Rhodococcus erytropolis applied for the removal of crystal violet from aqueous solutions

ESCUDERO, LETICIA B.; CANIZO, BRENDA V.; WEVAR OLER A.; AGOSTINI E.

San Luis

Congreso; VII Congreso Argentino de la Sociedad de Toxicología y Química Ambiental; 2018

SETAC ARGENTINA

Crystal violet (CV), a triphenylmethane dye, is a pollutant that is introduced into the environment mainly as waste from the textile industry. It is also used as mutagenic and bacteriostatic agent in medical solutions and antimicrobial agent to avoid the fungal growth in poultry feed. The presence of this dye molecule in the environment during a large period of time cause disorders in human health such as allergy, cyanosis, and skin irritation. The ingestion of CV is associated with nausea, headache, mental confusion, increase of the heart rate. Therefore, considerable interest in the development of more studies regarding to the removal of CV from the environment has arisen in the research field. Several operations have been applied in order to remove CV from wastewaters, including biological treatments, coagulation, oxidation, membrane filtration. However, biosorption is an excellent alternative to eliminate contaminants due to it is a low-cost, simple and efficient operation. Within biological substrates used for biosorption purposes, bacteria are known as promising biosorbents, since they offer a large area/volume ratio, low cost and relatively simple growth.To date, there are few studies of biosorption reported in the literature that use biomass of Rhodococcus erytropolis for the elimination of toxic compounds. In this context, the objective of this work was to study the biosorption between the aforementioned bacteria and the CV dye, for its removal from aqueous solutions. The biosorbent was characterized by zero charge point (pHZPC), infrared Fourier transform spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray scattering energy spectroscopy (EDS). A factorial design 32 was developed to optimize the pH and biosorbent mass. Under optimal experimental conditions (pH: 9, biosorbent concentration: 12.5 mg), a biosorption capacity of 90 mg/g and a removal of CV of 93% was achieved. Moreover, a kinetic study was performed and the results showed that the removal of the elemental species took place quickly, reaching the maximum response practically during the first 90 minutes of contact. These results showed that Rhodococcus erytropolis biomass is efficient for the removal of CV from aqueous solutions, following the concept of "green chemistry", by minimizing the use of reagents and the generation of toxic waste to the environment.