Effects of sandy desertified land rehabilitation on soil carbon sequestration and aggregation in an arid region in China

The rehabilitation of sandy desertified land in semi-arid and arid regions has a great potential to increase carbon sequestration and improve soil quality. Our objective was to investigate the changes in the soil carbon pool and soil properties of surface soil (0–15 cm) under different types of rehabilitation management. Our study was done in the short-term (7 years) and long-term (32 years) desertification control sites in a marginal oasis of northwest China. The different management treatments were: (1) untreated shifting sand land as control; (2) sand-fixing shrubs with straw checkerboards; (3) poplar (Populus gansuensis) shelter forest; and (4) irrigated cropland after leveling sand dune. The results showed that the rehabilitation of severe sandy desertified land resulted in significant increases in soil organic C (SOC), inorganic C, and total N concentrations, as well as enhanced soil aggregation. Over a 7-year period of revegetation and cultivation, SOC concentration in the recovered shrub land, forest land and irrigated cropland increased by 4.1, 14.6 and 11.9 times compared to the control site (shifting sand land), and increased by 11.2, 17.0 and 23.0 times over the 32-year recovery period. Total N, labile C (KMnO₄–oxidation C), C management index (CMI) and inorganic C (CaCO₃–C) showed a similar increasing trend as SOC. The increased soil C and N was positively related to the accumulation of fine particle fractions. The accumulation of silt and clay, soil C and CaCO₃ enhanced the formation of aggregates, which was beneficial to mitigate wind erosion. The percentage of >0.25 mm dry aggregates increased from 18.0% in the control site to 20.0–87.2% in the recovery sites, and the mean weight diameter (MWD) of water-stable aggregates significantly increased, with a range of 0.09–0.30 mm at the recovery sites. Long-term irrigation and fertilization led to a greater soil C and N accumulation in cropland than in shrub and forest lands. The amount of soil C sequestration reached up to 1.8–9.4 and 7.5–17.3 Mg ha^?1 at the 0–15 cm layer over a 7- and 32-year rehabilitation period compared to the control site, suggesting that desertification control has a great potential for sequestering soil C and improving soil quality in northwest China.     

The use of digital photos to assess visual cover for wildlife in rangelands

Grassland vegetation can provide visual cover for terrestrial vertebrates. The most commonly used method to assess visual cover is the Robel pole. We test the use of digital photography as a more accurate and repeatable method. We assessed the digital photography method on four forage grassland species (Pseudoroegneria spicata, Festuca campestris, Poa pratensis, Achnatherum richardsonii). Digital photos of 2-dimensional cutout silhouettes of three bird species sharp-tailed grouse, western meadowlark and savannah sparrow were used to model the impact of clipping (i.e., grazing) on visual cover. In addition, photos of artificial voles were used to model litter on cover available to small mammals. Nine sites were sampled and data were analyzed by the dominant grass species in each study plot. Regression analysis showed that digital photos (r² = 0.62) were a better predictor than the Robel pole (r² = 0.26) for assessment of cover. Clipping heights showed that clipping at less than 15 cm left the silhouettes 50% exposed. Digital photo analysis revealed that visual cover was affected by the type of grass species, with F. campestris > P. pratensis > A. richardsonii > P. spicata. Biomass and litter were both positively related to cover for small mammals.     

Environmental resource footprinting of drug manufacturing: Effects of scale-up and tablet dosage

The formulation and scale-up of batch processes is one of the major challenges in the development of pharmaceutical dosage forms and at the same time a significant resource demanding process which is generally overlooked in environmental sustainability assessments. First, this paper proposes general trends in the experience curve of cumulative resource consumption of pharmaceutical tablet manufacturing of PREZISTA^® 800 mg through wet granulation (WG) at four consecutive scales in both R&D and manufacturing environments (resp. WG1 = 1 kg/h, WG5 = 5 kg/h, WG30 = 30 kg/h and WG240 = 240 kg/h). Second, the authors aim at evaluating the environmental impact from a life cycle perspective of a daily consumption of PREZISTA^® 2× 400 mg tablets versus the bioequivalent PREZISTA^® 800 mg tablet which was launched to enhance patient compliance. Environmental sustainability assessment was conducted at three different system boundaries, which enables identification, localization and eventually reduction of burdens, in this case natural resource extraction. Exergy Analysis (EA) was used at process level (α) and plant level (β) while a cradle-to-gate Exergetic Life Cycle Assessment (ELCA) was conducted at the overall industrial level (γ) by means of the CEENE method (Cumulative Exergy Extraction from the Natural Environment). Life cycle stages taken into account are Active Pharmaceutical Ingredient (API) production, Drug Product (DP) production and Packaging. At process level (α), the total resource extraction for the manufacturing of one daily dose of PREZISTA^® (800 mg tablet) amounted up to 0.44 MJ_ex at the smallest scale (WG1) while this amount proved to be reduced by 58%, 79% and 83% at WG5, WG30 and WG240 respectively. Expanding the boundaries to the overall industrial level (γ) reveals that the main resource demand is at the production of the Active Pharmaceutical Ingredient (API), excipients, packaging materials and cleaning media used in DP production. At the largest scale (WG240) the use of cleaning media during DP production contributes considerably less to the total resource extraction. Overall, the effect of scale-up and learning on resource consumption during DP production showed to possess a power-law experience curve y = 2.40 * x^−0.57 when shifting from WG1 (smallest lab scale) to WG240 (industrial manufacturing). Tablet dosage (2× 400 mg versus 1× 800 mg) did not significantly affect the absolute environmental burden. However, the relative contribution of resource categories did change due to the different production technology. It could be concluded that in meeting social and economic demands by launching the PREZISTA^® 800 mg tablet, no trade-off in environmental burden occurred. On the long term, future research should strive to take into account R&D processes and all services related to pipeline activities taking place prior to market launch and eventually to allocate impacts to the final product.     

Norwegian farmers ceasing certified organic production: Characteristics and reasons

This article examines the characteristics of and reasons for Norwegian farmers’ ceasing or planning to cease certified organic production. We gathered cross-sectional survey data in late 2007 from organic farmers deregistering between January 2004 and September 2007 (n = 220), and similar data from a random sample of farmers with certified organic management in 2006 (n = 407). Of the respondents deregistering by November 2007, 17% had quit farming altogether, 61% now farmed conventionally, and 21% were still farming by organic principles, but without certification. Nearly one in four organic farmers in 2007 indicated that they planned to cease certification within the next 5–10 years. From the two survey samples, we categorised farmers who expect to be deregistered in 5–10 years into three groups: conventional practices (n = 139), continuing to farm using organic principles (uncertified organic deregistrants, n = 105), and stopped farming (n = 33). Of the numerous differences among these groups, two were most striking: the superior sales of uncertified organic deregistrants through consumer-direct marketing and the lowest shares of organic land among conventional deregistrants. We summarised a large number of reasons for deregistering into five factors through factor analysis: economics, regulations, knowledge-exchange, production, and market access. Items relating to economics and regulations were the primary reasons offered for opting out. The regression analysis showed that the various factors were associated with several explanatory variables. Regulations, for example, figured more highly among livestock farmers than crop farmers. The economic factor strongly reflected just a few years of organic management. Policy recommendations for reducing the number of dropouts are to focus on economics, environmental attitudes, and the regulatory issues surrounding certified organic production.     

Physicochemical characterization of hydroxyapatite and its application towards removal of nitrate from water

A laboratory study was conducted to investigate the efficiency of hydroxyapatite (HAP) towards removal of nitrate from synthetic nitrate solution. In the present research HAP synthesized from egg-shell was characterized using SEM, XRD, FTIR and TGA–DSC. The removal of nitrate was 96% under neutral conditions, using 0.3 g of adsorbent in 100 mL of nitrate solution having an initial concentration of 100 mg/L. An adsorption kinetic study revealed that the adsorption process followed first order kinetics. Adsorption data were fitted to a linearly transformed Langmuir isotherm with correlation coefficient (R²) > 0.98. Thermodynamic parameters were also calculated to study the effect of temperature on the removal process. In order to understand the adsorption type, equilibrium data were tested with the Dubinin–Radushkevich isotherm. The process was rapid and equilibrium was established within the first 40 min.     

Mineralization of integrated gasification combined-cycle power-station wastewater effluent by a photo-fenton process

The aim of this work was to study the mineralization of wastewater effluent from an integrated-gasification combined-cycle (IGCC) power station sited in Spain to meet the requirements of future environmental legislation. This study was done in a pilot plant using a homogeneous photo-Fenton oxidation process with continuous addition of H₂O₂ and air to the system.The mineralization process was found to follow pseudo-first-order kinetics. Experimental kinetic constants were fitted using neural networks (NNs). The NNs model reproduced the experimental data to within a 90% confidence level and allowed the simulation of the process for any values of the parameters within the experimental range studied. At the optimum conditions (H₂O₂ flow rate = 120 mL/h, [Fe(II)] = 7.6 mg/L, pH = 3.75 and air flow rate = 1 m³/h), a 90% mineralization was achieved in 150 min.Determination of the hydrogen peroxide consumed and remaining in the water revealed that 1.2 mol of H₂O₂ was consumed per each mol of total organic carbon removed from solution. This result confirmed that an excess of dissolved H₂O₂ was needed to achieve high mineralization rates, so continuous addition of peroxide is recommended for industrial application of this process.Air flow slightly improved the mineralization rate due to the formation of peroxo-organic radicals which enhanced the oxidation process.     

Subsoil TPH contamination in two oil pipeline pumping stations and one pipeline right-of-way in north Mexico

This investigation deals with the characterization carried out in zones around two pipeline pumping stations and one pipeline right-of-way in the north of Mexico. In particular those areas where contamination was evaluated: (a) south area of the separation ditch in the Avalos station, (b) the area between the separation ditch at the Avalos station, (c) km 194 + 420 of the Moctuzma station, and (d) km 286 + 900 in the Candelaria station. Results of this investigation showed that only four samples showed TPH values higher than the Mexican limit for 2004: AVA 1B, with 21,191 mg kg^?1; AVA 1C, with 9348 mg kg^?1; AVA 2B, with 13,970 mg kg^?1; and MOC 2A, with 4108 mg kg^?1.None of the sampled points showed the presence of PAHs at values higher than those found in the Mexican or American legislations. PAH were detected in the range of 0.0004 and 13.05 mg kg^?1.It is suggested to implement surfactant soil washing as a remediation technique for the approximately 600 m³ that need to be treated.     

Treatment of landfill leachates by nanofiltration

Landfill leachate contains high concentrations of organic matter, color, heavy metals and toxic substances. This study presents the feasibility of a commercial nanofiltration membrane (NF-300) in the removal of pollutants from a landfill leachate generated from the Treatment Stabilization and Disposal Facility in Gujarat state of India. Two different leachate samples (Leachates A and B) were collected from the downstream side of closed landfill cells A and B. The average quality of the leachate was 67 719 mg/L COD, 217 mg/L ammonical nitrogen, 22 418 mg/L BOD, 3847 mg/L chlorides and 909 mg/L sulphate. The operating variables studied were applied pressure (4–20 atm), feed flowrate (5–15 L/min) and pH (2, 4, 5.5 and 6.7). It was observed that the solute rejection (R_O) increased with increase in feed pressure and decreased with increase in feed concentration at constant feed flowrate. In the present study, the rejection of cations followed the sequence: R_O (Cr³⁺) > R_O (Ni²⁺) > R_O (Zn²⁺) > R_O (Cu²⁺) > R_O (Cd²⁺) for leachates A and B. The order of solute rejection sequence is inversely proportional to the diffusion coefficients. The rejection of sulphate ions by the NF-300 membrane was 83 and 85%, while the rejection of chlorides was 62 and 65% for leachates A and B, respectively. The NF-300 membrane was characterized by using the combined-film theory-Spiegler–Kedem (CFSK) model based on irreversible thermodynamics and the ion transport model based on the extended Nernst–Planck equation. The membrane transport parameters were estimated using the Levenberg–Marquadt method. The estimated parameters were used to predict the membrane performance and the predicted values are in good agreement with the experimental results.     

Kinetics of sulfur dioxide- and oxygen-induced degradation of aqueous monoethanolamine solution during CO2 absorption from power plant flue gas streams

Studies of the kinetics of sulfur dioxide (SO₂)- and oxygen (O₂)-induced degradation of aqueous monoethanolamine (MEA) during the absorption of carbon dioxide (CO₂) from flue gases derived from coal- or natural gas-fired power plants were conducted as a function of temperature and the liquid phase concentrations of MEA, O₂, SO₂ and CO₂. The kinetic data were based on the initial rate which shows the propensity for amine degradation and obtained under a range of conditions typical of the CO₂ absorption process (3–7 kmol/m³ MEA, 6% O₂, 0–196 ppm SO₂, 0–0.55 CO₂ loading, and 328–393 K temperature). The results showed that an increase in temperature and the concentrations of MEA, O₂ and SO₂ resulted in a higher MEA degradation rate. An increase in CO₂ concentration gave the opposite effect. A semi-empirical model based on the initial rate, ?r_MEA = {6.74 × 10⁹ e^?(29,403/RT)[MEA]^0.02([O]^2.91 + [SO₂]^3.52)}/{1 + 1.18[CO₂]^0.18} was developed to fit the experimental data. With the higher order of reaction, SO₂ has a higher propensity to cause MEA to degrade than O₂. Unlike previous models, this model shows an improvement in that any of the parameters (i.e. O₂, SO₂, and CO₂) can be removed without affecting the usability of the model.     

Optimization of Fenton oxidation pre-treatment for B. thuringiensis – Based production of value added products from wastewater sludge

Fenton oxidation pretreatment was investigated for enhancement of biodegradability of wastewater sludge (WWS) which was subsequently used as substrate for the production of value- added products. The Response surface method with fractional factorial and central composite designs was applied to determine the effects of Fenton parameters on solubilization and biodegradability of sludge and the optimization of the Fenton process. Maximum solubilization and biodegradability were obtained as 70% and 74%, respectively at the optimal conditions: 0.01 ml H₂O₂/g SS, 150 [H₂O₂]₀/[Fe²⁺]₀, 25 g/L TS, at 25 °C and 60 min duration. Further, these optimal conditions were tested for the production of a value added product, Bacillus thuringiensis (Bt) which is being used as a biopesticide in the agriculture and forestry sector. It was observed that Bt growth using Fenton oxidized sludge as a substrate was improved with a maximum total cell count of 1.63 × 10⁹ CFU ml^?1 and 96% sporulation after 48 h of fermentation. The results were also tested against ultrasonication treatment and the total cell count was found to be 4.08 × 10⁸ CFU ml^?1 with a sporulation of 90%. Hence, classic Fenton oxidation was demonstrated to be a rather more promising chemical pre-treatment for Bt - based biopesticide production using WWS when compared to ultrasonication as a physical pre-treatment.     

The use of recycled metal in dentistry: Evaluation of mechanical properties of titanium waste recasting

Environmental concerns are increasing rapidly, and the public and industry are concerned about natural resources. The products are produced to meet the customer's demand as to quality. However, today it is equally important to take into account cost, ecological factors in production and recycling of products. The same way, the dentistry must contribution with a recasting the alloys used to rehabilitation oral.This study evaluated the effect of the condition of Ti (as-received and re-cast) on its mechanical properties, microstructure and fractography. Castings (n = 6) with Ti in the as-received and once recast condition were made in a centrifugal casting machine using a high-purity argon gas. The ultimate tensile strength (UTS), proportional limit (PL) and elongation (EL) of the as-received specimens were evaluated in a universal testing machine at a crosshead speed of 1 mm/min. The fractured specimens were polished down for Vicker's microhardness (VHN) measurement (100 g/15 s) from 25 μm below the cast surface, then at depths of 50, 100, 200 and 500 μm. The microstructures of the alloys were also revealed. Scanning electron microscopy fractography was undertaken for the fractured surfaces after testing. The data from the mechanical tests and hardness were subjected to the Student's t-test and two-way repeated measures ANOVA, respectively. Tukey's test was used for pairwise comparison (α = 0.05). Higher UTS, PL and VHN and lower EL were observed for recast cp Ti. The microstructure was not influenced by recasting, but the mode of fracture was.The use of the recasting procedure can lower the costs of cp Ti castings and can be safely in dentistry.     

Application of polyacrylamide to reduce phosphorus losses from a Chinese purple soil: A laboratory and field investigation

Use of anionic polyacrylamide (PAM) to control phosphorus (P) losses from a Chinese purple soil was studied in both a laboratory soil column experiment and a field plot experiment on a steep slope (27%). Treatments in the column study were a control, and PAM mixed uniformly into the soil at rates of 0.02, 0.05, 0.08, 0.10, and 0.20%. We found that PAM had an important inhibitory effect on vertical P transport in the soil columns, with the 0.20% PAM treatment having the greatest significant reduction in leachate soluble P concentrations and losses resulting from nine leaching periods. Field experiments were conducted on 5 m wide by 21 m long natural rainfall plots, that allowed collection of both surface runoff and subsurface drainage water. Wheat was planted and grown on all plots with typical fertilizer applied. Treatments included a control, dry PAM at 3.9 kg ha^?1, dry PAM at 3.9 kg ha^?1 applied together with lime (CaCO₃ at 4.9 t ha^?1), and dry PAM at 3.9 kg ha^?1 applied together with gypsum (CaSO₄·2H₂O at 4 t ha^?1). Results from the field plot experiment in which 5 rainfall events resulted in measurable runoff and leachate showed that all PAM treatments significantly reduced runoff volume and total P losses in surface runoff compared to the control. The PAM treatments also all significantly reduced water volume leached to the tile drain. However, total P losses in the leachate water were not significantly different due to the treatments, perhaps due to the low PAM soil surface application rate and/or high experimental variability. The PAM alone treatment resulted in the greatest wheat growth as indicated by the plant growth indexes of wheat plant height, leaf length, leaf width, grain number per head, and dried grain mass. Growth indexes of the PAM with Calcium treatments were significantly lesser. These results indicate that the selection and use of soil amendments need to be carefully determined based upon the most important management goal at a particular site (runoff/nutrient loss control, enhanced plant growth, or a combination).     

Effect of salinity on metal-complex dye biosorption by Rhizopus arrhizus

In this study the biosorption of Yellow RL, a metal-complex anionic dye, by dried Rhizopus arrhizus, a filamentous fungus, was investigated as a function of initial solution pH, initial dye concentration and initial salt (sodium chloride) concentration. The fungus exhibited the maximal dye uptake at pH 2 in the absence and in the presence of salt. Dye uptake increased with the dye concentration up to 1000 mg l^?1 and diminished considerably in the presence of increasing concentrations of salt up to 50 g l^?1. The fungus biosorbed 85.4 mg dye g^?1of dried biomass at 100 mg l^?1 initial dye concentration in the absence of salt. When 50 g l^?1 salt was added to the biosorption medium, this value dropped to 60.8 mg g^?1 resulting in 28.8% reduction in biosorption capacity. The Redlich–Peterson and Langmuir–Freundlich were the most suitable adsorption models for describing the biosorption equilibrium data of the dye both individually and in salt containing medium. The pseudo-second-order and saturation type kinetic models depicted the biosorption kinetics accurately for all cases studied. Equilibrium and kinetic constants varied with the level of salt were expressed as a function of salt concentration.     

Transfer characteristics of cobalt from soil to crops in the suburban areas of Fujian Province,southeast China

The bioavailability of cobalt and its transfer from soil to vegetables and rice were investigated. Among 312 soils collected from vegetable and paddy fields in the suburban areas of some major cities of Fujian Province, southeast China, total soil Co ranged from 3.5 to 21.7 mg kg^?1, indicating a slight accumulation compared with the background value of the province. DTPA extracted 0.1–8.5% of soil total Co. Total and DTPA-extractable Co correlated with soil pH, CEC, free Fe, total Mn, clay and silt content more significantly in paddy soils than in the soils from vegetable fields. The average Co concentrations in the edible parts of vegetables and rice were 15.4 μg kg^?1 and 15.5 μg kg^?1, respectively. The transfer factor (the ratio of plant Co to soil DTPA-extractable Co, TF_DTPA) ranged from 0.003 to 0.126 with a median of 0.049. The TF_DTPA decreased in the order of leafy vegetables > fruit vegetables > root vegetables > rice. The TF_DTPA of all crops decreased with increasing DTPA-extractable Co. Increase in pH, CEC, organic matter, clay, silt, free iron and total Mn limited the soil-to-plant transfer of Co to varying degrees. The transfer of Co from the soils to the edible parts of the crops was lower than that of Zn, Cu and Cd, but higher than that of Pb in the same areas. The concentrations of Co in rice and vegetables in the study areas were considered to be safe for the local residents because of the slight anthropogenic input and the low transfer potential to the edible parts of Co from the soils.     

Application of pig slurry to soils. Effect of air stripping treatment on nitrogen and TOC leaching

The effect of physical–chemical slurry treatment on the mobility and transformation of nitrogen and organic matter from pig slurry after soil application is evaluated. Two different pig slurries (one treated by stripping with air at pH = 9 and another non-treated) were applied at the top of a soil column, containing approximately 100 kg of soil. Effluents were monitored measuring concentration values of ammonia, nitrites, nitrates and total organic carbon (TOC). The breakthrough curves were modelled using STANMOD and HYDRUS 1D codes. Low concentrations of ammonia were detected in the effluent recovered at the bottom of the soil profile for both types of slurry. Nitrate concentration in effluent was lower and more homogenous over time when applying stripping treated pig slurry. In N modelling, adsorption of ammonia by soil proved an important process, nitrite and nitrate adsorption being less significant, although not negligible. Transformation from ammonia to nitrite controls the kinetics of the nitrification process. Total organic carbon in the column effluent was higher in the experiment using treated pig slurry, which can be attributed to organic matter solubilisation in the stripping treatment process.     

Lead accumulation in different Chinese cabbage cultivars and screening for pollution-safe cultivars

Recently, the concept of pollution-safe cultivars (PSCs) was proposed to minimize the influx of pollutants to the human food chain. Variations in lead (Pb) uptake and translocation among Chinese cabbage (Brassica pekinensis L.) cultivars were investigated in a pot-culture experiment and a field-culture experiment to screen out Pb-PSCs for food safety. The results of the pot-culture experiment showed that shoot Pb concentrations under two Pb treatments (500 and 1500 mg kg^?1) varied significantly (p < 0.05) between cultivars, with average values of 3.01 and 6.87 mg kg^?1, respectively. Enrichment factors (EFs) and translocation factors (TFs) in cultivars were less than 0.50 and varied significantly (p < 0.05) between cultivars. Shoot Pb concentrations in 12 cultivars under treatment T₁ (500 mg kg^?1) were lower than 2.0 mg kg^?1. The field-culture experiment further confirmed Qiuao, Shiboqiukang and Fuxing 80 as Pb-PSCs, which were suitable to be cultivated in low-Pb (<382.25 mg kg^?1) contaminated soils and harmless to human health as foods.     

Treatment of municipal wastewater using a contact oxidation filtration separation integrated bioreactor

A new contact oxidation filtration separation integrated bioreactor (CFBR) was used to treat municipal wastewater. The CFBR was made up of a biofilm reactor (the upper part of the CFBR) and a gravitational filtration bed (the lower part of the CFBR). Polyacrylonitrile balls (50 mm diameter, 237 m²/m³ specific surface, 90% porosity, and 50.2% packing rate) were filled into the biofilm reactor as biofilm attaching materials and anthracite coal (particle size 1–2 mm, packing density 0.947 g/cm³, non-uniform coefficient (K₈₀ = d₈₀/d₁₀) < 2.0) was placed into the gravitational filtration bed as filter media. At an organic volumetric loading rate of 2.4 kg COD/(m³ d) and an initial filtration velocity of 5 m/h in the CFBR, the average removal efficiencies of COD, ammonia nitrogen, total nitrogen and turbidity were 90.6%, 81.4%, 64.6% and 96.7% respectively, but the treatment process seemed not to be effective in phosphorus removal. The average removal efficiency of total phosphorus was 60.1%. Additionally, the power consumption of the CFBR was less than 0.15 kWh/m³ of wastewater treated, and less than 1.5 kWh/kg BOD₅ removal.     

1D and 2D absorption-rate/kinetic modeling and simulation of carbon dioxide absorption into mixed aqueous solutions of MDEA and PZ in a laminar jet apparatus

The kinetics of the reaction between carbon dioxide (CO₂) and mixed solutions of methyldiethanolamine (MDEA) and piperazine (PZ) was investigated experimentally in a laminar jet apparatus. The experimental kinetic data were obtained under no interfacial turbulence and over a temperature range from 313 to 333 K, MDEA/PZ wt% concentration ratios of 27/3, 24/6 and 21/9, and CO₂ loadings from 0.0095 to 0.33 mol CO₂/mol amine. In addition, a new absorption-rate/kinetics model for the kinetics of the mixed of solvents was developed, which takes into account the coupling between chemical equilibrium, mass transfer, and all possible chemical reactions involved in the CO₂ reaction with MDEA/PZ solvent. The partial differential equations of this model were solved by the finite element numerical method (FEM) based on COMSOL software. The obtained experimental kinetics data were used to obtain the kinetic parameters of CO₂ absorption into MDEA/PZ solutions. The reaction-rate constant obtained for PZ blended with MDEA was kPZ = 2.572 × 10¹² exp(?5211/T). The 2D model for the blended amines MDEA/PZ has revealed the concentration profiles of all the species in both the radial and axial directions of the laminar jet which has enabled a better understanding of the correct sequence in which the reaction steps involved in the reactive absorption of CO₂ in aqueous mixed MDEA/PZ solution occur. It also revealed that PZ may be depleted by the time the solvent blend of MDEA/PZ with a loading greater than 0.015 mol/mol amine is exposed to CO₂ from the top of the laminar jet absorber.