Laura Carmen Apostol

UV/TiO2 Photocatalytic Degradation of Xanthene Dyes

UV/titanium dioxide (TiO2) degradation of two xanthene dyes, erythrosine B (Ery) and eosin Y (Eos), was studied in a photocatalytic reactor. Photocatalysis was able to degrade 98% of Ery and 73% of Eos and led to 65% of chemical oxygen demand removal. Experiments in buffered solutions at different initial pH values reveal the pH dependence of the process, with better results obtained under acidic conditions due to the electrostatic attraction caused by the opposite charges of TiO2 (positive) and of anionic dyes (negative). Batch activity tests under methanogenic conditions showed the high toxicity exerted by the dyes even at low concentrations (~85% with initial concentration of 0.3 mmol L−1), but the end products of photocatalytic treatment were much less toxic toward methanogenic bacteria, as detoxification of 85 ± 5% for Eos and 64 ± 7% for Ery were obtained. In contrast, the dyes had no inhibitory effect on the biogenic‐carbon biodegradation activity of aerobic biomass, obtained by respirometry. The results demonstrate that photocatalysis combining UV/TiO2 as a pretreatment followed by an anaerobic biological process may be promising for the treatment of wastewaters produced by many industries.

Removal of Erythrosine B dye from water effluents using crop waste pumpkin seed hulls as adsorbent

AbstractErythrosine B is widely used for coloring in various applications, especially in the food industry, despite its already proved toxicity and carcinogenicity. The agrowaste pumpkin seed hulls were applied as potential adsorbent for the removal of Erythrosine from aqueous solutions. Adsorption mechanism and kinetics were analyzed for design purposes. The seed hulls were characterized by specific techniques before and after dye retention. It was found that the attachment of Erythrosine B molecules on adsorbent surface may be attributed to the interactions between carboxyl and/or carbonyl groups of both dye and agrowaste wall components. A univariate approach followed by a factorial design was applied to study and analyze the experimental results as well as to estimate the combined effects of the process factors on the removal efficiency and dye uptake. Adsorption mechanism may be predominantly due to intraparticle diffusion, dependent on pore size. The four equilibrium models applied fitted the data w...

Overview of human health hazards posed by pesticides in plant products

Pesticides use, one of the hottest topics nowadays when it comes to human health, started to be a serious concern to consumers considering their known harmful effects. This paper provides a short overview on pesticides application and their corresponding maximum residue levels (MRLs) in plant products, risks associated to human health and steps in conducting a human health risk assessment. The procedure of assessing the MRLs is discussed and a methodology of assessing human health risks to pesticides is considered based on currently existing framework provided by USEPA. This analysis highlights the requisite of continuous monitoring programmes of pesticide residues in plant products, and deep knowledge of their toxic effects and assessment strategies necessary in human health risk estimation and mitigation.