Diblock Sodium Alginate Grafted Poly (N-vinylimidazole) in blank copolymeric beads and immobilized algal beads for water treatment

[Display omitted] •Diblock sodium alginate grafted with synthetic PNVI used for phenol removal.•Diblock SA-g-PNVI characterized using spectroscopic, thermal and optical means.•Adsorption optimization parameters fitted in linear and nonlinear regressions.•Adsorption isotherms revealed reversible desorption processes.•Low cost and environmentally friendly were significant characteristics of sorbents. Synthesis of diblock sodium alginate grafted poly (N-vinylimidazole), SA-g-PNVI, was investigated as preliminary step toward preparation of blank copolymeric beads (BCB) and immobilized algal beads (IAB) for the removal of phenol from aqueous solutions. The diblock SA-g-PNVI was self-crosslinked via calcium ions to make BCB, and crosslinked with dead green algae (Chlorella pyrenoidosa) to make the IAB. The diblock SA-g-PNVI was fully characterized using spectroscopic, thermal and optical means. Adsorption optimization parameters like effect of solution pH, dynamics, and adsorption isotherms were investigated; Optimum pH value for phenol removal was found at pH=5.0 for blank copolymer beads (BCB) and immobilized algal beads (IAB). The adsorption kinetics demonstrated pseudo-second order phenol removal with major contribution of intraparticle diffusion mechanism. Adsorption isotherms were fitted to equilibrium data in linear and nonlinear regressions using different objective functions. The low cost, natural origin, biodegradability and environmentally friendly characteristics of the diblock SA-g-PNVI sorbents adapt them to play promising role in recovery of missing ecology and in wastewater management.