Effects of Wet Oxidation Process on Biochar Surface in Acid and Alkaline Soil Environments

Biochar has been studied for remediation of heavy metal-contaminated soils by many researchers. When in external conditions, biochar in soils ages, which can transform its structural properties and adsorption capacity. This study was conducted with two oxidation processes, HNO3/H2SO4 and NaOH/H2O2, to simulate the effects of biochar in acid and alkaline soil conditions. The results show that the oxygen-containing functional groups increased in aged biochar, which led to improve the ratio of oxygen and carbon (O/C). Nitro functional groups were found in the acid-oxidation treated biochar. Destroyed ditches and scars were observed on the surface of aged biochar and resulted in growth in their specific surface area and porosity. Specific surface area increased by 21.1%, 164.9%, and 63.0% for reed-derived biochar treated with water washing, acid oxidation, and basic oxidation, respectively. Greater peaks in the Fourier Transform Infrared Spectroscopy (FTIR) results were found in C–O and O–H on the surface of field-aged biochar. Meanwhile, mappings of energy-dispersive spectroscopy showed that biochar aged in soil was abundant in minerals such as silicon, iron, aluminum, and magnesium. In summary, biochar subjected to wet oxidation aging had an increased capacity to immobilize Cd compared to unaged biochar, and the adsorption capacity of oxidized biochar increased by 28.4% and 13.15% compared to unaged biochar due to improvements in porosity and an increase in functional groups.

[1]  Qihang Wu,et al.  Insights into the simultaneous removal of Cr6+ and Pb2+ by a novel sewage sludge-derived biochar immobilized nanoscale zero valent iron: Coexistence effect and mechanism. , 2018, The Science of the total environment.

[2]  Xianqiang Yin,et al.  Sorption of lead ions onto oxidized bagasse-biochar mitigates Pb-induced oxidative stress on hydroponically grown chicory: Experimental observations and mechanisms. , 2018, Chemosphere.

[3]  Ü. Mander,et al.  Biochar enhances plant growth and nutrient removal in horizontal subsurface flow constructed wetlands. , 2018, The Science of the total environment.

[4]  Yaning Wang,et al.  Preparation and Characterization of Macroalgae Biochar Nanomaterials with Highly Efficient Adsorption and Photodegradation Ability , 2018, Materials.

[5]  A. Weatherley,et al.  Agronomic effectiveness of urban biochar aged through co-composting with food waste. , 2018, Waste management.

[6]  L. Chu,et al.  Effects of chemical oxidation on surface oxygen-containing functional groups and adsorption behavior of biochar. , 2018, Chemosphere.

[7]  I. Kögel‐Knabner,et al.  Effect of in-situ aged and fresh biochar on soil hydraulic conditions and microbial C use under drought conditions , 2018, Scientific Reports.

[8]  F. Dijkstra,et al.  Enhanced biological nitrogen fixation and competitive advantage of legumes in mixed pastures diminish with biochar aging , 2018, Plant and Soil.

[9]  M. Greenway,et al.  Nitrogen removal from sewage and septage in constructed wetland mesocosms using sand media amended with biochar , 2018 .

[10]  G. Cornelissen,et al.  Cation exchange capacity of biochar: An urgent method modification. , 2017, The Science of the total environment.

[11]  Robert B. Young,et al.  Organic coating on biochar explains its nutrient retention and stimulation of soil fertility , 2017, Nature Communications.

[12]  Yaqun He,et al.  Estimation of hydrophilicity of coals by using the quantum chemistry calculation , 2017 .

[13]  J. Paz-Ferreiro,et al.  Influence of pig manure and its biochar on soil CO2 emissions and soil enzymes , 2016 .

[14]  Q. Hussain,et al.  Does Biochar Alter the Speciation of Cd and Pb in Aqueous Solution , 2014 .

[15]  Baoliang Chen,et al.  Interactions of aluminum with biochars and oxidized biochars: implications for the biochar aging process. , 2014, Journal of agricultural and food chemistry.

[16]  J. Six,et al.  Use of chemical and physical characteristics to investigate trends in biochar feedstocks. , 2013, Journal of agricultural and food chemistry.

[17]  Minori Uchimiya,et al.  Retention of heavy metals by carboxyl functional groups of biochars in small arms range soil. , 2012, Journal of agricultural and food chemistry.

[18]  T. Mattila,et al.  Biochar addition to agricultural soil increased CH4 uptake and water holding capacity – Results from a short-term pilot field study , 2011 .

[19]  W. P. Ball,et al.  Sorption of aqueous Zn[II] and Cd[II] by multiwall carbon nanotubes: the relative roles of oxygen-containing functional groups and graphenic carbon. , 2010, Langmuir : the ACS journal of surfaces and colloids.

[20]  J. Skjemstad,et al.  Study of free and occluded particulate organic matter in soils by solid state 13C Cp/MAS NMR spectroscopy and scanning electron microscopy , 1994 .