Activated carbons were obtained from cocoa pod husk using two different initial particle sizes (ranges 0.25-0.50mm and 0.50-1.00mm), three chemical activation agents (K 2 CO 3 , KOH and ZnCl 2) and carbonization under nitrogen atmosphere during two hours at three different temperatures (500°C, 650°C and 800°C). The prepared activated carbons were characterized using Brunauer-Emmett-Teller (BET) and Langmuir surface areas, pore volume, average pore size, bulk density, moisture, ash content, and yield. The five best activated carbons were selected for further experiments according to the chemical activation agent used, high BET surface area, high pore volume and low ash content. Additionally, content of impurities, carbon content and FE-SEM micrographs were determined for these five best activated carbons. As adsorption tests were also carried out with these samples. Results of the experiments show that cocoa pod husk is a material that can be used to produce activated carbon by chemical activation and ZnCl 2 showed to be the best chemical activation agent based on the highest BET surface area (780 m 2 /g in the best case) and pore volume (0.58 m 3 /g in the best case), the lowest ash content (6.14% in the best case), and the highest carbon content (86.1% in the best case), compared with others chemicals. Carbons activated by ZnCl 2 are capable to adsorb As(V), getting As(V) removal levels up to 80% in less than 1 hour in the experimental conditions applied (initial pH 6-7, activated carbon concentration 0.1 g/l and 0.5 g/l, initial As concentration 100 ppb).

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Microporous-mesoporous activated carbons from five different types of agro-industrial wastes were produced using chemical activation with ZnCl 2 and carbonization at mild conditions of 600°C, comprehensively characterized and investigated for removal of methylene blue (MB) in aqueous solution, a model large-molecular-size organic pollutant. The external part of the mango pit (mango seed husk) was used for the production of activated carbon (AC) for the first time. Despite that the raw agro-materials exhibited significantly different porosity, all activated carbons produced possessed well-developed microporousmesoporous structures showing high surface areas and micropore volumes. Further, it was revealed that the pore size distribution of raw agro-material is a more important property in development of microporousmesoporous structure of produced ACs than their overall porosity. All activated carbons produced adsorbed MB, reaching in most cases 100 % removal from the aqueous phase. Adsorption data were fitted well to a pseudo-second-order kinetic model. For MB adsorption, the mesoporosity and the ratio of micropores accessible for MB were the key factors since there exists the sizeselectivity effect on MB adsorption due to MB molecular dimensions. The molecular dimensions of MB were estimated via DFT calculations to 1.66×0.82×0.54 nm, and this parameter was correlated with determined micropore size distributions of activated carbons. AbbreviationsS BET specific surface area calculated according to the classical BET theory (m 2 /g) S meso mesopore surface area calculated according to the modified BET equation (m 2 /g) V intruse pore volume determined by highpressure mercury intrusion (cm 3 /g) Water Air Soil Pollut (2015) 226:214

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 was 8.63 ± 7.8 mg kg-1 (n=30) and soil to grain transfer factor was 0.025 ± 0.018 for 12 matched samples. Compared to our previous pilot study in 2006 (samples collected from the same agricultural fields but not from exact locations) there was a 41% decrease in As soil concentration in this study. Rice samples collected in 2006 (n=5) had a mean concentration of 420 ± 109 µg kg-1. Our data provides a baseline of rice grain As concentrations in Peruvian province of Tumbes and warrants further studies on factors affecting uptake of As by the rice varieties cultivated in Peru and any potential human health risks.

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).

Two unconventional raw materials, the seeds from Spondias purpurea L. (red mombin) and Inga edulis (ice cream bean), were characterized and used as precursors to produce good‐quality zinc chloride‐activated carbons for potential use in water treatment applications. The red mombin seed was significantly more porous than the ice cream bean seed, while the activated carbons prepared from red mombin seed and ice cream bean seeds showed both a very well‐established microporous‐mesoporous structure. Equilibrium as well as kinetic adsorption experiments were conducted with methylene blue, methyl orange, and As(V). It was revealed that both seeds are unconventional, renewable, cheap, and suitable agro‐precursors for production of activated carbons with potential application in wastewater treatment.

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 first stage of the adsorption process and, in the case of experiments with less load of the composite AC-ZnO, because the light obstruction effect of the activated carbon is more for higher loads. The ZnO grown over AC improves the adsorption of cations such as Pb, Al and Fe in aqueous phase (polluted river water) and provides antibacterial capacity against Escherichia coli and Salmonella typhimurium.