| The effective use of agricultural by-products is definitely a major challenge in waste management. In the
walnut fruit processing industry, large amounts of shells are produced as agricultural by-products and
discarded or burned produced as fuel. Walnut (Juglans regia L.) is a valuable tree nut in the
Juglandaceae family. The fruit is composed of four main parts: the kernel, the skin, the shell, and the
husk. The importance of walnuts is mostly related to theirs valuable kernels. However, their shells are
currently experiencing as much interest as their kernels due to the beneficial effects of the shells. In the
past several years, walnut shell (WS) has been widely explored as a naturally inert plant-based biosorbent.
In this review, we first highlight recent scientific literature regarding the development of adsorbents from
WS in the form of carbon-based materials including unmodified/modified WS, and activated carbons
(ACs). Next, we discuss the potential applications of WS-derived by-products as natural yet effective
adsorbents for the removal of various hazardous materials including heavy metals (HMs), synthetic
industrial dyes, and harmful chemicals. |