Low temperature pickling regeneration process for remarkable enhancement in Cu(II) adsorptivity over spent activated carbon fiber
Introduction
Cu(II) is a common harmful pollutant threatening human health, which usually discharged by electroplating, metallurgy, printing and chemical fertilizer industries (Li and Bai, 2005). Excessive intake of Cu(II) may cause liver damage and acute poisoning in humans. Many governments have developed uniform Cu(II) emission standards, such as 2 mg/L in the US and 3 mg/L in Japan, and the standard will continue to raise with more need of human health. Adsorption method is the most promising purification technology for low-concentration Cu(II) pollutant, and activated carbon fiber felt (ACFF) is an efficient adsorbent for low-concentration specific adsorption (Macíasgarcía et al., 2017; Huang and Su, 2010).
ACFFs are commonly used as efficient adsorbents in the fields of wastewater purification (Kim et al., 2019) and gas pollutant purification (Son et al., 2016). While pollutant-adsorbed ACFFs are commonly discarded as new pollutants after once application of wastewater purification (L. Huang et al., 2014). The research of regeneration technology can achieve the cyclic utilization of ACFFs and reduce the secondary pollution of waste ACFFs (Zhan et al., 2016a, 2016b), which also has great significance for the enrichment/recovery of high-value biochemical substances (Li et al., 2018). In terms of environmental protection and resource recovery, the research on regeneration technology for pollutant-adsorbed ACFFs is needed urgently in the field of pollutant purification. At present, different kinds of regeneration technologies have been reported, which mainly include thermal regeneration (Spessato et al., 2019), solvent regeneration (Wang et al., 2017), electrochemical regeneration (Xiao and Hill, 2018), microwave regeneration (Yang et al., 2015), ultrasonic regeneration (Hamdaoui et al., 2005). The merits and demerits of different regeneration processes are shown in Table 1. However, these processes have some drawbacks of low regeneration rate, significant deterioration of pore structure or high-energy consumption, etc.
In these reported regeneration technology, chemical regeneration technology (Guo et al., 2011) and thermal regeneration technology (Robinson et al., 2019) are the widely-used regeneration processes in the industrial applications of activated carbon. Li et al. (2014) obtained a regeneration rate over 100% through 1 M NaOH and 0.31 M H2SO4 at 368 K as chemical regenerant for NaSA-saturated powered activated carbon. Mugisidi et al. (2007) modified activated carbon by treatment with 15% sodium acetate, which increased Cu(II) adsorptivity by 120%. Lu et al. (2017) added Uranium(VI)-saturated amidoxime-grafted activated carbon fibers to the prepared HNO3 solution under vibration at 298 K for 48 h. The adsorption efficiency of the regenerated adsorbent was still up to 80% after four cycles. Belgin and Öznur (2014) found that the regeneration efficiency of chromium(VI)-adsorbed activated carbon achieve 70% by a batch stirred electrochemical reactor with a voltage of 1.5 V. Jatta et al. (2019) exploited the potential of the thermal activated persulfate (TAP) process for toluene gas saturated activated carbon, which achieved a regeneration rate above 90%. Y. Huang et al. (2014) used water hyacinth as an efficient raw precursor for the preparation of activated carbons for Pb(II) adsorption. The desorbed materials regenerated with 0.1 M HCl can be used six times without significantly decreasing its adsorption capacities. Godino-Salido et al. (2016) prepare and characterize two functionalizated carbon materials with enhanced adsorptive properties for Cu(II). The desorption of Cu(II) from the ACs/H4L/Cu(II) materials in acid solution allows the regeneration of most active sites (78.5% in the case of Merck/H4L/Cu(II) and 83.0% in the case of F/H4L/Cu(II)). So far, the research of regeneration technology mainly focuses on the improvement of regeneration rate or the reduction of energy consumption. There are few studies related to the enhancement of ACs/ACFFs’ adsorptivity in the regeneration process.
In the chemical regeneration technology, some regenerants have strong oxidation effect, which can achieve the modification of adsorbent in the regeneration process. It provides a theoretical basis for the enhancement of adsorptivity during regeneration. Low-temperature pickling regeneration process refers to the regeneration of porous carbon materials with acid washing solution above boiling point in a closed space, which is proposed by this manuscript on the basis of the improving of traditional acid washing regeneration technology. It is proposed on the basis of the combination of chemical regeneration technology and thermal regeneration technology. With Cu(II)-adsorbed ACFFs used as research object, the regeneration process is implemented by acid regenerant (dilute HNO3 solution) above boiling point in a confined space. The novelty of this study is that the regeneration process realizes the simultaneous progress of regeneration and adsorbent modification, and finally realizes the reverse growth of adsorption performance during the regeneration process. This regeneration mainly uses the strong oxidation of acidic regenerant above boiling point to achieve the enhancement of adsorptivity in the regeneration process. Acid regenerant above boiling point is more durable and with high oxidation properties in confined spaces, which reduced the demand for high temperature and high pressure. Based on the modification of surface structure during regeneration, the process achieves a remarkable enhancement of Cu(II) adsorptivity for ACFFs with none demand for high temperature and high pressure.
The regeneration mechanism is to weaken the van der Waals force and the chemical bond between the adsorbent and the adsorbate by the acid washing solution at a certain heating temperature. The increase of temperature (above the boiling point of the acid washing solution) can also increase the attack of acidic solvent on the interaction between the adsorbent and the adsorbate, which is conducive to the removal of the adsorbate. On the other hand, acid washing solution above boiling point can further oxidize or remove the carbon atom and oxygen atom on the surface of adsorbent, which can further improve the surface structure parameters of adsorbent, such as specific surface area, pore volume and surface functional group content.
As there is no need for high temperature and high pressure, the technology has expanded research value to be scaling-up. The process conditions such as confined space and nitric acid above boiling point are easy to realize in continuous regeneration application. Moreover, nitric acid is easy to be recovered and recycled, which enhanced the real feasibility of the regeneration technique at full-scale. Therefore, the effects of the regeneration process on the surface structure and Cu(II) adsorptivity of ACFFs were analyzed in this study. Additionally, the kinetic studies and Cu(II) adsorption isotherm of regenerated ACFFs were investigated by different kinetic models (Sani et al., 2017).
Section snippets
Materials
Pristine felts (BET surface area 1055.65 m2/g, labeled as ACFF0) were provided by Carbon Fiber Engineering Technology Research Center, Shandong University. All the chemical reagents of copper sulfate pentahydrate, sodium diethyldithiocarbamate (DDTC-Na, analytical purity) and HNO3 (analytical purity) were provided by China Pharmaceutical Group Chemical Reagents Co., Ltd.. Deionized water was made by three-stages deionized water purification line in our laboratory. Oxygen-rich ACFFs (ACFFs with
Process optimization and regeneration effect
Parameters of pickling temperature (Fig. 2a), pickling time (Fig. 2b) and regenerant concentration (Fig. 2c) were optimized to the low-temperature pickling regeneration process for Cu(II)-adsorbed ACFFs. For the 50 mg/L Cu(II) standard working fluid, Q(ACFF0), Q(NO-ACFF) and Q(NM-ACFF) are 4.36, 15.88 and 23.13 mg/g respectively. After regeneration, Q(ACFF0), Q(NO-ACFF) and Q(NM-ACFF) present a significant nonlinear positive correlation with pickling temperature, pickling time and HNO3
Conclusions
Low-temperature pickling regeneration process is first proposed for the reutilization of ACFFs in the application of Cu(II) purification. The regeneration technology achieves a remarkable enhancement of Cu(II) adsorptivity along with a high efficiency regeneration simultaneously with none high pressure and high temperature. This technology mainly utilizes the strong oxidation of acidic regenerant above boiling point in a confined space to regenerate ACFFs. After optimization, the pickling
Credit author statement
The authors declared that they have no conflicts of interest to this work. We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work. There is no professional or other personal interest of any nature or kind in any product, service and company that could be construed as influencing the position presented in the manuscript entitled “Remarkable enhancement of Cu(II) adsorptivity of spent activated carbon fiber in
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
This work was supported by National Natural Science Foundation of China (Grant No. 51473088), National Key Research and Development Plan of China (Project No. 2016YFC0301402) and Key Research and Development Plan of Shandong (Project No. 2018GGX102029 and No. 2017CXGC0409).
References (41)
- et al.
Arsenic and selenium removal from water using biosynthesized nanoscale zero-valent iron: a factorial design analysis
Process Saf. Environ.
(2017) - et al.
Different solvents for the regeneration of the exhausted activated carbon used in the treatment of coking wastewater
J. Hazard Mater.
(2011) - et al.
Preparation and characterization of trihydroxamic acid functionalized carbon materials for the removal of Cu(II) ions from aqueous solution
Appl. Surf. Sci.
(2016) - et al.
Ultrasonic desorption of p-chlorophenol from granular activated carbon
Chem. Eng. J.
(2005) - et al.
Removal of copper ions from wastewater by adsorption/electrosorption on modified activated carbon cloths
J. Hazard Mater.
(2010) - et al.
Study on mechanism and influential factors of the adsorption properties and regeneration of activated carbon fiber felt (ACFF) for Cr(VI) under electrochemical environment
J. Taiwan Inst. Chem. Eng.
(2014) - et al.
Adsorption of Pb(II) on mesoporous activated carbons fabricated from water hyacinth using H3PO4 activation: adsorption capacity, kinetic and isotherm studies
Appl. Surf. Sci.
(2014) - et al.
A column study of persulfate chemical oxidative regeneration of toluene gas saturated activated carbon
Chem. Eng. J.
(2019) - et al.
Oil industry waste based non-magnetic and magnetic hydrochar to sequester potentially toxic post-transition metal ions from water
J. Hazard Mater.
(2020) - et al.
Unary and binary adsorption studies of lead and malachite green onto a nanomagnetic copper ferrite/drumstick pod biomass composite
J. Hazard Mater.
(2019)
Immobilization, enrichment and recycling of Cr(VI) from wastewater using a red mud/carbon material to produce the valuable chromite (FeCr2O4)
Chem. Eng. J.
Effects of activated carbon surface chemistry and pore structure on the adsorption of organic contaminants from aqueous solution
Carbon
Copper adsorption on chitosan-cellulose hydrogel beads: behaviors and mechanisms
Separ. Purif. Technol.
Study of the adsorption and electroadsorption process of Cu(II) ions within thermally and chemically modified activated carbon
J. Hazard Mater.
High performance carbon fibers from very high molecular weight polyacrylonitrile precursors
Carbon
Modification of activated carbon using sodium acetate and its regeneration using sodium hydroxide for the adsorption of copper from aqueous solution
Carbon
Thermal and chemical regeneration of spent activated carbon and its adsorption property for toluene
Chem. Eng. J.
Rapid and high-performance adsorptive removal of hazardous acridine orange from aqueous environment using abelmoschus esculentus seed powder single- and multi-parameter optimization studies
J. Environ. Manag.
Simultaneous adsorptive desulfurization of diesel fuel over bimetallic nanoparticles loaded on activated carbon
J. Clean. Prod.
Polyamide magnetic palygorskite for the simultaneous removal of Hg(II) and methyl mercury; with factorial design analysis
J. Environ. Manag.
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