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Adsorption of pharmaceuticals by novel carbonaceous materials from the leaves of Ailanthus altissima (Mill.) Swingle - Case study on the adsorption of tetracycline
No full textIn the last two decades, there has been a growing awareness of the presence of pharmaceuticals in the aquatic
environment. Antibiotics are particularly alarming because their occurrence may result in increased antibiotic
resistance. Difficulties in sample preparation and removal of low concentrations of pharmaceuticals from
environmental water could be overcome by their adsorption onto novel, non-polluting, and inexpensive
materials.
In this study, biochar prepared by pirolysis of biomass at 500°C (BC500) and 800°C (BC800) and activated
carbon prepared upon treatment with ZnCl2 at 800°C (AC800) were evaluated as potential adsorbents. Ailanthus
altissima was selected as a source of raw material, leaf, because it is a widespread invasive tree that negatively
affects biodiversity. Tetracycline hydrochloride was selected as a model substance, since it is an antibiotic
widely present in environmental water. Central composite design was employed to simultaneously investigate
the effects of adsorbate solution pH, ionic strength (KCl concentration), and adsorbent mass on removal
efficiency of all three adsorbents, and to find optimal conditions for studying adsorption kinetics and equilibrium
on the most promising adsorbent. The removal efficiency and adsorbed mass were calculated from the HPLCUV
determined concentration of tetracycline post-adsorption.
Under optimal conditions (10.18 mg of adsorbent, pH 4.42, and ionic strength 165mM), AC800 showed the
highest affinity for tetracycline, i.e. 38.22% removal and adsorbed mass of 56.32 mg g-1 compared to 14.57%
and 21.48 mg g-1 (BC500) and 18.82% and 27.73 mg g-1 (BC800). Removal efficiency of AC800 was strongly
influenced by the adsorbent mass and solution pH. The kinetics study showed a rapid adsorption process
(equilibrium attained in 120 minutes), while equilibrium studies revealed a high adsorption capacity for
tetracycline (131.55 mg g-1). AC800 has been shown to be a promising novel drug adsorbent and should be
further tested for its suitability in water treatment and sample preparation
Pelletization as a quality alternative for granulation of potassium and ammonium sulfate fertilizer
No full textPotassium and ammonium salts are necessary to meet the nutritional needs of crops. While the granulation of these materials has traditionally been done by roller compaction, the demand for a rounder and less angular product has led some fertilizer manufacturers to introduce an additional production line to their operations: pelletization (wet granulation) with a disc pelletizer. This paper presents possible alternatives in the production process of potassium and ammonium sulfate fertilizers, provided by the pelletization process
Thermal degradation kinetics of lignocellulosic peach stone waste
No full textThe decrease of fossil fuel resources as well as associated pollution induced by its applications has
increased the interest in findings of renewable fuels from various biomasses such as wood, energy
crops, and various waste disposed from agricultural and food-industry activities. Especially
interesting is lignocellulosic waste (LCW) biomass, found in large quantities after processing of the
raw biomass, which pose certain energetic properties that might be used to fulfil future
sustainability demands. This paper describes the thermal decomposition of waste peach stones (PS)
investigated via thermogravimetric (TG) analyses. TG/DTG analyses provided a set of experimental
mass loss data (obtained under different conditions), which were modelled by different kinetic
models, resulting in parameters that might be used for industrial application of the tested biofuel.
The goal of analyzing the kinetics of thermal degradation was to establish a relationship between
the rate of degradation, degree of conversion (α) and temperature. In this sense, the investigation of
the kinetics of thermal degradation was performed in non-isothermal conditions, with the heating
speed varying from 5 to 20 ºC/min in an oxygen stream. Activation energy (Ea) of the PS thermal
degradation was determined using Flynn-Wall-Ozawa (FWO) isoconversional model free method.
The possible reaction mechanism that controls the process was investigated by the method of Coats-
Redfern (C-R). The values of the Ea obtained by this method were not constant with the change in
the degree of conversion (α), indicating that the thermal decomposition of PS represents a complex
process that cannot be described by a one-step reaction in the entire range of conversions. PS
waste samples investigated in this paper, have certain physical and chemical properties which
satisfy request for energy density, small ash content and safe burn out. Presented results might
support the value of biowaste in a future circular bio economy of Serbia
Obtaining a filler based on limestone from the deposit "Glavatske Kuće"-Kotor, for use in various industrial branches
No full textThis paper presents results of investigations of the possibility of using “Glavatske Kuće”-Kotor limestone (Republic Montenegro) as filler in various industry branches. Micronization methods, granulometric composition, oil and water absorption and degree of whiteness were investigated, and chemical and thermal analyses (DT/TG) were performed. Physico-chemical properties of this limestone classify it among high quality carbonate raw materials with high CaCO3 content of 97,68%, as well as MgO content of 0,884% and low silicate content (SiO2 0,240%). The quality of this limestone meets the requirements of the standards for the use of calcium carbonate as a filler in the following industries: paints and coatings; glass, foundry, and sugar industry as well as metallurgy. Due to the low degree of whiteness (77,85%), limestone "Glavatska kuće" cannot be used in the paper and cosmetic-pharmaceutical industry. The high content of Cd is also unacceptable for the cosmetic-pharmaceutical industry. Due to the high content of Cu, this limestone cannot be used in the production of rubber and PVC. Due to the increased content of MgO, this limestone cannot be used in the production of mineral fertilizers. Due to the relatively high content of biogenic elements MgO, P2O5, K2O, Cu, and heavy metals Ni and Cd, limestone Glavatske Kuće”-Kotor cannot be used, in production of cattle feed and for neutralization of acidic soils
Phyllosilicate-based adsorbents decorated with iron oxyhydroxides: application for lead, chromates and selenites removal
No full textExpanded vermiculite (EVer) was acid activated and silanized in order to obtain suitable substrate’s surface for decoration with iron oxyhydroxides (IO). Obtained activated sample (EVa), was decorated by deposition of either prevailing goethite or amorphous iron oxyhydroxides (AIO) resulting in EV-A and EV-B adsorbent, respectively. Modifications of EVa showed improved adsorption performances when used as adsorbent of lead, chromates and selenites. Adsorption experiments conducted in a batch and column system demonstrated good potential for purification of water contaminated with Pb2+, Cr(VI), and Se(IV). Equilibrium adsorption capacity of EV-A in relation to Pb2+ and Cr(VI) were 48 and 54 mg g-1, respectively, while EV-B showed even better effectiveness for Se(IV) achieving 120 mg g-1 capacity. Regeneration of pollutant saturated adsorbents approved that prepared adsorbents possess fine removal potency even after five adsorption/desorption cycles from 87.58 (for Pb2+/EV-A) to 92.81 % (for Cr(VI)/EV-A) of initial adsorption capacity
Predicting Low-Modulus Biocompatible Titanium Alloys Using Machine Learning
No full textTitanium alloys have been present for decades as the main components for the production of various orthopedic and dental elements. However, modern times require titanium alloys with a low Young’s modulus, and without the presence of cytotoxic alloying elements. Machine learning was used with aim to analyze biocompatible titanium alloys and predict the composition of Ti alloys with a low Young’s modulus. A database was created using experimental data for alloy composition, Young’s modulus, and mechanical and thermal properties of biocompatible titanium alloys. The Extra Tree Regression model was built to predict the Young’s modulus of titanium alloys. By processing data of 246 alloys, the specific heat was discovered to be the most influential parameter that contributes to the lowering of the Young’s modulus of titanium alloys. Further, the Monte Carlo method was used to predict the composition of future alloys with the desired properties. Simulation results of ten million samples, with predefined conditions for obtaining titanium alloys with a Young’s modulus lower than 70 GPa, show that it is possible to obtain several multicomponent alloys, consisting of five main elements: titanium, zirconium, tin, manganese and niobium
Influence of Hydro-climate Extremes on Microplastic Environmental Pollution: what do we Know so Far?
No full textHydro-climate extremes, such as floods, heatwaves, and drought severely endanger ecosystems, energy, human health, and agricultural yields. The trend of the intensity, frequency, and duration of hydro-climate extreme events has seriously increased during the last decades at both regional and global scales. Supplemental hazards may occur by climate change's linkage with other environmental issues. Owing to its ubiquity in terrestrial, freshwater, and marine environments, microplastics (MPs) pollution, originating from plastics degradation into small debris via physical, chemical, and biological processes, has become a global environmental concern. Growing evidence of microplastics' negative effects on soil and water properties, and organisms populating those habitats have been reported. Furthermore, plastic debris presence disrupts ecosystems' ability for climate regulation, as its production directly contributes to greenhouse gas (GHG) emissions. Discovered microplastics affect to soil water regime, and may be of high importance during drought periods. Climate changes (wetting-drying, rain intensity, soil cracking, etc.) influence the microplastic migration rates into soil layers. The mobility of microplastics in certain environmental mediums, such as sediments, depends on the microplastics' shape and type. Accumulation of microplastics, together with variable environmental conditions may affect soil physicochemical properties, such as its water-air capacity. The impact of catastrophic flooding on microplastic organization has been reported in riparian soils, which could be considered sinks for microplastics. Also, dust storms, monsoons, and other meteorological phenomena could promote MPs' transboundary migration. Microplastic abundance positively correlates with climatic factors such as rainfalls and winds, especially in tropical countries possessing high volume and intensity precipitation, which could influence the transport and settlement of MPs suspended in the air. MPs deposition was found to be higher in wet periods, depending on the intensity of the occurring precipitation. Recent studies highlight that climate change further impact on plastic pollution concentration and fluxes in global distribution. Tropical storms and other extreme weather events already cause the dispersal of mismanaged waste between freshwater, marine, and terrestrial environments. Additional inputs of terrestrial MPs into aquatic environments might be increased by stronger winds, while sea level rises and frequent rain events may likely release plastic debris trapped in coastal sediments. Flooding has the potential to further intensify plastic pollution, and flood-risk areas often become high plastic mobilization sites. Recently a new type of plastic material was discovered, representing the rock-plastic complex, formed during microplastics' irreversible sorption onto the parent rock after the flooding events. Microplastics-rock complexes testify to the anthropogenic waste entering the geological cycles while inducing new potential ecological risks. Microplastic omnipresence as a potential hazard should be seriously considered as a component of the climate change impacts on ecosystems and the environment, on a worldwide level. Further research is needed for a beter understanding of the aging and risk assessments of microplastics under hydro-climate change
The advantages of using pelletelized gypsum compared to powdered gypsum
No full textPowdered gypsum products were the standard for agricultural gypsum for many years, but as growers look to maximize
their return on investment, they are increasingly turning toward pelletized gypsum – a premium alternative. Pelletized
gypsum offers several significant advantages over other forms of gypsum such as powdered or ultra-fine gypsum, these
advantages will be discussed in the paper. This has led to increased grower adoption and a greater demand for fertilizer
and soil amendment producers to offer gypsum in a pelletized form. Producers are also finding that they stand to gain a
few benefits from offering a pelletized product as well
Clay-chitosan-surfactant composites as efficient adsorbents of zearalenone
No full textIn this study bentonite was modified with two chitosans, commercial or chitosan synthesized from mushroom. Obtained
products were subsequently treated with hexadecyltrimethyl ammonium bromide in the amount of 50% of the bentonite`s
CEC value. Starting material and all prepared composites were characterized by FTIR-ATR spectroscopy in order to
confirm modification with organic molecules. Adsorption of zearalenone (ZEN) by clay-chitosan composites and claychitosan-surfactant composites was investigated at pH 3. Results showed that adsorption of ZEN was higher for
composites that had both chitosan and surfactant, confirming that surfactant ions are responsible for ZEN adsorption.
Additionally, the effect of adsorbent mass on ZEN adsorption was investigated for clay-chitosan-surfactant composites
(pH 3) and results have shown that adsorption increased with increasing the amount of both composites
Površinski modifikovani zeoliti - efikasni adsorbenti emergentnih zagađivača
No full textPovršinski modifikovani prirodni zeoliti sa katjonskim surfaktantima su se pokazali kao obećavajući adsorbenti za uklanjanje emergentnih zagađivača - nesteroidnih antiinflamatornih lekova (diklofenak, ibuprofen, naproksen i ketoprofen). Nelinaran oblik adsorpcionih izotermi kao i adsorpcioni kapaciteti (Qmax vrednosti iz Langmirovog modela) poslužili su da se izvedu zaključci o mehanizmu adsorpcije i uticaju izbora polaznog materijala, tipa i količine surfaktanta na adsorpciju odabranih lekova