 mL). The obtained solution was alkalized to pH 11 (with 1 M NaOH) and used directly as donor phase in SLM (supported liquid membrane) extraction. The SLM extraction was performed using 2 M NaCl (5 mL) as an acceptor phase. The flow rate of both phases (donor and acceptor) was set at 0.2 mL/min. The membrane extraction t…
Gamma-Ray-Induced Structural Transformation of GQDs towards the Improvement of Their Optical Properties, Monitoring of Selected Toxic Compounds, and …
2022
Structural modification of different carbon-based nanomaterials is often necessary to improve their morphology and optical properties, particularly the incorporation of N-atoms in graphene quantum dots (GQDs). Here, a clean, simple, one-step, and eco-friendly method for N-doping of GQDs using gamma irradiation is reported. GQDs were irradiated in the presence of the different ethylenediamine (EDA) amounts (1 g, 5 g, and 10 g) and the highest % of N was detected in the presence of 10 g. N-doped GQDs emitted strong, blue photoluminescence (PL). Photoluminescence quantum yield was increased from 1.45, as obtained for non-irradiated dots, to 7.24% for those irradiated in the presence of 1 g of …
An Overview of Functionalized Graphene Nanomaterials for Advanced Applications
2021
Interest in the development of graphene-based materials for advanced applications is growing, because of the unique features of such nanomaterials and, above all, of their outstanding versatility, which enables several functionalization pathways that lead to materials with extremely tunable properties and architectures. This review is focused on the careful examination of relationships between synthetic approaches currently used to derivatize graphene, main properties achieved, and target applications proposed. Use of functionalized graphene nanomaterials in six engineering areas (materials with enhanced mechanical and thermal performance, energy, sensors, biomedical, water treatment, and c…
The Application of Supercritical Fluids Technology to Recover Healthy Valuable Compounds from Marine and Agricultural Food Processing By-Products: A …
2021
Food by-products contain a remarkable source of bioactive molecules with many benefits for humans; therefore, their exploitation can be an excellent opportunity for the food sector. Moreover, the revalorization of these by-products to produce value-added compounds is considered pivotal for sustainable growth based on a circular economy. Traditional extraction technologies have several drawbacks mainly related to the consumption of hazardous organic solvents, and the high temperatures maintained for long extraction periods which cause the degradation of thermolabile compounds as well as a low extraction efficiency of desired compounds. In this context, supercritical fluid extraction (SFE) ha…
Revealing lattice disorder, oxygen incorporation and pore formation in laser induced two-photon oxidized graphene
2019
Abstract Laser induced two-photon oxidation has proven to be a reliable method to pattern and control the level of oxidation of single layer graphene, which in turn allows the development of graphene-based electronic and optoelectronic devices with an all-optical method. Here we provide a full structural and chemical description of modifications of air-suspended graphene during the oxidation process. By using different laser irradiation doses, we were able to show via transmission electron microscopy, electron energy loss spectroscopy, electron diffraction and Raman spectroscopy how graphene develops from its pristine form up to a completely oxidized, porous and amorphous carbon layer. Furt…
Precipitation of potassium as hazenite from washing water of spent alkaline batteries
2022
Hazenite (KNaMg2(PO4)2 × 14 H2O), a new type of struvite mineral, was precipitated from the potassium-rich washing water of spent alkaline battery black mass. Hazenite can be used as a fertilizer, which would be an additional benefit derived from the sustainable recovery of battery materials. Precipitation experiments were performed using different pH values (9.5–12), Mg:K:PO4 ratios ((1.0–1.5):1:(1.0–1.5)) and temperatures (10–40 °C). Based on the results, hazenite precipitated in a wide pH range under alkaline conditions. The precipitation kinetics were fast, and the purity of the hazenite was high. Overall, hazenite can be precipitated at room temperature without the addition of excess c…