Effect Of Carbonaceous Materials Prepared From Solid Wastes On Adsorption And Degradation Of Nonylphenol

The adsorption of carbonaceous materials (CMs) to hydrophobic organic pollutants(HOCs) are unquestionable, but their effects on the degradation of HOCs are still controversial. On one hand, CMs can reduce the bioavailability of HOCs by adsorption and inhibit the degradation of HOCs; on the other hand, CMs can act as a carrier for microorganisms and provide nutrients, thereby increasing the amount and activity of microorganisms and promoting the degradation of HOCs. The preliminary results showed that the appropriate rice-straw biochar addition could reduce the bioavailability of nonylphenol (NP), promote the growth of microorganisms, accelerate the degradation of NP and decrease NP residue, to achieve CMs-microorganisms coupling remediation.And the law is applicable only to rice-straw biochar, or it is widely applicable to all CMs that is unknown. In order to investigate this problem, the typical endocrine disrupting NP was used as the target pollutant. The adsorption properties of CMs prepared from plant solid waste (rice straw biochar (PRP (before pickling), PRC (after pickling)), bamboo biochar (PBP (before pickling), PBC (after pickling))), industrial solid waste (sludge biochar (ISP), fly ash (IFP (before pickling), IFC (after pickling))),livestock solid waste (chicken manure biochar (LCM)), and the effects of CMs at different dosages addition on NP biodegradation were studied, while compared with commercial CMs (graphite carbon (GC), carbon nanotubes (CNT), activated carbon(AC)). The main results were as follows:(1)The adsorption data of more than ten kinds of CMs could be better fitted with Freundlich and Dual-Mode models.The results showed that different CMs had a great effect on the adsorption capacity of NP. The adsorption capacity of CMs prepared from plant solid wastes (rice straw and bamboo chips) far exceeded carbon nanotubes,especially bamboo biochar. The Kf of PBP, PBC from Freundlich model fitting parameter was 61717.7, 78773.2 (mg/Kg)/(mg/L)", respectively, which was even close to that of activated carbon; the adsorption capacity of CMs prepared from fly ash,chicken manure and sludge were poor,especially the fly ash,while the Kf of IFP,IFC was 0,950.858 (mg/Kg)/(mg/L)n, respectively. It could be seen that the adsorption capacity of CMs prepared by plant solid wastes was best, followed by livestock and industrial solid wastes.(2) The correlation analysis between Kf , Kom and Qmax.d obtained by the two adsorption models and the physicochemical properties of CMs respectively showed that Kf , Kom and Qmax.d positively correlated with C%, specific surface area, pore volume(especially mesoporous) and carboxyl content of CMs, and negatively correlated with ash content. The fitting results of Dual-Mode model showed that the correlation between non-linear adsorption and pore volume was better, while the correlation between linear distribution and specific surface area was better. For PBC and CNT with large pore volume, when Ce = 1.5 mg/L, the proportion of non-linear adsorption was 79.67% and 55.85% respectively, while the proportion of linear distribution was 20.33%and 44.15% respectively.(3) NP could be degraded rapidly by microorganisms, and the degradation rate of NP was 50% without adding CMs in 10 d incubation. The first order degradation kinetic model was fitting better for NP biodegradation (R2> 0.930). The promoting effect of CMs prepared by the plant solid waste (rice straw and bamboo) was obvious on the degradation of NP, .especially bamboo biochar. When the addition amounts of bamboo biochar were 5 and 20 mg, the degradation rate of NP increased by 19.31% and 37.09%respectively, followed by CMs prepared from livestock solid waste (chicken manure);while the CMs prepared from industrial solid waste had an inhibitory effect on NP degradation, especially sludge biochar. When the addition amount of sludge biochar was 50 mg, the degradation rate of NP decreased by 85.09%.(4) For more than ten kinds of CMs, the addition of various types of CMs on the biodegradation of NP were different. In the first category, PRP, PRC, LCM, GC and CNT had an appropriate biochar dosage. Under this addition dosage, the liquid phase solubility of NP could be reduced to the proper range by adsorption, reduce the toxicity on microorganisms, and promote the biodegradation of NP. Therefore, the dosage of these CMs must be strictly controlled when these CMs were used as the repair agent for HOCs. In the second category, the inhibitory effect of IFP, IFC, ISP and AC on NP biodegradation increased with the increase of the addition dosage, mainly due to the strong toxicity and the lack of nutrients of CMs prepared by industrial solid waste and the superior adsorption capacity of AC, which were not suitable for the use of HOCs remediation. In the third category, the enhancement of PBP and PBC to NP degradation increased with the increase dosage .The main reason was due to its weak toxicity and rich nutrient, therefore bamboo biochar was a good repair agent for HOCs.In summary, different types of CMs on NP adsorption and degradation were very different, and not every kind of CMs were applicable to previous studies that appropriate biochar addition could promote biodegradation. Among them, bamboo biochar not only had a good adsorption capacity on NP but also could obviously promote the NP biodegradation, which was an environment-friendly material, and CMs prepared from industrial solid wastes showed obvious inhibitory effect, not suitable for organic pollution remediation. The paper not only provided the theoretical basis for the adsorption-degradation coupling remediation of HOCs contamination by CMs, but also gave the idea for the resource utilization of various solid wastes.