Biosorption of Cd2+ by untreated dried powder of duckweed Lemna aequinoctialis

Abstract

A B S T R A C TThe duckweed Lemna aequinoctialis was used as a biosorbent material for Cd 2+ adsorption in this study. Influencing factors of Cd 2+ adsorption by L. aequinoctialis in aqueous solution were investigated and the process of the Cd 2+ biosorption was optimized. The results of single-factor experiments suggested that all the factors studied except temperature had significant effects on the removal efficiency of Cd 2+ by L. aequinoctialis. Based on the results of single-factor experiments, optimization of the Cd 2+ biosorption was performed by varying four independent parameters using the central composite design under response surface methodology. The optimal conditions for the maximum removal of Cd 2+ were as follows: grain size of 150-200 mesh, stirring speed of 75 rpm, Cd 2+ initial concentration of 40 mg/L, and sorbent concentration of 8 g dry matter/L. The maximum removal efficiency of 83.5% was obtained, which was in consistence with the predicted value of 83.6%. This process followed pseudo-second-order kinetics and the experimental data fitted well to Langmuir and Freundlich isotherm models. The maximum capacity of duckweed to adsorb Cd 2+ was 33.0 mg/g, demonstrating that untreated dry powder of L. aequinoctialis represents a promising biosorbent for Cd 2+ removal. Fourier transform infrared spectroscopy analysis indicated that the -OH groups of carbohydrate compounds and the -NH 2 groups of amide compounds may be the main groups involved in the adsorption of Cd 2+ by L. aequinoctialis.

Interpretation of the adsorption process of toxic Cd2+ removal by modified sweet potato residue

“… 48 In another study of Cd 2+ removal from duckweed, the adsorption temperature was set at 15–45 °C, and the Cd 2+ removal rate was less than 70%. 42 However, the removal rate of Cd 2+ varied slowly by MSPR, from 97.44% to 98.06% when the temperature was increased from 20 °C to 60 °C, indicating that temperature had little effect on the adsorption performance of MSPR. Therefore, MSPR may be used in wastewater treatment in a wide temperature range.…”

“…In the 500–800 cm −1 range, the functional groups of the starch or other sugars could have undergone chemical reactions. 42 The adsorbent had abundant –OH, –COOH, and –CH groups, which provide more adsorption sites.…”

Chemical Treatment of Banana Blossom Peels Adsorbent as New Approach for Manganese Removal: Isotherm and Kinetic Studies

“…Sustainability 2023, 15, x FOR PEER REVIEW 8 of 20 4a. Figure 4b shows that the -OH or -NH stretch band was displaced to 3276 cm −1 , indicating that the adsorption involves -OH and C-O stretching of alcohol or -NH deformation [40]. In Figure 4a, BBP has a C-H stretching vibration of 2915 cm −1 , which shifts to 2919 cm −1 in Figure 4b, indicating the existence of an alkene functional group [8,41].…”

Simultaneous biosorption of the two synthetic dyes, Direct Red 89 and Reactive Green 12 using nonliving macrophyte L. gibba L.

“…The selected LGB as a biosorbent has some advantages because it can be easily found and provided by nature and it is easy to manipulate in laboratories. Furthermore, biomasses originated from various aquatic plants were successfully used as materials to remove pollutants (dyes, metal ions, and various types of pollutants) from wastewaters [17][18][19].…”