Adsorbed leucaena protein on citrate modified Fe 3 O 4 nanoparticles: synthesis, characterization, and its application a

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Sustainable Environment Research

(2020) 30:32

RESEARCH

Open Access

Adsorbed leucaena protein on citrate modified Fe3O4 nanoparticles: synthesis, characterization, and its application as magnetic coagulant Hans Kristianto* , Edwin Reynaldi, Susiana Prasetyo and Asaf K. Sugih

Abstract Natural coagulants from plants resources have gained a lot of attention as it is renewable, biodegradable, nonhazardous, lower cost, and less sludge generated compared to chemical coagulants. However there are still some drawbacks, namely long settling time and possible increase of dissolved organic carbon in the treated water. In this paper we tried to address these drawbacks by utilizing citrate modified Fe3O4 to adsorb protein from Leucaena leucocephala as the active coagulating agent. The effect of trisodium citrate concentration and protein adsorption pH to the adsorbed protein was investigated. It was found that the trisodium citrate concentration of 0.5 M and pH 4.0 gave the highest protein adsorption. The obtained magnetic coagulant was furthermore characterized using Scanning Electron Microscopy, X-ray Diffraction, Fourier Transform Infrared Spectroscopy, and Transmission Electron Microscopy to observe the characteristics before and after protein adsorption. Furthermore, the effect of pH (2 to 10) and coagulant dosage (60 to 600 mg L− 1) to the removal of synthetic Congo red wastewater and sludge volume formation was investigated. It was found that pH 3 was the best pH for coagulation due to charge neutralization mechanism of leucaena protein. Furthermore the highest removal was obtained at dosage 420 mg L− 1 with 80% removal. This result was comparable with crude extract of leucaena with half settling time (20 min) and lower increase of permanganate value, indicating lower increase of dissolved organics in the treated water. Keywords: Congo red, Fe3O4, Iron oxide nanoparticles, Leucaena leucocephala, Magnetic coagulant, Natural coagulant

Introduction In recent years, utilization of various natural resources as natural coagulant has gained a lot of interest due to its various advantages, such as: lower cost compared to chemical coagulants, it comes from renewable sources, less sludge volume generated, and biodegradable- nonhazardous sludge [1, 2]. However there are some drawbacks in natural coagulant application, which we addressed in this research. Firstly, the settling time needed for separation of flocs is most likely between 60 to 120 * Correspondence: [email protected] Department of Chemical Engineering, Parahyangan Catholic University, Bandung 40141, Indonesia

min by gravity. It is important to decrease the settling time, as long residence time could lead to larger designed settling tank needed, which could lead to higher capital cost. Secondly, direct utilization of plant parts or its crude extract could increase the dissolved organic carbon (DOC) in the treated water, due to some soluble non-coagulant compounds from the plant [3]. It is known that high DOC could stimulate high microbial activities, maki