Kinetic insights on wet peroxide oxidation of caffeine using EDTA-functionalized low-cost catalysts prepared from compost generated in municipal solid waste treatment facilities

Jose L Diaz De Tuesta,Helder T Gomes,Jessica R.P Oliveira,Flávio V.M De Almeida,Paulo Praça,Mário C Guerreiro

doi:10.1016/j.eti.2021.101984

Abstract

Nowadays, sorted organic fraction of municipal solid waste is typically treated by anaerobic digestion processes, resulting therein a solid stream, further processed to obtain compost, whose production is higher than the existing demand as fertilizer. The current work proposes an alternative strategy for the recovering of compost through the production of low-cost catalysts by calcination (1073 K) and sulfuric acid treatments, followed by sequential functionalization with tetraethyl orthosilicate (TEOS) and ethylenediamine tetraacetic acid (EDTA). Activity and stability of the catalysts are assessed in the wet peroxide oxidation of synthetic wastewater effluents contaminated with caffeine, a model micro-pollutant, achieving its complete removal after 6 h at 353–383 K and catalyst loads of 0.5–2.5 g L−1. The increase of the catalytic activity of the materials upon functionalization with TEOS and EDTA is demonstrated and a kinetic modeling of caffeine degradation and hydrogen peroxide consumption with the best catalyst is assessed by pseudo-first power-law rate equations.

Highlights

Nowadays, waste management through mechanical biological treatment (MBT) systems consists in the use of the organic fraction separated from undifferentiated municipal solid waste (MSW) to feed anaerobic digestion processes, resulting therein a biogas and a solid stream, further processed to compost
This section contains: (1) the reagents used for the materials preparation and catalytic wet peroxide oxidation (CWPO) experiments; (2) the methods followed in the preparation of the catalysts; (3) analytical techniques used for their characterization; (4) methods applied to assess their catalytic activity in the CWPO of caffeine; and (5) the mathematical development followed for the kinetic modeling in the CWPO of caffeine with the catalysts prepared
The results found by the methods described previously are presented and discussed related to: (1) characterization of the catalyst prepared from compost; (2) their application in the CWPO of caffeine; (3) the performance of a selected catalyst at different operating conditions; and (4) the development of a kinetic model for the CWPO of caffeine

Summary

Introduction

Waste management through mechanical biological treatment (MBT) systems consists in the use of the organic fraction separated from undifferentiated municipal solid waste (MSW) to feed anaerobic digestion processes, resulting therein a biogas and a solid stream, further processed to compost. One of the methods considered the preparation of hydrochars by hydrothermal carbonization upon 1–5 h under different operating conditions (423–503 K and compost:water = 30–130 g L−1), optimizing the catalytic performance of hydrochars in the decomposition of hydrogen peroxide (Roman et al, 2021). Another approach considered the recovery of compost by activation and thermal treatments at 673–1023 K to prepare active catalysts for the treatment of oily wastewater and for the removal of lipophilic substances by catalytic wet peroxide oxidation (CWPO) (Diaz de Tuesta et al, 2020a)

Methods

Results

Conclusion