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It is expected that microorganisms capable of arsenic (As) accumulation and volatilization can be used to remediate As-contaminated environments. In this paper, the arsenite [As(III)] resistance, accumulation, and volatilization properties of Trichoderma asperellum SM-12F1, Penicillium janthinellum SM-12F4, and Fusarium oxysporum CZ-8F1 were investigated. The results indicated that all three fungal strains exhibited significant As(III)-resistance. After being exposed to 40 and 80 mg/L As(III) for five days, the dry mycelium weights of P. janthinellum SM-12F4 and F. oxysporum CZ-8F1 were significantly increased compared to the controls. The spiked As(III) initially inhibited and subsequently promoted fungal growth (mainly in the logarithmic growth phase). The maximal biomasses of 0.25, 0.29, and 0.29 g for T. asperellum SM-12F1, P. janthinellum SM-12F4, and F. oxysporum CZ-8F1 after exposure to As(III), respectively, were all higher than their corresponding controls without As(III). When exposed to 40 mg/L As(III) for five days, the efficiencies of As(III) accumulation for T. asperellum SM-12F1, P. janthinellum SM-12F4, and F. oxysporum CZ-8F1 were 53.02, 13.67, and 13.65 µg/g/day, respectively, and the efficiencies of As(III) volatilization were 51.87, 54.34, and 46.35 µg/g/day, respectively. It seems that these fungal strains can be used in the future to tackle As-contaminated environments. [ABSTRACT FROM AUTHOR]

Arsenic (As) and cadmium (Cd) are two highly toxic elements. In recent years, many newly synthesized chemical materials have been used widely for treatments of As- and Cd-contaminated effluents. However, most materials do not exhibit high efficiencies for simultaneous removal of As and Cd from water systems. Our study established a simple scheme for synthesizing a sepiolite (SEP)-modified nanoscale zero-valent iron (S-nZVI) for simultaneous removal of coexisting As and Cd from water and illuminated a possible underlying mechanism. Batch experiments showed that the maximum capacities for adsorption of As(III) and Cd(II) by S-nZVI were 230.29 mg/g and 11.37 mg/g, respectively, which represented better effects than those of other materials, as reported previously. Removal of Cd(II) depended on pH, but As(III) removal showed little dependence on pH. Coexisting ions such as phosphate (PO 4 3−) and the conjugate base of humic acid (HA) significantly inhibited simultaneous removal of As(III) and Cd(II). In the mixed As(III)–Cd(II) system, the presence of As(III)-pretreated S-nZVI significantly enhanced Cd(II) adsorption by a factor of four over that seen for aqueous solution without As(III). XRD and XPS results showed that CdFe 2 O 4 (Fe–O–Cd), Fe 2 As 2 O 14 or FeAsO 4 (Fe–O–As) were formed after As(III) and Cd(II) were captured by S-nZVI. However, a further zeta (ζ) potential analysis showed that the mechanism for As(III) and Cd(II) adsorption by S-nZVI is not just simple formation of the above chemicals, since the adsorbed As(III) increased the negative charge of S-nZVI; this suggested an electrostatic attraction between S-nZVI and Cd(II) and indicated that adsorbed As(III) created new sorption sites for Cd(II), which enhanced Cd(II) sorption via formation of ternary complexes (Fe–As–Cd). These results suggested that S-nZVI is a promising material for in situ remediation of heavy metal-contaminated groundwaters or paddy soils. • A newly sepiolite modified nZVI was synthesized for co removal of As(III) and Cd(II). • S-nZVI has high sorption efficiency of As(III) and Cd(II). • Pre-treatment with As(III) can significantly promote Cd(II) adsorption by S-nZVI. • The mechanism of As–Cd co-removal is suggested by forming a ternary complex Fe–As–Cd. [ABSTRACT FROM AUTHOR]

• Arsenic is electrochemically adsorbed by birnessite from mining wastewater. • Electrochemical redox reactions of birnessite contribute to arsenic adsorption. • H 2 O 2 formation and high potential of birnessite anode facilitate As(III) oxidation. • Mn2+ in wastewater can also be effectively removed during arsenic adsorption. • Cell voltage reversal facilitates the continuous use of birnessite electrode. Manganese oxides have been extensively investigated for arsenic (As) adsorption from aqueous solution. However, the effect of electrochemical redox reactions on the adsorption performance and underlying mechanism remain elusive. Herein, birnessite was used for electrochemical adsorption of As from mining wastewater at a constant cell voltage, and the effect of cell voltage and the continuous use (without desorption) performance of birnessite electrode were also evaluated. At 1.2 V for 24 h, the concentrations of total As (As(T)) and As(III) in wastewater decreased from 3808.7 to 73.7 μg L−1 and 682.8 to 21.4 μg L−1, respectively. The As(T) removal ratio increased with increasing cell voltage and reached 98.1% at 1.2 V, which was higher than that at open circuit (84.1%). The Mn2+ concentration also significantly decreased in wastewater during As adsorption. The high potential of birnessite anode and the generation of H 2 O 2 on cathode facilitated As(III) oxidation, and the electrochemical redox reactions of birnessite contributed to the enhancement of As(T) removal. The application of cell voltage reversal could improve the utilization rate of birnessite electrodes by dissolution-recrystallization during continuous use, and the As(T) removal ratio was increased from 73.5% to 85.1% after five cycles of voltage alteration. The present work indicates that birnessite is a promising absorbent for the electrochemical adsorption of As from real wastewaters. [ABSTRACT FROM AUTHOR]