RESUMO
The data on the performance of sulfur polymer cement crosslinked with tung oil polymerization modifier are presented. Specimens of sulfur polymer cement (SPC) were prepared with different doses of tung oil in amounts of up to 8.85% of the sulfur mass. The obtained SPCs were used as binders to encapsulate two galvanic wastes differing in their toxic metal composition: waste I and waste II with loadings of approximately 25 and 50% of the composites' mass, respectively. For comparative purposes, appropriate samples of the SPCs and their composites with galvanic wastes were obtained using very similar doses of dicyclopentadiene sulfur modifier. Waste II was also encapsulated using SPC, in which a mixture of tung oil and dicyclopentadiene in a 1:1 weight ratio was used as the modifier. Crosslinking of the tung oil to the SPC matrix was assessed by FT-IR. The obtained SPCs and their composites with galvanic wastes were characterized by SEM and tested for water sorption capacity, compressive strength and metal leaching toxicity using TCLP and EN standards. The effectiveness of the tung oil binding to the SPC network was evidenced by the complete disappearance of methine C-H stretching vibrations at 3010 cm-1 and the double bond -C=C- wagging vibrations at 990 cm-1 in the FT-IR spectrum after processing with sulfur. SEM observations revealed that all the specimens prepared with dicyclopentadiene had a glassy-like fracture surface and also showed fewer cavities and defects in cements and composites when compared to their counterparts prepared with tung oil. The water sorption capacities of all the specimens were below 1%, where the values of those prepared with the tung oil were two to three fold higher than the values of their counterparts prepared with dicyclopentadiene. The pH of the TCLP leachates was in the range of 2.75-2.98, and a decreasing trend in the pH value was found with an increasing modifier dose. The TCLP leachate pH from the waste I monoliths with dicyclopentadiene were generally lower by 0.1-0.35 when compared to the corresponding monoliths with tung oil. The toxic metals immobilization order revealed from the TCLP test (leachate pH around 2.85) is Cd > Sr ≥ Zn > Cu > Ni > Cr > Pb, while the resulting order from the EN test, due to a higher leachate pH of about 5.9, follows Cd > Pb > Zn > Cu ≥ Ni > Sr > Cr. An increased tung oil dose from 2 to 8.85% enhanced the SPC compressive strength by three to four fold, while the same increase of the dicyclopentadiene dose led to an increase of this parameter for less than two fold. The addition of galvanic wastes to the SPCs resulted in a further increase in compressive strength for the corresponding SPC samples.
RESUMO
A study was made concerning the removal of copper(II) ions from model and galvanic waste solutions using a new sorption material consisting of lignin in combination with an inorganic oxide system. Specific physicochemical properties of the material resulted from combining the activity of the functional groups present in the structure of lignin with the high surface area of the synthesized oxide system (585m2/g). Analysis of the porous structure parameters, particle size and morphology, elemental composition and characteristic functional groups confirmed the effective synthesis of the new type of sorbent. A key element of the study was a series of tests of adsorption of copper(II) ions from model solutions. It was determined how the efficiency of the adsorption process was affected by the process time, mass of sorbent, concentration of adsorbate, pH and temperature. Potential regeneration of adsorbent, which provides the possibility of its reusing and recovering the adsorbed copper, was also analyzed. The sorption capacity of the material was measured (83.98mg/g), and the entire process was described using appropriate kinetic models. The results were applied to the design of a further series of adsorption tests, carried out on solutions of real sewage from a galvanizing plant.
RESUMO
O processo galvânico consiste na deposição de uma camada fina de metal sobre uma superfície metálica ou plástica. Este processo gera grande volume de efluentes que devem ser tratados para atender as legislações ambientais. O sistema de tratamento de efluentes é responsável pela geração do resíduo sólido galvânico, também chamado de lodo galvânico. As análises químicas e físico-químicas realizadas demonstram que o sistema de tratamento da empresa em estudo opera incorretamente, produzindo lodo galvânico em excesso. O teor de umidade deste resíduo galvânico foi de 63,5%, significando que o principal constituinte do lodo é água. Pelo potencial risco ambiental deste lodo gerado, avaliou-se o seu valor econômico ambiental pela somatória dos custos decorrentes do processo de tratamento de efluentes, da destinação final do resíduo galvânico e das perdas das substâncias químicas a base de cobre, cromo e níquel. A quantidade destes elementos químicos no resíduo galvânico foram 3,71, 3,34 e 0,58%, respectivamente. O valor econômico ambiental obtido foi de R$ 30.362,90 por ano, comprovando o potencial econômico ambiental do resíduo galvânico.
The galvanic process consists on the deposition of a thin metal layer on a metallic or plastic surface. This process generates large volumes of effluents that must be destined for the treatment systems in order to attend the Brazilian environmental standards regulations. The treatment system effluent is responsible for the generation of galvanic solid waste, also called galvanic sludge. The chemical and physicochemical analysis performed demonstrate that the company's treatment system under study operates incorrectly, producing an excess of galvanic sludge. The moisture content in the sludge was 63.5%, representing water as the main constituent. Due to the potential environmental risk of this generated sludge, was evaluated its economic value by the sum of the environmental costs related to the wastewater treatment process, the final destination of the waste galvanic and losses of chemicals based on copper, chromium and nickel. The amount of these chemicals in galvanic residue was 3.71, 3.34 and 0.58% respectively. The value obtained of R$ 30,362.90 per year confirms the environmental economic potential of the galvanic residue.
