In this work, we successfully fabricated boron nitride foams by assembling boron nitride into a 3D porous structure using freeze drying. Boron nitride was modified by Hummers method and NaOH, which results in the functionalization with OH groups. Such chemical functionalization enabled the attachment of the surfactant molecules, leading to a 3D foam structure. We found that the type of the surfactant molecules and method of freezing (in liquid nitrogen or in a deep freezer) have significant impact on the structure of the foams and consequently their absorbent properties. Fast freezing technique (with liquid nitrogen) created more stable and porous structures compared to the slow freezing technique (in a deep freezer). The best foam structures were obtained for the samples coded as h-BN-B-H-SA and h-BN-N-DA. The highest absorption capacity was found as 2014.3% for h-BN-B-H-SA. Absorption capacity results show that foams can absorb approximately 2–20 times their own weight. The method we use here is easy to apply, environmentally friendly, and can be readily scaled up for industrial use.

This paper provides a novel survey of current collections of frozen raptor carcasses and tissue samples in natural history museums (NHMs), environmental specimen banks (ESBs) and other research collections (ORCs e.g. at universities and research institutes) across Europe and assesses the extent to which collections might support pan-European raptor biomonitoring through the provision of samples for contaminant analyses. The paper is based on questionnaire responses received in late 2018 and early 2019 from 116 institutions. Issues covered include the number of raptor carcasses and diversity of raptor species arriving annually at collections, the number of carcasses stored in freezers, the extent to which collections retain frozen tissue samples, what records are kept of carcasses and tissue samples, constraints to expanding collections of frozen carcasses and tissues and the extent to which collections currently engage in ecotoxicological research and monitoring. Our findings show that collections in Europe receive well over 5000 raptor carcasses per annum, and that NHMs are the key recipients of raptor carcasses for most countries. Collections in Europe probably hold well over 10,000 raptor carcasses in their freezers, offering a substantial resource of frozen raptor carcasses and tissues from recent years. Moreover, these carcasses include good specimen numbers for species that have been prioritized for pan-European contaminant monitoring. Collections are becoming digitized aiding access to samples. However, freezer capacity is a key constraint to retention of carcasses, and contaminant biomonitoring is novel for most NHMs. Our findings on the repository and availability of frozen raptor carcasses and tissues held by collections in Europe can enable greater use of these specimens for pan-European contaminant monitoring in support of better chemicals management. We highlight opportunities to further optimize raptor collections for pan-European contaminant monitoring.

The study examined the individual and combined effects of potassium ferrate(VI) additions and freeze-thaw conditioning for the treatment and dewatering of sludge samples. The first part of the experiments, using primary sludge, compared potassium ferrate(VI) additions prior to freeze-thaw treatment (pretreatment) versus potassium ferrate(VI) additions following freeze-thaw treatment (posttreatment). A low dose (LD) of 1.0 g/L and a high dose (HD) of 10.0 g/L of potassium ferrate(VI) were evaluated along with a freezing temperature of −20 °C and freezing periods of 1, 8 and 15 days. Following the designated freezing period, the samples were removed from the freezer and thawed at room temperature for 12 h. The second part of the study, using anaerobically digested sludge, evaluated the effects of potassium ferrate(VI) pretreatment, using LD = 0.5 g/L and HD = 5.0 g/L, and used simulated drainage beds to separate meltwater from the sludge cake during the thawing period. The study demonstrated that stand-alone freeze-thaw can reduce faecal coliform by >3-log after being frozen for only 1 day, and pretreatment with potassium ferrate(VI) can be used to improve the effects of freeze-thaw on faecal coliform inactivation in sludge. Furthermore, the drainability of the sludge following freeze-thaw was not significantly deteriorated when potassium ferrate(VI) was added to the sludge prior to freezing, despite greater than fourfold increases in the concentrations of soluble proteins and soluble carbohydrates. The meltwater collected during the sludge thawing was approximately 85 % of the initial sludge volume. When 5 g/L of potassium ferrate(VI) was added to the sludge prior to freezing, the meltwater collected had <0.28 MPN/mL faecal coliform, the turbidity was <10 NTU and the pH was 9.1. Pretreatment with potassium ferrate(VI) also reduced the concentration of faecal coliform in the sludge cake, suggesting that freeze-thaw coupled with potassium ferrate(VI) additions can be used to stabilise sludge and reduce sludge volume.

Andra Environmental Specimen Bank (ESB) was established in 2010 as a part of the Perennial Observatory of the Environment (OPE), ongoing Long-Term Environmental Research Monitoring and Testing System located next to the Underground Research Laboratory (URL) at Bure, Meuse/Haute-Marne, France. The URL is used to study the deep geological disposal of high and intermediate level radioactive waste. Andra ESB is designed to archive during at least 100 years samples collected to define the initial state of environmental quality of the local area before the construction of industrial facilities and to ensure the traceability of long-term series of samples collected by the OPE (http://www.andra.fr/ope), using safe long-term conservation practices. Samples archived in the bank include some local food chain products (milk, cheese, honey, cereals, grass, cherry plum…) and specimen usually archived internationally to monitor the environmental quality (soil, sediment, water, fish, tree leaves, wild life, etc.). Regarding the different samples and analytical issues, three conservation modalities and facilities were designed: dry conservation under controlled temperature and humidity, cryopreservation in liquid nitrogen (LN2) vapor phase freezers (−150 °C) and in deep-freezing at −80 °C for temporary storage and raw samples before preparation. Andra ESB is equipped with a sample preparation clean room, certified ISO Class 5, dedicated to cryopreservation. This paper describes this first French experiment of long-term chemical quality monitoring and samples cryopreservation of different ecosystems and environmental compartments.