Aminated Rapeseed Husks (Brassica napus) as an Effective Sorbent for Removing Anionic Dyes from Aqueous Solutions

Abstract

The study investigated the effect of modifying rapeseed husks with ammonia and epichlorohydrin on their sorption capacity against anionic reactive dyes: Reactive Black 5 (RB5) and Reactive Yellow 84 (RY84). Its scope included sorbents characterization (FTIR, pHPZC), determination of pH influence on the sorption effectiveness of dyes, the adsorption kinetics of dyes, as well as the maximum sorption capacity. The study proved that the reaction of rapeseed husk biomass with ammonia can lead to its amination, namely to the introduction of amine functional groups into the material’s structure. The sorption effectiveness of RB5 and RY84 on the tested sorbents was the highest in the pH range of 2–3. The dye sorption kinetics was well described by the pseudo-second-order model. The sorption equilibrium time ranged from 90 to 180 min, and depended on the initial concentration of dyes and the number of amino groups on the sorbent’s surface. The most efficient of the sorbents tested were rapeseed husks pre-activated with epichlorohydrin and then aminated with ammonia. Their sorption capacity determined for RB5 and RY84 was 135.83 mg/g and 114.23 mg/g, respectively, which was 794% and 737% higher than that of the non-modified husks.

The Use of Various Types of Waste Paper for the Removal of Anionic and Cationic Dyes from Aqueous Solutions

“…The dye sorption equilibrium times of 60–90 min (i.e., the same as those achieved for NP, LWC, and OP) were also reported in studies investigating AR18 sorption on seaweed biomass (60 min) [ 84 ], activated carbon from carrot biomass (80 min) [ 85 ], and sunflower seed hulls (90 min) [ 69 ], and in the case of AY23 on activated carbon from coconut shells (60 min) [ 81 ], sawdust (70 min) [ 70 ], and activated carbon from cassava (90 min) [ 75 ]. In turn, equilibrium times reaching 120–150 min (like for the CC in the present study) were also noted during AR18 removal on carboxymethylcellulose (120 min) [ 86 ] and activated carbon from poplar wood [ 68 , 87 ], as well as during AY23 sorption onto commercial activated carbon (120 min) [ 88 ].…”

“…The dye sorption equilibrium times of 60-90 min (i.e., the same as those achieve NP, LWC, and OP) were also reported in studies investigating AR18 sorption on seaw biomass (60 min) [84], activated carbon from carrot biomass (80 min) [85], and sunflo seed hulls (90 min) [69], and in the case of AY23 on activated carbon from coconut s The dye sorption equilibrium times of 60-90 min (i.e., the same as those achieved for NP, LWC, and OP) were also reported in studies investigating AR18 sorption on seaweed biomass (60 min) [84], activated carbon from carrot biomass (80 min) [85], and sunflower seed hulls (90 min) [69], and in the case of AY23 on activated carbon from coconut shells (60 min) [81], sawdust (70 min) [70], and activated carbon from cassava (90 min) [75]. In turn, equilibrium times reaching 120-150 min (like for the CC in the present study) were also noted during AR18 removal on carboxymethylcellulose (120 min) [86] and activated carbon from poplar wood [68,87], as well as during AY23 sorption onto commercial activated carbon (120 min) [88].…”

“…A very similar pH effect on dye binding effectiveness was also noted in studies addressing AR18 sorption on rapeseed hulls [68], sunflower seed hulls [69], and carbonized biomass of common reed. In the case of AY23, the positive impact of low pH on its sorption effectiveness was observed in experiments with sawdust [70], cotton fibers [71], chitin [72], and activated carbons [73][74][75].…”