Zero-valent iron supported-lemon derived biochar for ultra-fast adsorption of methylene blue

Biomass Conversion and Biorefinery https://doi.org/10.1007/s13399-022-02362-y ORIGINAL ARTICLE Zero‑valent iron supported‑lemon derived biochar for ultra‑fast adsorption of methylene blue Eman M. Abd El‑Monaem1 · Ahmed M. Omer2 · Gehan M. El‑Subruiti1 · Mohamed S. Mohy‑Eldin2 · Abdelazeem S. Eltaweil1 Received: 5 November 2021 / Revised: 15 January 2022 / Accepted: 18 January 2022 © The Author(s) 2022 Abstract Green-based materials represent a new promising class of ecofriendly and economic adsorbents. Herein, nano zero-valent iron supported-lemon derived biochar (NZVI-LBC) was prepared for the first time and examined in the adsorptive removal of methylene blue as a model pollutant. Different characterization tools were used to ensure the successful fabrication of the NZVI-LBC composite including FTIR, XRD, TEM, XPS, VSM, BET, and zeta potential analysis. It was found that the fabricated NZVI–supported biochar composite attained the propitious adsorbent criteria since it provided a supreme efficient adsorption process at short time. The reckoned maximum adsorption capacity of MB onto NZVI-LBC reached 1959.94 mg/g within merely 5 min. The obtained data clarified that the adsorption process of MB onto NZVI-LBC fitted pseudo 2nd order kinetic model and Freundlich isotherm model. Besides, the adsorption process of MB onto NZVI-LBC was found to be endothermic in nature. In addition, NZVI-LBC composite revealed an excellent adsorption behavior even after seven cycles. The concrete results reflect the potentiality of NZVI-LBC composite to be a superb candidate to remove cationic pollutants from their aqueous solutions. Keywords Biochar · NZVI · Methylene blue · Removal · Magnetic · Lemon residue 1 Introduction Water pollution is the most enormous environmental dilemma that is rising swiftly day-by-day. As a result, myriad diseases have aggravated such as typhoid, hepatitis, and cancer since the polluted water directly affects human health [1–3]. Thence, researchers have exerted arduous efforts, pursuing crucial solutions to get rid of these fatal pollutants and fulfill safe drinking water [4]. Among these troublesome contaminants, methylene blue (MB) is the most pervasive * Eman M. Abd El‑Monaem * Abdelazeem S. Eltaweil 1 Chemistry Department, Faculty of Science, Alexandria University, Alexandria 21321, Egypt 2 Polymer Materials Research Department, Advanced Technology and New Materials Research Institute (ATNMRI), City of Scientific Research and Technological Applications (SRTA-City), New Borg El‑Arab City 21934, Alexandria, Egypt synthetic dyes in diversified potential industries such as food, paper, plastic, leather, and textile [5, 6]. Nevertheless, MB causes vast apprehensions on human health and our environment entirely. It was found that the existence of MB into water bodies even with minimal concentration has severe influences on human health including blood pressure, gastrointestinal pain, vomiting, headache, and irritation of throat [7, 8]. Hence, advanced techniques have evolved to face these catastrophic risks of MB such as electrolysis [9], catalytic reduction [10], photocatalysis [11–13], membrane separation [14], chemical oxidation [15], and particularly adsorption since it is quite simple, highly efficient, and costless techniques [16–18]. Biochar (BC) is a dusty carbonaceous compound that is produced via thermochemical decomposition of diverse and bountiful bio-wastes [19–23]. BC has received vast consideration as a promising adsorbent owing to its appreciable characteristics including porous structure, huge specific surface area, high mechanical strength, and plenty of oxygenated functional groups (i.e., carboxylic and phenolic) [24, 25]. Furthermore, recycling bio-wastes especially the agriculture crop residuals instead of burning them is considered 13 Vol.:(0123456789) Biomass Conversion and Biorefinery as the best of the best solution in terms of human health [26–28]. Several studies investigated that burning these crop residuals directly intensifies the suspended particulate matter, the main responsible for different respiratory diseases. Nonetheless, BC has a significant drawback which is a limited capacity to adsorb contaminants from aqueous media [29]. It was investigated that combining BC with magnetic nanomaterials is a feasible solution to overcome this flaw as well as it provides easy separation and good recyclability for BC. NZVI is one of the most popular magnetic nanoparticle for wastewater treatment due to its incomparable properties including high specific surface area, excellent adsorption property, high surface energy, and strong reducing ability [30, 31]. However, NZVI suffers many flaws including aggregation, poor transportability, and reduced electron transfer [32]. So, diversified approaches have been implemented to get rid of these demerits such as using surfactants [33] and forming a composite to isolate the surface of NZVI particles, protecting them from exposure to air [34]. It was reported in related studies that NZVI-modified BC nanocomposite is a propitious candidate for the adsorptive removal of miscellaneous contaminants such as organic dye [35, 36], nitroaromatic compound [37], and heavy metals [38]. Essentially, this combination has a dual benefit since BC enhances the dispersion of the magnetic NZVI particles and inhibits their aggregation [39]. Thence, BC endows NZVI more stability in air with low aggregation, retaining its good adsorption and reduction properties [40]. On the other hand, NZVI ameliorates the adsorption capability of BC, as well as their magnetic behavior, and facilitates the separation by an external magnet rather than centrifugation and filtration techniques that are less efficient and consume longer time [41]. Herein, we adopted the concept of fabricating a low-cost and ecofriendly adsorbent possessing extraordinary fast and super-adsorption capability. To the best of our knowledge, this is the first time to fabricate NZVI-supported lemonderived biochar composite. A complete characterization of the fabricated NZVI-LBC magnetic nanocomposite was performed. Moreover, the fabricated NZVI-LBC nanocomposite was tested for the selective removal of MB. 2 Experimental section 2.1 Materials Lemon residues were collected from a juice shop in Alexandria, Egypt. Ferric chloride hexahydrate (FeCl3.6H2O, 99%) was supplied from Alpha Chemika (India). Sodium borohydride (NaBH4, 98.7%) and ethanol ( C2H5OH, 99%) 13 were bought from Rankem (India). MB was obtained from MP Biomedicals, LLC (France). 2.2 Preparation of NZVI‑LBC nanocomposite Firstly, lemon residues were well washed with distilled water, then dried in an oven at 100 °C for 12 h. The formed crunchy lemon residues were grinded by a blender; afterwards, the obtained fine powder was carbonized in a muffle furnace at 500 °C for 5 h under oxygen-limited conditions since the crucible was put into a stainless steel cylinder. The air in the cyl (...truncated)