The hemp plant
Cannabis sativa
Linn, referring to industrial hemp, is a high-yielding annual industrial crop grown providing fibers from hemp stalk and oil from hemp seeds. Although hemp is a niche ...crop, hemp production is currently undergoing a renaissance. More than 30 countries grow hemp, with China being the largest hemp producing and exporting country. Europe and Canada are also important actors in the global hemp market. Traditionally, hemp as a fiber plant has been used for the production of apparels, fabrics, papers, cordages and building materials. The hurds, as waste by-product of fiber production, were used for bedding of animals, the seeds for human nutrition, e.g., as flour, and the oil for a wide range of purposes, from cooking to cosmetics. Hemp has also been an important crop throughout human history for medicine. Other more recent applications include materials for insulation and furniture, automotive composites for interior applications and motor vehicle parts, bioplastics, jewelry and fashion sectors, animal feed, animal bedding, and energy and fuel production. Foods containing hemp seed and oil are currently marketed worldwide for both animal and human nutrition. They also find applications in beverages and in neutraceutical products. Hemp oil is also used for cosmetics and personal care items, paints, printing inks, detergents and solvents. It is estimated that the global market for hemp consists of more than 25,000 products. Currently, the construction and insulation sector, paper and textile industries, and food and nutrition domains are the main markets while the cosmetics and automotive sector are growing markets. Innovative applications, e.g., in the medical and therapeutic domains, cosmeceuticals, phytoremediation, acoustic domain, wastewater treatment, biofuels, biopesticides and biotechnology, open new challenges. Hemp is also the object of numerous fundamental studies. This review presents and discusses the traditional and new uses of industrial hemp.
Chemical cross-linking using epichlorohydrin as cross-linking agent is the most straightforward method to produce water-insoluble β-cyclodextrin-based polymers. The numerous OH groups available on ...cyclodextrin (CD) molecules are active sites capable of forming a number of linkages. Although this cross-linking reaction has been known for 50 years and is well documented, and relatively easy to use for the preparation of CD-based networks, some basic questions concerning the reaction still continue to interest the scientific community. The main objectives of this review are (i) to describe the synthesis and characterization of insoluble CD–epichlorohydrin polymers, (ii) to provide useful information on their most important features, (iii) and to summarize the developments in the use of these materials for environmental purposes. In particular, the description of relevant environmental applications such as sorption-oriented processes, detoxification of wastewater, color removal, and concentration and purification of solutions is included. In this aim, an extensive pool of data from the literature, from 270 papers, reviews, patents and books, has been compiled. The various interactions occurring between pollutants and CD–epichlorohydrin polymer in the sorption processes are presented, and future research trends are discussed.
Cyclodextrins are a group of cyclic oligosaccharides obtained by enzymatic degradation of starch. They are remarkable macrocyclic molecules that have led major theoretical and practical advances in ...chemistry, biology, biochemistry, health science, and agriculture. Their molecular structure is composed of a hydrophobic cavity that can encapsulate other compounds to form inclusion complexes through host–guest interactions. This unique feature is at the origin of many applications. Cyclodextrins and their derivatives have a wide variety of practical applications in almost all sectors of the industry, including pharmacy, medicine, foods, cosmetics, chromatography, catalysis, biotechnology, and the textile industry. Villiers published the first reference to cyclodextrins in 1891, and since then, these molecules have continued to fascinate academia and industry. Currently, more than 2000 publications on cyclodextrins are published each year. On the occasion of the 130th anniversary of their discovery, in this review, we present an historical overview of the development and applications of cyclodextrins. First, we present the discovery and first chemical studies on cyclodextrins. Then, the main results obtained during the 1911–1970 exploration period are discussed. A third part presents the historical landmarks in the development of cyclodextrins from 1970 to the present day.
The rise of emerging contaminants in waters challenges the scientific community and water treatment stakeholders to design remediation techniques that are simple, practical, inexpensive, effective, ...and environmentally friendly. Emerging contaminants include antibiotics, hormones, illicit drugs, endocrine disruptors, cosmetics, personal care products, pesticides, surfactants, industrial products, microplastics, nanoparticles, and nanomaterials. Removing those contaminants is not easy because classical wastewater treatment systems are not designed to handle emerging contaminants, and contaminants often occur as traces in complex organo-mineral mixtures. Here, we review advanced treatments for the removal of emerging contaminants in wastewater, with focus on adsorption-oriented processes using non-conventional adsorbents such as cyclodextrin polymers, metal–organic frameworks, molecularly imprinted polymers, chitosan, and nanocellulose. We describe biological-based technologies for the degradation and removal of emerging contaminants. Then, we present advanced oxidation processes as the most promising strategies because of their simplicity and efficiency.
Chitosan is a biopolymer obtained from chitin, one of the most abundant and renewable materials on Earth. Chitin is a primary component of cell walls in fungi, the exoskeletons of arthropods such as ...crustaceans, e.g., crabs, lobsters and shrimps, and insects, the radulae of molluscs, cephalopod beaks, and the scales of fish and lissamphibians. The discovery of chitin in 1811 is attributed to Henri Braconnot while the history of chitosan dates back to 1859 with the work of Charles Rouget. The name of chitosan was, however, introduced in 1894 by Felix Hoppe-Seyler. Chitosan has attracted major scientific and industrial interests from the late 1970s due to its particular macromolecular structure, biocompatibility, biodegradability and other intrinsic functional properties. Chitosan and derivatives have practical applications in the food industry, agriculture, pharmacy, medicine, cosmetology, textile and paper industries, and in chemistry. In recent years, chitosan has also received much attention in dentistry, ophthalmology, biomedicine and bioimaging, hygiene and personal care, veterinary medicine, packaging industry, agrochemistry, aquaculture, functional textiles and cosmetotextiles, catalysis, chromatography, beverage industry, photography, wastewater treatment and sludge dewatering, and biotechnology. Nutraceuticals and cosmeceuticals are actually growing markets, and therapeutic and biomedical products should be the next markets in the development of chitosan. Chitosan is also the object of numerous fundamental studies. In this review, we highlight a selection of works on chitosan applications published over the past two decades.
Reclaiming of wastewaters contaminated by heavy metals has become a major challenge over the last decades. For this reason, nanoporous membrane processes have awaken the interest of industry and ...local community, and the possible ways to improve their performances has become a priority goal for researchers. Metal removal enhancement by polymer addition is a potential way that is deeply investigated herein on nickel ion rejection with chitosan and carboxymethyl cellulose addition. Due to the vanishing of electrostatic interactions induced by the large amount of salt usually contained in effluents, ion rejection consequently drastically drops. However, it is highlighted that a sufficient addition of polymer (higher than 10−2 M of monomer unit) can offset this decrease and allow good metal removal, while permeation flux is reduced by increased viscosity. Performances are greatly affected by the pH of the filtered solution whose increase notably improves the metal rejection. Finally, ultrafiltration of an industrial discharge water with and without chitosan enhancement step shows that the rejection increase generated by the polymer addition is very low due to the competing phenomenon between the various species present in the complex mixture.
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•Removal of Ni(II) by UF membranes falls drastically in salty conditions.•Polymer addition increases Ni(II) removal with both chitosan and CMC.•Chitosan should be chosen in acid or basic conditions due to better rejection.•CMC should be preferred at natural pH due to better flux and easier implementation.•Impact of polymer is weak for real effluents due to competition between ions.
The removal of contaminants from wastewaters is a major challenge in the field of water pollution. Among numerous techniques available for contaminant removal, adsorption using solid materials, named ...adsorbents, is a simple, useful and effective process. The adsorbent matter can be mineral, organic or biological. Activated carbon is the preferred, conventional material at the industrial scale. Activated carbon is extensively used not only for removing pollutants from wastewater streams, but also for adsorbing contaminants from drinking water sources, e.g., groundwater, rivers, lakes and reservoirs. However, the widespread use of activated carbon is restricted due to a high cost. In the last three decades, numerous approaches using non-conventional adsorbents have been studied for the development of cheaper and more effective adsorbents to eliminate pollutants at trace levels. This review gives an overview of liquid–solid adsorption processes using conventional and non-conventional adsorbents for pollutant removal. The manuscript outlines the principles of adsorption and proposes a classification for adsorbent materials. Finally, the various mechanisms involved in the adsorption phenomena are discussed.
Selenium (Se) removal from synthetic solutions and from real Flue Gas Desulfurization (FGD) wastewater generated by a coal-fired power plant was studied for the first time using a commercial iron ...oxide impregnated strong base anion exchange resin, Purolite® FerrIX A33E. In synthetic solutions, the resin showed high affinity for selenate and selenite, while sulfate exhibited a strong competition for both oxyanions. The FGD wastewater investigated is a complex system that contains Se (∼1200 μg L−1), SO42− (∼1.1 g L−1), Cl− (∼9.5 g L−1), and Ca2+ (∼5 g L−1), alongside a broad spectrum of toxic trace metals including Cd, Cr, Hg, Ni, and Zn. The resin performed poorly against Se in the raw FGD wastewater and showed moderate to good removal of several trace elements such as Cd, Cr, Hg, and Zn. In FGD effluent, sulfate was identified as a powerful competing anion for Se, having high affinity for the exchange active sites of the resin. The desulfurization of the FGD effluent using BaCl2 led to the increase in Se removal from 3% (non-desulfurized effluent) to 80% (desulfurized effluent) by combined precipitation and ion exchange treatment. However, complete desulfurization using equimolar BaCl2 could not be achieved due to the presence of bicarbonate that acts as a sulfate competitor for barium. In addition to selenium and sulfate removal, several toxic metals were efficiently removed (Cd: 91%; Cr: 100%; Zn: 99%) by the combined (desulfurization and ion exchange) treatment.
•Flue Gas Desulfurization (FGD) effluent was treated using FerrIX A33E resin.•FerrIX A33E showed limited Se removal (<3%) from raw FGD.•Desulfurization of FGD using BaCl2 led to 61% Se removal.•80% Se removal was achieved using desulfurized FGD effluent treated by FerrIX A33E.•Several toxic metals were also efficiently removed (Cd: 91%; Cr: 100%; Zn: 99%).
During the last 10years, the appearance of emerging organic compounds described as endocrine disrupters in wastewaters and water resources has become a major concern for both society and public ...health authorities, the whole industrial world and the agricultural sector. Endocrine disrupting compounds are found in various environmental compartments such as water, sediments, soils and atmosphere, as a result of their wide usage. Numerous products are concerned including surfactants, industrial additives and formulations, pharmaceuticals, and also personal care products. However, the existing conventional water treatment plants were not designed for these new contaminants. In the present study, an overview of the literature on methods for the elimination (removal and/or degradation) of emerging trace organic contaminants is presented. This review is limited to details of the treatment of one class of endocrine disrupters, namely alkylphenols and their polyethoxylate derivatives, which are suspected to interfere with the hormonal system of wildlife. The technologies proposed for alkylphenol treatment include membrane treatment using biological (membrane bioreactors) or physical processes (membrane filtration such as nanofiltration), biotechnological-based methods (biofilms, immobilized enzymes, etc.), adsorption-oriented processes using conventional (activated carbons) or nonconventional adsorbents (clays, cyclodextrin, etc.), and advanced oxidation processes (photocatalysis, photolysis, and sonochemistry). Examples are taken from the literature to illustrate various features of the technologies used in decontamination methods. Among them, photocatalytic oxidation is an interesting tool for alkylphenol treatment due to its potential to reach complete mineralization.
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