Application of magnetically modified sewage sludge ash (SSA) in ionic dye adsorption

Abstract

Incineration is a traditional method of treating sewage sludge and the disposal of derived ash is a problem of secondary waste treatment. In this study, sewage sludge ash (SSA) was coated with ferrite through a ferrite process and then used as an adsorbent for ionic dyes (methylene blue [MB] and Procion Red MX-5B [PR]). The modified SSA possessed surface potential that provided electrostatic attraction toward MB and PR. Adsorbent FA10 (named on the basis of being produced from 10 g of SSA in the ferrite process) was used for the adsorption of MB. Ideal pH for adsorption was 9.0 and maximum adsorption capacity based on Langmuir isotherm equation was 22.03 mg/g. Adsorbent FA2.5 (named on the basis of being produced from 2.5 g of SSA in the ferrite process) was used for PR adsorption. Ideal pH for adsorption was 3.0 and the maximum adsorption capacity (calculated as above) was 28.82 mg/g. Kinetic results reveal that both MB and PR adsorption fit the pseudo-second-order kinetic model better than the pseudo-firstorder model. The values of activation energy calculated from rate constants were 61.71 and 9.07 kJ/mol for MB and PR, respectively. Implications: Magnetic modified adsorbent could be synthesized from sewage sludge ash (SSA). In this study, the adsorption ability of SSA toward ionic dye (methylene blue [MB] and Procion Red MX-5B [PR]) was enhanced by ferrite process. The synthesized Fe 3 O 4 can act as an active site and provide electrostatic attraction toward cationic dye and anionic dye at different pH. The application of magnetic modified adsorbent in wastewater treatment can not only recycle the SSA, but also make SSA become an environmentally friendly material.

Sewage sludge ash characteristics and potential for use in concrete

“…The LOI data for SSA obtained from the sourced literature yielded an average value of 3.5%, though occasionally very high values up to 13% have been reported [2,7,12,13,[15][16][17]30,31,52,64,80,81,92,94,96,103,104] be generally able to comply with the LOI limit of 5% set for cement in EN 197 (2011) and fly ash for concrete in EN 450 (2012). Where SSA is earmarked for specific use in concrete, a thorough burn during incineration should be able to control the LOI.…”

“…Quartz and hematite have been identified as the most abundant minerals in SSA, whilst many other iron oxides, iron phosphates, calcium phosphates and aluminium phosphates have been reported to a lesser degree [3][4][5][11][12][13]16,21,24,[29][30][31][32][43][44][45]51,58,59,64,68,74,76,77,79,94,95,99,102,[105][106][107][108][109][110]. The amorphous content of SSA ranged from 35-75%, which suggests that the material is somewhat reactive and, when ground sufficiently fine, may have potential as a cement component.…”

Assessment of Remediation of Municipal Wastewater Using Activated Carbon Produced from Sewage Sludge

“…Then finally, they have to diffuse into the porous structure of the adsorbent. Hence, the solutions of higher initial concentrations will take relatively longer contact time to a ain equilibrium due to higher amount of heavy metal molecules [57,58]." In both cases, the results show that as the mass of the adsorbent increases, solute removal efficiency increases.…”

“…The adsorption isotherm is useful for describing how solutes interact with adsorbents and for optimizing adsorbent use. The fitting of adsorption equilibrium data into various isotherm models is also an important step in determining a model that can be used for design purposes [32,58]. The time series plots and kinetic curves of the adsorption process were also used to develop kinetic parameters.…”