Utilization of Bioflocculants from Flaxseed Gum and Fenugreek Gum for the Removal of Arsenicals from Water

Abstract

Mucilage-based flocculants are an alternative to synthetic flocculants and their use in sustainable water treatment relates to their non-toxic and biodegradable nature. Mucilage extracted from flaxseed (FSG) and fenugreek seed (FGG) was evaluated as natural flocculants in a coagulation–flocculation (CF) process for arsenic removal, and were compared against a commercial xanthan gum (XG). Mucilage materials were characterized by spectroscopy (FT-IR, 13C NMR), point-of-zero charge (pHpzc) and thermogravimetric analysis (TGA). Box–Behnken design (BBD) with response surface methodology (RSM) was used to determine optimal conditions for arsenic removal for the CF process for three independent variables: coagulant dosage, flocculant dosage and settling time. Two anionic systems were tested: S1, roxarsone (organic arsenate 50 mg L−1) at pH 7 and S2 inorganic arsenate (inorganic arsenate 50 mg L−1) at pH 7.5. Variable arsenic removal (RE, %) was achieved: 92.0 (S1-FSG), 92.3 (S1-FGG), 92.8 (S1-XG), 77.0 (S2-FSG), 69.6 (S2-FGG) and 70.6 (S2-XG) based on the BBD optimization. An in situ kinetic method was used to investigate arsenic removal, where the pseudo-first-order model accounts for the kinetic process. The FSG and FGG materials offer a sustainable alternative for the controlled removal of arsenic in water using a facile CF treatment process with good efficiency, as compared with a commercial xanthan gum.

A pyridinium-modified chitosan-based adsorbent for arsenic removal via a coagulation-like methodology

“…The better fit for the PFO kinetic model mirrors the trends observed for the removal of other pollutants during the CF process, unlike classical adsorption processes, as outlined elsewhere. 18,46,61 This further highlights the applicability of the prepared material for arsenic removal through this one-pot process, as compared to (batch) adsorption removal.…”

“…Currently, a drawback of conventional chemical systems is the lack of biodegradability, which as been described elsewhere. 18 Whereas the co-application of biodegradable polymers or biopolymers such as plant-based mucilage in conjunction with metal-salt coagulants offer an alternative strategy. Herein, a modified chitosan-based system was utilized as a dispersed solid-phase extraction (dSPE) material, where the insoluble adsorbent was directly added to afford facile separation during the treatment process.…”

“…17 Recent research efforts have been directed at development of alternate polysaccharide-based CF systems such as chitosan (Chi). 18 Chi represents a promising and versatile biopolymer that is derived from chitin, the second most abundant natural biopolymer. [19][20][21] Chitosan is a partially deacetylated form (typically >50%) of chitin, which has hydroxyl and amine groups that present additional functionalization sites.…”

Two New 1D Supramolecular Compounds Based on PbI2 for Efficient Iodine Capture

“…The color change of iodo-cyclohexane solution was observed during adsorption, and the removal rate of iodine was evaluated by UV-VIS spectrum. The iodine removal efficiency ( RE ; %) and the adsorption capacity ( q e ; mg·g −1 ) of the compound were calculated by Equations (1) and (2), respectively [ 47 ]. where C 0 is the initial concentrations (mg·L −1 ) of iodine; C e is the equilibrium concentrations (mg·L −1 ) of iodine; C t is the iodine concentrations (mg·L −1 ) at time t ; V is the volume (L) of iodo-cyclohexane solution; and m is the compound weight (g).…”