Please login first

List of accepted submissions

Show results per page
Find papers
  • Open access
  • 78 Reads
Application of coagulation-flocculation-decantation with sulfate radicals for agro-industrial wastewater treatment

Portugal is the 11th biggest wine producer in the world, with 6.4 MhL produced in 2020. This high production of wine leads to a great generation of a problematic agro-industrial effluent: winery wastewater (WW). WW presents elevated content of organic matter, polyphenols and low pH, therefore, it is necessary to treat the WW before it release into the environment. The aim of this work was (1) evaluate the application of the mixture potassium caseinate, bentonite and polyvinylpolypyrrolidone (PVPP) as a pre-treatment, (2) optimize the sulfate radical advanced oxidation process (SR-AOP) with a Box-Behnken design of Response Surface Methodology and (3) evaluate the combined treatment of coagulation-flocculation-decantation (CFD)-SR-AOP process. The Box-Behnken design was used to study the combinational effect of 3 influencing factors: sodium persulfate (SPS) concentration (15 – 75 mM), Fe2+ concentration (0.25 – 1.75 mM) and hydroxylamine (HA) concentration (0.00 – 8.75) on the total organic carbon (TOC) and chemical oxygen demand (COD) removal of a WW with a TOC and COD of 464 mg C/L and 1119 mg O2/L, respectively. With the statistical model it was obtained the best operational conditions, as follows: [SPS] = 51.96 mM, [Fe2+] = 0,90 mM, pH = 3.0, radiation UV-A (365 nm), Temperature = 298 K, time = 300 min, with a TOC and COD removal of 19.7 and 31.2%, respectively. With the combination of CFD process ([potassium caseinate] = 0.4 g/L, [bentonite] = [PVPP] = 0.1 g/L, pH = 3.0, rapid mix (rpm/min) = 150/3, slow mix (rpm/min) = 20/20, sedimentation time = 12 h) and SR-AOP it was achieved 38.9 and 45.3% removal of TOC and COD, respectively. The combined treatment was applied to a WW with a higher TOC and COD (997 mg C/L and 4640 mg O2/L) and it was achieved 51.2 and 73.3% removal, respectively. In conclusion the combined treatment reveals a good efficiency and potential to be applied in the treatment of agro-industrial wastewater.

  • Open access
  • 298 Reads
Impact of Hole Transport Layers in Inorganic Lead-Free CsSnI3 Perovskite Solar Cells: A Numerical Analysis

Tin-based halide perovskite compounds have attracted enormous interest as effective replacement to the conventional lead halide perovskite solar cells (PCSs). However, getting high efficiency for tin-based perovskite solar cells is still challenging. Herein, we demonstrate lead free tin-based CsSnI3 perovskite solar cells with introducing CuS as hole transport material to enhance the photovoltaic performance of the designed CsSnI3 perovskite solar cell. The CuS hole transport layer (HTL) with proper band structure can notably minimize the charge carrier recombination at the back side of the perovskite. In this study, lead free tin-based CsSnI3 perovskite solar cell structure consisting of CuS/CsSnI3/TiO2/ITO has been carried out using SCAPS-1D. The characteristics of the proposed device is numerically evaluated by varying the thickness, doping concentration, bulk defect density of the absorber layer. In addition, DFT-extracted physical parameters including band gap, the absorption spectrum of CuS are used in the SCAPS-1D to analyze the characteristics of the proposed solar cell device. Furthermore, different HTMs are further investigated to observe the characteristics of the proposed CsSnI3 perovskite solar cell. The power conversion efficiency (PCE) of ~29% is achieved with open circuit voltage (Voc) of 0.99 V, fill factor of ~87%, and short circuit current density (Jsc) of 33.49 mA/cm2 for the optimized device. This works addresses a proper guideline and introduces a convenient approach to design and fabricate highly efficient and stable lead free tin-based perovskite solar cells with lower cost.

  • Open access
  • 105 Reads
type ll collagen purified from chicken cartilage
, ,

The study presented in this work focused on the extraction and purification of type II collagen using an acid-enzymatic extraction starting with cartilage digestion using pepsin and acetic acid followed by precipitation using Nacl . collagen solubilized and recovered by acetic acid.

The extract obtained is purified by electrophoresis gives an alpha chain and its dimers of the betta chain on SDS PAGE so the analysis by scanning 200 to 400 nm on uv-visible spectrophotometer gives an absorbance at 225 nm.

The purified collagen from chicken sternum cartilage was type 2 collagen and could find applications in the induction of arthritis .

  • Open access
  • 87 Reads
Model-Based Design and Optimization of Electrochemical Processes for Sustainable Aviation Fuels

Aviation accounts for around 12% of all CO2 emissions from the transport sector, necessitating the use of sustainable aviation fuels. Electrofuels, which are gained from renewable sources, are attractive options for sustainable aviation fuels. Model-based electrochemical process design and optimization could very well assist in improved design and operation methods towards better conversion, selectivity, energy conversion, and economics - at a lower cost and time than the experimental approach. Moreover, nowadays, process models are also an indispensable technology for realizing Industry 4.0 and digital twin ideas for process intensification and monitoring. Thus, to design better electrofuel manufacturing processes and create digital process representations, this paper makes use of a first-principles model for electroreduction of furfural to furfuryl alcohol and methylfuran as well as hydrogen evolution. In detail, the Volmer reaction forms adsorbed hydrogen, represented by a Frumkin type isotherm. The hydrogen evolution is described by the potential dependent Heyvrosky reaction and the potential independent Tafel reaction. We critically discuss the simulation results using a global parameter sensitivity study and show its potential application for an AI-assisted process optimization strategy, i.e., predicting an optimal potential profile using the derived first-principle model and a neural network.

  • Open access
  • 48 Reads
Cobalt nanocomposites as catalysts for carbon dioxide conversion to methanol

Carbon capture and utilisation (CCU), has arised as one of the alternatives for the reduction of CO2 concentration in atmosphere by converting it into value added products. CO2 conversion to methanol presents certain drawbacks such as high pressure and temperature conditions, and to solve these issues new materials are being investigated. Among them, cobalt stands out due to its abundance and low price when compared to noble metals. Cobalt and its oxides exhibit interesting electronic and magnetic properties and are used as catalysts in a wide range of reactions. In this work we present a systematic comparison among different cobalt and cobalt oxide nanocomposites in terms of their efficiency as catalysts for CO2 hydrogenation to methanol, and how porous and non porous supports can enhance their catalytic capacity. With this purpose a fixed bed reactor operating with continuous flow is used, under mild conditions of temperature (160-260 ºC) and pressure (10-15 bar). Several parameters are measured in order to evaluate the efficiency of the catalysis: CO2 conversion; space time yield (STY), which indicates the metanol production yield per mass unit of catalyst and time of reaction, and methanol selectivity, which evaluates the production of side products of the reaction such as carbon monoxide. It is confirmed how the adsorption capacity provided by the porous supports can enhance the catalytic capacity of cobalt and cobalt oxide, and how porous supports such as zeolite and graphene clearly improve this capacity if compared with a non porous support such as silicon dioxide.

  • Open access
  • 26 Reads
Influence of vibroacoustic phenomena from FFF process on surface characteristics of printed parts

The fused filament fabrication (FFF) process deals with the manufacturing of parts by adding fused plastic filament in successive layers, following certain fill patterns. For fabrication to be successful, different filling parameters must be defined. Given the sequential nature of the FFF process, the fabrication of the first layer is considered one of the most critical points for fault detection. The FFF process takes place in a 3D printer, where the filling patterns are achieved by moving the extruder and/or printing table along the X, Y and Z axes. Different models of 3D printers move the axes in different ways. The optical profilometry method showed good results when analyzing different topographic characteristics, such as roughness and others related to the peaks and valleys of a printed surface when moving only the extruder. However, given that the filament deposition occurs on the printing table, the most susceptible place for vibroacoustic phenomena during process, the present work aims to evaluate, by means of optical profilometry, the surface characteristics of a region of a certain part manufactured by moving only the printing table. The results obtained demonstrate that the surface characteristics evaluated by optical profilometry are greatly influenced by the vibroacoustic phenomena, varying significantly from the values observed when only the extruder moves.

  • Open access
  • 41 Reads
Hemispherical directional reflectance in the analysis of the expired and unexpired tablets containing nifuroxazide – the results of a pilot study

Physical and chemical changes which may occur during storage of the drug form often adversely affect its quality and in turn, the safety and efficacy of the treatment. The degradation of the active substance or excipients is caused in particular by sunlight. The development of modern techniques allows for the identification of changes occurring in the solid phase. There are no data on the use of hemispherical directional reflectance in the tablet stability. Recently, this method was used to distinguish the original Viagra® tablets from the counterfeit ones (Wilczynski et al. 2016). This is a fast, time-saving method of high sensitivity and specificity and no destruction of the drug form is required. The present study aimed to assess the possible usage of directional reflectance in terms of the stability of tablets during storage.

The expired (n=6; expire date 112019) and unexpired (n=6; expire date 112024) coating tablets containing nifuroxazide (Nifuroksazyd 200 Hasco, HASCO-LEK S.A., Poland) were analyzed. Directional reflectance was determined to assess the total reflectance in seven wavelength bands (i.e. ultraviolet, visible light, near infrared) using SOC-410 Directional Hemispherical Reflectometer (Surface Optics Corporation, USA). For each tablet 6 measurements within all bands were done. Statistical analysis was performed using Statistica software.

Significantly lower (p<0.001) mean directional reflectance was observed for expired tablets in relation to unexpired tablets for all the spectral bands apart from one of the infrared range (1000-1700 µm). The highest total directional reflectance was observed for one of the spectral band of near infrared (700-1100 µm) while the lowest – for the near ultraviolet band (335-380 µm) both for expired and unexpired tablets.

The presented method can be a useful tool for monitoring the stability and quality control of solid dosage forms. The results indicated that total reflectance lowered during the storage in all spectral bands except infrared.

  • Open access
  • 27 Reads
Synthesis and ionic conductivity of NASICON-type lithium titanium phosphate doped with zirconium and aluminum

Today, due to the growing demand for powerful energy storage devices, lithium-ion batteries are of increasing interest. Generally, commercial samples of such energy sources are based on liquid electrolytes (solution of lithium salt in aprotic organic solvents). However, their use has a number of disadvantages: flammability and insufficient electrochemical stability. Solid electrolytes can be a promising solution to the safety problem. One of the most well-known types of solid electrolytes is lithium titanium phosphate LiTi2(PO4)3 with a NASICON-type structure. Its structure is composed of TiO6 octahedra and PO4 tetrahedra connected by oxygen atoms, enabling for lithium-ion conductivity. To improve LiTi2(PO4)3 conductivity, doping with various elements is carried out. Titanium substitution by Zr4+ leads to unit cell expansion, while Al3+ ion doping results in increase in Li+ interstitial concentration, which makes it possible to create structural defects in the lattice, in this way improving Li+ migration.

Thus, the aim of this work was to synthesize and study the ionic conductivity of Li1+yTi2-x-yZrxAly(PO4)3 (х = 0–0.2, y = 0–0.3) compounds with the NASICON-type structure.

In this work, the morphology and ionic conductivity of the Li1+yTi2‑x‑yZrxAly(PO4)3 (х = 0–0.2, y = 0–0.3) compounds prepared by both the sol-gel and solid-state methods were investigated, with the aim to study the effect of synthesis method. The Li1+yTi2‑x‑yZrxAly(PO4)3 systems were studied by X-ray diffraction, scanning electron microscopy, and 31P NMR spectroscopy. For all materials, the dependences of ionic conductivity on temperature were evaluated by impedance spectroscopy. It is shown that the Li1.1Ti1.7Zr0.1Al0.2(PO4)3 composition has the highest conductivity at 25°C (7.23×10-5 S/cm). The activation energy of Li+ conductivity was calculated. Its values are in the range of 34-40 kJ/mol for different materials.

  • Open access
  • 79 Reads

Date fruit (Phoenix dactylifera L.) is largely produced in North Africa and in the Middle East oases. Tunisia is a major worldwide producer and exporter; the annual production is estimated to 260 000 tons dominated by Deglet Nour variety. Date fruit is a principal source of carbohydrates and dietary fiber and is considered as a complete food or added in many traditional recipes. Lben is one of the popular traditional dairy products in North Africa and is characterized by its specific acid taste, nutritional value, and health attributes. The main objective of the current study was to evaluate the effect of the addition of date powder (6%; w/v) on the main quality attributes of Lben produced under optimized conditions in terms of starter level, temperature, and time of fermentation (temperature: 18.5°C, fermentation time: 20.6 h, and starter-level: 1.1 × 101 g/L). Solubility, antioxidant and total phenols of date powder were determined to evaluate its supplementation aptitude in the food matrix. Techno-functional properties of date powder were described by its solubility index (93.72±0.01 ml/gbs) in water and density (0.45±0.05 g/cm3). Phenolic content of date is 588.59 mg GAE/100 gbs and DPPH radical scavenging capacity is 55.25 %. L*, a*, b* color parameters of date powder were 63.35±1.72, 19.10±0.50, and 29.91±0.08, respectively. The supplementation of date powder in Lben allowed better flavor appreciation with a significant contribution to the sweet taste; to the reduction of the acidity from 84 to 76.37°D and the final lactic bacteria count from 1.9.109 to 1.5.108 CFU/mL. The incorporation of date powder affected also the final pH of Lben which increased from 4.51 to 4.58 and the mean sensory acceptance (4.7/6 points scale) with some modifications of appreciation attributes of the product mainly the color, sweet taste, and balance sweet/sour taste. These descriptors were correlated in the principal components biplot representation of Lben sensory attributes. Date powder improves the physicochemical and sensory attributes of supplemented Lben and could be used as fortifying ingredient having multifunctional properties.

  • Open access
  • 74 Reads
A new cost-effective and eco-friendly way to recover sulfuric acid waste using bleaching soil

Sulfuric acid is one of the acidic wastes produced in the edible oil refining industry during testing to determine the oxidation stability of the oil. Sulfuric acid is required as a rinsing solvent to clean Rancimat glass tubes. This acid cannot be discharged directly into the environment. Use processing and acid consumption must be performed to comply with environmental quality standards. The aim of this study was to purify and recover acid waste. In this new method, first water and other solvents are removed under a vacuum system at 80 ° C, then bleaching soil is added to sulfuric acid and placed at 80 ° C for half an hour, and then white soil. The solvent is separated by centrifugation. Recovery was about 90%. An identical sample of oil with oxidation stability was tested with a Rancimat device And the results showed no change with fresh sulfuric acid. This study developed an innovative, effective, and simple method for the recycling of acid waste that can successfully resolve this significant problem in industry. This method both reduces carbon emissions and recycles valuable resources, which is of important environmental and economic significance.