Obtaining a Bioadsorbent from Orange Peel suitable for Batch and Continuous Treatment

Abstract— One form of chemical contamination involves the contribution of heavy metals to the ecosystem mainly from industrial spills and mining operations. The most toxic heavy metals are cadmium, copper, chromium, mercury, nickel, lead and zinc. The importance of this type of toxic lies in the tendency to be accumulated and concentrated by the different species, being more dangerous as it ascends the evolutionary chain towards man.

Chemical precipitation is the most widely used technique for metal recovery. This process is conditioned by the pH, metal concentration and anions present in the water to be treated.

Bioadsorption is considered a viable alternative to the physico-chemical methods currently used for the recovery or removal of heavy metals dissolved in liquid effluents. Its main attractiveness, from an industrial point of view, is its low cost due to the great abundance, easy obtaining and low price of the bioadsorbent material. Bioadsorption is very effective in the treatment of metal concentrations below 100 mg/L, where the application of physical-chemical methods is not technically and economically feasible.

One of these materials of interest is orange peels because, due to their abundance as a waste product of the food industries, they have problems for their disposal and currently have little economic value. However, this residue has a low adsorption capacity, so both physical and chemical modifications are required to increase its adsorption properties.

The objective of this work has been to optimize the treatment of orange peel intended to obtain a bioadsorbent that allows the removal of heavy metals both in a discontinuous process (Batch) and in an ongoing process. The verification of the characteristics of the bioadsorbent obtained has been carried out with a series of synthetic solutions of Cu (II).

The particle size and consistency of the final bioadsorbent has been optimized. In addition, to achieve a homogeneous elution in the continuous process, additional heat treatment has been necessary to prevent the development of microorganisms in a period of time less than one week.