Application of nanofiltration to treat rare earth element (neodymium) containing water

The scope of present work was to study the feasibility of a commercial nanofiltration (NF) membrane to reject Nd(III) ions from synthetic aqueous solution. The permeates were analyzed using inductively coupled plasma-atomic emission spectrometry (ICP-AES) to find Nd(III) concentration. Experimental results indicated that the Nd(III) rejection increased with increase in applied pressure and feed flow rate; and decreased with increase in feed concentration. Rejection of Nd(III) ions using NF membrane were widely influenced by solution pH due to the charged nature of the membrane which changed with the variation in pH. The use of a surfactant (sodium dodecyl sulphate) in aqueous solution resulted in its adsorption on the membrane surface, thereby changing membrane characteristics, and in turn influencing the rejection. The complexation step induced had also increased the rejection to a greater extent by forming [Nd-EDTA]− complex thereby increasing its molecular weight and thus increasing rejection.