orabase and ferrous-chloride

Biomass-based adsorbents have been widely studied as a cost-effective and environmentally-benign means to remove pollutants and nutrients from water. A two-stage treatment of aspen wood particles with solutions of carboxymethyl cellulose (CMC) and ferrous chloride afforded a biosorbent that was effective in removing phosphate from test solutions. FTIR spectroscopy of the biosorbent samples showed a decrease in the intensity of the carboxylate signal coinciding with a decrease in particle size. Elemental analysis results showed the iron content of both the biosorbent samples, and wood particles treated with ferrous chloride alone, to also decrease with particle size. The relationship between iron content and particle size for the biosorbent samples appeared to be a function of both the amount of CMC-Fe complex and the efficiency of removing free iron ions after treating. Sorption testing results showed a strong linear correlation between the phosphorous uptake capacities and the iron contents of the samples adjusted for losses of iron during testing. As anticipated, pretreating with the anionic polymer provided additional sites to complex iron and thereby imparted a greater phosphorous uptake capacity. Although the larger wood particles provided a greater amount of iron for phosphate removal, smaller wood particles may be preferred since they afforded the lowest release of iron relative to the amount of phosphate removed.

Topics: Adsorption; Carboxymethylcellulose Sodium; Ferrous Compounds; Particle Size; Phosphates; Phosphorus; Polymers; Spectroscopy, Fourier Transform Infrared; Wood

Biomass-based filtration media are of interest as an economical means to remove pollutants and nutrients found in stormwater runoff. Refined aspen wood fiber samples treated with iron salt solutions demonstrated limited capacities to remove (ortho)phosphate from test solutions. To provide additional sites for iron complex formation, and thereby impart a greater capacity for phosphate removal, a fiber pretreatment with an aqueous solution of a non-toxic anionic polymer, carboxymethyl cellulose (CMC), was evaluated. Problems with excessive viscosities during the screening of commercially available CMC products led to the selection of an ultra low viscosity CMC product that was still usable at a 4% concentration in water. Soxhlet extractions of chipped aspen wood and refined aspen wood fiber samples showed a higher extractives content for the refined material. Analysis of these extracts by FTIR spectroscopy suggested that the higher extractives content for the refined material resulted from the fragmentation of cell wall polymers (e.g., lignin, hemicelluloses) normally insoluble in their native states. Spectroscopic analysis of CMC and ferrous chloride treated fibers showed that the complex formed was sufficiently stable to resist removal during subsequent water washes. Equilibrium sorption data, which fit better with a Freundlich isotherm model than a Langmuir isotherm model, showed that phosphate removal could be enhanced by the CMC pretreatment. Results suggest that the process outlined may provide a facile means to improve the phosphate removal capacity of biomass-based stormwater filtration media.

Topics: Adsorption; Carboxymethylcellulose Sodium; Ferrous Compounds; Filtration; Phosphates; Populus; Temperature; Water Pollutants, Chemical; Wood