Activable carboxylic acid functionalized crystalline nanocellulose/PVA- co -PE composite nanofibrous membrane with enhanced adsorption for heavy metal ions

Cross‐Linked Nanocellulosic Materials and Their Applications

“…[63,64] However,t he maximum 471.55 mg g À1 Pb II adsorption of BTCA functionalized CNCs-poly(vinyl alcohol-co-ethylene) (PVA-co-PE) composite membranes was reported by Zhu et al,w hichc onfirmed the significant improvement in heavy metal adsorption ability of cross-linked NC-based materials. [36] The BTCA-functionalized CNCs-PVA-co-PE composite membranes werea ctivated by NaHCO 3 which converts the carboxyl group COOH to carboxylate COONa to improvet he absorptivity of heavy metal ions. BTCA wasu sed as the absorbent and ab ridge between CNCs and PVA-co-PE.…”

“…After immobilization, there are still two unoccupied carboxyl groups from BTCA as chelating groupsf or heavy metal ions. [36] Moreover, the carboxylate form (COO À Na + )i s easier to dissociatet han the carboxylic group, so Na + could more easily exchange with heavy metal ions. [ Thiol-modified spherical NC (SNC) was functionalized with 3mercaptopropionica cid (3-MPA) to generate at hiol-based new adsorbent (SNC-3-MPA).…”

“…High adsorption of Cr VI was observed at acidic pH of 1-3, [23b] however,t he highest adsorption of Pb II ,C u II ,C d II ,a nd Hg II appeared aroundn eutralp H, [23a, 59,62] while carboxylic groups are difficult to dissociate at al ower pH value. [36] This might be ascribed to different adsorption steps for variousm etal ions. [23] Ta king Cr as an example, Cr VI exists in the forms of HCrO 4 À (pH < 4), CrO 4 2À ,a nd Cr 2 O 7 2À (pH > 4) in aqueous solution;i tw as first reduced to Cr III by hydroxy groups, whereas the hydroxy groups were oxidized to carboxylg roups.…”

“…Moreover,amore economic regenerationa nd reuse method by direct mechanical squeezing after adsorbing metal ions was reported by Li et al [60] MostN C-based materials can be reused for at least five cycles, which indicates that these adsorbents have highr etention capacities. [23a, 36,62]…”

“…[23a] Nanoscale materialsh ave showng reat potential for wastewater treatment as highers pecific surface areas result in highera dsorption capacities compared to the same materials in their micro-or macro-structural scales. [36] Negatively charged NC particles can bind heavy metal ions by ionic interactions in aqueous media, which showsasustainable and cost-effective path to tackle heavy metal contamination in wastewater. [23b] The purpose of this Minireview is to summarize recenta dvancements and applicationso fc ross-linked NC-based materials.…”