Reduction of hexavalent chromium: photocatalysis and photochemistry and their application in wastewater remediation

Machado, Tiele Caprioli; Lansarin, Marla Azário; Matte, Natália

doi:10.2166/wst.2014.193

Cited by 15 publications

(7 citation statements)

References 14 publications

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“…The adsorbed HA, being an electron-rich molecule, acts as a scavenger for positive holes at the ZrO 2 valence band, which reduces the electron-hole recombination rate [59] and consequently increases the Cr(VI) photocatalytic reduction efficiency. This was also reported for Cr(VI) photocatalytic reduction using TiO 2 in the presence of organic compounds, such as humic acid [1,16], phenol [16,68], ethanol [58,69], and citric acid [15].…”

Section: Effects Of Ha and Ph On The Cr(vi) Photocatalytic Reduction Under Different Catalyst Dosagessupporting

confidence: 62%

Photocatalytic Reduction of Cr(VI) in the Presence of Humic Acid Using Immobilized Ce–ZrO2 under Visible Light

et al. 2020

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Cr(VI) has several industrial applications but it is one of the most dangerous pollutants because of its carcinogenicity and high toxicity. Thus, the removal of Cr(VI) by photocatalytic reduction was investigated. The catalyst applied, Ce–ZrO2, was immobilized, through a sol–gel process on a silicon carbide (SiC) support, to increase the efficiency and avoid using suspended nanoparticles. The influence of initial pH, humic acid (HA), and catalyst dosage was investigated for Cr(VI) containing solutions. Then, a real galvanizing industry effluent (Cr(VI) = 77 mg L-1mg.L−1, Zn = 1789 mg L−1) was treated. It was observed that Cr(VI) adsorption and photoreduction are greatly favored at low pH values. HA can decrease Cr(VI) adsorption but also acts as holes scavenger, reducing the electron–hole recombination, favoring then the photoreduction. With the immobilized Ce–ZrO2, more than 97% of Cr(VI) was removed from the diluted effluent. These results indicate the feasibility to treat Cr(VI) effluents even in the presence of other metals and natural organic matter. The developed material has great chemical and mechanical resistances and avoids the use of nanoparticles, dangerous for the environment and hard to recover. Moreover, solar light can be used to drive the process, which contributes to the development of more sustainable, cleaner, and cost-effective wastewater treatments.

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Section: Effects Of Ha and Ph On The Cr(vi) Photocatalytic Reduction Under Different Catalyst Dosagessupporting

confidence: 62%

Photocatalytic Reduction of Cr(VI) in the Presence of Humic Acid Using Immobilized Ce–ZrO2 under Visible Light

et al. 2020

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“…Cr(III) is an essential element in the metabolism of lipids and carbohydrates [ 6 ]. Various conventional chemical and physical methods have been applied to remove heavy metals from the environment; these methods include ion exchange, photo catalytic reduction, precipitation, ultrafiltration, and reverse osmosis [ 7 , 8 , 9 ]. These processes lead to incomplete metal removal, which is influenced by several criteria, and the production of secondary contamination, high-energy consumption, and high operating cost [ 2 , 10 ].…”

Section: Introductionmentioning

confidence: 99%

Biosorption Potential of Bacillus salmalaya Strain 139SI for Removal of Cr(VI) from Aqueous Solution

Dadrasnia

Wei

Shahsavari

et al. 2015

IJERPH

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The present study investigated the biosorption capacity of live and dead cells of a novel Bacillus strain for chromium. The optimum biosorption condition was evaluated in various analytical parameters, including initial concentration of chromium, pH, and contact time. The Langmuir isotherm model showed an enhanced fit to the equilibrium data. Live and dead biomasses followed the monolayer biosorption of the active surface sites. The maximum biosorption capacity was 20.35 mg/g at 25 °C, with pH 3 and contact time of 50 min. Strain 139SI was an excellent host to the hexavalent chromium. The biosorption kinetics of chromium in the dead and live cells of Bacillus salmalaya (B. salmalaya) 139SI followed the pseudo second-order mechanism. Scanning electron microscopy and fourier transform infrared indicated significant influence of the dead cells on the biosorption of chromium based on cell morphological changes. Approximately 92% and 70% desorption efficiencies were achieved using dead and live cells, respectively. These findings demonstrated the high sorption capacity of dead biomasses of B. salmalaya 139SI in the biosorption process. Thermodynamic evaluation (ΔG0, ΔH0, and ΔS0) indicated that the mechanism of Cr(VI) adsorption is endothermic; that is, chemisorption. Results indicated that chromium accumulation occurred in the cell wall of B. salmalaya 139SI rather than intracellular accumulation.

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“…No entanto, dentre os álcoois estudados, o etanol foi considerado o mais suscetível para aplicação industrial, devido ao seu baixo custo, não toxicidade e facilidade de aquisição (Machado et al, 2014). …”

Section: Ensaios Com Efluente Industrialunclassified

Redução Fotoquímica De Cromo Hexavalente Por Álcoois Sob Radiação Uv

Machado¹,

Theisen²,

Lansarin³

2015

Anais Do XX Congresso Brasileiro De Engenharia Química

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RESUMO -No presente trabalho se estuda a redução fotoquímica de Cr(VI) por álcoois, metanol, etanol e propan-2-ol, sob radiação UV. Os experimentos foram realizados em um reator batelada de vidro com controle de temperatura e agitação, sob radiação UV. Primeiramente, avaliou-se a influência do pH inicial da solução, do volume de álcool e da concentração inicial de cromo hexavalente na redução total de Cr(VI). Os resultados obtidos permitiram concluir que a redução total de Cr(VI) é dependente da natureza do álcool, diminuindo na seguinte ordem: propan-2-ol > etanol >> metanol. Por fim, realizaram-se experimentos com um efluente industrial, originado em uma indústria de galvanoplastia, tendo sido observados altos valores de redução total de Cr(VI). INTRODUÇÃOO cromo hexavalente é tóxico para a maioria dos organismos, sendo carcinogênico e mutagênico para os animais, podendo causar irritação e corrosão na pele humana. Os metais pesados encontrados no ambiente originam-se, principalmente, da descarga inadequada de efluentes industriais (Ku e Jung, 2001), estando as empresas de curtimento de couro, tintas, corantes, materiais fotográficos, galvanoplastia, mineração, metalúrgicas e de eletrônicos, entre as possíveis fontes de cromo (Schrank et al., 2002;Mohapatra et al., 2005; Chakrabarti et al., 2009). Dentre estas, a indústria de galvanização é caracterizada pelo excessivo consumo de água e energia e pela grande geração de efluentes líquidos contendo metais pesados, tais como, cobre, níquel e cromo. Estes efluentes provêm, principalmente, do descarte das águas de enxágue das peças retiradas dos banhos eletroquímicos.O cromo ocorre na natureza em dois estados de oxidação, Cr +3 e Cr +6 ou Cr(III) e Cr(VI). O Cr(VI) é altamente solúvel, o que possibilita a contaminação de lençóis freáticos e outras fontes de água potável, sendo mais estável que o trivalente. A forma hexavalente do cromo é 100 vezes mais tóxica que a trivalente (Mohapatra et al., 2005; Das et al., 2006;Xu et al., 2006; Yang e Chan, 2009; Chakrabarti et al., 2009). Por outro lado, o cromo trivalente é facilmente precipitado e não apresenta toxicidade, sendo considerado um elemento essencial para o metabolismo humano, em níveis controlados (Kim et al., 2002;Mohapatra et al., 2005).O tratamento convencional para águas residuais contendo Cr(VI) é a redução com sulfito de sódio ou metabissulfito. Este método, no entanto, apresenta alguns problemas: exige um excesso de Área temática: Engenharia Ambiental e Tecnologias Limpas 1

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Reduction of hexavalent chromium: photocatalysis and photochemistry and their application in wastewater remediation

Cited by 15 publications

References 14 publications

Photocatalytic Reduction of Cr(VI) in the Presence of Humic Acid Using Immobilized Ce–ZrO2 under Visible Light

Photocatalytic Reduction of Cr(VI) in the Presence of Humic Acid Using Immobilized Ce–ZrO2 under Visible Light

Biosorption Potential of Bacillus salmalaya Strain 139SI for Removal of Cr(VI) from Aqueous Solution

Redução Fotoquímica De Cromo Hexavalente Por Álcoois Sob Radiação Uv

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