“…Some of the techniques that have been used include centrifugation, filtration, flotation, evaporation, distillation, ion exchange, precipitation, electrolysis, electrodialysis, adsorption, crystallization, micro and ultra-filtration, sedimentation and gravity separation, reverse osmosis, and coagulation. [59] However, these current technologies have a number of drawbacks, including the fact that they are time-consuming and expensive, as well as the fact that they produce dangerous sludge. There are four types of nanomaterials: 1) nano adsorbents, 2) nanomembranes, 3) nanocatalysts, and 4) nanofiber.…”