Design of low-cost Jhingan gum-based flocculant for remediation of wastewater: flocculation and biodegradation studies

Abstract

Natural-based polymers can be designed into remarkably excellent flocculants for wastewater treatment after their chemical modification. One commonly adopted method for modification of polysaccharides is free radical polymerization. Jhingan gum also known as Moi gum or Odina gum or Jeol gum is one unexplored natural gum that needs special attention. Adopting microwave-assisted technique, different grades of Jhingan-grafted copolymer were synthesized by varying the amount of acrylamide (5–15 g) and potassium persulphate (0.05–0.3 g). The synthesized material was confirmed through analytical techniques, and the best grafted grade (Jh-g-PAM 3) was assayed through intrinsic viscosity and grafting percentage. Flocculation experiments in kaolin (0.25%), iron ore (1%) and coal fine (1%) suspensions revealed flocculation efficacy of 80%, 69% and 62%, respectively, in contrast with commercial PAM with 54%, 46% and 39% efficacy and Jhingan gum with 37%, 26% and 22%, respectively. Flocculation performance under different pH (2–10) and temperatures (10–55 °C) revealed that neutral pH and room temperature (25 °C) were congenial for optimum flocculation. Furthermore, magnitude of zeta potential increased from − 2.65 to − 17.17 mV while the particle size decreased from 2041 to 1092 d.nm as pH was increased suggesting the stability of kaolin suspension in acidic condition. Metal ions removal study conducted in river revealed that the grafted material could remove Cr, Fe and Pb from 0.004 mg/L to below detection limit (− 0.003 mg/L), 0.65 mg/L to 0.011 mg/L and 0.015 mg/L to below detection limit (− 0.011 mg/L), respectively. The grafted material was found to degrade completely in 180 days with a half-life of 28 days.