Arsenic(III) removal from aqueous solution by raw and zinc-loaded pine cone biochar: equilibrium, kinetics, and thermodynamics studies
Arsenic(III) removal from aqueous solution by raw and zinc-loaded pine cone biochar: equilibrium, kinetics, and thermodynamics studies
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DOI：
10.1007/s13762-014-0507-1
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发表时间：
2015-04
影响因子：
3.1
通讯作者：
N. Vinh;M. A. Zafar;S. Behera;H. Park
中科院分区：
文献类型：
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作者：
N. Vinh;M. A. Zafar;S. Behera;H. Park
生松果（PC）生物炭及其改性形式（锌负载生物炭）的潜力进行了评估，从水溶液中去除三价砷[As（III）]。采用元素分析仪、比表面积分析仪、热重分析仪、傅里叶变换红外光谱仪和扫描电镜等分析手段，研究了Zn（NO3）2对PC生物炭理化性质的影响。实验结果表明，As（III）的去除几乎一致在2-4的酸性pH范围内，由于带正电荷的生物炭表面与主要砷物种之间的高亲和力，在生生物炭和负载Zn的生物炭上分别为66.08 ± 3.94和87.62 ± 3.88（H3 AsO 3和H2 AsO 4 −），然后随着pH值在4-12范围内的增加而降低。Langmuir吸附等温线模型与实验数据拟合良好（R2= 0.93），表明PC生物炭对Zn的最大吸附量分别为5.7和7.0 μg g− 1。As（III）在PC生物炭和Zn负载PC生物炭上的吸附符合准二级动力学方程，反应速率常数k2分别为0.040和0.282 mg g− 1 min，吸附过程主要受边界层扩散控制，其次是颗粒内扩散。吸附过程是自发的，具有吉布斯自由能（ΔG°，−4.42 ± 0.72和−11.86 ± 1.78 kJ mol−1），并且在性质上是放热的，对于原始吸附剂和负载锌的吸附剂，焓（ΔH°，13.25和31.10 kJ mol−1）和熵（ΔS°，0.058和0.141 kJ mol− 1 K −1）分别为Δ H °，13.25和31.10 kJ mol − 1。
The potential of raw pine cone (PC) biochar and its modified form (Zn-loaded biochar) was evaluated for the removal of trivalent arsenic [As(III)] from the aqueous solution. The influence of treatment of PC biochar with Zn(NO3)2on the physico-chemical properties of biochar was examined using elemental analyzer, surface area analyzer, thermo-gravimetric analyzer, Fourier transform infrared spectroscopy, and scanning electron microscopy. Experimental results revealed that the removal of As(III) was almost consistent (66.08 ± 3.94 and 87.62 ± 3.88 % on raw and Zn-loaded biochar, respectively) over an acidic pH range of 2–4 as a consequence of high affinity between the positively charged biochar surface and the predominant arsenic species (H3AsO3and H2AsO4−), followed by a decrease with increase in pH in the range of 4–12. Langmuir isotherm model was well fitted to the experimental equilibrium data (R2= 0.93) rendering the maximum adsorption capacity of 5.7 and 7.0 μg g−1on raw and Zn-loaded PC biochar, respectively. The adsorption of As(III) was well represented by pseudo-second order with reaction rate constant (k2) of 0.040 and 0.282 mg g−1min on raw and zinc-loaded PC biochar, respectively, and was mainly controlled by boundary layer diffusion followed by some extent of intra-particle diffusion. The adsorption process was spontaneous with Gibb’s free energy (ΔG°, −4.42 ± 0.72 and −11.86 ± 1.78 kJ mol−1) and exothermic in nature with enthalpy (ΔH°, 13.25 and 31.10 kJ mol−1) and entropy (ΔS°, 0.058 and 0.141 kJ mol−1K−1) for raw and zinc-loaded adsorbent, respectively.