Sustainable Low-Concentration Arsenite [As(III)] Removal in Single and Multicomponent Systems Using Hybrid Iron Oxide–Biochar Nanocomposite Adsorbents—A Mechanistic Study

Abstract

Rice and wheat husks were converted to biochars by slow pyrolysis (1 h) at 600 °C. Iron oxide rice husk hybrid biochar (RHIOB) and wheat husk hybrid biochar (WHIOB) were synthesized by copyrolysis of FeCl3-impregnated rice or wheat husks at 600 °C. These hybrid sorbents were characterized using X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy (SEM), SEM–energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, physical parameter measurement system, and Brunauer–Emmett–Teller (BET) surface area techniques. Fe3O4 was the predominant iron oxide present with some Fe2O3. RHIOB and WHIOB rapidly chemisorbed As­(III) from water (∼24% removal in first half an hour reaching up to ∼100% removal in 24 h) at surface Fe–OH functions forming monodentate Fe–OAs­(OH)2 and bidentate (Fe–O)2AsOH complexes. Optimum removal occurred in the pH 7.5–8.5 range for both RHIOB and WHIOB, but excellent removal occurred from pH 3 to 10. Batch kinetic studies at various initial adsorbate–adsorbent concentrations, temperatures, and contact times gave excellent pseudo-second-order model fits. Equilibrium data were fitted to different sorption isotherm models. Fits to isotherm models (based on R 2 and χ2) on RHIOB and WHIOB followed the order: Redlich–Peterson > Toth > Sips = Koble–Corrigan > Langmuir > Freundlich = Radke–Prausnitz > Temkin and Sips = Koble–Corrigan > Toth > Redlich–Peterson > Langmuir > Temkin > Freundlich = Radke–Prausnitz, respectively. Maximum adsorption capacities, Q RHIOB 0 = 96 μg/g and Q WHIOB 0 = 111 μg/g, were obtained. No As­(III) oxidation to As­(V) was detected. Arsenic adsorption was endothermic. Particle diffusion was a rate-determining step at low (≤50 μg/L) concentrations, but film diffusion controls the rate at ≥100–200 μg/L. Binding interactions with RHIOB and WHIOB were established, and the mechanism was carefully discussed. RHIOB and WHIOB can successfully be used for As­(III) removal in single and multicomponent systems with no significant decrease in adsorption capacity in the presence of interfering ions mainly Cl–, HCO3 –, NO3 –, SO4 2–, PO4 3–, K+, Na+, Ca2+. Simultaneous As­(III) desorption and regeneration of RHIOB and WHIOB was successfully achieved. A very nominal decrease in As­(III) removal capacity in four consecutive cycles demonstrates the reusability of RHIOB and WHIOB. Furthermore, these sustainable composites had good sorption efficiencies and may be removed magnetically to avoid slow filtration.

Synthesis, Characterization, and Application of Ag-Biochar Composite for Sono-Adsorption of Phenol

“…Some of these elements were originated from the biomolecules present in L. lucidum leaf extracts that were bound to the surface of AgNPs. The results were almost similar to the previous literature (Kaushal et al, 2019;Singh et al, 2020).…”

“…SEM images of synthesized Ag-WBC were found to show the spherical morphology of Ag nanoparticles with an average size of 80-100 nm on the surface of WBC (Figure 3B). The EDX spectrum of synthesized Ag-WBC confirms the fact that the composite not only has higher amounts of elemental carbon and oxygen, but it also contains significant quantities of ash elements such as Al, Si, Cl, and Ag as reported in previous studies (Nebojsa et al, 2012;Li et al, 2017;Kaushal et al, 2019;Singh et al, 2020). Some of these elements were originated from the biomolecules present in L. lucidum leaf extracts that were bound to the surface of AgNPs.…”

ANN-GA based biosorption of As(III) from water through chemo-tailored and iron impregnated fungal biofilter system

“…Arsenic contamination of groundwater is a serious global environmental concern affecting a large number of populations, especially in developing countries. Chronic arsenic toxicity causes severe consequences to human health, such as skin lesions, circulatory and nervous disorders, black foot disease, melanosis, keratosis, non pitting oedema, Bowen’s disease gangrene and cancers of different organs 1 , 2 . Thus, the removal of arsenic from potable water is an essential requirement.…”

Degradation of textile dyes from aqueous solution using tea-polyphenol/Fe loaded waste silk fabrics as Fenton-like catalysts

“…8(b) and (c) display the C 1s spectra of the surface of the SF and TP-SF/Fe samples, and the C 1s XPS spectra are fitted to the absorption peaks at 284.7, 285.7, 286.5 and 288.1 eV, corresponding to the C–C, C–N, C–OH, and O–C O bonds, respectively. 60–62 Furthermore, Fig. 8(d) shows the core-level Fe 2p on the surface of the TP-SF-Fe, and the characteristic peaks are attributed to Fe 2p 3/2 (711.1 eV) and Fe 2p 1/2 (724.5 eV), respectively.…”

“…12(b) and (c) , a similar character has been found in the other two dyes (reactive orange GRN and cationic violet X-5BLN) as a function of time. 60 However, it can be observed that as the concentration of the dye solution increases, the final degradation rate gradually reduces. Although for a maximum dye concentration of 80 mg L −1 , the degradation efficiency was the lowest compared with other concentrations, but it still stayed over 91%, 83% and 91%, respectively.…”