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Papers by Antonio Violante

Communications in Soil Science and Plant Analysis

Violante, A., Del Gaudio, S., Pigna, M., Ricciardella, M. Benerjee, D. (2007). Coprecipitation of arsenate within metal oxides: 2 nature, mineralogy and reactivity of iron(III) precipitates. Environmental Sci. & Technol. 41, 8275-8280

Environmental Science and Technology

European Journal of Soil Science, 2015

ABSTRACT Iron oxy-hydroxides in soil are known to have a large affinity for arsenate (As(V)) inor... more ABSTRACT Iron oxy-hydroxides in soil are known to have a large affinity for arsenate (As(V)) inorganic species. At the soil–root interface such mineral components are embedded by mucilaginous material that is secreted from continuously growing root cap cells. In order to determine the role of plant mucilages in As(V) sorption by iron oxy-hydroxides, we layered a calcium (Ca)-polygalacturonate network (CaPGA) on to amorphous iron (Fe) (III) hydroxide (ferrihydrite, Fh) particles. The scanning electron micrographs of the CaPGA network coating the ferrihydrite (Fh–CaPGA) show a regular structure with a honeycomb-like pattern where interlacing fibrils form a porous system. The FT-IR spectra of Fh–CaPGA suggest that CaPGA fibrils are retained by the surface Fe(III) nuclei of Fh through electrostatic interactions. The sorption experiments carried out at pH 4.3 and 5.8 indicated a smaller amount of As(V) sorbed by Fh–CaPGA than by Fh alone, being less after 3 and 24 hours of reaction by about 70 and 30%, respectively. The sorption of As(V) by Fh was also studied in the presence of caffeic acid (CAF), an important root exudate. Simultaneous sorption kinetics show that As(V) sorption by Fh is almost independent of CAF concentration, indicating a greater affinity of arsenate ions towards the Fh surfaces. However, the amount of As(V) sorbed by the Fh coated by CaPGA, in the presence of 0.25, 0.5 and 1.0 mm CAF, is markedly smaller by about 20, 27 and 40%, respectively, than that found in the As(V)–CAF-Fh ternary systems. This is caused mainly by redox reactions involving CAF and the surface Fe(III) nuclei of Fh leading to the formation of CAF oxidation products which prevent As(V) sorption.

Environmental science and pollution research international, 2015

Pot experiments were conducted to investigate the effects of γ-polyglutamic acid (γ-PGA), phospha... more Pot experiments were conducted to investigate the effects of γ-polyglutamic acid (γ-PGA), phosphate rock (PR), and γ-PGA-activated PR (γ-PGA-PR) on the immobilization and phytotoxicity of Pb in a contaminated soil. The proportion of residual Pb (Re-Pb) in soil was reduced by the addition of γ-PGA but was increased by the application of PR and γ-PGA-PR. The addition of γ-PGA in soil improved the accumulation of Pb in pak choi and decreased the growth of pak choi, suggesting the intensification of Pb phytotoxicity to pak choi. However, opposite effects of PR and γ-PGA-PR on the phytotoxicity of Pb to pak choi in soil were observed. Moreover, in the examined range, γ-PGA-PR activated by a higher amount of γ-PGA resulted in a greater proportion of Re-Pb in soil and weaker phytotoxicity of Pb to pak choi. The predominance of γ-PGA-PR in relieving the phytotoxicity of Pb was ascribed mainly to the increase of soil pH and available phosphate after the amendment, which could facilitate the ...

Environmental Engineering Science, 2015