Simultaneous removal of Cd, Co, Cu, Mn, Ni, and Zn from synthetic solutions on a hemp‐based felt. III. Real discharge waters

Abstract

Two hemp‐based materials were used as nonconventional adsorbents for the final treatment of industrial discharge waters (DWs) from a metal‐finishing plant. The first adsorbent, referred as HEMP, was a felt made of 100% hemp fiber. The second was the same felt coated with a maltodextrin‐1,2,3,4‐butanetetracarboxylic crosslinked polymer (HEMPM) in order to provide ion‐exchange properties to the material by introducing carboxylic groups. The batch experiments showed that both materials exhibited high adsorption capacities toward metal ions present in 12 DWs, leading to concentrations well below those allowed by the French regulation. Measurements of the germination rate of Lactuca sativa seeds and of mobility inhibition of Daphnia magna, used as ecotoxicological tests, were carried out on DWs before and after hemp treatment. The average germination rate before and after treatment were 47.2 ± 4.1 for untreated DWs, 71.2 ± 6.3 for DWs treated by HEMP, and 89.3 ± 4.7 for DWs treated by HEMPM. The EC50 values for four DWs were between 2.1 and 10.4% of DW, indicating high toxicity. After HEMPM treatment, exposure to the DW for 24 h did not cause immobilization (EC50 > 90%). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48823.

Simultaneous Removal of Inorganic and Organic Pollutants from Polycontaminated Wastewaters on Modified Hemp-Based Felts

“…To identify the inorganic and organic substances present in each wastewater, we analyzed eight broad family of substances classified as follows (in agreement with the French Water Authority): 46 inorganic substances including 33 metals, 58 volatile organic compounds (VOCs), 16 polycyclic aromatic compounds (PAHs), 24 chlorophenols (CPs), 16 alkylphenols (APs), 5 chloroaniline (CAs), 7 polychlorobiphenyls (PCBs) and 4 organo-tin complexes. All the protocols have already been detailed elsewhere [28,31,35,36]. The analytical characteristics of three samples, taken on three consecutive weeks, are shown in Table 2 (water parameters), Table 3 (inorganic contaminants), and Table 4 (organic contaminants).…”

“…Chemical structures are reported in Scheme 1. The process and associated chemical pathway to produce a felt cross-linked with 1,2,3,4-butanetetracarboxylic acid (HEMPBA), a felt coated with a maltodextrin-1,2,3,4-butanetetracarboxylic cross-linked polymer (HEMPM), and a felt coated with hydroxypropyl-β-cyclodextrin-1,2,3,4-butanetetracarboxylic cross-linked polymer (HEMPCD) have been detailed elsewhere [26,27,[30][31][32][33][34]. During the synthesis, a cross-linking reaction occurs by esterification in three possible cases (Scheme 2), depending on the reagents used: (1) a reaction between the BTCA carboxylic groups and the cellulose hydroxyl groups of hemp fibers (synthesis of HEMPBA); (2) an esterification between the BTCA carboxylic groups and the MALTO hydroxyl groups on the one hand, and cellulose hydroxyl groups of hemp fibers on the other hand (HEMPM); and (3) a cross-linking reaction between the BTCA carboxylic groups and the HPβCD hydroxyl groups on the one hand, and cellulose hydroxyl groups of hemp fibers on the other hand (HEMPCD).…”

“…The recent literature reports a multitude of low-cost, readily available and effective non-conventional agricultural and forestry materials for the treatment of contaminated waters, such as coir, jute, date pits, corncob, fruit peel waste, sawdust and bark [6][7][8][9][10][11][12][13]. Hemp-based materials have also been proposed for the removal of metals, mainly present in synthetic aqueous solutions [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. The Romanian group of Păduraru [14][15][16][17][18], the Serbian group of Kostić [18][19][20] and the French group of Crini [25][26][27][28][29][30][31] are particularly active in this field.…”

“…In previous works [27,28,31], we first proposed the use of a hemp material in felt form to treat metals present in synthetic polymetallic aqueous solutions and in discharge waters containing a mixture of metals. These discharges contained a relatively low contaminant load, but complied with regulations.…”

“…The two main objectives were to determine the ability of the materials to treat high contaminant loads and to highlight the role of the structure of the material in its performance in removing organic and inorganic contaminants. Four hemp-based materials were compared using batch experiments, a felt made of 100% hemp fiber, the same felt cross-linked with 1,2,3,4-butanetetracarboxylic acid, a felt coated with a maltodextrin-1,2,3,4-butanetetracarboxylic cross-linked polymer, and a felt coated with hydroxypropylβ-cyclodextrin-1,2,3,4-butanetetracarboxylic cross-linked polymer [26][27][28][29]31]. The chemical modification was made to provide ion-exchange properties to the material by introducing carboxylic groups [32][33][34].…”