Carmencita Lavado-Meza

Face Centered Cube Central Composite Design (FCCCCD) methodology was applied to optimize the Cr(VI) adsorption capacity of Arabica-coffee pulp biomass (WAC), qe, as a function of key-factors, such as pH, chromium concentration C0 and WAC-dose. The quadratic dependence of qe, with the considered...

El material particulado (MP) es un contaminante atmosférico que representa un desafío significativo para la calidad del aire en diversas ciudades, incluyendo Huancayo, Perú. El objetivo de este artículo es analizar desde la revisión documental el efecto del material particulado y humedad de suelo en Huancayo y Pampas/ Perú. Se centra en la investigación cualitativa, el estilo de investigación es de carácter descriptivo-hermenéutico, documental y bibliográfico. La muestra son los documentos alusivos al tema tanto nacional como internacional. El diseño fue documental. Se tuvo como resultado que, un estudio teórico experimental sobre la influencia del material particulado (PM2.5) emitido por plantas hidrometalúrgicas en Nasca indica que este afecta la calidad del aire, del suelo y el agua en áreas circundantes. Concluyendo que, las concentraciones promedio de PM10 (92.3, 48.5 y 89.5 µg/m³) y PM2.5 (14.0, 7.0 y 22.3 µg/m³) en Huancayo se encuentran dentro de los estándares de calidad ambiental.

En la etapa de docencia que realice desde el año 2014, he presenciado ausencia de bibliografía peruana adecuada para los cursos relacionados a la contaminación del aire. Así mismo, he observado en aula la deficiencia en los estudiantes de pregrado en la manipulación de modelos atmosféricos, procesamiento de datos satelitales y compresión en la temática de contaminación de aire, con especial interés en aerosoles atmosféricos También he observado la falta de motivación al investigar temas relacionados a los aerosoles atmosféricos. Por ello, me he motivado en escribir el presente libro con gran apoyo de los demás autores, para inculcar y motivar a los lectores a realizar investigaciones que contribuyan a plantear soluciones para mitigar impactos ambientales ocasionados por los aerosoles atmosféricos. Por ello el presente libro de investigación constituye una versión que plantea investigaciones y conceptos básicos relacionados a la temática o área de aerosoles atmosfericos, enfocados a la contaminación del aire y a la vez al cambio climático, así mismo aborda las amenazas e impactos ambientales. Así mismo, en el presente libro se plasma conocimientos de ciencia e ingeniería, y estará disponible para profesionales, maestros y estudiantes. Con esto es posible situar de forma apropiada al público laico en asuntos de contaminación del aire por aerosoles atmosféricos. Por consecuencia, estoy agradecido y en deuda con mis colegas científicos por sus ideas sobre cómo incorporar las nuevas tendencias de investigaciones atmosféricas.

This work presents results of Aerosol Optical Depth (AOD) and Direct Radiative Force (DRF) at the top of the atmosphere (TOA), obtained during monitoring campaigns carried out at the Huancayo Observatory of the Geophysical Institute of Peru (OH-IGP ) in April and August 2022. In these campaigns, a Sun CIMEL photometer was used to measure the microphysical and optical properties of aerosols at wavelengths ranging from 340 to 1020 nm, and a low-cost Purple-air sensor to quantify the concentration of material particulate (PM), in fine and coarse modes. The AOD results indicated values in the range 0.06-0.22. The daily averages of PM2.5 and PM10 did not exceed Peru's current Environmental Quality Standards (50 μg/m3 and 100 μg/m3). The air quality index (AQI) calculated for PM2.5 and PM10 was classified as good. On some days during the campaigns, the air quality was classified as moderate. These results contribute to a better understanding of the current climatic conditions of the Peruvian Altiplano.

El principal objetivo de esta investigación es evaluar el efecto que produce el aprendizaje basado en problemas para desarrollar competencias matemáticas en estudiantes de administración y sistemas en una universidad privada de Chanchamayo (Perú). La metodología es cuantitativa, de nivel explicativo y con diseño cuasi experimental. El grupo experimental está formado por estudiantes de administración y sistemas y el grupo control por estudiantes de derecho, ambos de primer semestre. Se diseñaron tres instrumentos para evaluar las competencias matemáticas. Los resultados en el post test evidencian diferencias significativas respecto al grupo control: ningún estudiante se encuentra en el nivel bueno, mientras que el grupo experimental alcanzó el 25% de los estudiantes en este nivel máximo. En conclusión, el aprendizaje basado en problemas mejora significativamente el desarrollo de competencias matemáticas en futuros profesionales de administración y sistemas.

Theobroma cacao agro-industrial waste (WTC) has been characterized and tested as an effective biosorbent to remove Cd(II) from aqueous media. At the optimum pH of 5.0, a maximum adsorption capacity of q_e,max = 58.5 mg g⁻¹ was determined. The structural and morphological characterization have been conducted by FTIR, SEM/EDX, and TGA measurements. The SEM/EDX results confirmed that the metals are adsorbed on the surface. C-O-C, OH, CH, NH, and C=O functional groups were identified by FTIR. TGA results were consistent with the presence of hemicellulose. Biosorption kinetics were rapid during the first 30 min and then reached equilibrium. The corresponding experimental data were well fitted to pseudo-first and -second order models, the latter being the best. The biosorption isotherm data were also well fitted to Temkin, Langmuir, and Freundlich models, showing that several sorption mechanisms may be involved in the Cd(II) biosorption process, which was characterized as exothermic (ΔH⁰ < 0), feasible, and spontaneous (ΔG⁰ < 0). In binary (Cd–Pb and Cd–Cu) and ternary (Cd–Pb–Cu) systems, Cu(II) and particularly Pb(II) co-cations exert strong antagonistic effects. Using HNO₃, effective good regeneration of WTC was obtained to efficiently remove Cd(II) up to three times.

In this study, cladodes of Opuntia ficus indica (OFIC), chemically modified with NaOH (OFICM), have been prepared, characterized, and tested as an effective biomass to remove Pb(II) and/or Cd(II) from aqueous media. At an optimum pH of 4.5, the adsorption capacity, q_e, of treated OFICM was almost four times higher than that of untreated OFIC. The maximum adsorption capacities (q_max) in the single removal of Pb(II) and Cd(II) were 116.8 and 64.7 mg g⁻¹, respectively. These values were 12.1% and 70.6% higher than those for the corresponding q_max in binary removal, which indicates the strong inhibitive effect of Pb(II) on the co-cation Cd(II) in a binary system. Structural and morphological characterization have been carried out by FTIR, SEM/EDX, and point of zero charge (pH_PZC) measurements. The SEM/EDX results confirmed that the metals are adsorbed on the surface. The presence of C-O, C=O, and COO- functional groups were identified by FTIR on both OFIC and OFICM surfaces. On the other hand, we found that the adsorption processes followed the pseudo-second-order kinetics for both single and binary systems, with a fast biosorption rate of Pb(II) and Cd(II). The equilibrium data (adsorption isotherms) were better described by Langmuir and modified-Langmuir models for single and binary systems, respectively. A good regeneration of OFICM was obtained with an eluent of 0.1 M HNO₃. Therefore, OFICM can be efficiently reused to remove Pb or Cd, up to three times.

Arabica-coffee and Theobroma-cocoa agroindustrial wastes were treated with NaOH and characterized to efficiently remove Pb(II) from the aqueous media. The maximum Pb(II) adsorption capacities, q_max, of Arabica-coffee (WCAM) and Theobroma-cocoa (WCTM) biosorbents (q_max = 303.0 and 223.1 mg·g⁻¹, respectively) were almost twice that of the corresponding untreated wastes and were higher than those of other similar agro-industrial biosorbents reported in the literature. Structural, chemical, and morphological characterization were performed by FT-IR, SEM/EDX, and point of zero charge (pH_PZC) measurements. Both the WCAM and WCTM biosorbents showed typical uneven and rough cracked surfaces including the OH, C=O, COH, and C-O-C functional adsorbing groups. The optimal Pb(II) adsorption, reaching a high removal efficiency %R (>90%), occurred at a pH between 4 and 5 with a biosorbent dose of 2 g·L⁻¹. The experimental data for Pb(II) adsorption on WACM and WCTM were well fitted with the Langmuir-isotherm and pseudo-second order kinetic models. These indicated that Pb(II) adsorption is a chemisorption process with the presence of a monolayer mechanism. In addition, the deduced thermodynamic parameters showed the endothermic (ΔH⁰ > 0), feasible, and spontaneous (ΔG⁰ < 0) nature of the adsorption processes studied.

A new biosorbent based on Nostoc commune (NC) cyanobacteria, chemically modified with NaOH (NCM), has been prepared, characterized and tested as an effective biomass to remove Pb(II) in aqueous media. The adsorption capacity of NCM was determined to be q_e = 384.6 mg g⁻¹. It is higher than several other biosorbents reported in the literature. Structural and morphological characterization were performed by FTIR, SEM/EDX and point zero of charge pH (pH_PZC) measurements. NCM biosorbent showed more porous surfaces than those NC with heterogeneous plates including functional adsorption groups such as OH, C = O, COO⁻, COH or NH. Optimal Pb(II) adsorption occurred at pH 4.5 and 5.5 with a biomass dose of 0.5 g L⁻¹. The experimental data of the adsorption process were well fitted with the Freundlich-isotherm model and pseudo-2nd order kinetics, which indicated that Pb(II) adsorption was a chemisorption process on heterogeneous surfaces of NCM. According to the thermodynamic parameters, this process was exothermic (∆H⁰ < 0), feasible and spontaneous (∆G⁰ < 0). NCM can be regenerated and efficiently reused up to 4 times (%D > 92%). NCM was also tested to remove Pb (%R~98%) and Ca (%R~64%) from real wastewater.

Agro-industrial waste biosorbents of arabica–coffee (WCA) and theobroma–cocoa (WCT) have been characterized and tested to remove Pb(II) from aqueous media. The maximum adsorption capacity of WCA and WCT (q_max = 158.7 and 123.5 mg·g⁻¹, respectively) is comparable or even higher than for several other similar agro-industrial waste biosorbents reported in the literature. Structural and morphological characterization were performed by infrared spectrometry with Fourier transform (FT-IR), scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), and charge measurements at the zero point charge (pH_PZC). Both biosorbents, WCA and WCT, show cracked surfaces with heterogeneous plates which ones include functional adsorption groups such as OH, C = O and C-O-C. Optimal Pb(II) adsorption occurs for a pH between 4 and 5 at [WCA] and [WCT] dose concentrations of 2 g·L⁻¹. We found that the adsorption process follows pseudo-second order kinetics with a rapid growth rate (almost six times larger for WCA than for WCT), basically controlled by the chemisorption process. The regeneration of both biosorbents was carried out in an eluent of 0.1M HNO₃ and they can be efficiently reused up to 5 times.