Tailoring electrospun nanocomposite fibers of polylactic acid for seamless methylene blue dye adsorption applications

The introduction of biopolymers, which are sustainable and green materials, desegregated nature's water purification proficiency with science and technology, opens a new sustainable methodology in water reclamation. In order to introduce an efficacious adsorbent system for MB dye-toxic pollutant, adsorption, providing robust mechanical properties and facile processability, a facile system was introduced via electrospinning utilizing polylactic acid (PLA) and Ti3C2Tx, viz., PMX. The addition of 3 wt.% Ti3C2Tx led to a 3-fold substantial augmentation in the uptake capacity of the membrane from 197.28 to 307 mg/g when the adsorbate concentration was 100 ppm. The adsorption followed a PSO behavior, proposing that the rate-limiting stage is chemisorption and data best fitted to Freundlich isotherm, indicating heterogeneous adsorption sites and multi-layer adsorption. Further, biodegradability was studied by simulating natural environmental conditions where the nanofibers exhibited 42-64% degradation after 270 days. Based on the result with PLA, it is anticipated that the prepared fibrous system will introduce a new perspective as a potential candidate for MB removal from wastewater, opening new directions toward the research and development in wastewater treatment with electrospun biopolymer fibers using waste PLA.

Silk adsorbent for green and efficient removal of methylene blue from wastewater

Silk, a naturally occurring proteinaceous biopolymer with remarkable adsorbent properties, has been employed in wastewater remediation. The sericin coating, functioning as a protective barrier and rendering fibres impervious to external chemical attacks and preventing their involvement in chemical reactions, was removed using a greener alternative to harness silk as an effective adsorbent. Subsequently, the silk fibres underwent intermittent microwave degumming to extract sericin, and the fibres were utilized for the adsorptive exclusion of the hazardous methylene blue (MB) dye. The comparative batch adsorption studies (kinetics and isotherm) between raw silk fibres and degummed fibres were performed to comprehend the role of degumming on fibre adsorption efficacy by varying operating conditions, including pH, time of contact, initial adsorbate and dosage of adsorbent. The paramount adsorption capacity of raw silk was observed to be 137.08 mg g-1 and 179.14 mg g-1 for degummed silk when adsorbate conc. was 100 ppm. The kinetics of adsorption obeyed pseudo-second order suggesting that the rate controlling step is chemisorptions, and data demonstrated greatest fit to Langmuir isotherm exhibiting mono-layer adsorption. Further, biodegradability was studied by mimicking natural environmental conditions where the raw and degummed silk fibres demonstrated 51% and 53% degradation, respectively, after 180 days. Overall, based on obtained results, this study highlights the suitability of silk as an effective as well as sustainable adsorbent for the exclusion of toxic methylene blue dye from wastewater.

PFAS: exploration of neurotoxicity and environmental impact

Per- and polyfluoroalkyl substances (PFAS) are widespread contaminants stemming from various industrial and consumer products, posing a grave threat to both human health and ecosystems. PFAS contamination arises from multiple sources, including industrial effluents, packaging, and product manufacturing, accumulating in plants and impacting the food chain. Elevated PFAS levels in water bodies pose significant risks to human consumption. This review focuses on PFAS-induced neurological effects, highlighting disrupted dopamine signalling and structural neuron changes in humans. Animal studies reveal apoptosis and hippocampus dysfunction, resulting in memory loss and spatial learning issues. The review introduces the BKMR model, a machine learning technique, to decipher intricate PFAS-neurotoxicity relationships. Epidemiological data underscores the vulnerability of young brains to PFAS exposure, necessitating further research. Stricter regulations, industry monitoring, and responsible waste management are crucial steps to reduce PFAS exposure.

3D-Printed Biomimetic Hierarchical Nacre Architecture: Fracture Behavior and Analysis

Nacreous architecture has a good combination of toughness and modulus, which can be mimicked at the micron to submicron level using 3D printing to resolve the demand in numerous applications such as automobile, aerospace, and protection equipment. The present study examines the fabrication of two nacre structures, a nacre columnar (NC) and a nacre sheet (NS), and a pristine structure via fused deposition modeling (FDM) and explores their mechanically superior stacking structure, mechanism of failure, crack propagation, and energy dissipation. The examination reveals that the nacre structure has significant mechanical properties compared to a neat sample. Additionally, NS has 112.098 J/m impact resistance (9.37% improvement), 803.415 MPa elastic modulus (11.23% improvement), and 1563 MPa flexural modulus (10.85% improvement), which are all higher than those of the NC arrangement.

Algal mediated intervention for the retrieval of emerging pollutants from aqueous media

Water is a crucial elemental contributor for all sectors; however, the agricultural sector alone accounts for 70% of the world's total water withdrawal. The anthropogenic activity from various industries including agriculture, textiles, plastics, leather, and defence has resulted in the release of contaminants into water systems, resulting harm to the ecosystem and biotic community. Algae-based organic pollutant removal uses several methods, such as biosorption, bioaccumulation, biotransformation, and biodegradation. The adsorption of methylene blue by algal species Chlamydomonas sp. showed a maximum adsorption capacity of 2744.5 mg/g with 96.13% removal efficiency; on the other hand, Isochrysis galbana demonstrated a maximum of 707 µg/g nonylphenol accumulation in the cell with 77% removal efficiency indicating the potential of algal systems as efficient retrieval system for organic contaminants. This paper is a compilation of detailed information about biosorption, bioaccumulation, biotransformation, biodegradation, and their mechanism, along with the genetic alteration of algal biomass. Where the genetic engineering and mutations on algae can be advantageously utilized for the enhancement of removal efficiency without any secondary toxicity.

Emerging Strategies in Stimuli-Responsive Silk Architectures

The utilization of implantable devices beseeches highly invasive surgeries considering the adversaries in the insertion of large, impliable devices through the body channels, which necessitate the development of implantable devices using biocompatible shape memory polymers. Silk displays prodigious heterogeneity in its genetic structure and physical properties in accordance with the spinning and storage process, where proteins undergo folding and unfolding. The stimuli-responsive nature of silk can be explained with the help of the structural morphology and composition of the material, where the hydrogen bonds in β-sheet domains and amorphous region act as switch points and net points, respectively. This review provides a primary attempt to enswathe all the literature available to date on the stimuli-responsive nature of silk and silk-based materials as a natural and biodegradable alternative for commercially used synthetic shape memory materials taking their elastomeric nature and reduction in glass transition temperature into account. Further constitutive model using the continuum approach has been utilized to explain the anisotropic elasticity damping effect and plastic deformation based on the α-helix chains, β-sheets, and β-spiral structures. The practicability to develop biomedical devices such as patient-specific-injectable scaffolds, drug carriers, and artificial muscles has been encompassed in this article.

A review on algal biosorbents for heavy metal remediation with different adsorption isotherm models

Biosorbent composites like chitin, alginate, moss, xanthene, and cotton can be derived from biotic species such as plants, algae, fungi, and bacteria which can be used for the exclusion of both organic and inorganic toxicants from sewage, industrial effluent, polluted soils, and many more. The use of composites in place of raw substrates like alginate and chitin increases the adsorption capacity as CS₄CPL₁ beads increase the adsorption capacity for copper and nickel from 66.7 mg/g and 15.3 mg/g in the case of alginate microsphere to 719.38 mg/g and 466.07 mg/g respectively. Biosorbent fabricated from algae Chlorella vulgaris having surface area of 12.1 m²/g and pore size of 13.7 nm owing to which it displayed a higher adsorption capacity for Pb 0.433 mmol/g indicating their potential as an efficient biosorbent material. This article contains detailed information related to heavy metals as well as biosorbent that includes different isotherms, kinetics, techniques to estimate heavy metal concentration, removal methods, and adverse health effects caused due to heavy metal pollution. Apart from the above recovery and reuse of biosorbent, correlation with the sustainable development goals has also been included.

Biopolymer - A sustainable and efficacious material system for effluent removal

Undesired discharge of various effluents directly into the aquatic ecosystem can adversely affect water quality, endangering aquatic and terrestrial flora and fauna. Therefore, the conceptual design and fabrication of a sustainable system for alleviating the harmful toxins that are discharged into the atmosphere and water bodies using a green sustainable approach is a fundamental standpoint. Adsorptive removal of toxins (∼99% removal efficacy) is one of the most attractive and facile approaches for cleaner technologies that remediate the environmental impacts and provide a safe operating space. Recently, the introduction of biopolymers for the adsorptive abstraction of toxins from water has received considerable attention due to their eclectic accessibility, biodegradability, biocompatibility, non-toxicity, and enhanced removal efficacy (∼ 80-90% for electrospun fibers). This review summarizes the recent literature on the biosorption of various toxins by biopolymers and the possible interaction between the adsorbent and adsorbate, providing an in-depth perspective of the adsorption mechanism. Most of the observed results are explained in terms of (1) biopolymers classification and application, (2) toxicity of various effluents, (3) biopolymers in wastewater treatment and their removal mechanism, and (4) regeneration, reuse, and biodegradation of the adsorbent biopolymer.

Regenerated silk fibroin loaded with natural additives: a sustainable approach towards health care

According to World Health Organization (WHO), on average, 0.5 Kg of hazardous waste is generated per bed every day in high-income countries. The adverse effects imposed by synthetic materials and chemicals on the environment and humankind have urged researchers to explore greener technologies and materials. Amidst of all the natural fibers, silk fibroin (SF), by virtue of its superior toughness (6 × 10⁴∼16 × 10⁴ J/kg), tensile strength (47.2-67.7 MPa), tunable biodegradability, excellent Young's modulus (1.9-3.9 GPa), presence of functional groups, ease of processing, and biocompatibility has garnered an enormous amount of scientific interests. The use of silk fibroin conjoint with purely natural materials can be an excellent solution for the adverse effects of chemical-based treatment techniques. Considering this noteworthiness, vigorous research is going on in silk-based biomaterials, and it is opening up new vistas of opportunities. This review enswathes the structural aspects of silk fibroin along with its potency to form composites with other natural materials, such as curcumin, keratin, alginate, hydroxyapatite, hyaluronic acid, and cellulose, that can replace the conventionally used synthetic materials, providing a sustainable pathway to biomedical engineering. It was observed that a large amount of polar functional moieties present on the silk fibroin surface enables them to compatibilize easily with the natural additives. The conjunction of silk with natural additives initiates synergistic interactions that mitigate the limitations offered by individual units as well as enhance the applicability of materials. Further the current status and challenges in the commercialization of silk-based biomedical devices are discussed.

Sustainable conversion of saturated adsorbents (SAs) from wastewater into value-added products: future prospects and challenges with toxic per- and poly-fluoroalkyl substances (PFAS)

Following circular economy principles, the reuse or recycling of saturated adsorbents (SAs or adsorbate-laden adsorbents) into a low-cost engineered product is a valuable alternative to eliminate secondary pollution after adsorption. This review evaluates the application of SAs for the generation of products that can serve as (i) antimicrobial agents or disinfectants, (ii) materials for civil construction, (iii) catalysts, (iv) fertilizers, and (v) secondary adsorbents. The importance of SAs configuration in terms of functional groups, surface area and pore morphology played a crucial role in their reutilization. The SAs-laden silver ions (Ag⁺) strongly inhibit (~ 99%) the growth of Escherichia coli and Staphylococcus aureus microbes found in drinking and wastewaters. The intra-solidification of SAs containing toxic metal pollutants (As³⁺ and F^-) with cementitious materials can effectively reduce their leaching below permissible limits of USEPA standards for their utility as additives in construction work. The existence of transition metal ions (Cu²⁺, Cr^3+/6+, Ni²⁺) on the surface of SAs boosted activity and selectivity towards the desired product during catalytic oxidation, degradation, and conversion processes. The thermally recycled SAs can assist in the secondary adsorption of pollutants from another waste solution due to a larger surface area (> 1000 m²g^-1). However, there are chances that the SAs discussed above will contain traces of PFAS. The article summarizes the challenges, performance efficacy, and future prospects at the end of each value-added product. We also highlight critical challenges for managing PFAS-laden SAs and stimulate new perspectives to minimize PFAS in air, water, and soils.

Removal of Zwitterionic PFAS by MXenes: Comparisons with Anionic, Nonionic, and PFAS-Specific Resins

Zwitterionic per- and polyfluoroalkyl substances are increasingly detected in aquatic environments. The magnitude of their concentration and increased frequency of detection worldwide raise questions on their presence in drinking water and associated health risk. Scientific knowledge on the identification of treatment technologies to effectively capture such zwitterionic PFAS from contaminated water sources remains largely unknown. In this study, we investigated the application of anionic organic scavenger ion exchange (IX) resins (A860), nonionic IX resins (XAD 4 and XAD 7), PFAS-specific resins (A694 and A592), and Ti₃C₂ MXenes (novel two-dimensional metal carbides) for the removal of select fluorotelomer zwitterionic PFAS from natural waters. The cumulative removal of zwitterionic PFAS at pH ∼ 7 follows the order: Ti₃C₂ MXenes > A694 > A592 > A860 > XAD 4 ∼ XAD 7. Ti₃C₂ MXenes were able to capture >75% of the total influent zwitterionic PFAS and the performance remained consistent in natural and synthetic water. Ti₃C₂ MXenes also exhibited efficient regeneration (>90% recovery) with 0.4 M Na₂SO₃ solution, while the regeneration efficacy of other IX resins generally remained below 20%. Treatment with ∼180 J/cm² UV dosage in the 0.4 M Na₂SO₃ regenerant brine solution yielded >99.9% reduction in the zwitterionic PFAS concentration indicating that UV-sulfite systems exhibit promising potential for the treatment of zwitterionic PFAS concentrates.

Graphene-based TiO2 composites for photocatalysis & environmental remediation: synthesis and progress

Photoactive nanomaterials constitute an emerging field in nanotechnology, finding an extensive array of applications spanning diverse areas, including electronics and photovoltaic devices, solar fuel cells, wastewater treatment, etc. Titanium dioxide (TiO₂), in its thin-film form, has been exhaustively surveyed as potential photocatalysts for environmental remediation owing to its innocuousness, stability, and photocatalytic characteristics when subjected to ultraviolet (UV) irradiation. However, TiO₂ has some shortcomings associated with a large bandgap value of around 3.2 eV, making it less efficient in the visible spectral range. TiO₂ is often consolidated with various carbon nanomaterials to overcome this limitation and enhance its efficiency. Graphene, a 2-dimensional allotrope of carbon with a bandgap tuned between 0 and 0.25 eV, exhibits unique properties, making it an attractive candidate to augment the photoactivity of semiconductor (SC) oxides. Encapsulating graphene oxide onto TiO₂ nanospheres demonstrates intensified photocatalytic properties and exceptional recyclability for the degeneration of certain dyes, including Rhodamine B. This review encompasses various techniques to synthesize graphene-based TiO₂ photoactive composites, emphasizing graphene capsulized hollow titania nanospheres, nanofibers, core/shell, and reduced graphene oxide-TiO₂-based nanocomposites. It also consolidates the application of the aforestated nanocomposites for the disintegration of various synthetic dyes, proving efficacious for water decontamination and degradation of chemicals and pharmaceuticals. Furthermore, graphene-based TiO₂ nanocomposites used as lithium (Li)-ion batteries manifesting substantial electrochemical performance and solar fuel cells for energy production are discussed here.

Anti-barnacle biofouling coatings for the protection of marine vessels: synthesis and progress

Marine biofouling has gnawed both mobile and non-mobile marine structures since time immemorial, leading to the deterioration of designed operational capabilities as well as a loss of valuable economic revenues. Mitigation of biofouling has been the primary focus of researchers and scientists from across the globe to save billions of dollars wasted due to the biological fouling of marine structures. The availability of an appropriate environment along with favorable substrata initiates biofilm formation within a few minutes. The crucial element in establishing a gelatinous biofilm is the excreted metabolites of destructive nature and exopolymeric substances (EPSs). These help in securing as well as signaling numerous foulants to establish themselves on this substrate. The larvae of various benthic invertebrates adhere to these suitable surfaces and transform from juveniles to adult barnacles depending upon the environment. Despite biofouling being characteristically witnessed for a month or lengthier timeframe, the preliminary phases of the fouling process typically transpire on a much lesser timescale. A few natural and synthetic additives had demonstrated excellent non-toxic anti barnacle establishment capability; however, further development into commercial products is still far-fetched. This review collates the specific anti-barnacle coatings, emphasizing natural additives, their sources of extraction, general life cycle analysis, and concluding future perspectives of this niche product.

Nano-fluoro dispersion functionalized superhydrophobic degummed & waste silk fabric for sustained recovery of petroleum oils & organic solvents from wastewater

Superwettable and chemically stable waste silk fabric and degummed silk were used in this study for treatment of oily wastewater and oil/solvent recovery. Silk functionalized with a nano-fluoro dispersion showed a superhydrophobic and oleophilic nature. The functionalized silk demonstrated superoleophilicity towards petroleum oils and organic solvents, and exhibited filtration efficiencies of more than 95%, and up to 70% till 25 re-usable cycles. Furthermore, the functionalized silk materials demonstrated high permeation flux of 584 L.m^-2.h^-1 (for Diesel) for continuous oil-water separation operation. The pH based study in highly acidic and alkaline mediums (pH from 1 to 13) showed excellent stability of nano-fluoro coated silk. Thermogravimetric analysis showed thermal stability up to 250 °C, and 400 °C, for functionalized waste silk, and degummed silk, respectively. FE-SEM analysis revealed randomly oriented spindle shaped nano particles anchored on the silk surface exhibiting hierarchical patterns, as required for the superhydrophobic Cassie-Baxter state. The rate absorption study showed close curve fitting for pseudo second order kinetics (R² = 0.999), which indicated physical absorption process. BET analysis confirmed the porous nature, while the elemental XPS and EDX analysis confirmed strong bonding and uniform coating of fluoro nanoparticles on silk surface. The results demonstrated that nano-fluoro dispersion functionalized silk can be successfully employed for effective oil/solvent-water filtration, oil/solvent-spill cleanups, and treatment of oily wastewater for protection of water resources.

Functionalized non-woven surfaces for combating the spread of the COVID-19 pandemic

The worldwide outbreak of SARS-CoV-2 infection has necessitated mandatory use of face masks, personal protective equipment and intake of a healthy diet for immunity boosting. As per WHO's recommendation, continuous use of masks has been proven effective in decreasing the SARS-CoV-2 infection rate. The present study reports on the bacterial filtration efficacy (BFE) of a novel 4-ply functionalized non-woven face mask. We synthesized a polypropylene-based fabric with inner layers of melt-blown fine fibres coated with polylactic acid and immune-boosting herbal phytochemicals. Experimental studies on the synthesized face mask demonstrated a BFE of greater than 99% against Staphylococcus aureus (a bacterium species frequently found in mammalian respiratory tract). A thorough computational analysis using LibDock algorithm demonstrated an effective docking performance of herbal phytochemicals against harmful virus structures. More importantly, the face mask also showed sufficient and stable breathability as per regulatory standards. A breathing resistance of 30 Pa at an aerosol flow rate of 30 l h⁻¹ was reported under standard temperature and pressure conditions, indicating a high potential for real-world applications.

Application of MXenes for water treatment and energy-efficient desalination: A review

MXenes are a new type of two-dimensional (2D) material which are rapidly gaining traction for a range of environmental, chemical and medical applications. MXenes and MXene-composites exhibit high surface area, superlative chemical stability, thermal conductivity, hydrophilicity and are environmentally compatible. Consequently, MXenes have been successfully employed for hydrogen storage, semiconductor manufacture and lithium ion batteries. In recent years, MXenes have been utilized in numerous environmental applications for treating contaminated surface waters, ground and industrial/ municipal wastewaters and for desalination, often outperforming conventional materials in each field. MXene-composites can adsorb multiple organic and inorganic contaminants, and undergo Faradaic capacitive deionization (CDI) when utilized for electrochemical applications. This approach allows for a significant decrease in the energy demand by overcoming the concentration polarization limitation of conventional CDI electrodes, offering a solution for low-energy desalination of brackish waters. This article presents a state-of-the-art review on water treatment and desalination applications of MXenes and MXene-composites. An investigation into the kinetics and isotherms is presented, as well as the impact of water constituents and operating conditions are also discussed. The applications of MXenes for CDI, pervaporation desalination and solar thermal desalination are also examined based on the reviewed literature. The effects of the water composition and operational protocols on the regeneration efficacy and long-term usage are also highlighted.

Application of neural network in metal adsorption using biomaterials (BMs): a review

ANN models for predicting wastewater treatment efficacy of biomaterial adsorbents.

Three-dimensional printing of molluscan shell inspired architectures via fused deposition modeling

Nature always astonishes us with its marvelous creations which act as a model for acquiring a solution to complex human problems, this practice of designing and manufacturing the product replicating processes that occur in nature is referred to as biomimicking. Molluscan shell is nature's one such offering that delivers remarkable mechanical properties by virtue of its hierarchical multi-layered structure. In this work, a peculiar avenue for facile biomimicking multitudinous molluscan shell architectures such as complex cross lamellar, cross lamellar, foliated, prismatic, columnar nacre, and sheet nacre structure are manufactured by 3D prototyping of biodegradable, biocompatible polylactic acid (PLA). Here, the reliance of mechanical attributes of PLA on various architectures is studied and demonstrated that the nacre, owing to its complex structure, leads to high energy dissipation (12.5094 J/m) imparting high toughness.

Needleless electrospun phytochemicals encapsulated nanofibre based 3-ply biodegradable mask for combating COVID-19 pandemic

The emergence of COVID-19 pandemic has severely affected human health and world economies. According to WHO guidelines, continuous use of face mask is mandatory for personal protection for restricting the spread of bacteria and virus. Here, we report a 3-ply cotton-PLA-cotton layered biodegradable face-mask containing encapsulated phytochemicals in the inner-filtration layer. The nano-fibrous PLA filtration layer was fabricated using needleless electrospinning of PLA & phytochemical-based herbal-extracts. This 3-layred face mask exhibits enhanced air permeability with a differential pressure of 35.78 Pa/cm² and superior bacterial filtration efficiency of 97.9% compared to conventional face masks. Close-packed mesh structure of the nano-fibrous mat results in effective adsorption of particulate matter, aerosol particles, and bacterial targets deep inside the filtration layer. The outer hydrophobic layer of mask exhibited effective blood splash resistance up to a distance of 30 cm, ensuring its utilization for medical practices. Computational analysis of constituent phytochemicals using the LibDock algorithm predicted inhibitory activity of chemicals against the protein structured bacterial sites. The computational analysis projected superior performance of phytochemicals considering the presence of stearic acid, oleic acid, linoleic acid, and Arachidic acid exhibiting structural complementarity to inhibit targeted bacterial interface. Natural cotton fibers and PLA bio-polymer demonstrated promising biodegradable characteristics in the presence of in-house cow-dung based biodegradation slurry. Addition of jaggery to the slurry elevated the biodegradation performance, resulting in increment of change of weight from 07% to 12%. The improved performance was attributed to the increased sucrose content in biodegradation slurry, elevating the bacterial growth in the slurry. An innovative face mask has shown promising results for utilization in day-to-day life and medical frontline workers, considering the post-pandemic environmental impacts.

Silk Fibroin As an Immobilization Matrix for Sensing Applications

The development of flexible, biocompatible, and environment-friendly sensors has attracted a significant amount of scientific interest for the past few decades. Among all the natural materials, silk fibroin (SF), due to its tunable biodegradability, biocompatibility, ease of processing, presence of functional groups, and controllable dimensions, has opened up opportunities for immobilizing multitudinous biomolecules and conformability to the skin, among other attractive opportunities. The silk fibroins also offer good physical properties, such as superior toughness and tensile strength. The sensors made of SF as an immobilization matrix have demonstrated excellent analytical performance, sensing even at low concentrations. The significant advantage of silk fibroins is the presence of functional groups along with a controllable conformation transition that enables immobilization of receptor molecules using silk fibroins as an immobilization matrix enables us to entrap the receptor molecules without using any chemical reagents. This review encompasses a detailed discussion on sensors, the advantages of using silk fibroins as an immobilization matrix for various receptors, their applications, and the future research scope in this state-of-the-art technology based upon the explorable applications for silk fibroin-based sensors.

Effect of microplastics in water and aquatic systems

Surging dismissal of plastics into water resources results in the splintered debris generating microscopic particles called microplastics. The reduced size of microplastic makes it easier for intake by aquatic organisms resulting in amassing of noxious wastes, thereby disturbing their physiological functions. Microplastics are abundantly available and exhibit high propensity for interrelating with the ecosystem thereby disrupting the biogenic flora and fauna. About 71% of the earth surface is occupied by oceans, which holds 97% of the earth's water. The remaining 3% is present as water in ponds, streams, glaciers, ice caps, and as water vapor in the atmosphere. Microplastics can accumulate harmful pollutants from the surroundings thereby acting as transport vectors; and simultaneously can leach out chemicals (additives). Plastics in marine undergo splintering and shriveling to form micro/nanoparticles owing to the mechanical and photochemical processes accelerated by waves and sunlight, respectively. Microplastics differ in color and density, considering the type of polymers, and are generally classified according to their origins, i.e., primary and secondary. About 54.5% of microplastics floating in the ocean are polyethylene, and 16.5% are polypropylene, and the rest includes polyvinyl chloride, polystyrene, polyester, and polyamides. Polyethylene and polypropylene due to its lower density in comparison with marine water floats and affect the oceanic surfaces while materials having higher density sink affecting seafloor. The effects of plastic debris in the water and aquatic systems from various literature and on how COVID-19 has become a reason for microplastic pollution are reviewed in this paper.

3D Printing for Hip Implant Applications: A Review

There is a rising demand for replacement, regeneration of tissues and organ repairs for patients who suffer from diseased/damaged bones or tissues such as hip pains. The hip replacement treatment relies on the implant, which may not always meet the requirements due to mechanical and biocompatibility issues which in turn may aggravate the pain. To surpass these limitations, researchers are investigating the use of scaffolds as another approach for implants. Three-dimensional (3D) printing offers significant potential as an efficient fabrication technique on personalized organs as it is capable of biomimicking the intricate designs found in nature. In this review, the determining factors for hip replacement and the different fabrication techniques such as direct 3D printing, Fused Deposition Modelling (FDM), Selective Laser Sintering (SLS) and stereolithography (SLA) for hip replacement. The study also covers surface modifications of 3D printed implants and provides an overview on 3D tissue regeneration. To appreciate the current conventional hip replacement practices, the conventional metallic and ceramic materials are covered, highlighting their rationale as the material of choice. Next, the challenges, ethics and trends in the implants' 3D printing are covered and conclusions drawn. The outlook and challenges are also presented here. The knowledge from this review indicates that 3D printing has enormous potential for providing a pathway for a sustainable hip replacement.