Carlos Alexander Lucho-Constantino

Manganese accumulation in plants of the mining zone of Hidalgo, Mexico

Soil, sediments, water and plant samples from the mining zone of Molango were collected and analyzed and Mn-tolerant and Mn-accumulator plants were identified. Soil and sediments presented moderately alkaline and reducing conditions, a normal electrical conductivity, a sandy texture and medium-to-high cation exchange capacities. These properties favored the presence of Mn(2+), which is the form most easily assimilated by plants, and the total Mn concentration (11,637-106,104 mg kg(-1) dried weight, DW) was at phytotoxic level. Water was also an important Mn source. Equisetum hyemale and Telypteris kunthii survived in the presence of such Mn concentrations using an exclusion strategy, while Cnidoscolus multilobus, Platanus mexicana, Solanum diversifolium, Asclepius curassavica L. and Pluchea sympitifolia employed an accumulation strategy. These plants could be useful to re-vegetate and stabilize Mn tailings in order to decrease the erosion effects.

Cadmium Removal from Aqueous Systems Using Opuntia albicarpa L. Scheinvar as Biosorbent.

The aim of this research was to investigate the use of a natural adsorbent like nopal (Opuntia albicarpa L. Scheinvar) for removing cadmium from aqueous solutions with low concentrations of this metal. Two treatments were applied to the cladodes: a dehydration to get dehydrated nopal (DHN) and heating up to 90°C to obtain a thermally treated nopal (TN). After examining the effect of various pH values (2–7), the capacity of each biosorbent was examined in batch sorption tests at different dosages (0, 500, 1000, 1500, 2000, and 3000 mg L−1). The results indicated that adsorption of cadmium to biomass of DHN and TN was highly dependent on pH and biosorbent dosage. The best removal of cadmium (53.3%, corresponding to q e of 0.155 mg g−1) was obtained at pH 4.0 by using the TN sorbent. Infrared and Raman spectra confirmed that cadmium removal occurred via adsorption to –OH functional groups.