Progress in silk materials for integrated water treatments: Fabrication, modification and applications

The oil-spill accidents in oceans, and discharge/percolation of polluted wastewater by industries in environment causes severe damage to environment and water sources. Release of hazardous chemicals in an environment causes infertility to agricultural lands and contamination of natural water sources. In this sense, researchers have developed advanced materials and technologies for oil/solvent-water separation, and for removal of toxic pollutants from contaminated wastewater, however, their disposal and non-degradation after service life is one of the major environment related issue. Considering environmental concerns and compatibility of materials towards nature during their service life has compelled the scientific community to shift the focus on utilization biopolymeric materials for water treatment applications. Considering various biopolymeric materials, Silk is a naturally available, biocompatible, biodegradable, yet mechanically strong material. On commercial scale, silk is mainly produced by silkworms (bombyx mori, Tasar etc.), which is widely used in textiles and biomedical applications, due to their excellent biocompatibility, mechanical strength, and non-toxic nature. Literature analysis shows that silk materials have been widely used for biomedical applications, however, they are not much explored for water treatment applications like oil-water separation, effluent treatments, and unidirectional water transportation, etc. In this sense, this review extensively discusses utilization of silk biomaterials for water treatment applications like removal of toxic ions from wastewater, oil-water separation, unidirectional water transportation, etc. The review discusses important physical & chemical methods utilized for functionalization of silk biomaterials for above mentioned applications. Finally, the review concludes with biodegradation of silk materials under in-vivo/-in-vitro conditions, and various microorganisms, for mitigating their disposal problem in an environment.