Diagnostico de intemperismo en la catedral de puebla

This paper presents a physicochemical approach to diagnose basalt weathering at Cathedral of Puebla facade, building located at downtown Puebla, which was built in the XVII century and has the particularity of having three sides exposed to the action of rain, wind and sun. Applied methodology included physical inspection of the building, collection of weathered samples, which were grounded, mixed with distilled water to prepare an analytical sample, determined physicochemical parameters allowed to discriminate which anions are causing basalt weathering.

Solar Photo-Assisted Degradation of Bipyridinium Herbicides at Circumneutral pH: A Life Cycle Assessment Approach

This study investigated the degradation of the herbicides diquat (DQ) and paraquat (PQ) by a solar photo-Fenton process that is mediated by Fe(III)-oxalate complexes at circumneutral pH = 6.5 in compound parabolic collectors (CPC)-type reactors. The photo-Fenton process operates efficiently at acidic pH; however, circumneutral operation was key to overcome drawbacks, such as acidification and neutralization steps, reagent costs, and the environmental footprint of chemical auxiliaries. This work revealed a remarkable reduction of total organic carbon for PQ (87%) and DQ (80%) after 300 min (at ca. 875 kJ L−1). Phytotoxicity assays confirmed that the treatment led to a considerable increase in the germination index for DQ (i.e., from 4.7% to 55.8%) and PQ (i.e., from 16.5% to 59.7%) using Cucumis sativus seeds. Importantly, treatment costs (DQ = USD$8.05 and PQ = USD$7.72) and the carbon footprint of the process (DQ = 7.37 and PQ = 6.29 kg CO2-Eqv/m3) were within the ranges that were reported for the treatment of recalcitrant substances at acidic conditions in CPC-type reactors. Life cycle assessment (LCA) evidenced that H2O2 and electricity consumption are the variables with the highest environmental impact because they contribute with ca. 70% of the carbon footprint of the process. Under the studied conditions, a further reduction in H2O2 use is counterproductive, because it could impact process performance and effluent quality. On the other hand, the main drawback of the process (i.e., energy consumption) can be reduced by using renewable energies. The sensitivity study evidenced that carbon footprint is dependent on the energy share of the local electricity mix; therefore, the use of more renewable electrical energy sources, such as wind-power and photovoltaic, can reduce greenhouse gases emissions of the process an average of 26.4% (DQ = 5.57 and PQ = 4.51 kg CO2-Eqv/m3) and 78.4% (DQ = 3.72 and PQ = 2.65 kg CO2-Eqv/m3), respectively. Finally, from the economic and environmental points of view, the experimental results evidenced that photo-assisted treatment at circumneutral pH is an efficient alternative to deal with quaternary bipyridinium compounds

Eliminación de arsénico del suelo mediante una barrera reactiva permeable de hierro acoplada a un proceso electroquímico

This paper presents a study in which it is tested the effectiveness of zero-valent iron for arsenic remediation of a soil treatment leachate, experimental approach considers to investigate Fe° permeable reactive barrier performance for the treatment of arsenic polluted soil obtained from a mining area in central Mexico. By applying electro-remotion using a series of continuous-flow columns, allowed to obtain experimental data for critical parameters optimization to electro remediate the polluted soil, as electroosmotic flow occurs across the columns. A flow-through electrochemical reactor with major capacity was used to scale up the treatment. This experimental disposition was used with a soil sample in which porosity was enhanced by the presence of glass-fiber (relation of 1:1). Application of a 45 mA current during 7 h in an electrochemical treatment allowed obtaining arsenic removal efficiencies around 94 % at pH 7 and close to 41 % at pH 11. Polarography results indicates there is a strong interaction of Fe(OH)3(s) - AsO4 3- in specific conditions, which results the highest electroremotion of As(III) at neutral pH

Eliminación de arsénico del suelo mediante una barrera reactiva permeable de hierro acoplada a un proceso electroquímico

This paper presents a study in which it is tested the effectiveness of zero-valent iron for arsenic remediation of a soil treatment leachate, experimental approach considers to investigate Fe° permeable reactive barrier performance for the treatment of arsenic polluted soil obtained from a mining area in central Mexico. By applying electro-remotion using a series of continuous-flow columns, allowed to obtain experimental data for critical parameters optimization to electro remediate the polluted soil, as electroosmotic flow occurs across the columns. A flow-through electrochemical reactor with major capacity was used to scale up the treatment. This experimental disposition was used with a soil sample in which porosity was enhanced by the presence of glass-fiber (relation of 1:1). Application of a 45 mA current during 7 h in an electrochemical treatment allowed obtaining arsenic removal efficiencies around 94 % at pH 7 and close to 41 % at pH 11. Polarography results indicates there is a strong interaction of Fe(OH)3(s) - AsO4 3- in specific conditions, which results the highest electroremotion of As(III) at neutral pH