Biosorption and Bioleaching of Heavy Metals from Electronic Waste Varied with Microbial Genera

Industrialization and technological advancements have led to the exploitation of natural resources and the production of hazardous wastes, including electronic waste (E-waste). The traditional physical and chemical techniques used to combat E-waste accumulation have inherent drawbacks, such as the production of harmful gases and toxic by-products. These limitations may be prudently addressed by employing green biological methods, such as biosorption and bioleaching. Therefore, this study was aimed at evaluating the biosorption and bioleaching potential of seven microbial cultures using E-waste (printed circuit board (PCB)) as a substrate under submerged culture conditions. The cut pieces of PCB were incubated with seven microbial cultures in liquid broth conditions in three replicates. Atomic absorption spectroscopy (AAS) analysis of the culture biomass and culture filtrates was performed to evaluate and screen the better-performing microbial cultures for biosorption and bioleaching potentials. The best four cultures were further evaluated through SEM, energy-dispersive X-ray spectroscopy (EDX), and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) studies to identify the possible culture that can be utilized for the biological decontamination of E-waste. The study revealed the highest and differential ability of Pleurotus florida and Pseudomonas spp. for biosorption and bioleaching of copper and iron. This can be attributed to bio-catalysis by the laccase enzyme. For both P. florida and Pseudomonas spp. on the 20th day of incubation, laccase exhibited higher specific activity (6.98 U/mg and 5.98 U/mg, respectively) than other microbial cultures. The biomass loaded with Cu2+ and Fe2+ ions after biosorption was used for the desorption process for recovery. The test cultures exhibited variable copper recovery efficiencies varying between 10.5 and 18.0%. Protein characterization through SDS-PAGE of four promising microbial cultures exhibited a higher number of bands in E-waste as compared with microbial cultures without E-waste. The surface topography studies of the E-waste substrate showed etching, as well as deposition of vegetative and spore cells on the surfaces of PCB cards. The EDX studies of the E-waste showed decreases in metal element content (% wt/% atom basis) on microbial treatment from the respective initial concentrations present in non-treated samples, which established the bioleaching phenomenon. Therefore, these microbial cultures can be utilized to develop a biological remediation method to manage E-waste.

Construction of efficient bismuth/boron-based flexible electrode in organic media toward neutral hydrogen evolution

Preparing high-efficient, low-cost and stable catalysts to produce hydrogen in neutral electrolyte is a major challenge due to the sluggish kinetics, low conductivity and complex hydrogen adsorption-desorption process. Here, series...

Evaluation of the Adsorption and Desorption Dynamics of Beet Juice Red Dye on Alginate Microbeads

The use of alginate microcapsules has often been mentioned as one of the ways to remove dyes from waste solvents, water and materials from the food industry. In addition, alginate can be used as a wall material for the microencapsulation of food dyes and their further application in the food industry. The aims of this study were to: (i) determine the effect of the alginate concentration (1, 2, 3 and 4%) on the ability of the adsorption and desorption of natural beetroot red dye and (ii) evaluate the kinetic parameters of the adsorption and desorption process, as well as the factors affecting and limiting those processes. According to the obtained results, the viscosity of alginate solutions increased with an increase in the alginate concentration. Based on k2 values (the pseudo-second order kinetic rate constant), when a more concentrated solution of alginate was used in the adsorption process, the beads adsorbed a smaller amount of dye. Furthermore, based on the values for n derived from the Korsmeyer–Peppas model, the dye release rates (k) were higher for beads made with lower alginate concentrations, and this release was governed by a pseudo-Fickian diffusion mechanism (n values ranged from 0.2709 to 0.3053).

Sugarcane biomass as а potential carrier for drug delivery system

Non-steroidal anti-inflammatory drugs are well-known medications for reducing pain and a group of drugs that can cause mucosal damage of the stomach. The negative effects on the digestive system can be reduced by immobilization of drugs on various carriers, for instance, on the components of plant biomass, for the creation of drug delivery system. Plant biomass is a lignocellulosic complex consisting of lignin, cellulose and hemicellulose that can potentially be regarded as a carrier of pharmaceuticals. Sugarcane residues such as bagasse and straw are biomass by-products of the sugarcane industry. One of the prospective ways for their efficient utilization can include chemical processing with the aim of obtaining effective biosorbents or so-called carriers of different composition and structure. The aim of the work was to study the structural, morphological, and sorption properties of cellulose, lignin, and lignocellulose, derived from sugarcane biomass (bagasse and straw) by means of delignification and hydrolysis, as potential components for drug delivery system. Sugarcane straw samples show higher densities in comparison with bagasse samples. Both lignin samples from bagasse and straw have greater bulk and true density if compared to other materials from sugarcane biomass of cellulosic and lignocellulosic nature. The increase in adsorption pore volume in lignins is observed, being indicative of better sorption ability. Both samples of cellulose and lignocellulose from straw have greater pore structure if compared to the initial material. The values of sodium diclofenac sorption efficiency correlate with the values of pore volume for corresponding materials. Lignin from sugarcane straw, which shows greater porosity, has greater sorption properties. SEM images show that the initial materials and treated materials have complex morphology. FTIR spectra show a clear difference in the structure of lignocellulose, cellulose, and lignin from sugarcane bagasse and straw. The potential application of biopolymers from bagasse and straw as organic carriers of sodium diclofenac was studied. With this purpose, plant polymers were impregnated with an alcoholic solution of sodium diclofenac and the desorption process was investigated. The lignin sample from sugarcane straw has a longer period of drug release, which indicates the obtained effect of prolongation.

Development of Dioctyl Phthalate@Fe3O4 Nanocomposite Reinforced Hollow Fiber Solid/ Liquid Phase Microextraction Followed by HPLC-DAD for the Determination of Atorvastatin and Gemfibrozil in Human Urine

Background: The desirable levels of lipids, especially in patients with coronary artery disease, might not be achievable with a single lipid-lowering drug; thus, combination therapy using atorvastatin and gemfibrozil seems to be a promising approach. However, the potential for drug-drug interaction needs to be taken into consideration, and the combination (atorvastatin and gemfibrozil) is recommended only when other options for reducing lipids have been exhausted. Objectives: Many studies are conducted for the determination of atorvastatin or gemfibrozil in biological fluids and tablets; however, the simultaneous determination of the two drugs in complex biological matrices is limited. Consequently, the development of a sensitive method for simultaneous determination of atorvastatin and gemfibrozil in urine samples is urgently needed to make sure that the doses of both medications are given to patients correctly to prevent the risk of side effects outcomes associated with the adverse drug-drug interaction. Methods: A synthesized nanocomposite sorbent, dioctyl phthalate coated on the surface of magnetite (DOP@Fe3O4), was reinforced and immobilized into the pores of 2.5 cm segment hollow fiber microtube via ultrasonication, and the lumen of the microtube was filled with 1-octanol as an organic solvent with two ends heat-sealed. The prepared (DOP@Fe3O4-HF-SLPME) device was directly immersed into 10 mL of a sample solution containing atorvastatin and gemfibrozil with agitation. Subsequently, the microextraction device was transferred to HPLC-micro-vial containing an appropriate solvent, and the selected analytes were desorbed under ultrasonication prior to HPLC-DAD analysis. The main factors influencing the adsorption and desorption process of the selected drugs have been optimized. Results: The DOP@Fe3O4-HF-SLPME combined with the HPLC-DAD method was analytically evaluated for the simultaneous determination of atorvastatin and gemfibrozil in human urine samples using the optimized conditions. In spiked urine samples, the method showed a good linearity R2˃ 0.998, RSD from 1.41- 5.33%, and the limits of detection/ quantification (LOD/ LOQ) were 0.11/ 0.36 and 0.73/ 2.42 µg L-1 for atorvastatin and gemfibrozil, respectively. The enrichment factors of atorvastatin and gemfibrozil were 83.4 and 101.2, with extraction recoveries of 80.9% and 99.0%, respectively. The developed method demonstrated comparable results against referenced methods and a satisfactory result for determining the selected drugs in the patient’s urine samples. Conclusion: The DOP@Fe3O4-HF-SLPME followed by HPLC-DAD was proved to be an efficient, sensitive, and cost-effective biopharmaceutical analysis method for trace levels of atorvastatin and gemfibrozil in the biological fluid matrix.

Influence of Hydrogen Generation During Thermal Processes of Water Decomposition on the Surface of Nano- ZrO2+3 mol.%Y2O3

The physicalchemistry properties and crystal structure of were nano-ZrO2+3mol.%Y2O3 determined. The kinetics of the formation of H2 as a result of the decomposition of H2O on the surface of nano-ZrO2+3mol.%Y2O3 was studied. Effects of adsorption and desorption process on ZrO2+3 mol.%Y2O3 nanoparticles were studied at different (T=400÷10000C) temperature. The study of H2 in thermal processes at nano-ZrO2+3 mol.%Y2O3 system increased. Such an increase in H2 generation in comparison with a pure H2O as thermal processes had formedactive centers for H2O decomposition on the surface of the catalyst at the expense of δ-electrons emitted on the surface of nano-ZrO2+3 mol.%Y2O3. This showed that the dimensions of the studied nanoscale particles systems are comparable to the free running distance of energy carriers generated by of nano-ZrO2+3 mol.%Y2O3 as a result of thermal processes. These results are promising for hydrogen generation by waer spliting in near future.

Functionalization of Zeolite NaP1 for Simultaneous Acid Red 18 and Cu(II) Removal

The efficiency of azo dye Acid Red 18 (AR18) and Cu(II) ions simultaneous removal from an aqueous solution on NaP1CS and NaP1H was investigated, taking into account the effect of the phase contact time, pH, initial concentration, temperature, and interfering ions presence. Zeolite denoted as NaP1CS was modified by chitosan (CS) and zeolite denoted as NaP1H was modified by hexadecyltrimethylammonium bromide (HDTMA). In order to characterize sorption properties of NaP1CS, the obtained sorbent was characterized using Fourier transform infrared spectroscopy (FTIR) and nitrogen adsorption/desorption (ASAP). The kinetic parameters were determined by means of the pseudo first order (PFO), pseudo second order (PSO), and intraparticle diffusion (IPD) kinetic models. To present the adsorption data, three different isotherm models (Langmuir, Freundlich and Dubinin-Radushkevich) were used. The desorption process was also examined. It was found that for sorbent NaP1CS the pseudo second order (PSO) kinetic model and the Langmuir isotherm fitted best the experimental data. Moreover, it was noted that the acidic pH is appropriate to achieve the best sorption properties of NaP1CS for Cu(II) and NaP1H for AR18 and Cu(II). The thermodynamic parameters indicate an endothermic process. The most effective solution for the desorption process was found to be 1 M HCl. The results indicate that simultaneous removal of dye AR18 and Cu(II) on modified zeolite NaP1CS or NaP1H is possible and proceeds with a very good efficiency. The obtained zeolites could effectively adsorb AR18 an Cu(II) simultaneously, but their adsorption abilities were rather different.

Circular Economy in the Oil and Gas Exploration and Production: Resource Recovery from Drill Cuttings and other Oily Wastes

With an increasing awareness of minimising the environmental footprint combined with the inclusion of circularity in the oil and gas industry, stricter laws and therefore more rigorous treatment targets will have to be implemented in the waste/resource management. Increasingly complex solid and liquid waste streams result in the further need to implement safer, more advanced technologies. Emission levels, resource recovery, energy efficiency, worker safety, and input material flexibility will become key assessment factors. The vacuum thermal desorption process allows for the recovery of resources from different industrial hazardous wastes. At the core of the process is a specially designed vacuum evaporator chamber utilizing indirect heat and controlled vacuum to evaporate contaminants. With this process, resources can be recovered and solids/mineral fractions decontaminated therefore minimising the hazardous waste and bringing valuable resources back into the value chain. A wide range of input materials, independently from their consistency, can be treated using the same process, as a result of the batch-wise working principle of the vacuum evaporator. The process reduces air emissions derived from two sources. One originates from the thermal oil heating system (flue gas), the other from the vacuum desorption process (exhaust). For the latter, in an oily waste recycling facility that processes approximately 30,000 tonnes per year, <<100 m3/h are emitted, of which on average 96 % are nitrogen. Regarding resource recovery, typical output material parameters include clean solids with a TPH (up to C40) content < 0.5 %, oil in product quality with a recovery rate > 99.5 %, and clean water for moistening of the solids. Highest energy efficiency is achieved because the vacuum reduces the boiling point of the hydrocarbons by more than 100 °C. In addition, the recovered oil can be used as fuel to run the equipment. In conclusion, resources will be recovered and therefore hazardous waste reduced, emissions decreased and highest safety for workers observed. Aside from the above stated advantages of using indirectly heated thermal desorption, this process also offers the possibility to be operated using renewable energy. Therefore, guaranteeing zero emissions supporting the health & safety of our environment and its people.

Heavy Metal Adsorption Using Magnetic Nanoparticles for Water Purification: A Critical Review

Research on contamination of groundwater and drinking water is of major importance. Due to the rapid and significant progress in the last decade in nanotechnology and its potential applications to water purification, such as adsorption of heavy metal ion from contaminated water, a wide number of articles have been published. An evaluating frame of the main findings of recent research on heavy metal removal using magnetic nanoparticles, with emphasis on water quality and method applicability, is presented. A large number of articles have been studied with a focus on the synthesis and characterization procedures for bare and modified magnetic nanoparticles as well as on their adsorption capacity and the corresponding desorption process of the methods are presented. The present review analysis shows that the experimental procedures demonstrate high adsorption capacity for pollutants from aquatic solutions. Moreover, reuse of the employed nanoparticles up to five times leads to an efficiency up to 90%. We must mention also that in some rare occasions, nanoparticles have been reused up to 22 times.