Impact of magnetic field on electrochemistry of heavy metals removal processes by duckweed (lemna)

The influence of various factors (initial concentration of the solution, contact time of the biosorbent with the solution, and the action of a constant parallel magnetic field of intensity 4 kA/m (50 Oe)) on the processes of extraction of heavy metal ions (Zn, Cd, Cu) from wastewater with the help of bioelectrochemical reactor - duckweed is in the focus of this study

Cotton Fiber and Carbon Materials Filters for Efficient Wastewater Purification

Carbon materials and cotton fibers (CFs) are eco-friendly and cost-effective solutions for water purification. However, enhancing the filtration efficiency of these materials remains challenging. In this study, the capacity of heat-treated sorbents (CFs and low-temperature graphite intercalation compounds (LT-GICs)) to improve the efficiency of wastewater purification from heavy metals and petroleum compounds, was investigated. The properties of the thermally modified CFs were studied in order to obtain a material which is highly efficient in purifying wastewater from heavy metal ions (HMIs). The duration of sorption equilibrium and the optimal ratio of heat-treated cotton fibers (HTCFs) and wastewater were determined. The adsorption capacities of CFs for iodine and methylene blue were determined before and after the heat treatment. Experimental results indicated that thermal treatment of CFs resulted in increased numbers of micropores and mesopores, indicating a high sorption capacity for petroleum products (PPs) in wastewater (A = 11.5 g/g) with an efficiency score of 90%. Furthermore, LT-GIC/CF composite filters were optimized for efficient purification. The results indicated that a filter with a composition of 1 g LT-GIC + 3 g CF had the highest sorption capacity for HMIs (28.7 mg/g) and PPs (80.6%) due to its looser surface structure. The X-ray phase analysis of the sintered composite filters showed the presence of carbon in the amorphous phase, which had a similar structure to the activated carbon from black coal. In summary, the high sorption capacities and simple preparation processes of LT-GIC/CF composites make them potential candidates for wastewater purification

Graphene Oxide-Chitosan Composites for Water Treatment from Copper Cations

This paper considers modern sorption materials for wastewater treatment. The literature data on wastewater treatment with materials based on graphene and chitosan are presented. The production and application of composite sorbents is discussed. It is shown that a promising application of graphene oxide (GO) as a filler enhances the mechanical and sorption properties of the polymer matrix. The biopolymer chitosan (Ch) is a challenging matrix for GO, having unique sorption, chelate-forming, ion-exchange, and complex-forming properties. Composite adsorbents based on graphene oxide and chitosan have a high extraction efficiency of heavy and radioactive metals, dyes, and pharmaceutical compounds dorzolamide and tetracycline. GO-Ch composites with various ratios of chitosan and graphene oxide (2–7%) were formed by drop granulation. The composites obtained were investigated in terms of the ability to extract copper cations from the effluents, and it was shown that the composite having the content of GO:Ch = 55.5:44.5% (by mass in dry granules) had the best sorption and mechanical properties. This sample had high purification efficiency from copper cations (96%) and the required mechanical properties (attrition ≤ 0.4%, grindability ≤ 4%). For this sample, the influence of various factors (pH, sorbent dosage, temperature, and time of sorption) on sorption processes were studied. The best conditions for the sorption processes by the GO-Ch sorbent were determined. The sorbent dosage was 20 g/L, the sorption time was 20 min, and the temperature was 20 ± 2 °C, pH = 7. The adsorption isotherm was plotted and the maximum sorption capacity of copper cations A = 58.5 mg/g was determined. Microstructural and infrared (IR) spectroscopy studies of GO-Ch composites showed the presence of a porous surface and OH- and C=O functional groups. A mechanism for the extraction of copper cations due to physical sorption of the porous surface by GO-Ch composites, and due to chemisorption processes by functional groups, was proposed. The sorption properties for methylene blue and iodine absorption, and the specific surface area of the GO-Ch samples, were determined. The spent sorbent is proposed to be used as a soil improver

Physico-chemical studies of sorption materials based on biomass waste

This article discusses the possibility of using cheap raw materials for the treatment of wastewater from heavy metal ions using residual biomass and agricultural waste (sunflower husk, millet, buckwheat). Residual biomass is formed after the extraction of valuable components from microalgae and duckweed. The authors proposed to modify the sorption material using heat treatment and the introduction of additives, such as chitosan and thermally expanded graphite. Chitosan allows you to get sorption materials in the form of granules, which are convenient to use. The physicochemical properties of sorbents were studied. The sorption capacity for the obtained materials was from 5.0 to 32.0 mg/g

Influence of extraction conditions on the recovery lipids extracted from the dry biomass of duckweed Lemna minor

Previous studies on the composition of lipid content of higher aquatic plants can be found in the literature. The present work aims to study the effect of various solvent extraction systems on the recovery of lipids extracted from the dry biomass of Lemna minor, using the same polar solvent (ethanol) and variating the non-polar solvent as follow: methanol-ethanol, chloroform-ethanol, hexane-ethanol, diethyl ether-ethanol, petroleum ether-ethanol at different volume ratio. The goal is to select a Sohxlet extraction method that shortens the extraction duration and increases the lipid recovery using various solvents. To intensify the extraction process, homogenization was used as a cell disruption method. It is shown that the yield of total lipids is increased by using homogenization from 4.6% to 6.0%. When studying the influence of the solvent system, the highest yield of total lipids was obtained by using hexane-ethanol with a volume ration of 1:1 (8.0% total lipids by dry mass). The yield of lipids recovered from dry biomass of Lemna minor increases by increasing the extraction time. The optimum extraction time was found to be no more than 300 minutes. The composition of the lipid fraction is mainly represented by sterols, fatty acids and triglycerides

Fermentation of plant residues to produce biogas

In this paper, we consider the process of producing biogas with a high methane content when used as a co-substrate for fermentation of plant residues of microalgae. Microalgae Chlorella sorokiniana are a valuable source for obtaining valuable components such as lipids, pigments, proteins, chlorophyll and others. After the extraction of valuable components, residual biomass is formed, which requires further disposal. In this experiment, the digestion process is carried out using an inoculant-lyophilically dried activated sludge from sewage treatment plants in Hamburg in the amount of 450 ml and residual biomass of the microalga Chlorella sorokiniana in the amount of 2.1 g. The studies were carried out in the Anaerobes Test system AMPT-II system. Fermentation produces 205 ml of methane gas

Adsorption of rare earth elements using bio-based sorbents

Rare earth elements (REEs) have recently received significant attention due to their irreplaceable industrial application for the number of crucial advanced technologies in production of permanent magnets, batteries, luminescence lamps, lasers and other electronic and electrical goods. These technologies have been strongly affecting present consumption of REEs as well as looking for alternative sources, that would guarantee their sufficient supply for the future demand. This study investigates one of the possible and widely employed techniques for the efficient and at the same time, environmentally friendly recovery of REEs by adsorption using bio-based adsorbents. Overall, three bio-sorbents with different composition (residual biomass originated from agriculture and bio-refineries) were examined to study removal efficiency of the 7 most commonly used REEs in mixed aqueous solution. Batch adsorption experiments were carried out at the room temperature, varying the pH value (pH=1,54; 4,24) and different initial concentration of REEs to determine optimum condition for their recovery. Results revealed that removal efficiency for most of the REEs was much higher at pH=4,24 and reached 70-100% for the minimal concentrations and 30-40 % at maximal initial concentrations respectively. Adsorbent containing residual biomass and chitosan showed to be the most effective bio-sorbent for recovery of most of the REEs. In order to describe and fit the obtained data Langmuir and Freundlich isotherms models were employed

Fermentation of plant residues to produce biogas

In this paper, we consider the process of producing biogas with a high methane content when used as a co-substrate for fermentation of plant residues of microalgae. Microalgae Chlorella sorokiniana are a valuable source for obtaining valuable components such as lipids, pigments, proteins, chlorophyll and others. After the extraction of valuable components, residual biomass is formed, which requires further disposal. In this experiment, the digestion process is carried out using an inoculant — lyophilically dried activated sludge from sewage treatment plants in Hamburg in the amount of 450 ml and residual biomass of the microalga Chlorella sorokiniana in the amount of 2.1 g. The studies were carried out in the Anaerobes Test system AMPT-II system. Fermentation produces 205 ml of methane gas

Influence of extraction conditions on the recovery lipids extracted from the dry biomass of duckweed Lemna minor

Previous studies on the composition of lipid content of higher aquatic plants can be found in the literature. The present work aims to study the effect of various solvent extraction systems on the recovery of lipids extracted from the dry biomass of Lemna minor, using the same polar solvent (ethanol) and variating the non-polar solvent as follow: methanol-ethanol, chloroform-ethanol, hexane-ethanol, diethyl ether-ethanol, petroleum ether-ethanol at different volume ratio. The goal is to select a Sohxlet extraction method that shortens the extraction duration and increases the lipid recovery using various solvents. To intensify the extraction process, homogenization was used as a cell disruption method. It is shown that the yield of total lipids is increased by using homogenization from 4.6% to 6.0%. When studying the influence of the solvent system, the highest yield of total lipids was obtained by using hexane-ethanol with a volume ration of 1:1 (8.0% total lipids by dry mass). The yield of lipids recovered from dry biomass of Lemna minor increases by increasing the extraction time. The optimum extraction time was found to be no more than 300 minutes. The composition of the lipid fraction is mainly represented by sterols, fatty acids and triglycerides

Features of the Phytoremediation by Agricultural Crops of Heavy Metal Contaminated Soils

The novelty of the present research consisted in the study of the features of heavy metals accumulation in the phytomass of agricultural plants under the conditions of complex heavy metals contamination of podzolized chernozem (ashy soil) in the Ryazan region (Russia). Results of the vegetation experiments conducted on four crops—oats, black beans, buckwheat, and soybeans—were analyzed, which made it possible to assess the ability of these plants to accumulate heavy metals in their phytomass depending on the level of the heavy metals contamination of the soil. Results of the study showed that the removal of copper, zinc, and lead by beans was noticeably higher than that by oats, buckwheat and soy, due to their greater tolerance and ability to form a large phytomass, which must be taken into consideration when choosing phytoremediation for soil decontamination. This made it possible to evaluate the possibility of using the analyzed plants for the biological purification of polluted soil. The results are also planned to be used in the digitalization of agricultural production