The environmental problems in Peru are rooted in the waste management of the residual agricultural biomass. Via our cooperative international research, nine different agricultural wastes from Peru were used as renewable sources to produce activated carbons that were tested in gas-phase xylene adsorption. The special properties of agro-waste activated carbons are the very large mesopore surface area, the narrow pore size distribution within the microporous–mesoporous region, and the slightly acidic character in the presence of oxygen-containing surface groups. The textural, structural, and surface properties of nine agro-waste activated carbons were correlated with their adsorption capacities in xylene adsorption and compared with those of a commercial activated carbon made of black coal. Adsorption capacities of agro-waste activated carbons were in the range of 371–115 mgxylene/gAC, whereas the adsorption capacity was 214 mgxylene/gAC for black coal-activated carbon. Higher adsorption capacities of ACs can be assigned to the synergism of their textural properties (larger mesopore surface area and larger micropore volume related to total pore volume) and their surface properties (lower content of surface oxygen functional groups related to their less acidic character and higher π–π* transitions in aromatic rings resulting in fewer defects within the graphitic structure).

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Aplicación de tecnología de oxidación avanzada en la descontaminación de aguas residuales procedentes del empaque de banano en Tumbes Application of advanced oxidation technology in the decontamination of wastewater from banana packing in Tumbes

Much research related to the production of materials with high-quality adsorption capacity from agricultural residues has been done. However, the adsorbents themselves do not have the antibacterial capacity, an essential property in different water treatment applications. Hydrothermal treatment is an environmentally friendly approach to impregnated nanoparticles over a substrate. This paper aims to obtain and characterize activated carbon made of corn cob and red mombin seed impregnated with chitosan via the hydrothermal treatment to be tested as an antibacterial material for aqueous phase applications. The FESEM micrographics, RAMAN spectroscopy, and FTIR-ATR analyses confirmed the presence of chitosan nanoparticles (NPs) over the surface of the activated carbons. The impregnation of Chitosan NPs affected the pore size distribution in the activated carbon, but not total pore surface area or pore volume. The impregnation of chitosan increases the antibacterial capacity against Escherichia coli and Shigella flexneri.

ResumenLa presente investigación tuvo como objetivo producir carbón activado mediante activación química de un material no convencional, residuos de cáscara de zapallo "hueso" (Cucurbita sp.), con la finalidad de remover el cloro total y residual del agua potable que llega a viviendas de la ciudad de Tumbes. La activación de la biomasa residual se realizó con cloruro de zinc a 600 °C durante un periodo de 2 h en atmosfera de nitrógeno. El carbón activado preparado a partir de cascara de zapallo mostro una buena estructura micro-mesoporosa alcanzando un área superficial de 774,6 m 2 /g, volumen total de poros de 0,50 cm 3 /g y un volumen microporoso de 0,34 cm 3 /g. El adsorbente producido se utilizó para remover satisfactoriamente el cloro total y residual de agua potable que llega a cinco zonas de la ciudad de Tumbes. Los datos de cinética de adsorción de cloro residual y total por parte del carbón activado producido se ajustan mejor al modelo de pseudosegundo orden con valores máximos de capacidad de adsorción en el equilibrio (qe) de cloro residual y total de hasta 3,6 y 3,1 mg/g respectivamente. Adicionalmente el hecho de que los datos de cinética de adsorción se ajusten al modelo de difusión intraparticular supone que este es el mecanismo que limita el proceso de adsorción. Los porcentajes de remoción de cloro total y residual del agua potable llegan a valores de hasta 100%. El carbón activado producido de cáscara de zapallo es un adsorbente promisorio para su uso en el tratamiento de agua. AbstractThis research aimed to produce activated carbon by chemical activation of an unconventional material, squash (Cucurbita sp.) peel residues, with the purpose of removing total and free chlorine from drinking water in Tumbes city. Activation of the residual biomass was carried out with zinc chloride at 600 °C for of 2 h in inert conditions (nitrogen flux). Prepared activated carbon depicted a good micro-mesoporous structure reaching a surface area of 774.6 m 2 /g, total pore volume of 0.50 cm 3 /g and a microporous volume of 0.34 cm 3 /g. The produced adsorbent was used to satisfactorily remove of total and free chlorine of drinking water in Tumbes city. The free and total chlorine adsorption kinetics data from the produced activated carbon are adjusted the best to the pseudo-second order model with maximum values of equilibrium adsorption capacity (qe) of free and total chlorine of up to 3.6 and 3.1 mg/g respectively. Additionally, the fact that the adsorption kinetic data are adjusted to the intraparticular diffusion model assumes that this is the mechanism that limits the adsorption process. The percentages of removal of total and residual chlorine from drinking water reach values of up to 100%. Produced activated carbon from squash peel is a promising adsorbent for using in water treatment.

ResumenDiferentes carbones activados fueron obtenidos de residuos agroindustriales de los departamentos de Piura y Tumbes (Perú): cáscara de la vaina de Theobroma cacao, parte externa e interna de la semilla de Manguifera indica y cáscara de Coffea arabica. Los materiales tamizados a tamaños de 0,5 -1 mm fueron activados químicamente con ZnCl2 y carbonizados en atmosfera de nitrógeno por 2 horas a 600 °C. Los carbones activados fueron caracterizados como rendimiento (%), análisis elemental (%), área superficial de BET (Brunauer-Emmett-Teller, SBET) en m 2 /g, área superficial en la región microporasa en m 2 /g y área superficial en la región mesoporosa en m 2 /g. Se aplicaron también análisis de microscopia y test de adsorción de azul de metileno. Se obtuvieron carbones con alta área superficial de BET de entre 892 y 1180 m 2 /g, y predominante área superficial en la región microporosa. Basados en imágenes de microscopia electrónica, los carbones activados presentan una estructura porosa bien desarrollada, con distintos poros de múltiples formas y tamaño. Todas las muestras de carbones activados analizados, presentaron capacidad de remoción de azul de metileno, llegando a remociones de casi el 100 %. Adicionalmente el tipo de interacción entre el azul de metileno y el carbón activado es de naturaleza química al ajustarse los valores de remoción a un modelo de cinética de pseudo-segundo orden.Palabras clave: carbón activado, residuos agroindustriales, activación ZnCl2, características poros, adsorción azul de metileno Abstract Different activated carbons were obtained from agro-industrial waste of Piura and Tumbes (Peru): shell pod of Theobroma cacao, outside and inside part of Manguifera indica pits and husk of Coffea arabica. Materials sizes of 0.5 to 1 mm were chemically activated with ZnCl2 and carbonized under nitrogen for 2 hours at 600°C. Activated carbons were characterized as yield (%), elemental analysis (%) surface area BET (Brunauer-Emmett-Teller, SBET) in m 2 /g, surface area on microporous region in m 2 /g, surface area in the region mesoporous in m 2 /g, and methylene blue adsorption test were performed. The obtained activated carbons exhibited high BET surface area of between 892 and 1180 m 2 /g, and predominant superficial area in the microporous region. Based on electron microscopy images, the activated carbons present a porous developed well structure with different pores of many shapes and sizes. All samples analyzed showed activated carbon removal capacity of methylene blue, reaching removal of almost 100%. Additionally the type of interaction between the methylene blue is activated carbon and chemical nature of the removal values adjusted to a kinetic model of pseudo-second order

Tratamiento complementario de agua potable utilizando un filtro de carbón activado impregnado con quitosano producidos a partir de biomasa residual Complementary treatment of potable water using a filter of activated carbon impregnated with chitosan