Adsorption of Hexavalent Chromium by Sodium Alginate Fiber Biochar Loaded with Lanthanum.

Xinzhe Sun,Yuanyuan Sun,Yuqian Cui,Peng Guo

doi:10.3390/ma14092224

Abstract

Lanthanun oxide (La2O3) is a lanthanum chemical compound incorporates a sensible anionic complexing ability; however, it lacks stability at a low pH scale. Biochar fibers will give the benefit of their massive space and plethoric uses on the surface to support a metal chemical compound. Herein, wet spinning technology was used to load La3+ onto sodium alginate fiber, and to convert La3+ into La2O3 through carbonization. The La2O3-modified biochar (La-BC) fiber was characterized by SEM, XRD and XPS, etc. An adsorption experiment proved that La-BC showed an excellent adsorption capacity for chromates, and its saturation adsorption capacity was about 104.9 mg/g. The information suggested that the adsorption was in step with both the Langmuir and Freundlich models, following pseudo-second-order surface assimilation mechanics, which showed that the Cr (VI) adsorption was characterized by single-phase and polyphase adsorption, mainly chemical adsorption. The thermodynamic parameters proved that the adsorption process was spontaneous and endothermic. The mechanistic investigation revealed that the mechanism of the adsorption of Cr (VI) by La-BC may include electrostatic interaction, ligand exchange, or complexation. Moreover, the co-existing anions and regeneration experiments proved that the La-BC is recyclable and has good prospects in the field of chrome-containing wastewater removal.

Highlights

Chromium in nature mainly exists in two stable states in a wide pH range: trivalent chromium (Cr (III)) and hexavalent chromium (Cr (VI))
Cr (VI) are more dangerous because it has toxicity, and higher solubility and mobility [4]. It appears in the forms of chromate (CrO4 2−, HCrO4 − ) and dichromate (Cr2 O7 2− ), which have caused great environmental concern [3,8]
As a priority toxic pollutant identified by the US environmental protection agency, Cr (VI) can cause serious toxic and detrimental effects to human health and ecosystems

Summary

Introduction

Chromium can cause serious environmental problems and harm human health due to its problematic characteristics of bioaccumulation, non-biodegradability and potential carcinogenicity in the food chain [2,3]. Cr (VI) are more dangerous because it has toxicity, and higher solubility and mobility [4] It appears in the forms of chromate (CrO4 2− , HCrO4 − ) and dichromate (Cr2 O7 2− ), which have caused great environmental concern [3,8]. When the Cr (VI) content in drinking water exceeds 0.05 mg/L and that in water for different uses exceeds 0.1 mg/L, it can cause harm to human health, such as kidney, liver and stomach damage, skin allergies and lung cancer [9], but in contaminated natural water and industrial wastewater, Cr (VI)

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