This work has been financially supported by the International Program for Physical Science of Uppsala University (IPPS), the Instituto de Investigación of Universidad Nacional de Ingenieria, and CONCYTEC (Peruvian Research Council).

The research of new materials and methods for water treatment is necessary. Two sets of materials were prepared. The one set is composed from CuO/ZnO oxides with variable content of CuO and the second set consists of its biochar impregnated counterparts. The structure and phase composition was determined using X-ray diffraction method and morphology of the materials was studied using scanning electron microscopy. The photodegradation activity and adsorption properties were tested on model pollutant - Methylene blue (MB) dye solution. The experimental kinetic of the data was analyzed using pseudo-first-order and pseudo-second-order kinetic models and the equilibrium data was evaluated using Langmuir, Freundlich and Dubinin-Radushkievic models. It was found that optimal material for photodegradation of MB is 1% CuO/ZnO oxide and for the adsorption of MB is the best material raw corn cob bi...

A millenary building material that has been used in many cultures is "adobe". In the Peruvian Andean regions during the winter, the temperature decreases drastically (+5 to -15°C), affecting the health of people of vulnerable age, agriculture and bovine livestock. Bioclimatic techniques must be considered to provide a comfortable thermal environment in the interior of housing. Furthermore, knowing the thermal conductivity of the elements that compose the houses allows us to perform thermal exchange simulations before construction is developed. Specifically, in this investigation, the thermal conductivity of adobe with and without Stipa ichu was measured as 0.371 W/m K and 0.349 W/m K, respectively, considering the norm ASTM C177 for that purpose. The mechanical behavior is as important as the thermal properties, and a value of 2.41 N/mm2 was obtained for unit compression. Additionally, ...

Nanoestructured TiO2 solar cells modified with MgO (TiO2-MgO) were assembled and characterized; they were sensitized with N791 dye. The MgO modification of the TiO2 films was performed using suspensions with different concentrations of Mg(OH)2 prepared from magnesium nitrate in aqueous solution. One drop of the suspension was placed on top of the film and then was sintered at 530 °C during 30 min. Unsealed cells and sealed cells were obtained, the latter achieved an efficiency of 4.4%, representing an increase of 69% compared to the unmodified sealed cells, which showed an efficiency of 2.6%. Solar efficiency measurements were also performed in darkness and under illumination. It was found that the efficiency diminished 19% in darkness after 22 days, but under illumination diminished 76 % in two days. 

Spherical cooper oxide (CuO) nanoparticles were synthetized by wet route using cooperacetate and sodium hydroxide. The CuO nanoparticles were characterized by dynamiclight scattering (DLS) and small angle X-ray scattering (SAXS). Furthermore to completestructural and morphological studies of the nanoparticles were performed X-ray diffractionand electron microscopy analysis. The results displayed that the CuO nanoparticles showedhigh dispersion; however, has a narrow size distribution for particles with size less than100 nm. Besides, the correlation between dispersion analysis, light and X-ray, and X-raydiffraction and electron microscopy was very good.

The characterization of the thermal insulation properties of construction materials represents a fundamental step on building insulation assessment. The present work aims to design and build a portable apparatus, namely, Portable LAMBDA UNI, capable of measuring the thermal conductivity of insulation materials. This portable apparatus is based on the standard ASTM C 518, which is a secondary method for measuring thermal conductivity. The apparatus also measures the effective thermal conductivity of square prism thermal insulation materials of 60 mm per side and a maximum thickness of 14 mm. The thermal conductivity of the drywall and adobe with Stipa ichu was measured with the Portable LAMBDA UNI, with the values being 0.265 W m-1 K-1and 0.357 W m-1 K-1, respectively. © 2021 Published under licence by IOP Publishing Ltd.

This work was financially supported by the University of Buenos Aires (UBACyT; TX 117 and X093), ANPCyT (Agencia nacional de Promoción de Ciencia y Tecnología) PICT 10621, the International Program for Physical Science of Uppsala University, Sweden (IPPS), the Research Institute of Universidad Nacional de Ingeniería, the CONCYTEC (Peruvian Research Council), and CYTED network VIII-G.

The Academy of Sciences of the Czech Republic and Consejo Nacional de Ciencia, Tecnologia e Innovación Tecno-lógica (CONCYTEC) in Peru (joint project reg. No. 002/PE/ 2012) are gratefully recognized for their support.

Composite material (AC-ZnO) was prepared by growing ZnO nanoparticles during the production of biomass based-activated carbon (AC) via the incorporation of zinc acetate in the process. Comprehensive analyses confirmed the presence of ZnO nanoparticles over the AC surface and described the particular nature of the composite adsorbent. Methylene blue (MB) equilibrium data fitted the Dubinin-Radushkevich model. The MB adsorption capacity was higher for the bare activated carbons (197.9–188.7 mg/g) than the activated carbons with ZnO nanoparticles (137.6–149.7 mg/g). The adsorption of the MB on the adsorbents is physical because the mean adsorption energy (E) is between 1.76 and 2.00 kJ/mol. Experiments that combine adsorption and photocatalysis were carried out with different loads of adsorbents and with and without UV-light exposure. Photocatalytic activity was identified mostly at the...

ZnCl2-activated carbon was prepared using coffee husk for phosphate adsorption in aqueous solutions. Textural, morphological and structural analyses were carried out to characterize the produced materials. XRD detected the presence of ZnO in the activated carbon structure, and the measured nitrogen isotherm showed a micro-macroporous structure with 989 m2/g of specific surface area for this material. Phosphate equilibrium and kinetic experiments were conducted. Equilibrium data fit best to the Dubinin-Radushkevich model (r2≥0.96), with maximum adsorption capacities of 59.38 – 63.87 mg P/g in the pH range between 5 and 9. Intraparticle diffusion was the rate-limiting mechanism of the adsorption.

An activated carbon (adsorbent) was prepared from a forestry residual biomass (Capparis scabrida sawdust) by chemical activation with ZnCl2. The adsorbent was tested in kinetic experiments to remove three anionic dyes widely used in the food industry: tartrazine (TR), brilliant scarlet 4R (BS4R) and brilliant blue (BB). The adsorbent was able to remove the dyes in different intensities, and the revealed order of their adsorption ability was BS4R>TR>BB. Most of the kinetic data fit best to the pseudo-second order model; however, high accordance with other models indicates that there is more than one phenomenon to explain the adsorption process. Analyzing the data that fit well to the pseudo-second order model and considering that the equilibrium was reached, the equilibrium adsorption capacity (qe) for TR was 55.3 mg/g (when the AC load was 1 g/l and the TR initial concentration was 50 mg...

Arsenic (As) exposure from surface and groundwater in Peru is being recognised as a potential threat but there are limited studies on As in the food-chain and none on As in Peruvian rice. In this study, we have determined the As content in rice cultivated in the Tumbes river basin located in the northern province of Peru, an area known for extensive rice cultivation. We collected rice and soil samples from agricultural fields, soil was collected using grid sampling technique while rice was collected from the heaps of harvested crop placed across the fields. The average total As concentration in rice was 167.94 ± 71 μg kg−1 (n = 29; range 68.39–345.31 μg kg−1). While the rice As levels were not highly elevated, the As content of few samples (n = 7) greater than 200 μg kg−1 could contribute negatively to human health upon chronic exposure. Average concentration of As in soil wa...

The utilization of unconventional agricultural wastes to obtain new porous carbonaceous materials, at mild pyrolysis temperatures and without complex procedures, for either water treatment and energy storage applications is important from the economic and environmental perspective. In this study, biochars and hydrochars were prepared from banana rachis, cocoa pod husks, and rice husks at 600 °C-2 h, under nitrogen flux. The prepared materials were characterized to better understand how their morphological, textural, physical-chemical and/or structural properties correlate with their methylene blue (MB) adsorption capacities. The material with the best properties (mainly SBET > 800 m2/g) and MB adsorption capacity was a novel biochar prepared from banana rachis (BW-BC). This novel material was selected for additional kinetics and equilibrium adsorption tests for lead (Pb) along with i...

Se produjo biocarbón a partir de residuos de coronta de maíz (Zea mays) para remover plomo de soluciones acuosas. La carbonización del residuo se realizó a 600 °C por 2 h a 1 atmosfera de nitrógeno controlada. Se realizaron análisis texturales, morfológicos y estructurales para caracterizar el material. De los datos de la isoterma de adsorción de N2, el material mostró una estructura microporosa de 144,13 m2/g de área superficial. Se realizaron experimentos de adsorción de Pb2+ en equilibrio y cinética, donde los datos de equilibrio se ajustan mejor al modelo de Dubinin-Radushkevich (R2 ≥ 0,990) con capacidad de adsorción máxima de 12,16 mg/g con. Asimismo, para los datos de cinética, el modelo con mejor ajuste fue el de Elovich (R2 ≥ 0,994). Sin embargo, la cinética de adsorción también se ajustó a los modelos de Pseudo-Primer orden (R2 ≥ 0,990) y Pseudo- Segun...

Se produjo biocarbón a partir de residuos de coronta de maíz (Zea mays) para remover plomo de soluciones acuosas. La carbonización del residuo se realizó a 600 °C por 2 h a 1 atmosfera de nitrógeno controlada. Se realizaron análisis texturales, morfológicos y estructurales para caracterizar el material. De los datos de la isoterma de adsorción de N2, el material mostró una estructura microporosa de 144,13 m2/g de área superficial. Se realizaron experimentos de adsorción de Pb2+ en equilibrio y cinética, donde los datos de equilibrio se ajustan mejor al modelo de Dubinin-Radushkevich (R2 ≥ 0,990) con capacidad de adsorción máxima de 12,16 mg/g con. Asimismo, para los datos de cinética, el modelo con mejor ajuste fue el de Elovich (R2 ≥ 0,994). Sin embargo, la cinética de adsorción también se ajustó a los modelos de Pseudo-Primer orden (R2 ≥ 0,990) y Pseudo- Segun...