Effective removal of anionic textile dyes using adsorbent synthesized from coffee waste

Syieluing Wong,Ibrahim Mohammed Inuwa,Norzita Ngadi,Nor Aishah Saidina Amin,Ramli Mat,Nawal Abd Ghafar,Fatin Amirah Razmi

doi:10.1038/s41598-020-60021-6

Syieluing Wong, Ibrahim Mohammed Inuwa + Show 5 more

Open Access

https://doi.org/10.1038/s41598-020-60021-6

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Abstract

Adsorption of Reactive Black 5 and Congo Red from aqueous solution by coffee waste modified with polyethylenimine was investigated. The removal percentages of both dyes increased with amount of polyethyleneimine in the modified adsorbent. Characterization revealed that polyethyleneimine modification improved the adsorbent surface chemistry, while slight improvement of adsorbent textural properties was also observed. The adsorbent’s excellent performance was demonstrated by high removal percentages towards the anionic dyes in most experimental runs. The modelling result showed that anionic dyes adsorption occurred via monolayer adsorption, and chemisorption was the rate-controlling step. The adsorbent possesses higher maximum adsorption capacity towards Reactive Black 5 (77.52 mg/g) than Congo Red (34.36 mg/g), due to the higher number of functional groups in Reactive Black 5 that interact with the adsorbent. This study reveals the potential of adsorbent derived from coffee waste in textile wastewater treatment. Furthermore, surface chemistry modification is proven as an effective strategy to enhance the performance of biowaste-derived adsorbents.

Highlights

Adsorption of Reactive Black 5 and Congo Red from aqueous solution by coffee waste modified with polyethylenimine was investigated
Similar observation was made in this study, where raw Coffee waste (CW) showed lower adsorption performance towards Reactive Black 5 (RB5) and Congo red (CR) dyes, with removal percentages of 7.42% and 14.35% respectively (Fig. 1), while all PEI-CW adsorbents removed more than 80% RB5 and 76% CR dyes from the solutions under similar conditions
It is more probable for RB5 dye molecules to bind strongly to the adsorbent, leading to a higher removal percentage compared to CR dye

Summary

Introduction

Adsorption of Reactive Black 5 and Congo Red from aqueous solution by coffee waste modified with polyethylenimine was investigated. Recent studies revealed the potential of surface chemistry modification in enhancing the adsorbents’ performance[7] Such modification can be achieved via treatment with chemicals (especially acids and bases) as well as introduction of ionic polymer groups onto the adsorbent precursors. The adsorbents developed solely via surface chemistry modification are reported to possess satisfactory performance in removal of dyes[8] and heavy metals[9] from the wastewater. These findings make modified biomass an attractive option of adsorbent, considering their economic advantage due to the less energy input during synthesis procedure when compared to the activated carbon preparations, where carbonization and activation steps are necessary. The effects of contact time, initial dye concentration, temperature, solution pH, and adsorbent dosage on RB5 and CR dyes adsorption onto PEI-CW were investigated, followed by interpretation of the adsorption data from the modelling result

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Conclusion