Magnetic nanocellulose-based adsorbent for highly selective removal of malachite green from mixed dye solution.

Herein, a novel magnetic adsorbent (BC/AA/MN@Fe3O4) was successfully prepared from waste bamboo fiber tissue and montmorillonite, and subsequently applied for the highly selective removal of malachite green (MG, removal efficiency = 97.3 %) from the mixed dye solution of MG with methyl orange (MO, removal efficiency = 4.5 %). The magnetic adsorbent has a high porosity with abundant mesopores. In the single dye MG solution, the adsorbent could effectively remove MG over a wide pH range from 4 to 10, and the maximum adsorption capacity (qmax) was 2282.3 mg/g. Moreover, the magnetic adsorbent could remove MG from various solutions including mixed dye solution, high salinity solution, and real river water dye solution. The thermodynamic results proved that the adsorption process of MG was spontaneous and endothermic. The adsorption of MG was due to the comprehensive effects of electrostatic attraction, hydrogen bonding interactions and ions exchange, between the adsorbent and MG. Furthermore, the BC/AA/MN@Fe3O4 exhibited an excellent reusability with adsorption efficiency above 53.4 % after five consecutive cycles. Therefore, the prepared magnetic nanocellulose-based adsorbent was expected to be a promising material for highly selective adsorption and separation of MG from mixed dye solution.

Bamboo Nanocellulose/Montmorillonite Nanosheets/Polyethyleneimine Gel Adsorbent for Methylene Blue and Cu(II) Removal from Aqueous Solutions.

In recent years, the scarcity of pure water resources has received a lot of attention from society because of the increasing amount of pollution from industrial waste. It is very important to use low-cost adsorbents with high-adsorption performance to reduce water pollution. In this work, a gel adsorbent with a high-adsorption performance on methylene blue (MB) and Cu(II) was prepared from bamboo nanocellulose (BCNF) (derived from waste bamboo paper) and montmorillonite nanosheet (MMTNS) cross-linked by polyethyleneimine (PEI). The resulting gel adsorbent was characterized by Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (SEM), X-ray photoelectron spectroscopic (XPS), etc. The results indicated that the MB and Cu(II) adsorption capacities of the resulting gel adsorbent increased with the solution pH, contact time, initial concentration, and temperature before equilibrium. The adsorption processes of MB and Cu(II) fitted well with the fractal-like pseudo-second-order model. The maximal adsorption capacities on MB and Cu(II) calculated by the Sips model were 361.9 and 254.6 mg/g, respectively. The removal of MB and Cu(II) from aqueous solutions mainly included electrostatic attraction, ion exchange, hydrogen bonding interaction, etc. These results suggest that the resulting gel adsorbent is an ideal material for the removal of MB and Cu(II) from aqueous solutions.

Bamboo-Based Biofoam Adsorbents for the Adsorption of Cationic Pollutants in Wastewater: Methylene Blue and Cu(II).

Human health is being threatened by cationic pollutants in wastewater, for example, methylene blue (MB) and Cu(II). Our research team successfully fabricated biofoam adsorbents from recycled bamboo waste that removed cationic pollutants via introducing bamboo fiber sources, i.e., bamboo fiber, bamboo α-cellulose fiber, and bamboo nanocellulose fiber, into a polyurethane (PU) foam matrix. The biofoam adsorbent with 1 g of nanocellulose (PUN1) presented high removal efficiencies for MB (95.52%) and Cu(II) (100%) in low cationic pollutant concentration aqueous solutions. The biofoam adsorbent with 1 g of bamboo fiber (PUB1) also displayed excellent removal efficiency for MB (98.61%) at pH 11. Meanwhile, 100% removal of Cu(II) was obtained by PUB1 at pH 7 (initial content = 15 mg/L). Furthermore, the PUN1 sample had excellent reusability, evidenced by 61.25% removal of MB after five adsorption-desorption cycles, suggesting that PUN1 is a promising renewable adsorbent for cationic pollutants. In addition, PUB1 is a low-cost adsorbent with good adsorption efficiencies for MB in weak alkaline solutions and Cu(II) in neutral aqueous solutions.