https://pubs.rsc.org/en/content/articlepdf/2020/gc/d0gc01647k

Review of recent advances in the biodegradability of polyhydroxyalkanoate (PHA) bioplastics and their composites

Levulinic acid (LA) is one of the top bio-based platform molecules that can be converted into many valuable chemicals. It can be produced by acid catalysis from renewable resources, such as sugars, lignocellulosic biomass and waste materials, attractive candidates due to their abundance and environmentally benign nature. The LA transition from niche product to mass-produced chemical, however, requires its production from sustainable biomass feedstocks at low costs, adopting environment-friendly techniques. This review is an up-to-date discussion of the literature on the several catalytic systems that have been developed to produce LA from the different substrates. Special attention has been paid to the recent advancements on starting materials, moving from simple sugars to raw and waste biomasses. This aspect is of paramount importance from a sustainability point of view, transforming wastes needing to be disposed into starting materials for value-added products. This review also discusses the strategies to exploit the solid residues always obtained in the LA production processes, in order to attain a circular economy approach.

https://www.mdpi.com/2073-4344/6/12/196/pdf

New Frontiers in the Catalytic Synthesis of Levulinic Acid: From Sugars to Raw and Waste Biomass as Starting Feedstock

Environmental impacts and consumer concerns have necessitated the study of bio-based materials as alternatives to petrochemicals for packaging applications. The purpose of this review is to summarize synthetic and non-synthetic materials feasible for packaging and textile applications, routes of upscaling, (industrial) applications, evaluation of sustainability, and end-of-life options. The outlined bio-based materials include polylactic acid, polyethylene furanoate, polybutylene succinate, and non-synthetically produced polymers such as polyhydrodyalkanoate, cellulose, starch, proteins, lipids, and waxes. Further emphasis is placed on modification techniques (coating and surface modification), biocomposites, multilayers, and additives used to adjust properties especially for barriers to gas and moisture and to tune their biodegradability. Overall, this review provides a holistic view of bio-based packaging material including processing, and an evaluation of the sustainability of and options for recycling. Thus, this review contributes to increasing the knowledge of available sustainable bio-based packaging material and enhancing the transfer of scientific results into applications.

Bio-Based Packaging: Materials, Modifications, Industrial Applications and Sustainability.

Adsorption of Ciprofloxacin from Water: A Comprehensive Review

CO2 capture by Li4SiO4 sorbents and their applications: Current developments and new trends

CO2 sorption/desorption performance study on K2CO3-doped Li4SiO4-based pellets

In order to produce sustainable, bio-based and highly biodegradable materials, composites based on poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) and fibers of Posidonia oceanica (PO), a dominant Mediterranean seagrass, were produced by simple melt mixing and characterized in terms of thermal stability, morphology and rheological/mechanical properties. In view of their potential application in marine environments, degradation of the developed composites was evaluated under simulated and real marine environmental conditions for 1 year. Using 10 wt % of acetyl tributyl citrate (ATBC) as a plasticizer, smooth processing was achieved for up to 30 wt % of PO fibers, despite the reduction of the melt fluidity observed with increasing fiber loading. The tensile modulus slightly increased (from 2 to 2.4 GPa) while the tensile strength and the elongation decreased (from 23.6 to 21.5 MPa and from 3.2 to 1.9%, respectively) by increasing the PO fiber content from 0 to 30 wt %. Interestingly, the impact resistance of the composites increased with the increasing of the PO content: the Charpy’s impact energy increased from 3.6 (without fiber) to 4.4 kJ/m2 for the composite with 30 wt %. The results of the aerobic biodegradation under simulated marine conditions showed that the presence of PO fibers favored the physical disintegration of the composite increasing the biodegradation rate of the polymeric matrix: after 216 days, the composite with 20 wt % PO fibers showed a biodegradability of about 30% compared to 20% of the composite without fibers. Under real marine conditions, the specimens containing PO fibers showed higher weight losses and deterioration of tensile properties compared to those without fibers. Presumably, biodegradation occurred after colonization of the specimen, and the specimens with 20 wt % PO fibers showed well-developed biofilm consisting of bacteria and fungi on the surface after only 3 months of incubation in marine sediments, unlike the no-fiber specimens. Consequently, the persistence of an adequate mechanical performance for a relatively long period (1 year), due to a moderate rate of biodegradation in the marine environment, make the developed PHBV/PO composites particularly suitable for the production of relatively low-cost and biodegradable items which are usable in the sea and/or sand dunes, increasing the market opportunities for biopolymers such as PHBV and, at the same time, finding an eco-sustainable valorization for the PO fibrous residues accumulated in large quantities on Mediterranean beaches, which represents a problem for coastal municipalities.

https://www.mdpi.com/1996-1944/11/5/772/pdf

Novel Sustainable Composites Based on Poly(hydroxybutyrate-co-hydroxyvalerate) and Seagrass Beach-CAST Fibers: Performance and Degradability in Marine Environments

Hydrothermal Carbonization of Sewage Sludge: Analysis of Process Severity and Solid Content

Ciprofloxacin (CIP) is a broad-spectrum antibiotic of the fluoroquinolone group. The low biodegradability of this compound enhances its accumulation in the environment, with associated interference on non-target pathogens, photosynthesis of plants, alterations in the structure of algae and increasing risk of resistant bacteria development. Production plants and hospitals are the main sources of water contamination. Hence, the development of efficient technologies for the treatment of wastewaters is recommended. Here, ultrasound irradiation coupled with the electrochemical generation of hydroxyl radicals by Nb/BDD anode were investigated to remove CIP from aqueous solutions. A solid polymer electrolyte (SPE) was used to overcome the low conductivity of the solution treated. Response Surface Methodology (RSM) was applied with the aim to evaluate the effects of electric current, ultrasound irradiation and stirring rate on the removal and the energy requirements associated to the treatment. Up to 91.36 % of CIP disappearance was attained within 20 min. at 1.16 A and 520 rpm. Ultrasound irradiation at 40 kHz enhanced the removal of the compound only at low current intensity, while strongly affected the energy demand. A treatment time of 30 min. at 0.642 A and 660 rpm has been suggested to minimize the specific energy consumption, estimated to be

Ciprofloxacin removal: BDD anode coupled with solid polymer electrolyte and ultrasound irradiation

Hydrothermal carbonization (HTC) is a thermo-chemical process for recovery and valorization of biomass and organic waste that uses sub-critical liquid water as a reaction medium for converting feedstock into valueadded products.. HTC treatment produces a carbonaceous solid, named hydrochar, with attractive characteristics that can be used in a variety of applications, such as activated carbon or soil amendment. In this study, activated carbons were prepared by KOH chemical activation of hydrochars obtained from hydrothermal carbonization of green waste and municipal solid waste. The effects of precursors and different KOH/char mass ratios on physical characteristics of the activated carbon were investigated. Methylene blue and iodine numbers were determined to evaluate the adsorption properties of obtained activated carbons. The results have shown a significant increase of porosity and a change in hydrochar structure by KOH activation method. The amount of mesopores and micropores increase with increasing KOH/char ratio. In particular, the sample by treatment of hydrochar from green waste activated with a 2:1 KOH/char weight ratio presented good mesoporosity, with a methylene blue number of 385 mg/g, and a well-developed micropore structure, with iodine number of 747 mg/g. Therefore, the application of KOH activated hydrochar as activated carbon appears to be promising.

Eleonora Stefanelli

Papers

CO2 sorption/desorption performance study on K2CO3-doped Li4SiO4-based pellets

Novel Sustainable Composites Based on Poly(hydroxybutyrate-co-hydroxyvalerate) and Seagrass Beach-CAST Fibers: Performance and Degradability in Marine Environments

Hydrothermal Carbonization of Sewage Sludge: Analysis of Process Severity and Solid Content

Ciprofloxacin removal: BDD anode coupled with solid polymer electrolyte and ultrasound irradiation

Activated Carbon from Hydrochar Produced by Hydrothermal Carbonization of Wastes