Heavy metals removal using adsorption and nanofiltration techniques

The removal of some heavy metals Cu (II), Cd(II), Mn(II), Pb(II) As(III), and As(V) from water solution using absorption and nanofiltration membrane techniques is presented. The influence of temperature, sorbent mass, solution pH, flow rate and sorbent chemical modification in the adsorption process are discussed. Among the listed sorbents the best performers for higher initial heavy metal concentration are: montmorillonite, kaolin, tobermorite, magnetite, silica gel and alumina that removed more than 80% from a solution of initial concentration range 1-100 ppm for cadmium, chitosan coated magnetic nanoparticles modified with α-ketoglutaric acid removed >95% from a solution of initial concentration 200 ppm for copper, polymeric cation exchanger containing nano-Zr(HPO₃-S)₂ absorbs 98% of lead with initial concentration ∼80 ppm, acid modified carbon black has absorption efficiency of 80% with initial concentration 200 ppm of As(V); and polonite sorbent absorb 98.7% of manganese with initial concentration 0.01 ±0.031 ppm. For the nanofiltration (NF) membrane, research showed removal efficiencies around 97% for cadmium (initial concentration C0 = 500 ppm), 99.9% for copper (C0 = 12000 ppm), 84% lead (C0 = 0.64 ppm, 93% As (V) and 89% As (III) (total arsenic concentration = 600 ppm) and 98% for Mn (C0 =310 ppm).