Effect of pyrolysis temperatures and times on the adsorption of cadmium onto orange peel derived biochar

Abstract

The mechanism and capacity of adsorption of cadmium (Cd) on orange peel (OP)-derived biochar at various pyrolysis temperatures (400, 500, 600, 700 and 800°C) and heating times (2 and 6 h) were investigated. Biochar was characterized using proximate analysis, point of zero charge (PZC) analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. Equilibrium and kinetic experiments of Cd adsorption on biochar were performed. The results indicated that the pH value at PZC of biochar approached 9.5. Equilibrium can be reached rapidly (within 1 min) in kinetic experiments and a removal rate of 80.6-96.9% can be generated. The results fitted the pseudo-second-order model closely. The adsorption capacity was estimated using the Langmuir model. The adsorption capacity of Cd on biochar was independent of the pyrolysis temperature and heating time (p>0.01). The maximum adsorption capacity of Cd was 114.69 (mg g(-1)). The adsorption of Cd on biochar was regarded as chemisorption. The primary adsorption mechanisms were regarded as Cπ-cation interactions and surface precipitation. Cadmium can react with calcite to form the precipitation of (Ca,Cd)CO3 on the surface of biochar. The OP-derived biochar can be considered a favourable alternative and a new green adsorbent for removing Cd(2+) ions from an aqueous solution.

Characteristics and mechanisms of nickel adsorption on biochars produced from wheat straw pellets and rice husk

“…The rapid reaction in this study coincides with the findings of Saleh et al (2016) and Tran et al (2016). Saleh et al (2016) used sunflower seed husk biochar (≤0.5 mm) to adsorb Cu 2+ (Solid to liquid ratio 1:200 g/mL, initial Cu 2+ concentration 1.5 mM) in aqueous solutions and observed that more than 95% of the totally adsorbed Cu 2+ at equilibrium was adsorbed on the biochar within 5 min.…”

“…Saleh et al (2016) used sunflower seed husk biochar (≤0.5 mm) to adsorb Cu 2+ (Solid to liquid ratio 1:200 g/mL, initial Cu 2+ concentration 1.5 mM) in aqueous solutions and observed that more than 95% of the totally adsorbed Cu 2+ at equilibrium was adsorbed on the biochar within 5 min. Similarly, Tran et al (2016) used orange peel-derived biochar (≤0.71 mm) to adsorb Cd 2+ (solid to liquid ratio 2 g/L, initial Cd 2+ concentration 100 mg/L) and found that approximately 80.6–96.9% of the totally adsorbed Cd 2+ was removed within 1 min. The ability of the biochars to rapidly remove Ni 2+ from solution and no appearance of desorption within 24 h suggests that there is a potential for the biochars to rapidly treat heavy metals in soil and water.…”

Biochar as heterogeneous support for immobilization of Pd as efficient and reusable biocatalyst in C–C coupling reactions

“…[8] Therefore, nanoparticles are widely employed as solid supports for heterogenization of homogeneous catalysts. [18][19][20] In fact, biochar (which is called black carbon) is charcoal which is used for soil amendment, reduction in greenhouse gas emissions from soil, adsorption, water retention, agricultural waste recycling, climate change mitigation and energy production. Biochar is a novel type of nanoparticles, which is a stable carbon solid and used in various fields in past few years for science and engineering.…”

“…[21,22] Therefore, it is inexpensive and environmentally friendly. Despite various studies of the morphology, application, properties and preparation of biochar, [18][19][20][21][22][23][24][25][26][27] currently no reports are available of the application of biochar as a catalyst support. [25] Surfaces of biochar nanoparticles are covered with carbonyl, hydroxyl and carboxylic acid functional groups.…”

Removal of nitrate, ammonia and phosphate from aqueous solutions in packed bed filter using biochar augmented sand media

“…In recent years, the interest in using biochar in wastewater treatment has been increasing due to its low cost of production, relatively high surface area and active surface functional groups [2,3]. A number of researchers reported that biochar can be used to remove nutrients from aqueous solutions in batch and column experiments [4][5][6].…”