Adsorption of Sulfonamides in Aqueous Solution on Reusable Coconut-Shell Biochar Modified by Alkaline Activation and Magnetization

Abstract

Biochar is a low-cost adsorbent for sorptive removal of antibiotics from wastewater, but the adsorption efficiency needs to be improved. In this study, coconut-shell biochar was activated with KOH to improve the adsorption efficiency and magnetically modified with FeCl3 to enable recycling. The amount of KOH and the concentration of FeCl3 were optimized to reduce the pollution and production cost. The KOH-activated and FeCl3-magnetized biochar gave good sulfonamide antibiotic (SA) removal. The maximum adsorption capacities for sulfadiazine, sulfamethazine and sulfamethoxazole were 294.12, 400.00 and 454.55 mg g−1, respectively, i.e., five to seven times higher than those achieved with raw biochar. More than 80% of the adsorption capacity was retained after three consecutive adsorption-desorption cycles. A combination of scanning electron microscopy, Brunauer-Emmett-Teller analysis, X-ray diffraction, Fourier-transform infrared and Raman spectroscopies, and magnetic hysteresis analysis showed that KOH activation increased the specific surface area, porosity, and number of oxygen-rich functional groups. Iron oxide particles, which were formed by FeCl3 magnetization, covered the biochar surface. The SAs were adsorbed on the modified biochar via hydrogen bonds between SA molecules and -OH/-COOH groups in the biochar. Investigation of the adsorption kinetics and isotherms showed that the adsorption process follows a pseudo-second-order kinetic model and a monolayer adsorption mechanism. The adsorption capacity at low pH was relatively high because of a combination of π+-π electron-donor-acceptor, charge-assisted hydrogen-bonding, electrostatic, and Lewis acid-base interactions, pore filling, van der Waals forces and hydrophobic interactions. The results of this study show that magnetically modified biochar has potential applications as an effective, recyclable adsorbent for antibiotic removal during wastewater treatment.

A stable Fe/Co bimetallic modified biochar for ofloxacin removal from water: adsorption behavior and mechanisms

“…2(b)) was eroded to form a rough porous structure, the CO, CO 2 , and other gases produced at high temperatures were lost through the pores, which resulted in the formation of micropores on the MBC surface. 31 Furthermore, the FMBC (Fig. 2(c)) showed a more irregular, uneven, and pore-developed surface morphology aer loading with Fe/Co metals, and the number of micropores on the surface increased substantially.…”

The Role of Nanoengineered Biochar Activated with Fe for Sulfanilamide Removal from Soils and Water

“…The pH of the solutions during sorption experiments has to be considered [ 49 ], and in this work, they ranged between 7.6 and 7.8, indicating that SFA is present mostly as a neutral molecule. Hydrophobic interactions dominated by the higher C content of BC-Fe ( Table 1 ) would be mainly responsible for this increase in sorption rather than the pH, together with the formation of charge-assisted H-bonds [ 11 , 50 , 51 , 52 ]. Since an increase in sorption was observed upon activation without great variations in the specific surface area values, this increase can be attributed to the microsite modifications on BC’s surface in BC-Fe and the changes in the texture as observed from SEM micrographs ( Figure 1 ) and data from Table 1 .…”

“…This situation has stimulated the development of economical and effective mitigation methods for antibiotic removal from the environment [ 11 , 12 ]. Therefore, the sorption and persistence of sulfonamides need to be assessed since these are key factors determining their adverse impact [ 13 , 14 ].…”

Functionalized typha biochar for antibiotic removal via low‐carbon integrated method: Performance and mechanism analyses

“…Step Temperature (time lasted) [56] The satellite peak located at 288.8 eV, which is attributed to π-π stacking, indicated graphite structures in TBI K (Figure 4A H groups, respectively. [57] Meanwhile, the intensity of the peak was very small at a binding energy of 533.1 eV, which indicated that the O-H content in TBT K is quite low (Figure 4E).…”

“…As shown in Figure 4A, the peaks of the C 1s spectra are located at 284.6, 285.6, and 286.5 eV, which correspond to C = C, C‐O, and C = O functional groups, respectively. [ 56 ] The satellite peak located at 288.8 eV, which is attributed to π‐π stacking, indicated graphite structures in TBI K (Figure 4A and D). The O 1s spectra of TBI K and TBT K are shown in Figure 4B and E, respectively.…”