Study On The Sporption Behavior Of Typical PPCPs To Carbonaceous Materials

In recent years,pharmaceuticals and personal care products(pharmaceuticals and personal care products,PPCPs)percolate into surface water,groundwater as well as soil by different ways their release and environmental impact have gained much attention.Triclosan is a type of widely used antimicrobial agent found in numerous commercial products and sulfamethoxazole is a kind of antibacterial drug.However,most of the PPCPs(include triclosan and sulfamethoxazole)could not be removed by traditional waste water treatment technologies and frequent detected in wastewater and ground water.Carbonaceous materials were used for different types of water treatment processes due to the significant advantage of easy operation and high efficiency.Although a great deal of work has been published in the past years,data are still limited in terms of a kinds of sorbent,the sorption behavior of PPCPs on different kinds of carbonaceous material remain poorly understood.In this study,triclosan and sulfamethoxazole were chose as sorbates,and seven different kinds of carbonaceous materials(active carbon,coconut shell carbon,pristine CNTs,CNTs-OH,CNTs-COOH,rice shell carbon,bamboo carbon)were selected as sorbents.The sorption behavior and sorption mechanism of triclosan and sulfamethoxazole on different kinds of carbonaceous materials were studied systematically.Carbon nanotubes(CNTs)was a kind of special carbonaceous material,with large specific surface area and abundant pore structure,were demonstrated a good sorbate to be used in water treatment.However,CNTs tend to be aggregate as a result of the van der Waals force.In present research,the sorption behavior of a series of aggregation CNTs was studied.But the effect of dispersion state of carbon nanotubes on the sorption behavior was poorly understood.Dispersed CNTs by sonication may be inevitably released from the industry to the environment and be transported along with the environmental pollutants,and thus their sorption could significantly influence the fate and risk of both CNTs and pollutants.As a result,the influence of the dispersion state of CNTs in the sorption process should be systematically investigated.There was a significance to reveal the sorption behavior and sorption mechanism of different dispersion state of CNTs.The main aspects which studied through the static experiments in this research were shows as following:(1)The sorption behavior of triclosan and sulfamethoxazole on different kinds of carbonaceous materials were studied,respectively,and the results showed that the sorption capacity was decreased as follows: active carbon> coconut shell carbon > pristine CNTs> CNTs-OH> CNTs-COOH>rice shell carbon> bamboo carbon.And the sorption kinetics and the sorption isotherms of the triclosan and sulfamethoxazole on seven carbonaceous materials were well fitted by pseudo-second-order model and Dubinin-Ashtakhov model,respectively.(2)Combined with different solution chemistry(inion strength and p H)and sonication on the sorption process of three types CNTs(with different functional groups)with and without sonication was also studied.Acording to the sorption kinetics and isothermal sorption tests combined the results of experimental characterization,sonication change the dispersion state of all types CNTs significantly,the sorption rates and the sorption capacity increased for both triclosan and sulfamethoxazole.And the sorption kinetics and the sorption isotherms were still well fitted by pseudo-second-order model and Dubinin-Ashtakhov model,respectively.The inion strength has less effect of the sorption capacity of all types CNTs with and without sonication,with the increased of inion strength,the sorption capacity of CNTs increased slightly initially and then decreased gradually for both triclosan and sulfamethoxazole.The maximum sorption capacity of all types CNTs with and without sonication was at 0.035 M and 0.0075 M NaCl for triclosan and sulfamethoxazole,respectively.The sorption capacity of all types CNTs with and without sonication was significantly effect by p H.For triclosan,the sorption capacity decreased with the increased of pH.While the sorption capacity of CNTs for sulfamethoxazole was increased with the p H initially and then decreased gradually,the maximum soption capacity of all types CNTs was at pH 5.The results may be due to the different surface charge for both sorbents and sorbates in different pH.(3)The effect of different concentration of HA and FA on the sorption process of CNTs with different functional groups and triclosan(8 mg/L)was studied.The results suggested that for the sorption capacity of all types CNTs decreased sharply with the concentration increased from 0 to 20 mg/L,while the sorption capacity increased slowly with the concentration increased from 20 to 200 mg/L which may be due to the balance of “competition” and “disperson”.Based on the above analysis,three HA/FA concentration(0,20,200mg/L)was selected to study the effect of the sorption isotherms of CNTs.From the results,for HA,the inhibit effect of 20 mg/L higher than other HA concentration.Compared to 0 mg/L HA,200 mg/L HA inhibit the sorption when at lower concentration of triclosan,however,the sorption capacity was increased when the concentration of triclosan was higher.For FA,compared to 0 mg/L FA,the sorption capacity of CNTs with the presence of 20 and 200 mg/L FA were decreased.The different effects of HA and FA on the sorption of CNTs and triclosan may be due to the different characteristics of HA and FA.The results will improve the understanding in the sorption behavior between different kinds of carbonaceous materials and triclosan/sulfamethoxazole,and explain the sorption mechanism of different dispersion state of CNTs with triclosan.The data generated will be vital for evaluating the potential applications of different kinds of carbonaceous materials as efficient sorbents in waste water treatment process.