Iron-coated nutshell waste bioadsorbents: Synthesis, phosphate remediation, and subsequent fertilizer application

Chandra M Tummala; Mohammed Dardona; Sai Praneeth; Sanjay K Mohanty; Timothy M Dittrich

doi:10.1016/j.envres.2023.117468

Iron-coated nutshell waste bioadsorbents: Synthesis, phosphate remediation, and subsequent fertilizer application

Environ Res. 2024 Jan 1;240(Pt 2):117468. doi: 10.1016/j.envres.2023.117468. Epub 2023 Oct 21.

Authors

Chandra M Tummala¹, Mohammed Dardona¹, Sai Praneeth¹, Sanjay K Mohanty², Timothy M Dittrich³

Affiliations

¹ Department of Civil and Environmental Engineering, Wayne State University, 5050 Anthony Wayne Dr., Detroit, MI, 48202, USA.
² Department of Civil and Environmental Engineering, University of California, Los Angeles, CA, 90095, USA.
³ Department of Civil and Environmental Engineering, Wayne State University, 5050 Anthony Wayne Dr., Detroit, MI, 48202, USA. Electronic address: timothy.dittrich@wayne.edu.

PMID: 37871784
DOI: 10.1016/j.envres.2023.117468

Abstract

The increasing incidence of freshwater nutrient pollution worldwide has highlighted the need for improved phosphate capture technologies. Successful phosphate recovery from agricultural sources and commercial wastewater can help prevent freshwater algal bloom contamination, while also reducing the dependency on finite phosphate reserves. Biodegradable biosorbents have the potential to remove phosphate from water; however, their potential as slow-release fertilizers has not been tested. Novel biosorbents were developed by coating pistachio and walnut shells with iron oxides; batch and column experiments were conducted to investigate their adsorption capacities and performances. Surface characterization studies were also conducted to investigate changes in the surface area and morphology. The potential of using iron-coated shells loaded with phosphorus as slow-release fertilizers was also evaluated. Advanced characterization techniques (scanning electron microscopy, Brunauer-Emmett-Teller (BET) physisorption analysis, and x-ray diffraction) showed that hematite was successfully coated onto the surface, resulting in increased surface area and roughness. The iron-coated pistachio and walnut shell phosphate removal capacity was 12.63 mg g^-1 and 9.25 mg g^-1, respectively. The phosphate sorption data fitted well with the Freundlich isotherm model and pseudo-second-order kinetics. Inner sphere complex formation, coprecipitation, diffusion, and electrostatic attraction were the main uptake mechanisms. Results from sequential release experiments with simulated pore water suggested both fast and slow desorption components. The Mehlich-3 extraction revealed that more than 90% of the released phosphate was available for plant uptake. In addition, nutrient priming showed that corn seed shoot growth increased by more than 43% when pretreated with phosphate-loaded biosorbents, demonstrating that the released phosphate could be used for plant growth. This research provides a pathway for two important zero-waste, cyclical economic goals: (1) the beneficial use of agricultural waste, and (2) a low-cost technology that can recover phosphorus from waste streams while potentially adding an additional unconventional phosphate source to apatite mineral ores.

Keywords: Biosorbent; Phosphate recovery; Slow-release phosphate fertilizer; Waste nutshells.

MeSH terms

Fertilizers
Iron*
Phosphates*
Phosphorus
Water

Substances

Phosphates
Iron
Fertilizers
Phosphorus
Water