Flocculation properties of a natural polyampholyte: The optimum condition toward clay suspensions

Abstract

Polyelectrolytes are commonly used as flocculants in drinking water treatment. However the growing concerns about their toxicity have motivated the search for biocompatible flocculants. Here, we show that gelatin, a natural amphoteric polyelectrolyte, can be effectively adsorbed on clay surfaces and can potentially be a suitable substitute for existing flocculants. The adsorption of gelatin from its aqueous solution onto the mineral clay surfaces at different conditions was systematically investigated using the design of experiments methodology. The gelatin adsorption was found to vary considerately with pH variation showed a maximum adsorption at its isoelectric point. The amount of adsorbed gelation increased with increasing pH from 3 to 5, attained a maximum at pH 5 and then decreased with increasing pH from 5 to 11. Similarly, the amount of adsorbed gelatin showed decreasing trends around salt concentration of 0.05 M and temperature 35°C. On the other hand, the adsorption was continuously increased with time and polymer concentration in the range of 0.1-0.9 mg/dL. Finally, the jar tests confirmed the ability of gelatin for using a natural flocculant for water treatment.

Desain Bioflokulan Gelatin Tulang Ikan Lele (Clarias Batrachus) Untuk Penjernihan Air

“…Gelatin adalah produk alami dengan komponen utama protein yang diperoleh melalui proses hidrolisis kolagen dari kulit, jaringan ikat putih, dan tulang hewan; menggunakan asam, basa, atau ensim (GMIA, 2012). Nazarzadeh et al (2017) menyatakan gelatin adalah poliamfolit yang artinya mampu mengembangkan interaksi kationik, anionik dan hidrofobik. Hal ini memungkinkan molekul gelatin untuk berasosiasi dengan antarmuka kedua elektrostatik dan hidrofobik.…”

“…Sehingga dapat mengakibatkan gagalnya pengikatan dan pembentukan flok. Nazarzadeh et al (2017) menjelaskan dengan meningkatnya konsentrasi poliamfolit, jumlah rantai teradsorpsi pada permukaan partikel meningkat, sehingga tidak ada permukaan kosong yang cukup pada permukaan partikel untuk menjembatani antar partikel. Jadi, ukuran flok menjadi lebih kecil dan kekeruhan meningkat.…”

Interactions between smectites and polyelectrolytes

“…Gelatin, a natural amphoteric polyelectrolyte, due to biocompatibility, biodegradable properties, and no toxicity and availability, can potentially be a suitable substitute for the existing flocculants (Karimi et al, 2013). Gelatin can be effectively adsorbed on montmorillonite surfaces thereby changing the electrochemical nature of montmorillonite particle surface changes (Nazarzadeh et al, 2017). The adsorbed gelatin chains introduce bridging forces and steric forces in addition to electrostatic repulsion and Van der Waals attraction.…”