Upcycling Waste Streams from a Biorefinery Process-A Case Study on Cadmium and Lead Biosorption by Two Types of Biopolymer Post-Extraction Biomass.

This study investigated the possibility of using the spent kind of biomass of Pseudomonas putida CA-3 and Zobelella denitrificans MW1 obtained after the pilot-scale production of polyhydroxyalkanoates (PHAs) as a biosorbent for the bioremediation of aqueous solutions containing toxic cadmium and lead ions. The material was characterized by means of scanning electron microscopy, Fourier-transformed infrared spectroscopy, nuclear magnetic resonance spectroscopy and amino acid profiling. To check the sorption capacity of spent biomass against Pb and Cd ions, equilibrium studies were performed. To learn about the nature of the sorption process, kinetic modelling was carried out and the obtained results showed that the adsorption process is best described by the pseudo-second-order kinetic model (PSO), which suggests that the sorption process is connected with the chemical bonding of the ions on the sorbent surface. Information provided by the amino acid profile made it possible to predict the adsorption mechanism and FTIR analysis proved the participation of different chemical groups in the removal process. According to the equilibrium studies, the best-fitted isotherm was the Freundlich model for all used materials and metal ions considering the correlation coefficient. Summarizing the results, the spent biomass after the PHA production is an effective biosorbent and can be reused for heavy metal bioremediation.

Bio-Hybrid Hydrogels Incorporated into a System of Salicylic Acid-pH/Thermosensitive Nanocarriers Intended for Cutaneous Wound-Healing Processes.

In this paper, the preparation method of bio-hybrid hydrogels incorporated into a system of salicylic acid-pH/thermosensitive nanocarriers to speed up the wound-healing process was developed. This combination creates a dual drug delivery system, which releases the model hydrophobic active substance-salicylic acid-in a gradual and controlled manner for an extended time. Our research team has determined the various properties of bio-hybrid hydrogels based on their physicochemical (swelling degree, and degradation), structural (FT-IR), morphological (SEM), and mechanical (elongation tests) traits. Moreover, empty pH/thermosensitive nanocarriers and their salicylic acid-containing systems were characterized using the following methods: DLS, TG/DTG, and DSC. Additionally, salicylic acid release profiles directly from thermosensitive nanocarriers were compared to the bio-hybrid matrix. These studies were conducted in PBS (pH = 7.4) for 7 days using the USP4 method. To evaluate the antibacterial properties of the obtained materials, the inhibition of growth of Staphylococcus aureus, Escherichia coli, Candida albicans, and Aspergillus niger-as the main microorganisms responsible for human infections-were tested. The obtained results indicated that the pH/thermosensitive nanocarrier-salicylic acid system and bio-hybrid hydrogels are characterized by antibacterial activity against both S. aureus and E. coli.

Raphia-Microorganism Composite Biosorbent for Lead Ion Removal from Aqueous Solutions.

This study investigated the possibility of obtaining a raphia-microorganism composite for removing lead ions from aqueous solutions using immobilized yeast cells Saccharomyces cerevisiae on Raphia farinifera fibers. The obtained biocomposite was characterized using scanning electron microscopy and Fourier transform infrared spectroscopy. Studies were conducted to determine the influence of contact time, initial concentration of Pb(II), and pH allowed for the selection of nonlinear equilibrium and kinetic models. The results showed that the biocomposite had a better Pb(II) removal capacity in comparison to the raphia fibers alone, and its maximum Pb(II) adsorption capacity was 94.8 mg/g. The model that best describes Pb(II) sorption was the Temkin isotherm model, while kinetic studies confirmed the chemical nature of the sorption process following the Elovich model. The obtained research results provide new information on the full use of the adsorption function of biomass and the ubiquitous microbial resources and their use in the remediation of aqueous environments contaminated with heavy metals.

Adsorption of Cadmium, Manganese and Lead Ions from Aqueous Solutions Using Spent Coffee Grounds and Biochar Produced by Its Pyrolysis in the Fluidized Bed Reactor.

The adsorption process of cadmium ions (Cd), manganese ions (Mn) and lead ions (Pb) onto the spent coffee grounds (SCG) and activated spent coffee grounds (biochar, A-SCG) was investigated. The SCG activation was carried out in the pyrolysis process in a fluidized bed reactor. scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) measurements and CHN analysis were used in order to define the differences between biomaterials. In the study the different mass of materials (0.2-0.5 g) and constant heavy metal volume and concentration (20 cm3/100 ppm) were investigated on the adsorption process. In order to describe the sorption parameters the Langmuir, Freundlich and Temkin isotherms were used. The maximum adsorption for biochar reached 22.3 mg/g for Pb ions, 19.6 mg/g for Mn ions and 19.4 mg/g for Cd ions which were noticeably higher than the results obtained for spent coffee grounds which reached 13.6 mg/g for Pb ions, 13.0 mg/g for Mn ions and 11.0 mg/g for Cd ions. Metal ion adsorption on both SCG and A-SCG was best described by the Langmuir model, thus chemisorption was a dominant type of adsorption. Studying the kinetics of the sorption process, one can see that the process is of a chemical nature according to the best fit of the pseudo-second rate order model. The obtained results show that the chosen sorbents can be used for the removal of cadmium, manganese and lead compounds from aqueous solutions with high efficiency.

Sorption behavior of Arachis hypogaea shells against Ag+ ions and assessment of antimicrobial properties of the product.

The paper presents sorption behavior of Arachis hypogaea shells towards silver ions and possibility of their use as antimicrobial product. During the modification process of the natural sorbent, equilibrium tests were carried out. Moreover, the possibility of obtaining biocomposite Arachis hypogaea shells/nAg has been determined, and its antimicrobial properties have been evaluated. Additionally, sorption kinetics has been calculated. In the last step, silver ions were desorbed. The conducted equilibrium tests allowed to adjust the sorption isotherm model and determine the sorption capacity of tested material. This process is best described by Freudlich's isotherm, and the sorption capacity is equal to 12.33 mg/g. On the basis of kinetic studies, the chemical nature of this process has been proved (by choosing a pseudo-second order model for the sorption process). It has been confirmed that the obtained peanut shells modified with silver ions have antimicrobial properties. The tests allowed to obtain 100% inhibition of Aspergillus niger and ~ 98% Escherichia coli.

Safety of the application of nanosilver and nanogold in topical cosmetic preparations.

The safety of the use of cosmetic preparations with silver or gold nanoparticles was assessed. This study describes the methodology and results of research involving the generation of suspensions of silver and gold nanoparticles and creams with added silver or gold at concentrations of 20, 65, 110, 155, and 200 mg/kg. The silver nanoparticles ranged from 8 to 140 nm, and the gold nanoparticles, measured 13-99 nm. The sizes were determined using dynamic light scattering. The presence of metallic nanoparticles in the obtained oil-in-water emulsions was confirmed with UV-vis spectroscopy and transmission electron microscopy with an X-ray scattering spectrometer (TEM-EDX). Additionally, based on the TEM-EDX results, it was possible to analyse the distributions of the silver nanoparticles in the tested cosmetic emulsions. Microbiological tests showed that both the silver and gold nanoparticle emulsion possessed satisfactory fungicidal properties. Based on viscosity curves, the lowest estimated yield limits were achieved by the reference cream and the creams with the gold and silver nanoparticles at concentrations of 20 and 65 mg/kg, respectively, which improved their consistencies and distributions on the skin. The best appraisals from the respondents in terms of consistency, absorption, oiling, colour, and smell were received for the emulsion containing 200 mg/kg gold nanoparticles. The worst assessment in terms of uniformity, colour, and smell were obtained for the emulsion with 200 mg/kg silver nanoparticles. However, the most important aspect of this study was the assessment of the permeabilities of the metallic nanoparticles through imitation skin in the form of dermal membranes. The highest permeabilities were confirmed for the creams with metallic nanoparticles present at 110--200 mg/kg. This permeability is an issue of concern given the toxic properties of metallic nanoparticles for living organisms.

Analysis of the physicochemical properties of antimicrobial compositions with zinc oxide nanoparticles.

In this study, an antimicrobial composition based on polyvinyl alcohol (PVA) and zinc oxide (ZnO) was developed. The aim of the work was to obtain a film-forming product for antimicrobial treatment of surfaces. To improve the physical, mechanical, and film-forming properties of the compositions, three natural stabilizing agents were added to the formulation: gelatine, guar gum and hydroxyethyl cellulose. Formulations with different concentrations of each stabilizer were tested, and the physicochemical properties of the obtained products were measured. The size of zinc oxide particles in obtained compositions varied from 232 to 692 nm. The compositions had a slight acidic nature. Their pH ranged from 6.84 to 6.99. The average density of products was equal to 1.37 × 103 (kg/m3). It was confirmed that zinc oxide nanoparticles do not penetrate through a model dermal membrane which is a desired effect concerning their toxicity. The antimicrobial activity of the obtained compositions was assessed against Aspergillus niger strain. After 24 h of studying, the growth inhibition was in 71% greater than in reference material. After statistical analysis of the results, it was concluded in order to achieve the most desirable physicochemical and utilitarian properties, the concentrations of gelatine, guar gum and hydroxyethylcellulose should be equal to 0.5%, 0.03% and 0.055%, respectively.

The kinetic reduction of Cr(VI) by yeast Saccharomyces cerevisiae, Phaffia rhodozyma and their protoplasts.

Chromium in the sixth oxidation state may easily penetrate cellular membranes via non-specific sulfate transporters due to its tetrahedral symmetry (high similarity to SO4(2-) and HPO4(2-)). This feature makes chromium a toxic and hazardous pollutant responsible for the deterioration of midland water quality. The aim of the study was to evaluate the capacity of two yeast species - Saccharomyces cerevisiae and Phaffia rhodozyma - and their protoplasts to reduce Cr(VI) to lower oxidation states. The study also deals with the behavior of the yeasts upon the presence of elevated sulfate ions as a competitive inhibitor of chromate transport by the sulfate transporters. The chromate-reducing activities were monitored by determination of Cr(V) free radical form with the use of L-band (1.2 GHz) EPR (electron paramagnetic resonance) spectroscopy. It was observed that both of the studied yeast strains exhibited the ability to reduce Cr(VI) applied at 4 mM. The cells of P. rhodozyma showed about 3.5 times higher reduction than S. cerevisiae. The reduction efficiency was significantly improved when the protoplasts of both strains were used and reached 100% in the first 10 minutes of the reduction process which suggests that the cellular wall may have a notable influence on the uptake and/or inhibition of chromium reduction process. The reduction effect of P. rhodozyma cells and protoplasts may be associated with the more sufficient production of metabolites (such as glutathione and cysteine), which may also be responsible for the increased tolerance of the strain towards high concentrations of toxic chromium.