International audienceThe potential of using a hemp-based material in felt form as an adsorbent for removing the metals from aqueous mixturesof Cd, Co, Cu, Mn, Ni, and Zn is investigated in the present study using batch experiments at an initial pH between 4.9 and5.2. The operating variables studied were initial metal concentration, adsorbent dosage, contact time, agitation speed, temperature,presence of NaCl, and pH. Experiments showed that this nonconventional adsorbent exhibited interesting capacities: 1 g of hemp wasable to remove 7.4 mg of metals at a concentration of 25 mg/L for each metal present in 100 mL of solution. Kinetic results showedthat the process was uniform and rapid: adsorption of metals reached equilibrium in 10 min. The adsorption capacities were almostindependent of temperature between 25 and 50 8C and pH between 4 and 6, but dependent on the presence of electrolytes such asNaCl. Interesting results were also obtained for real polymetallic effluents. All these findings are significant for the future developmentof hemp-based materials for use as bag filters for metal removal from industrial effluents

et al.. Hempbased adsorbents for sequestration of metals: a review. AbstractWith the increasing focus on renewable materials and sustainability issues, the development of non-conventional materials from natural resources and possessing complexing properties is currently an area of extensive research due to their potential applications in biosorption processes for pollutant removal. Among them, the hemp plant (Cannabis sativa), an annual high yielding industrial crop grown for its fibres and seeds, is one of the most promising materials for biosorption of metal ions from diluted waste streams. In this review, an extensive list of hemp-based biosorbent literature has been compiled and discussed. After a brief description of hemp and its properties and applications, the review gives a general overview of liquid-solid biosorption processes for metal sequestration from aqueous solutions onto hemp-based materials. Fig. 1 Hemp field (a) and dioecious male plant (b)

International audienceIn this study, we propose a chemical pretreatment to improve the performance of a hemp-based material in felt formused as an adsorbent for removing the metals from aqueous mixtures of Cd, Co, Cu, Mn, Ni, and Zn. The felt was coated with amaltodextrin-1,2,3,4-butane tetracarboxylic polymer in order to provide ion-exchange properties to the material by introducing carboxylicgroups. It was characterized by solid-state 13 C-NMR technique and by Energy-dispersive X-ray spectroscopy. This new adsorbentwas then used in batch experiments and its performances were compared with those of non-modified hemp. Differentcontrolling experimental conditions have been investigated. Modified hemp exhibited strong adsorption capacities due to a chemisorptionmechanism (complexation, ion exchange): up to 25 mg/L (in reality, 150 mg of metals per L), all metals in the solutionwere removed. A modified hemp dosage of 1 g was able to remove 13.91 mg of metals in 100 mL of solution at a concentration of25 mg/L for each metal, whereas non-modified hemp only removed 7.4 mg in the same experimental conditions. Adsorption of metalsreached equilibrium in 60 min and the performances were pH-independent between 3 and 6, but dependent on the presence ofNaCl, except for Cu

BACKGROUND In this study, a hemp‐based material in the form of a felt was used to adsorb metals in individual aqueous solutions and in polycontaminated effluents using the batch method. The factors affecting the biosorption process were initial metal concentration, biosorbent dosage, contact time and pH. RESULTS In controlled conditions, results showed that: (i) the felt exhibited high adsorption capacities towards metals in the following order: Pb > Cd > Cu > Zn > Co ∼ Fe ∼ Ni ∼ Cr ∼ Al ∼ Mn; (ii) no significant differences were observed for the three salts used (sulfate, chloride and nitrate); (iii) the process was rapid: 10 min were sufficient to attain equilibrium; (iv) the biosorption efficiency increased considerably with the increase of the biosorbent dosage; and (v) the adsorption capacities were independent of pH between 4 and 6. The maximum adsorption capacities for Cd, Cu, Zn, Co, Fe, Ni, Cr, Al and Mn were 27.47, 14.64, 10.59, 7.99, 7.85, 7.87, 6.53, 6.38 and 4.55 mg g–1, respectively. Interesting results also were obtained for real polymetallic effluents. Ecotoxicological tests also confirmed the efficiency of the biosorption to radically decrease the effluent toxicity. CONCLUSIONS Based on these results, hemp‐based felt could serve as a novel and efficient biosorbent material for pollutant removal from industrial effluents. © 2018 Society of Chemical Industry