Associated petroleum hydrocarbons and heavy metals of an oil spilled site in the Niger Delta, Nigeria

Soil samples were collected from an oil polluted site in the Niger - Delta, of the southern region of Nigeria, and were analyzed for petroleum hydrocarbons and heavy metals, which may have been introduced to the soil as a result of the oil spillage that was incidence at the site. The total extractable hydrocarbon content (THC) of 1.13×105±2.91 ×104 mg/kg of the affected soil revealed a high level of petroleum hydrocarbon contamination that far exceeds compliance limits. The gas chromatographic analyses conducted on the samples showed significant contamination in the n-C12 - n-C17 range, especially the n-C13 and n-C17 fractions, and pristane being more abundant than phytane. It also showed a significant concentration of the polycyclic aromatic hydrocarbons (PAHs) with naphthalene which may actually be oxidized before many saturates which are the most prone to biodegradation and attenuation, whileindeno 1, 2, 3 cd pyrene was the most abundant. The results also depicted a substantial concentration of the benzene, toluene, ethyl benzene and xylene (BTEX) fractions with 1, 3, dichlorobenzene as the most abundantfraction while o-xylene had the least concentration. Heavy metals were detected in varying concentration in polluted soils. Zinc had the highest concentration of 9.84 ± 0.93mg/kg while Arsenic had the least concentration of 0.12± 0.04mg/kg. These results suggest that as at the time of sample collection, the spilled oil was still fresh on site. Thatpristane was more abundant than phytane inferred an oxic depositional environment of a probable non-waxy, marine derived organic matter and a phytoplankton input for the spilled oil

Polymer reaction engineering tools to tailor smart and superabsorbent hydrogels

Experimental and theoretical tools to describe and tailor polymer network formation processes are here addressed. Although a special emphasis is given to the synthesis, characterization, and applications of smart and superabsorbent polymers, other networks with higher cross-linker contents are also prospected. Purely synthetic and cellulose-based hydrogels are both considered in this research. The reactor type (e.g., batch or continuous flow micro-reactor), polymerization process (e.g., bulk, inverse suspension, or precipitation polymerization), and polymerization mechanism (e.g., classic free radical polymerization or reversible deactivation radical polymerization RDRP) are highlighted as possible tools to change the morphology and the molecular architecture of polymer networks and hydrogels. The tailoring of cellulose-synthetic hybrid materials is also addressed through the use of RAFT-mediated polymer grafting. Case studies showing the applications of the synthesized materials are presented, namely, molecularly imprinted hydrogel particles for retention of aminopyridines, molecularly imprinted polymers for polyphenols, caffeine or 5-fluorouracil selective uptake/ release, as well as modified cellulose adsorbents for polyphenol retention. Cellulose-based hydrogels are also considered as possible vehicles for polyphenol-controlled release. The mechanisms of liberation of polyphenols from these materials are analyzed, namely, when supercritical CO2 is used in the hydrogel impregnation processParts of this work are a result of project “AIProcMat@N2020 – Advanced Industrial Processes and Materials for a Sustainable Northern Region of Portugal 2020,” with the reference NORTE-01-0145-FEDER-000006, supported by Norte Portugal Regional Operational Programa (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF) and of Project POCI-01-0145-FEDER-006984 – Associate Laboratory LSRE-LCM funded by ERDF through COMPETE2020 (Programa Operacional Competitividade e Internacionalização (POCI)) – and by national funds through FCT (Fundação para a Ciência e a Tecnologia). We also acknowledge the contribution of the master student Gayane Sadoyan in the framework of the thesis “Development of amphiphilic adsorbents for the stimulated uptake and release of polyphenols.”info:eu-repo/semantics/publishedVersio

Cross-Linked Chitosan-Based Hydrogels for Dye Removal

International audienceSynthetic dyes are a major class of recalcitrant organic compounds, often occurring in the environment as a result of their wide industrial use. More than 100,000 dyes are commercially available. Synthetic dyes are common contaminants, many of them being toxic or carcinogenic. Colored effluents from industrial plant are also perceived by the public as an indication of the presence of a dangerous pollution. Even at very low concentrations, dyes are both highly visible, inducing an esthetic pollution, and impacting the aquatic life and food chain, as a chemical pollution. Dye contamination of water is a major problem worldwide and the treatment of wastewaters before their discharge into the environment is a priority. Dyes are difficult to treat due to their complex aromatic structure and synthetic origin. In general, a combination of different physical, chemical and biological processes is often used to obtain the desired water quality. However, there is a need to develop new removal strategies and decolorization methods that are more effective, acceptable in industrial use, and ecofriendly. Currently, there is an increasing interes