Modified os sepiae of Sepiella inermis as a low cost, sustainable, bio-based adsorbent for the effective remediation of boron from aqueous solution

Abstract

The occurrence of boron in low concentration is essential; however, a higher concentration of boron source in water has a toxic effect on humans as well as have retard effect on agricultural plant growth. Thus, the affordable and facile method to remediate water from higher boron concentrations is highly demanded. This report explores the ability of naturally occurring sustainable bio-waste os sepiae (cuttlefish bone, CFB) as an effective adsorbent for the removal of boron from water. Chemical activation of the os sepiae powder was examined to improve the efficiency of boron adsorption. A batch adsorption study for boron considering various parameters such as chemical modification of os sepiae, pH, initial boron concentration, and the temperature was scrutinized. Untreated (CFB), alkali-treated (CFB-D) and acid-treated (CFB-A) os sepiae powders were investigated and the adsorption capacities reached up to 53.8 ± 0.04 mg/g, 66.4 ± 0.02 mg/g and 69.8 ± 0.02 mg/g, respectively, at optimal pH 8 and 25 °C. Boron adsorption by CFB, CFB-D, and CFB-A were well fitted with the linear Freundlich adsorption isotherm model with a correlation coefficient of 99.4%, 99.8%, and 99.7% respectively. Thermodynamic parameters indicated that the adsorption of boron by CFB is an exothermic process and more feasible at a lower temperature around 25 °C. Moreover, detailed morphological and chemical characterization of the influence of adsorbed boron on adsorbents was conducted and discussed. The Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis spectra confirms the involvement of various functional groups including amino, carbonate (CO₃)^2-, and hydroxyl groups on the adsorbent in the adsorption mechanisms for boron removal. The results indicate that CFB can be an excellent example for the recycling and reuse of biowaste for water remediation.

Keywords: Adsorption; Boron; Os sepiae; Upcycling; Water treatment.

Fig. 1

(A) X-ray diffraction spectra. (B) Fourier transform infrared spectra of CFB, CFB-D, and CFB-A

Fig. 2

Effect of different pH values on the removal of boron by CFB, CFB-D and CFB-A. (Experimental conditions: Initial boron concentration: 100 mg/L (50 mL), Adsorbent mass: 0.05 g, Agitation speed: 150 rpm, contact time: 24 h, Temperature: 25 °C, pH: 2–10)

Fig. 3

Effect of initial concentrations on boron adsorption onto CFB, CFB-D and CFB-A. (Experimental conditions: Initial boron concentration: 1.75 mg/L – 17.50 mg/L (50 mL), Adsorbent mass: 0.05 g, Agitation speed: 150 rpm, contact time: 24 h, Temperature: 25 °C, pH: 8)

Fig. 4

Effect of temperature on boron adsorption onto (A) CFB (B) CFB-D and (C) CFB-A. (Experimental conditions: Initial boron concentration: 1.75–17.50 mg/L (50 mL), Adsorbent mass: 0.05 g, Agitation speed: 150 rpm, contact time: 24 h, Temperature: 25 °C, 35 °C & 45 °C, pH: 8)

Fig. 5

The linear adsorption isotherms for (A) Langmuir, (B) Freundlich, (C) Temkin, (D) Dubinin-Radushkevich at 25.0 °C, 35.0 °C, and 45.0 °C for CFB

Fig. 6

The linear adsorption Isotherms for (A) Langmuir, (B) Freundlich, (C) Temkin, (D) Dubinin-Radushkevich at 25.0 °C, 35.0 °C, and 45.0 °C for CFB-D

Fig. 7

The linear adsorption Isotherms for (A) Langmuir, (B) Freundlich, (C) Temkin, (D) Dubinin-Radushkevich at 25.0 °C, 35.0 °C, and 45.0 °C for CFB-A

Fig. 8

Fourier transform infrared spectra of (A) CFB, CFB-D and CFB-A, (B, C, D) before (black line) and after boron adsorption (red line) of CFB, CFB-A, and CFB-D respectively

Fig. 9

Schematic representation of possible interactions of CFB (upper), CFB-D (middle), and CFB-A (bottom) with boron

Fig. 10

SEM images of (A) CFB (B) CFB-D and (C) CFB-A before boron adsorption and. (A1) CFB (B1) CFB-D and (C1) CFB-A after boron adsorption at 25 °C

Fig. 11

(A) High-resolution XPS spectra of CFB, CFB-D, and CFB-A before and after boron adsorption. (B) B1s spectra of boric acid after adsorption by CFB-A

Fig. 12

High-resolution XPS spectra of (A, B, &,C) Ca before and after adsorption (D, E, & F) O1s before and after adsorption of CFB, CFB-D and CFB-A respectively