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.