Synthesis of Ca(OH) and NaCO through anion exchange between CaCO and NaOH: effect of reaction temperature.

The CO released upon calcination of limestone accounts for the largest portion of the emissions from the cement, lime, and slaked lime manufacturing industries. Our previous works highlighted the possibility for a no-combustion decarbonisation of CaCO through reaction with NaOH solutions to produce Ca(OH) at ambient conditions, while sequestrating the process CO in a stable mineral NaCO·HO/NaCO. In this study, the effect of temperature was assessed within the range of 45-80 °C, suggesting that the process is robust and only slightly sensitive to temperature fluctuations.

Decarbonisation of calcium carbonate in sodium hydroxide solutions under ambient conditions: effect of residence time and mixing rates.

The decarbonisation of CaCO is essential for the production of lime (Ca(OH) and CaO), which is a commodity required in several large industries and the main precursor for cement production. CaCO is usually decarbonised at high temperatures, generating gaseous CO which will require post-process capture to minimise its release into the environment. We have developed a new process that can decarbonise CaCO under ambient conditions, while sequestering the CO as NaCO·HO or NaCO in the same stage.

Correction: Rahmani, O., et al. Experimental Investigation and Simplistic Geochemical Modeling of CO Mineral Carbonation Using the Mount Tawai Peridotite. 2016, , 353.

After careful consideration, we found that Figure 2 [...

Experimental Investigation and Simplistic Geochemical Modeling of CO₂ Mineral Carbonation Using the Mount Tawai Peridotite.

In this work, the potential of CO₂ mineral carbonation of brucite (Mg(OH)2) derived from the Mount Tawai peridotite (forsterite based (Mg)₂SiO4) to produce thermodynamically stable magnesium carbonate (MgCO3) was evaluated. The effect of three main factors (reaction temperature, particle size, and water vapor) were investigated in a sequence of experiments consisting of aqueous acid leaching, evaporation to dryness of the slurry mass, and then gas-solid carbonation under pressurized CO2. The maximum amount of Mg converted to MgCO₃ is ~99%, which occurred at temperatures between 150 and 175 °C.

Stabilization of heavy metals in MSWI fly ash using silica fume.

The objective of this work was to investigate the feasibility and effectiveness of silica fume on stabilizing heavy metals in municipal solid waste incineration (MSWI) fly ash. In addition to compressive strength measurements, hydrated pastes were characterized by X-ray diffraction (XRD), thermal-analyses (DTA/TG), and MAS NMR ((27)Al and (29)Si) techniques. It was found that silica fume additions could effectively reduce the leaching of toxic heavy metals.

Synergy between surface adsorption and photocatalysis during degradation of humic acid on TiO2/activated carbon composites.

A photocatalyst comprising nano-sized TiO(2) particles on granular activated carbon (GAC) was prepared by a sol-dipping-gel process. The TiO(2)/GAC composite was characterized by scanning electron microscopy (SEM), X-ray diffractiometry (XRD) and nitrogen sorptometry, and its photocatalytic activity was studied through the degradation of humic acid (HA) in a quartz glass reactor. The factors influencing photocatalysis were investigated and the GAC was found to be an ideal substrate for nano-sized TiO(2) immobilization.

Disposal of water treatment wastes containing arsenic - a review.

Solid waste management in developing countries is often unsustainable, relying on uncontrolled disposal in waste dumps. Particular problems arise from the disposal of treatment residues generated by removing arsenic (As) from drinking water because As can be highly mobile and has the potential to leach back to ground and surface waters. This paper reviews the disposal of water treatment wastes containing As, with a particular emphasis on stabilisation/solidification (S/S) technologies which are currently used to treat industrial wastes containing As.

Precipitation of heavy metals from wastewater using simulated flue gas: sequent additions of fly ash, lime and carbon dioxide.

Lime is a preferred precipitant for the removal of heavy metals from industrial wastewater due to its relatively low cost. To reduce heavy metal concentration to an acceptable level for discharge, in this work, fly ash was added as a seed material to enhance lime precipitation and the suspension was exposed to CO2 gas. The fly ash-lime-carbonation treatment increased the particle size of the precipitate and significantly improved sedimentation of sludge and the efficiency of heavy metal removal.

Application of accelerated carbonation with a combination of Na2CO3 and CO2 in cement-based solidification/stabilization of heavy metal-bearing sediment.

The efficient remediation of heavy metal-bearing sediment has been one of top priorities of ecosystem protection. Cement-based solidification/stabilization (s/s) is an option for reducing the mobility of heavy metals in the sediment and the subsequent hazard for human beings and animals. This work uses sodium carbonate as an internal carbon source of accelerated carbonation and gaseous CO(2) as an external carbon source to overcome deleterious effects of heavy metals on strength development and improve the effectiveness of s/s of heavy metal-bearing sediment.

Characterization of carbonated tricalcium silicate and its sorption capacity for heavy metals: a micron-scale composite adsorbent of active silicate gel and calcite.

Adsorption-based processes are widely used in the treatment of dilute metal-bearing wastewaters. The development of versatile, low-cost adsorbents is the subject of continuing interest. This paper examines the preparation, characterization and performance of a micro-scale composite adsorbent composed of silica gel (15.