Formation Of Biocomposites Research Articles

Structural arrangement, electroconductivical and electrochemical behaviours of solid amino acid-based electrodes

This paper presents the study on the structural dependence of the electroconductivity and electrochemical activity of model amino acids, aspartate and glycine, which are used as solid electrodes in hybrid capacitor systems. It has been established that the presence of carbonyl, aliphatic, and amide functional groups on the surface enhances the electrochemical activity and electrical conductivity. The frequency dependence of conductivity is typical for polymer compounds with a proton conduction mechanism, which is provided by the surface migration of the charge. It was found that deposition on the surface of carbon templates of the amino acids in the formation of biocomposites increases the number of active reaction centers and provides effective electronic charge transport. As a result, it leads to a significant increase in the contribution of pseudocapacitance and capacitance processes. The electrochemical activity was caused by the pseudocapacitive accumulation of charge due to the course of redox reactions with amino acids and capacitive accumulation of charge, which occurs with the participation of amino acids and carbon templates. It has been proven that the porous structure of the carbon nanotubes provides a more dispersed and uniform distribution of amino acids on the surface, which is ensured in the growth of pseudocapacitive charge accumulation.

Biocomposites of Poly(Lactic Acid) and Microcrystalline Cellulose: Influence of the Coupling Agent on Thermomechanical and Absorption Characteristics.

In this study, poly(lactic acid) (PLA) and microcrystalline cellulose (MCC)-based green biocomposites were developed using a solution casting technique. Essentially, the bonding between PLA and MCC is quite feeble; therefore, the current study is conducted to strengthen the bonding by incorporating a coupling agent, thereby enhancing the overall quality of the biocomposites. Thus, the present study aimed to examine the influence of combined coupling agents-maleic anhydride (MAH) and maleic acid (MA) (MAH-MA)-on the properties of polylactic acid (PLA)/microcrystalline cellulose (MCC) biocomposites. The investigation also encompassed an examination of the impact of MCC loading (2, 3, and 5% w/w) into a PLA matrix. The Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) examination revealed the interfacial interaction and adhesion among MCC, PLA, and coupling agents and the formation of biocomposites. The incorporation of MAH-MA led to improved mechanical properties of the PLA/MCC biocomposites. Furthermore, the incorporation of MAH-MA into the PLA/3 wt % MCC composite exhibited enhancements in both the tensile strength and tensile modulus, accompanied by a reduced elongation at break. In addition, it is worth noting that the thermogravimetric analysis (TGA) curve of the PLA composite with 3% w/w of MCC and MAH-MA displayed a significant decrease in weight beyond a temperature threshold of 492.65 °C. The water absorption demonstrates that the incorporation of MAH-MA into the PLA/MCC composite led to advantageous water barrier characteristics. The observed improvements were attributed to the efficient dispersion of MCC at the most favorable amount of coupling agents, along with the chemical interactions involving grafting and esterification between MCC and the MAH-MA coupling agent. Furthermore, the incorporation of MAH-MA into the PLA/3% (w/w) MCC composite exhibited enhancements in both the tensile strength and tensile modulus, accompanied by a reduction in the elongation percentage at break. The experimental results about water absorption demonstrate that the incorporation of MAH-MA into the PLA/MCC composite led to advantageous water barrier characteristics. These improvements were attributed to good MCC dispersion and the chemical interactions involving grafting and esterification between the MCC and the MAH-MA coupling agent.

The Influence of Alkaline Pretreatment of Waste Nutshell for Use in Particulate Biocomposites

The aim of this work was to determine how different types of alkaline pretreatment influence the properties of waste almond and hazelnut nutshell, as well as their compatibility with model inorganic geopolymer matrixes for the formation of biocomposites with potential use in civil engineering. For alkaline pretreatment, 3, 6 and 9% NaOH water solutions and milk of lime were used under different temperature and time conditions. The rise in the crystallinity index was confirmed by X-ray powder diffraction analysis, while the corroboration of the removal of amorphous and undesirable components was demonstrated through Fourier-transform infrared spectroscopy. Furthermore, the effectiveness of the pretreatments was confirmed via simultaneous differential thermal and thermogravimetric analysis, and the positive change in the morphology of the surface of the waste nutshell (WN) and the deposition of the desired phases was established using scanning electron microscopy. Surface free energy and adhesion parameters were calculated using the Owens, Wendt, Rabel and Kaelble method for WN as fillers and geopolymers as model novel inorganic binders. This research indicates that the 6% NaOH treatment is the optimal pretreatment process for preparing WN as the filler in combination with potassium and metakaolin geopolymer that has been cured at room temperature.

Synthesis, characterization and biomedical applications of Poly (methyl methacrylate)/Chitosan (derived from oyster shell powder)

The biocomposite (PMMA/Chitosan) is synthesized by combining MMA as a monomer and modified chitosan as a filler material extracted from oyster shell powder. The method used for extraction includes deproteinization, demineralization, and deacetylation. The synthesized biomaterial is characterized by using different techniques. The DLS shows the uniform distribution of particles of filler materials, FTIR analysis peaks confirm the formation of biocomposite on interaction of Chitosan with MMA, X-ray diffraction study shows a strong peak at 2θ = 10.3° indicating the formation of a stable biocomposite,SEM image indicates the uniform distribution of fillers, andTGA indicates that the biocomposite is stable up to 500 °C and after that weight loss is observed. The analysis result indicates that the biopolymer chitosan forms a covalent bond with the PMMA matrix and forms a porous structure. The thermal stability of the synthesised biomaterial is gradually enhanced by the increase in the concentration of chitosan microscopic particles at the surface of the matrix, particularly at low thermal expansion. The synthesised novel biomaterial can be used successfully in various applications, such as flexible electronic printing and organic printing. The synthesized biomaterial is highly effective for drug release in the targeted drug delivery system.

Biosilica/Silk Fibroin/Polyurethane biocomposite for toxic heavy metals removal from aqueous streams

Development of green, eco-friendly, and efficient adsorbents for wastewater treatment is highly researched to mitigate the alarming rate of water pollution. In this work, a novel biocomposite of biosilica (BS)/silk fibroin (SF)/polyurethane foam (PUF) was prepared and studied for the adsorptive recovery of toxic copper (Cu 2 + ) and chromium (Cr 6＋ ) ions from synthetic wastewater. XRD and FTIR studies confirmed the formation of biocomposite with amorphous structure and –OH, –NH, C=O surface functionalities. SEM results confirmed the successful incorporation of SF and PUF into BS. The biocomposite possessed a specific surface area of 751.9 m 2 /g and a mean pore size of 7.21 nm. Further, effects of pH, adsorbent dose, contact time, and initial metal ion concentration on the adsorptive removal of Cu 2 + and Cr 6＋ metal ions by the BS/SF/PUF biocomposite were studied in detail. Equilibrium and kinetic analysis showed that the metal ions sequestration by the BS/SF/PUF biocomposite followed the Freundlich isotherm and Elovich model, respectively. Maximum adsorption capacities of 331.69 mg/g and 201.56 mg/g were estimated for the Cu 2 + and Cr 6＋ ions, respectively. A plausible mechanism for the adsorption of the metal ions onto BS/SF/PUF biocomposite is postulated. Reusability studies of the biocomposite using EDTA eluent showed that the biocomposite could be efficiently reused up to four consecutive adsorption/desorption cycles. Thus, this study provides comprehensive data for applying the BS/SF/PUF biocomposite to treat Cu 2 + and Cr 6＋ metal ions polluted wastewater streams. • Amorphous BS/SF/PUF biocomposite was prepared through polymer blending. • Specific surface area and pore size of BS/SF/PUF were 751.9 m 2 /g and 7.21 nm. • High adsorptive removal efficiency of >80% for Cu 2+ and Cr 6+ heavy metal ions. • Freundlich isotherm & Elovich kinetic model best described adsorption operation. • BS/SF/PUF biocomposite was successfully reused up to 4 cycles through EDTA washing.

Apatitic calcium phosphate/montmorillonite nano-biocomposite: in-situ synthesis, characterization and dissolution properties

Recently, calcium phosphate/montmorillonite composites have received attention as a synthetic bone substitutes. In this study, apatitic calcium phosphate/Montmorillonite nano-biocomposites were in-situ synthesized at 22 °C by reaction between calcium hydroxide and orthophosphoric acid in the presence of different contents of montmorillonite (MNa). Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Brunauer–Emmett–Teller (BET) surface areas were used to characterize the prepared powders. The XRD results show that the composites prepared with 2 and 5 wt% MNa and sintered at 900 °C, show the formation of hydroxyapatite (HAP) structure, whereas that prepared with 10 wt% MNa leads to the formation of β-tricalcium phosphate (β-TCP) structure. The HAP structure decomposes at 1000 °C and leads to the formation of biocomposite containing HAP, β and α-TCP. However, β-TCP composites show thermal stability. FTIR and structural refinement results show the incorporation of clay ions into the apatitic structure causing changes in the crystal structure of the formed calcium phosphate phases. The changes in the composition and structure lead to an increase in the dissolution rate of HAP and a decrease in that of β-TCP.

Biogenic synthesis of hydroxyapatite/Musa paradisiaca floral sap for biomedical applications

The present study encompasses the Gastropoda shells as a source of calcium for the biogenic synthesis of hydroxyapatite (HAP), and this biogenic derived HAP has poor antibacterial properties. Hence, the study aimed to investigate the effect of addition of Musa paradisiaca sap (M. paradiasica) in the formation of biocomposite with HAP for improving the antibacterial property. The biocomposite was synthesized under the ultrasonication process and were characterized for its structural, morphological and antibacterial properties. The obtained results pointed out that the nano-HAP/M. paradiasica sap biocomposite exhibited a controlled shape in the presence of M. paradisiaca sap along with ultrasonication. Also, the bacterial investigation for the nHAP/M. paradiasica sap against bacterial strains (Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus)) substantiates the higher resistance of bacterial growth The in vitro cell viability by MTT assay proved the biocompatibility of the as synthesized nHAP/M. paradiasica sap biocomposite.

Synthesis, characterization and biological applications of biosilica based composites

Agricultural wastes like sugarcane bagasse, rice husk, wheat husk, rice hull are the cheapest sources of biosilica (BS). In this study, sugarcane bagasse was used to extract biosilica by chemical treatment and combined with silk fibroin (SF), Polyurethane Foam (PUF) and TiO2 to prepare a novel biocomposites BS/SF/PUF and BS/SF/PUF/TiO2. The prepared biocomposites were analyzed using FT-IR and SEM analysis. The presence of various functional groups and the formation of biocomposites were confirmed by the FT-IR studies. The SEM analysis displayed rough surface morphology of the biocomposites. The antioxidant properties were studied using the DPPH assay. The biocomposites exhibited excellent antioxidant properties. The antimicrobial activities of the biocomposites were studied against three bacterial (Bacillus sp., Klebsiella sp. and Proteus sp.) and three fungal strains (Rhizopus sp., Aspergillus niger and Candida sp.). The results revealed that the prepared biocomposites were active against the selected bacterial and fungal species

Valorization of Hemp Hurds as Bio-Sourced Additives in PLA-Based Biocomposites.

Sourced from agricultural waste, hemp hurds are a low-cost renewable material with high stiffness; however, despite their potential to be used as low-cost filler in natural fiber reinforced polymer biocomposites, they are often discarded. In this study, the potential to add value to hemp hurds by incorporating them into poly(lactic acid) (PLA) biopolymer to form bio-based materials for packaging applications is investigated. However, as with many plant fibers, the inherent hydrophilicity of hemp hurds leads to inferior filler-matrix interfacial interactions, compromising the mechanical properties of the resulting biocomposites. In this study, two chemical treatments, alkaline (NaOH) and alkaline/peroxide (NaOH/H2O2) were employed to treat hemp hurds to improve their miscibility with poly(lactic acid) (PLA) for the formation of biocomposites. The effects of reinforcement content (5, 10, and 15 wt. %), chemical treatments (purely alkaline vs. alkaline/peroxide) and treatment cycles (1 and 3 cycles) on the mechanical and thermal properties of the biocomposites were investigated. The biocomposites of treated hemp hurd powder exhibited enhanced thermal stability in the temperature range commonly used to process PLA (130–180 °C). The biocomposites containing 15 wt. % hemp hurd powder prepared using a single-cycle alkaline/peroxide treatment (PLA/15APHH1) exhibited a Young’s modulus of 2674 MPa, which is 70% higher than that of neat PLA and 9.3% higher than that of biocomposites comprised of PLA containing the same wt. % of untreated hemp hurd powder (PLA/15UHH). Furthermore, the tensile strength of the PLA/15APHH1 biocomposite was found to be 62.6 MPa, which was 6.5% lower than that of neat PLA and 23% higher than that of the PLA/15UHH sample. The results suggest that the fabricated PLA/hemp hurd powder biocomposites have great potential to be utilized in green and sustainable packaging applications.

Fast Setting Binders for Application in 3D Printing of Bio-Based Building Materials

The construction industry is one of the largest emitters of CO2 because the production of traditional building materials is highly energy-intensive and uses considerable amounts of raw materials. This research aims to decrease the negative environmental impact of the construction industry by providing biocomposites with a low environmental impact due to their bio-based components and efficient use of the materials through 3D printing. Agricultural waste products—hemp shives—are used in these materials as a filler together with three different types of fast-setting binders—magnesium, calcium sulphoaluminate (CSA) and those that are gypsum-based. The study determines the setting time and compressive strength of these binders, as well as the formation of biocomposites of different densities for different applications; extrusion tests and preliminary life cycle assessment (LCA) are also performed. Results show that biocomposites with hemp shives and fast setting binders have a possible application in 3D printing due to their shape stability and buildability, as well as relatively high compressive strength, which allows for load-bearing use at high densities and thermal insulation use at low densities, although printability at low binder content remains a significant challenge. Preliminary LCA results show that CSA and gypsum binders have the lowest environmental impact from the binders considered.

(Bio)Degradable Polymeric Materials for Sustainable Future-Part 3: Degradation Studies of the PHA/Wood Flour-Based Composites and Preliminary Tests of Antimicrobial Activity.

The need for a cost reduction of the materials derived from (bio)degradable polymers forces research development into the formation of biocomposites with cheaper fillers. As additives can be made using the post-consumer wood, generated during wood products processing, re-use of recycled waste materials in the production of biocomposites can be an environmentally friendly way to minimalize and/or utilize the amount of the solid waste. Also, bioactive materials, which possess small amounts of antimicrobial additives belong to a very attractive packaging industry solution. This paper presents a study into the biodegradation, under laboratory composting conditions, of the composites that consist of poly[(R)-3-hydroxybutyrate-co-4-hydroxybutyrate)] and wood flour as a polymer matrix and natural filler, respectively. Thermogravimetric analysis, differential scanning calorimetry and scanning electron microscopy were used to evaluate the degradation progress of the obtained composites with different amounts of wood flour. The degradation products were characterized by multistage electrospray ionization mass spectrometry. Also, preliminary tests of the antimicrobial activity of selected materials with the addition of nisin were performed. The obtained results suggest that the different amount of filler has a significant influence on the degradation profile.

Structural and Spectroscopic Investigation of Biomimetic Composites—Promising Agents for the Remineralization of Native Dental Tissue

Biomimetic materials (biocomposites) with an organic-mineral composition related to natural dental tissues (enamel and dentin) are obtained for the first time and their structural and optical characteristics are studied. It is demonstrated by a complex of structural and spectroscopic methods that in the formation of biocomposites, the introduced organic component, bearing a number of amino acids, does not affect the structure of the inorganic component (carbonate-substituted calcium hydroxyapatite) of the sample. The carbonate-substituted calcium hydroxyapatite synthesized using a biogenic source of calcium, which forms the basis of the biocomposite, has a luminescence spectrum similar to that of apatite tooth enamel. The spectrum of the intact dentin of a human tooth has a broader luminescence band than that for the enamel spectrum. It is determined that both organic and inorganic components contribute to the dentin luminescence band. The features found in the luminescence spectra of intact tissues and in simulating biocomposites can be used to develop a procedure for effective early diagnosis of the demineralization of hard dental tissues and general dental examination.

Biocomposite formation using β-cyclodextrin as a biomaterial in poly(acrylamide-co-acrylic acid): preparation, characterization, and salinity profile

A biocomposite of poly(acrylamide-co-acrylic acid) hydrogel with β-cyclodextrin as a biomaterial was prepared through one-pot synthesis in water as a green solvent. The formation of biocomposite was confirmed by advanced techniques such as FTIR spectroscopy, XRD, DSC, TGA, and FE-SEM. In this report, straight forward and efficient synthetic protocol for biocomposite formation responded without any environmental hazard. Swelling capacity of P(AM-co-AA) and biocomposite was studied by addition of different saline solutions including monovalent, divalent, and trivalent salts. By addition of β-cyclodextrin, the swelling and saline water-absorbing properties of the biocomposite hydrogel were significantly improved. In this regard, the possible formation mechanism of the composite hydrogel is also discussed. It is deduced that the biocomposite formation can be the result of intermolecular interactions between polymer and β-cyclodextrin. The water-soluble polymer seems to have entered into the inner cavity of β-cyclodextrin to form supramolecular biocomposite structure. The results indicate that the order of water uptake decreases with increase in valency of the salts. It is believed that this is an effective method to prepare supramolecular biocomposite hydrogel materials. Its applications can be extended in marine water industries as a basis for antifouling coating, waste water treatment, and even in medical field. Hence, the synthesized materials can be biodegradable, environment-friendly, and biocompatible inspired by the green chemistry concept.

Caracterization and Compressive Strength of Biocomposite Hydroxyapatite-Borosilicate with Hight Temperature Sintering

The use of Hydroxyapatite as bone graft material continues to increase. To utilize hydroxyapatite, it is often formed into biocomposite. The formation of hydroxyapatite biocomposite intended to address the fragile hydroxyapatite weaknesses. The added element in the formation of this biocomposite is borosilicate. Mixing of this material is arranged with certain composition using ball miling. To form a test specimen, it was printed with compacting force of 5 KN, 15 KN and 25 KN. Test results Compressive Strength.and XRD showed that addition of borosilicate did not change the compound that is hydroxyapatite, but the intensity of hydroxyapatite tends to decrease with addition of borosilicate amount, this is corroborated by FTIR testing. For visible compressive strength, the maximum value occurs at 75: 25 compositions, ie 45 MPa, 42.9 MPa and 52.3 MPa. This suggests that the addition of borosilicate in biocomposite formation does not alter hydroxyapatite compound and can generally increase the compressive strength and modulus of elasticity to 25% wt% borosilicate addition.

Synthesis, characterization and drug release properties of 3D chitosan/clinoptilolite biocomposite cryogels

Three-dimensional (3D) biocomposites based on chitosan (CS) and clinoptilolite (CPL) were prepared by cryogelation and their potential application as drug carriers was investigated. Variation of CPL content from 0 to 33wt.% allowed the formation of biocomposites with heterogeneous morphologies consisting of randomly distributed pores. The further increase of CPL content led to ordered porous architectures where parallel pore channels were observed. The CPL content had a strong influence on water uptake, as well as on the cumulative release of diclofenac sodium (DS) and indomethacin (IDM). It was demonstrated that the drug delivery preferentially takes place in phosphate buffer saline (pH 7.4) in comparison to simulated gastric fluid (pH 1.2), where only a reduced drug release was observed. The drug release mechanism dominating these systems is described as a pseudo-Fickian diffusion, but it changes to non-Fickian release when 33wt.% of CPL was entrapped into the CS matrix or when IDM was loaded into biocomposites.

Preparation and properties of luffa fiber- and kenaf fiber-filled poly(butylene succinate-co-lactate)/starch blend-based biocomposites

Biodegradable poly(butylene succinate-co-lactate) (PBSL)/starch blends that contain various amounts of starch were prepared. In addition, luffa fiber (LF) and kenaf fiber (KF) were incorporated, individually, into PBSL/starch (70/30) blend to achieve biocomposites. The LF and KF were treated with NaOH(aq) prior to their addition to the blend. The Young's modulus and flexural modulus of PBSL increased with the addition of starch and increased further after the formation of the biocomposites. The highest Young's modulus increment, which was found in the KF-added system, was up to a 2.2-fold increase compared with neat PBSL. The tensile/flexural/impact strength of PBSL declined after the formation of the blends. With the further addition of LF/KF, the said properties leveled off. The blends exhibited higher complex viscosity and dynamic storage modulus in the melt state than the neat PBSL, and the values further increased in the biocomposites. The crystallization temperature of PBSL slightly decreased in the blends. By contrast, the biocomposites showed an increment in PBSL crystallization temperature, from 73.0 °C (PBSL) to 75.3 °C (KF-added composite), thereby confirming the surface nucleation effect of LF/KF. The blends showed a higher degree of water absorption than PBSL. The formation of biocomposites led to an even higher degree of water absorption. The current approach of including LF/KF in the PBSL/starch blend to enhance the rigidity and biodegradability was advantageous in expanding the applications of PBSL.

Enzymatic Dissolution of Biocomposite Solids Consisting of Phosphopeptides to Form Supramolecular Hydrogels.

Enzyme-catalyzed dephosphorylation is essential for biomineralization and bone metabolism. Here we report the exploration of using enzymatic reaction to transform biocomposites of phosphopeptides and calcium (or strontium) ions to supramolecular hydrogels as a mimic of enzymatic dissolution of biominerals. (31) P NMR shows that strong affinity between the phosphopeptides and alkaline metal ions (e.g., Ca(2+) or Sr(2+) ) induces the formation of biocomposites as precipitates. Electron microscopy reveals that the enzymatic reaction regulates the morphological transition from particles to nanofibers. Rheology confirms the formation of a rigid hydrogel. As the first example of enzyme-instructed dissolution of a solid to form supramolecular nanofibers/hydrogels, this work provides an approach to generate soft materials with desired properties, expands the application of supramolecular hydrogelators, and offers insights to control the demineralization of calcified soft tissues.

Preparation and characterization of a stereocomplex of poly(lactide-co-ε-caprolactone)/tricalcium phosphate biocomposite using supercritical fluid technology

A novel biocomposite material from a stereocomplex of poly (L-lactide-co-!-caprolactone) (PLLCL) and poly (D-lactide-co-!-caprolactone) (PDLCL) and inorganic tricalcium phosphate (TCP) was prepared by supercritical fluid method. Both pristine and poly (L-lactide)-grafted-TCP (PLLA-g-TCP) were used. PLLA-g-TCP was produced by ring- opening polymerization of L-lactide in the presence of surface-activated TCP. Infrared (IR) spectroscopy and scanning electron microscopic (SEM) images confirm the attachment of PLLA onto the activated TCP surface. The stereocomplex formation of biocomposite was confirmed by differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD). The biocomposite containing PLLA-g-TCP has higher stereocomplex degree and more homogeneous TCP distri- bution compared to the biocomposite containing pristine TCP. The presence of PLLA-g-TCP in the stereocomplex PLLCL- PDLCL (s-PDLCL) enhance the stereocomplex degree up to a certain content and also supports the homogeneous TCP dispersion in the stereocomplex matrix. These phenomena support the improvement in mechanical properties of the s-PDLCL composite the optimum content of PLLA-g-TCP being 10%. The biocomposites containing TCP materials are promising materials for biomedical application, especially for bone tissue engineering.

Hybrid Method for the Formation of Biocomposites on the Surface of Stainless Steel Implants

This study reports a hybrid method which allows the formation of biocomposites on stainless steel implants. The main idea of the method is to create multilayer coatings consisting of titanium primer layer and a microarc calcium-phosphate coating. The titanium layer is deposited from plasma of continuous vacuum-arc discharge, and calcium-phosphate coating is formed by the microarc oxidation technique. The purpose of the hybrid method is to combine the properties of good strength stainless steel with high bioactivity of calcium-phosphate coating. This paper describes the chemical composition, morphology characteristics, adhesion and the ability of the formed biocomposites to stimulate the processes of osteoinduction. It is expedient to use such biocomposites for implants which carry heavy loads and are intended for long-term use, e.g. total knee endoprosthesis.

Formation of biocomposites based on natural geyserites and synthetic opals academician

Development of matrices (carriers) for cells with the use of micro- and nanoparticles of various types is one of the key problems in creation of bioartificial organs, because the sizes and structural characteristics of these particles may make them compatible with cultured cellular structures. There are various physicochemical methods of the formation of microheterogeneous mosaic structures imitating the morphological and other characteristics of the surface of biological structures. Therefore, it is important to study the interaction of synthetic and natural (geyserite) opal matrices with cellular systems in order to develop biocompatible materials, including those used in reconstructive plastic surgery. Geyserites (siliceous sinters) are deposits of amorphous silica formed from thermal waters of hot springs, microorganisms being necessarily involved in the process. Specific bacterial communities consisting of both producers (phototrophs and chemotrophs) and reducers occur in places where thermal waters come out of the ground. Bacterial mats varying in the silica content are often formed in these systems; therefore, geyserites are usually classified with biogenic deposits. Several “genetic” types of geyserites are distinguished; they differ from one another in the size and distribution of silica particles and the amount of silicified remnants of microorganisms [1, 2].