Preparation of bio-absorbents by modifying licorice residue via chemical methods and removal of copper ions from wastewater

Abstract

In this paper, a series of bio-adsorbents (LR-NaOH, LR-Na2CO3 and LR-CA) were successfully prepared by modifying Licorice Residue with NaOH, Na2CO3 and citric acid, which were used as the adsorbents to remove Cu2+ from wastewater. The morphology and structure of bio-adsorbents were characterized by Fourier Transform Infrared, SEM, TG and XRD. Using static adsorption experiments, the effects of the adsorbent dosage, the solution pH, the adsorption time, and the initial Cu2+ concentration on the adsorption performance of the adsorbents were investigated. The results showed that the adsorption process of Cu2+ by the bio-adsorbents can be described by pseudo-second order kinetic model and the Langmuir model. The surface structure of the LR-NaOH, LR-Na2CO3 and LR-CA changed obviously, and the surface-active groups increased. The adsorption capacity of raw LR was 21.56 mg/g, LR-NaOH, LR- Na2CO3 significantly enhanced this value up to 43.65 mg/g, 43.55 mg/g, respectively. After four adsorption-desorption processes, the adsorption capacity of LR-NaOH also maintained about 73%. Therefore, LR-NaOH would be a promising adsorbent for removing Cu2+ from wastewater, and the simple strategy towards preparation of adsorbent from the waste residue can be as a potential approach using in the water treatment.

Preparation of Hydrogels Based Radix Isatidis Residue Grafted with Acrylic Acid and Acrylamide for the Removal of Heavy Metals

“…Various functional groups in hydrogels were determined by FTIR, as shown in Figure 5. The absorption band around 3430 cm −1 is related to the O-H bond [16], the sharp peak at 2927 cm −1 is related to the C sp3-stretching vibration [52], the peak at 1623 cm −1 is the stretching of the C-N bond, the peak at 1413 cm −1 is related to the stretching vibration of the -CO-bond in the phenyl hydroxyl group in lignin, the peak at 1314 cm −1 is the C-N absorption band (amide III band), the peaks at 1158 cm −1 are attributed to the stretching vibration of the ester bond in the cellulose ester group [16], the peak at 1030 cm −1 is attributed to the bending vibration of the hydroxyl group [53], and the characteristic peaks of cellulose still exist in RIR/AA-co-AM, RIR/PAA 4 , and RIR/PAM 3 hydrogels. The peak at 2852 cm −1 is the characteristic absorption peak of methylene symmetry stretching vibration, and 1454 cm −1 is the characteristic absorption peak of methylene deformation [54], the vibration peak of C=O at 1561 cm −1 , the absorption peak at 1119 cm −1 is related to the C-N stretching vibration, these characteristic peaks are all from polyacrylamide and polyacrylic acid.…”

“…Recently, biosorbents have attracted more attention due to their high removal efficiency, low cost, no chemical sediment, and easy availability [15,16]. However, preparing biosorbents with high adsorption capacity and fast adsorption rate needs intensive study [17,18].…”

“…In addition, according to our previous study, Radix Isatidis residue (RIR) can remove Cu 2+ from the water to some degree, but it was found that its adsorption capacity was extremely low (16.5 mg/g). Additionally, our team previously prepared a series of biosorbents to remove Cu 2+ in water by chemically modified licorice residue (LR) [16] and RIR, but the adsorption capacity of modified RIR (31.0 mg/g) was low because cellulose was embedded in lignocellulose and its functional groups were difficult to expose, which made Chinese herb residues sparingly soluble in water. Although the researchers had taken advantage of the cellulose in Chinese herb residues to remove contaminants from wastewater, the cellulose mostly is wrapped in lignin and is compact, resulting in low adsorption capacities and rates [38].…”

Recent Advances in Functional Polymer Materials for Energy, Water, and Biomedical Applications: A Review

“…In recent years, natural polymeric bio-sorbents are gaining more interest over synthetic classical adsorbents, due to their tunable physicochemical properties, structural diversity, reusability, and environmental benefits [303][304][305]. Indeed, several low-cost polymeric adsorbents have been prepared through the valorization and the functionalization of wastes from different sources, such as plants, fish shells, marine algae (green, brown and red species), vegetables, etc.…”

Efficient Removal of Heavy Metals from Aqueous Solution Using Licorice Residue-Based Hydrogel Adsorbent

“…There has been considerable interest in the development of low-cost adsorbents derived from plants or agricultural solid wastes, primarily due to their wide availability, low market value, and potential for large-scale wastewater treatment [5]. Examples of such environmentally sustainable adsorbents include agricultural wastes like bagasse, Gels 2023, 9, 559 2 of 21 potato peels, apple peels, and Chinese herb residues, which offer benefits such as cost-effectiveness, efficiency, biocompatibility, and biodegradability [12][13][14][15][16]. Moreover, their abundant functional groups (such as -OH, -COOH, and -NH 2 ) contribute to their enhanced adsorption performance [17].…”