Complexation, retention and release pattern of arsenic from humic/fulvic acid extracted from zinc and iron enriched vermicompost. (15th September 2022)

• Record Type: Journal Article
• Authors: Sengupta, Sudip; Bhattacharyya, Kallol; Mandal, Jajati; Chattopadhyay, Asoke Prasun
• Is Part Of: Journal of environmental management. Volume 318(2022)
• Publication Date: 2022-09-15
• Subjects: Enriched vermicompost -- Zinc -- Iron -- Arsenic -- Humic/fulvic acid -- Complexation; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2022.115531
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: Arsenic (As) is a highly poisonous heavy metal with major environmental ramifications. Inorganic components such as zinc (Zn) and iron (Fe), as well as organic vermicompost, have been used as management solutions, with limited attempts of using them together. The current study involved preparing non-enriched vermicompost as well as six distinct Zn and Fe enriched vermicomposts and analyzing their chemical composition using the standard procedures. Organic fractions from these seven vermicompost and arsenic polluted soils of West Bengal, India were recovered and separated into humic (HA) and fulvic acid (FA) fractions. Potentiometric titrations, viscometric assays, and visible spectrophotometry were used to characterize the HA and FA samples. In aqueous phase the stability constant (log K) of the complexes formed with As indicates that stability of FA extracted from enriched vermicompost V4 (Zn and Fe sulphate @ 10% w/w dry weight basis of composting substrates before application of vermiworms) was maximum as 10.20 with a mole ratio (x) value of 1.36. Fourier-transform infrared (FT-IR) spectroscopy and Scanning Electron Microscopy (SEM) studies confirmed the complexation of As with HA/FA. The release isotherm of As from the HA/FA complexes in the presence of competitive oxy-anions was found to follow the order of sulphate > nitrate > phosphate. Graphical abstract: Image 1 Highlights: Zinc and Iron enrichment improves physicochemical and enzymatic properties of vermicompost. Humic and Fulvic acid were extracted and characterized for non-enriched and enriched vermicompost. Highest stability of arsenic (log K = 10.20) was for enriched vermicompost. FTIR and SEM images confirmed the binding of arsenic by enriched vermicompost. Sulphate > nitrate > phosphate influenced the release of arsenic from the complexes.