TEMPO-Oxidized Microcrystalline Cellulose for Rapid Adsorption of Ammonium

Abstract

As low as 1 ppm concentration of ammonia is sufficient to pose a threat to fish cultured in the fish farm, and therefore effective ammonia removal method is necessary to minimize the ammonia concentration. In this study, cellulose, which is one of the low-cost and highly versatile green polymers, has been modified by TEMPO-mediated oxidation and first applied for ammonia removal from water. For the TEMPOoxidized cellulose of 0.78 mmol/g carboxylate group content, the adsorption capacity was measured to be 8.21 mg/g (empirically, 9.465 mg/g derived from Langmuir isotherm model) from water at pH around 7.0, which is comparable with the existing carbon-based sorbent for the reduction of ammonia. This also indicates close to 100% utilization of the carboxylate adsorption sites. In addition, equilibrium adsorption can be achieved within 5 min. The ammonium adsorption data fit the Langmuir model very well, indicating a monolayer chemical adsorption process. The adsorption performance of the material was minimally influenced by a pH range of 5.0−9.0 but substantially affected by the presence of competing ions. Despite a slight decrease in adsorption performance, the material can be regenerated and applied in a real water sample. Electrostatic interaction and hydrogen bonding between the introduced carboxylate groups and ammonium ions appear to be the adsorption mechanisms governing the material performance in ammonia removal. Further discussion on performance comparison, alternative modification methods, production cost, and potential usage of the postadsorption material is also included.

Efficient Isolation of Cellulosic Fibers from Coffee Parchment via Natural Acidic Deep Eutectic Solvent Pretreatment for Nanocellulose Production

“…78 The successful oxidation of cellulose was confirmed by the presence of a strong absorption peak at 1603 cm −1 (corresponding to the C�O stretching in carboxyl groups) in the ATR-FTIR spectra of TONC-CP (Figure S5). 79,80 As shown in Figure 6c, TEM images revealed that the prepared TONC-CP possessed a fiber-like network structure with a cross-sectional dimension of 3−10 nm, which was smaller than commercial CNCs (3−12 nm). These findings suggested that the production process could effectively transform the cellulose fibers isolated from CP into cellulose nanoparticles.…”

Water-redispersible and high-yield α-chitin nanocrystals isolated using electron-beam irradiation as adsorbents to remove heavy metals and dye

“…Unfortunately, it was difficult to determine the removal rates of the heavy metals and the dye because they reached equilibrium adsorption capacities within a few minutes during the vortexing process. 57 This might be attributed to the excellent dispersibility of ChNC-E1000 (RU) in water. This adsorbent based on eco-friendly EBI-treated chitin nanocrystals with anionic carboxylate groups holds good potential for the removal of various aquatic pollutants from waste streams, such as toxic heavy metals and organic dye cations.…”

Selective Oxidation of Cellulose—A Multitask Platform with Significant Environmental Impact

“…Many studies have reported on the functional products of cellulose oxidation, but TEMPO-mediated and periodate oxidation reactions stood out due to their enhanced regioselectivity, high degree of substitution, mild conditions, increased yields. Even more, oxidized cellulose thus obtained can be further processed into more complex materials [ 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 ].…”