Articles in Press

Contamination of groundwater by chlorinated solvents such as trichloroethylene (TCE, tetrachloroethylene (PCE), and 1,1-dichloroethylene (1,1DCE) is a widespread problem that can seriously threaten human health and the environment. These compounds are often present as dense nonaqueous phase liquid (DNAPL) mixtures in the subsurface that serve as a long-term groundwater contamination sources. The objective of this study is to test the effectiveness of different in-situ flushing agents (SDS, Tween 80, MCD, and water) for the recovery of DNAPL mixtures (TCE, PCE, 1,1DCE) entrapped in heterogeneous aquifer media. A series of batch tests were first performed to assess the multiphase behavior of water-DNAPL mixture-reagent system. Intermediate scale tank experiments were then performed to compare the performance of the reagent solutions. The flushing breakthrough curves were also used to investigate the impact of solubilization agents on mass-flux reduction/mass-removal behavior relationships. Performance of agents on DNAPL mixture source zone remediation was found to be in the following order: Tween 80>SDS>MCD>>Water. Individual DNAPL constituents exhibited transient effective solubilities that depend on the reagent contents and DNAPL compositions. Although high fractions of DNAPL source zones in heterogeneous porous media were removed through chemical flushing (SDS, Tween 80, MCD, and water), the heterogeneous system exhibited an extended multi-step concentration behavior. The results emphasized that in the early stage, some portion of the organic liquid is hydraulically accessible (matrix) whereas the later stage of mass removal was controlled by the more poorly accessible mass (pool) associated with higher-saturation zones. Our results also showed that the distribution and the emplacement of organic liquid, flow-field heterogeneity, sorption and desorption, and flushing solution all influenced the DNAPL mixture removal. The results from this study underline the need for understanding the multiphase behaviour of a system, particularly when DNAPL mixtures are present, prior to field-scale remediation implementation.

Fly ash, solid waste from coal-fired power plant, had been utilized as raw material for porous geopolymer by alkaline activation and addition of hydrogen peroxide (H2O2) blowing agent. Porous geopolymer had higher surface area and total pore volume compared to fly ash and geopolymer without blowing agent, namely 45.511 m2 g-1 and 0.05131 cc g-1, respectively. Porous geopolymer was applied as adsorbent for anionic dyes Eriochrome Black T (EBT) and cationic dyes Methyl Violet (MV) from aqueous solutions. In this paper, factors affecting adsorption process such as adsorbent dosage, pH, time, and initial concentration were studied, in addition to adsorption kinetics and isotherm studies. Adsorbent dosage, time, and initial concentration factors had the same effect on the adsorption process for both EBT and MV dyes. The optimum removal efficiency was obtained at adsorbent dosage of 2 g L-1 and adsorption time of 90 minutes. The increase of the initial concentration of dyes would decrease the removal efficiency. For pH factor, adsorption of EBT dyes was better at pH of 2, while adsorption of MV dyes was better at pH of 10. Both adsorption of EBT and MV dyes by porous geopolymer followed pseudo-second-order kinetics model and Langmuir isotherm model with maximum adsorption capacity of 45.454 mg g-1 and 49.261 mg g-1, respectively.

Diesel engines cause major pollutants such as hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx). These emissions affect environmental systems and lead to global warming and climatic change effects. These pollutants also affect humans and lead to health problems like lung cancer, breathing problems, and headaches, etc. Hence, some necessary action has to be taken to minimise these pollutants. There are several steps available to control these emissions. The coating of the piston using catalytic material is an effective method and novel approach of reducing emissions in diesel engines with alternate fuel operated diesel engines. The copper-chromium-zirconium alloy (CuCr1Zr) is known for its good thermal conductivity and good catalyst material, and the piston is coated bycopper-chromium-zirconium alloy with 250µm thickness. Tamanu oil was blended with diesel fuel in a 20% (B20) to 40% (B40) ratio and used as an alternate fuel for the coated engine. The results showed a significant reduction in emissions and improvements in performance. In this research, the Taguchi with grey relational analysis (GRA) optimization technique is also used to study the effect of engine operating parameters on the emission level such as load and fuel for copper-chromium-zirconium alloy-coated diesel engine. Based on experimental results found that fuel is the most influential factor for CO and HCexhaust gas emissions reductions for coated type diesel engines.

The Yellow River Basin is an important economic zone in China and an important base for energy, chemical, raw materials and basic industries. However, the sloppy development pattern of "high consumption and high pollution" in nine provinces along the Yellow River Basin has become an important obstacle to achieving the carbon peaking and carbon neutrality goals. Using the extended STIRPAT model and combining scenario analysis and Monte Carlo simulation to build a prediction model, the future trend of carbon emissions in the nine provinces of the Yellow River Basin was predicted and the optimal path to reach the peak of carbons in the Yellow River Basin was explored. The results show that the nine provincial areas in the Yellow River Basin will not be able to reach the carbon peaking before 2035 under the baseline scenario. By further comparing the carbon peaking conditions of provinces under the low-carbon scenario and the technology breakthrough scenario, it is found that the peaking time, carbon peak value and the number of provinces under the technology breakthrough scenario are significantly better than those under the low-carbon scenario. Under the technology breakthrough scenario, the energy efficiency of the nine provinces in the Yellow River Basin will be greatly improved, the innovation capacity will be significantly enhanced, and the synergistic emission reduction mechanism and related policies between provincial areas will be perfected. Technological breakthroughs will become an important engine for high-quality development in the Yellow River Basin.