Effects of chemical conditioners on reactive brilliant red X-3B adsorption performance of sludge biochar

The effects of three typical chemical conditioners, namely polyaluminium chloride (PAC), polyferric sulfate (PFS), and polyacrylamide (CPAM), on the reactive brilliant red X-3B (X-3B) adsorption performances of sludge biochar were investigated. Before being used for preparation of biochar, the sludge was conditioned using the three conditioners and 10% PAC resulted in the maximal improvement in sludge dewaterability (46.3%). CPAM and PAC increased the Brunauer-Emmett-Teller (BET) surface area of the sludge biochar (15.5-44.1%) and X-3B adsorption capacity (9.1-33.9%), whereas PFS decreased them (2.9% and 6.8%). The sludge biochar prepared from CPAM-conditioned sludge had the maximum BET surface area and the minimum mean pore size, whereas that prepared from PAC-conditioned sludge had the maximum X-3B adsorption capacity. The adsorption of X-3B onto the three sludge biochars was affected by biochar dosage, adsorption time, and initial X-3B concentration, and was well fitted by the pseudo-second-order model (R-2 > 0.99) and the Langmuir isotherm model (R-2 > 0.99). The adsorption of X-3B onto the three sludge biochars was spontaneous, favorable, and endothermic, with the biochar prepared from PAC-conditioned sludge being the most favorable. The conditioners reduced the total cost of sludge biochar preparation by 15.40-22.55% and PAC was the preferred conditioner in terms of the biochar preparation cost and X-3B adsorption.

Automated summary

The effects of three typical chemical conditioners, namely polyaluminium chloride (PAC), polyferric sulfate (PFS), and polyacrylamide (CPAM), on the adsorption performances of sludge biochar were studied. CPAM and PAC increased the surface area and adsorption capacity of biochar, while PFS decreased them. The adsorption of X-3B onto the biochar was influenced by various factors and fitted well with the pseudo-second-order model and the Langmuir isotherm model. The conditioners reduced the total cost of biochar preparation, with PAC being the preferred choice.