Valorization of Biomass into Micronutrient Fertilizers

Katarzyna Chojnacka,Mateusz Samoraj,Łukasz Tuhy

doi:10.1007/s12649-017-0108-6

Abstract

Biological waste constitutes a resource that could be valorised into micronutrient fertilizers. Micronutrient fertilizers (berries seeds residues enriched with micronutrients—blackcurrant Ribes nigrum L., raspberry Rubus idaeus L., strawberry Fragaria × ananasa) produced via biosorption were developed. Micronutrient content was investigated by Scanning Electron Microscope with Energy Dispersive X-ray analysis (SEM-EDX) as an alternative method to Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) which is known as costly, time-consuming and sample-destructive method. X-ray mapping of SEM images and ICP-OES analysis showed the differences in the concentration of micronutrients on the materials surface (natural and enriched biomass—from 3 to 24 times). The highest content of micronutrients (ICP-OES) was achieved for enriched blackcurrant [Cu(II)-12.8 mg g−1, Zn(II)-10.8 mg g−1] and strawberry seeds [Mn(II)-5.13 mg g−1]. The highest atomic concentration of micronutrients was found on the surface (SEM-EDX) of enriched strawberry [24.5% for Cu(II), 8.43% for Mn(II) and 11.1% for Zn(II)]. It was shown that increasing content of micronutrient ions in biological material after biosorption was connected with decreased level of the following cations: Ca(II), Mg(II) and K(I) (ion exchange). The uniform distribution of micronutrient ions was observed on SEM micrographs. The structure of the surface, surface topography (steps, bends and broken edges) were also investigated. The content of micronutrients in biomass determined with ICP-OES and SEM-EDX revealed high correlations between these methods for manganese, zinc and copper ions (0.848, 0.739, 0.735, respectively). Described experiments showed that SEM-EDX was an efficient tool and an alternative for ICP-OES.

Highlights

Micronutrient cations [Cu(II), Mn(II), Zn(II)] can be bound to the biomass via biosorption
There is a lot of papers describing the use of SEM-EDX for adsorption of metal ions to the surface of artificial material while only few studies were focused on the application of electron microscopy in biosorption studies
Multielemental analysis of the biomass carried out with the use of SEM-EDX (Table 1) and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) (Table 2) showed that increasing content of micronutrient ions in biological material after biosorption was connected with decreased level of abundant cations such as K +, Na+ Ca2+, Mg2+ in native biomass

Summary

Introduction

Micronutrient cations [Cu(II), Mn(II), Zn(II)] can be bound to the biomass via biosorption. Ion exchange is supposed to be one of the main mechanisms responsible for the process. Usually negatively charged sites on its surface. Biosorption is a property of certain types of inactive and dead biomass to bind and concentrate metal ions from even very dilute aqueous solutions. Among the mostly often used biosorbents, plant waste biomass [1], algae [2], fungi [3] and bacteria [4] should be mentioned. Micronutrient cations are bound to the surface of the biomass in the equilibrium process. Reversed process (desorption) occurs when biomass is added to soil. Micronutrient ions can be transferred to the soil solution from where they can be taken up by plants

Methods

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Discussion

Conclusion