Polyacrylamide Application Research Articles

Effects of polyacrylamide on soil erosion and soil nutrient loss in sloped apple orchards.

In order to improve the soil environment, reduce soil erosion and soil nutrient loss, and explore the suitable dry broadcasting rate of polyacrylamide (PAM) in sloped apple orchard, experiments of different dry broadcasting rates of polyacrylamide were carried out in apple orchards with a slope of 20° in the hilly-gully region of northern Shaanxi from 2010 to 2012. PAM treatment levels included 0, 0.6, 0.8, 1.0, 1.2, 1.4 and 1.6 g·m-2. Surface runoff, eroded sediment, soil nutrient loss, and the growth of apple trees were monitored. Results showed that the surface runoff and runoff yield times from May to July exhibited a "V" shape with the increase of PAM application rate, and reached a minimum at the 1.0 g·m-2 level. However, the sediment yield decreased with increasing the PAM application rate. The concentrations of the ammonium nitrogen, available phosphorus, and available potassium in surface runoff and sediment decreased with increa-sing the PAM application rate. PAM significantly reduced the content of nitrate nitrogen in surface runoff, whereas it had no significant effect on nitrate nitrogen in sediment. Organic matter, total nitrogen, total phosphorus, and total potassium in the sediment decreased with increasing the PAM application rate. Moreover, PAM improved average fruit mass and fruit yields in sloped orchards, but it had no significant effect on the growth of apple trees and apple fruit flavor. An application le-vel of PAM at 1.0 g·m-2 should be suitable in sloped apple orchards.

Application of polyacrylamide flocculation with and without alum coagulation for mitigating ultrafiltration membrane fouling: Role of floc structure and bacterial activity

There is a growing interest in the use of ultrafiltration (UF) for the treatment of micro-polluted surface waters for drinking water supplies. Effective pretreatment is required to mitigate membrane fouling and in this paper we have evaluated the application of polyacrylamide (PAM) flocculation with alum coagulation. Bench scale tests were conducted over extended periods with two types of PAM (different molecular weights (MW)) applied with, and without alum coagulation, in order to investigate their impact on membrane fouling. The structure of the resulting flocs formed in the process and the activity of bacteria within the membrane tank were identified as two key factors influencing UF system performance. It was found that development of the cake layer and hydraulic resistance of the membrane were influenced by the floc properties, which were in turn related to the MW and dose of the PAM. Coagulation and flocculation using the larger MW PAM formed amorphous flocs with a lower fractal dimension, which contributed to a lower density of the cake layer and lower rate of increase in trans-membrane pressure. PAM flocculation without alum coagulation induced severe membrane fouling by forming a continuous gel-like layer on the membrane surface. By alum-PAM dosing it was found that the concentration of bacteria present in the membrane tank and adhering to the cake layer, was sufficient to remove nearly all of the ammonia and around 80% phosphorus in the raw water. These results demonstrate that the combination of a high MW PAM with alum as a pretreatment method of UF process can effectively improve the floc properties and cake layer structure for controlling membrane fouling and producing high quality treated water.

Effect of straw and polyacrylamide on the stability of land/water ecotone soil and the field implementation

Poor stability of land/water ecotone (L/WE) soil is a serious and increasing problem in the context of ecological restoration. Effective management by adding straw and polyacrylamide (PAM), i.e., SPAM, to soil may increase soil stability, including structure and fertility. Thus, it is important to explore the effects of SPAM on L/WE soil, as well as to determine the appropriate ratio of straw and PAM to achieve optimal increases. To investigate the soil properties and provide basis for ecological restoration, an indoor soil culture experiment, including nine straw and PAM combinations, was conducted. It was found that 3g/kg straw with 1g/kg PAM was optimal; thus, this scale was applied in engineering of Gonghu L/WE, which was turning Fishery to Lake. The survey explored changes in soil nutrients and structure, dry-sieved aggregate stability, and wet-sieved water aggregate stability under nine measures. Results indicated that the measurement of SPAM strongly affected soil properties, such as improvements in the fine sand and clay fraction, decreased coarse sand fraction and density, and enhanced content of the larger aggregates (>2mm), organic matter (OM), available nitrogen (AN), available phosphorus (AP), and available potassium (AK). For soil nutrients, applying of Straw/PAM significantly improved the contents of OM/AN, respectively; showing an increasing trend with a dosage rate. Meanwhile, it was shown that SPAM was more effective than treating each individual component on AP and AK improvements. Regarding soil structure, application of PAM significantly increased contents of the dry-sieved aggregates and wet-sieved water-stable aggregates, especially aggregates >2mm. Straw mulching only improved the content of dry-sieve medium size aggregates. However, when combining SPAM, the straw improved the medium particle size fraction, after which PAM converted a portion of the medium particles into >2.0mm aggregates. Furthermore, the measure proved to be beneficial to land/water ecotone engineering.

Aggregate Stability and Water Retention Near Saturation Characteristics as Affected by Soil Texture, Aggregate Size and Polyacrylamide Application

AbstractUnderstanding the effects of soil intrinsic properties and extrinsic conditions on aggregate stability is essential for the development of effective soil and water conservation practices. Our objective was to evaluate the combined role of soil texture, aggregate size and application of a stabilizing agent on aggregate and structure stability indices (composite structure index [SI], the α and n parameters of the VG model and the S‐index) by employing the high energy (0–5·0 J kg−1) moisture characteristic (HEMC) method. We used aggregates of three sizes (0·25–0·5, 0·5–1·0 and 1·0–2·0 mm) from four semi‐arid soils treated with polyacrylamide (PAM). An increase in SI was associated with the increase in clay content, aggregate size and PAM application. The value of α increased with the increase in aggregate size and with PAM application but was not affected by soil texture. For each aggregate size, a unique exponential type relationship existed between SI and α. The value of n and the S‐index tended, generally, to decrease with the increase in PAM application; however, an increase in aggregate size had an inconsistent effect on these two indices. The relationship between SI and n or the S‐index could not be generalized. Our results suggest that (i) the effects of PAM on aggregate stability are not trivial, and its application as a soil conservation tool should consider field soil condition, and (ii) α, n and S‐index cannot replace the SI as a solid measure for aggregate stability and soil structure firmness when assessing soil conservation practices. Copyright © 2016 John Wiley & Sons, Ltd.

Polyacrylamide as coagulant aid with polytitanium sulfate in humic acid-kaolin water treatment: Effect of dosage and dose method

This study focused on the application of polyacrylamide (PAM) as a coagulant aid of polytitanium sulfate (PTS) in humic acid-kaolin water treatment. Coagulation performance and floc properties were all measured in terms of dose amount and dose sequence of PAM and PTS which is meaningful for the practical application. Results showed that PTS-PAM (PTS dosed firstly) attained better natural organic matter (NOM) removal and PAM-PTS (PAM dosed firstly) attained better turbidity removal. Floc size was significantly enhanced by the PTS-PAM, while floc size of PAM-PTS attained similar size as that of PTS alone. Floc strength and recovery ability were also significantly improved by PTS-PAM. Moreover, PTS-PAM floc had a looser structure than that of PTS, while PAM-PTS floc and PTS floc had similar and more compact structure. The effect of PAM on the sludge reuse process was also studied. Results showed that the addition of PAM had a positive effect on the photocatalytic activity of sludge prepared TiO2.

Trade-off between runoff and sediments from treated erosion plots and polyacrylamide and acrylamide residues

ObjectiveThe present study aimed to evaluate the quantitative effect of polyacrylamide (PAM) on runoff and soil loss, and the amount of PAM polymer and acrylamide (AMD) monomer emissions from experimental plots under laboratory conditions. Materials and methodsThe different levels of treatment of 0, 0.4, 0.6, 1, 2, 3, 4, and 6gm−2 PAM were applied to small plots of 0.05m2 installed in the Rainfall and Soil Erosion Simulation Laboratory of Tarbiat Modares University, Iran, with a simulated rainfall intensity of 72mmh−1, duration of 0.5h, and slope of 20% (i.e., 11.5°) applied to a silty loam, similar to that for real conditions. To determine the optimal level of PAM application for soil and water conservation under laboratory condition, PAM polymer and AMD monomer were measured in outing runoff and sediment. An analytical technique based on a spectrophotometer was developed to quantify the amount of PAM polymer present; the determination of amide groups by the NBM was also formulated for the quantification of PAM polymer. The background AMD concentrations in runoff and sediment were determined using the EPA method 8032A in triplicate. The analysis of AMD was performed on a gas chromatograph system equipped with an electron capture detector and Clarity 4.2 Data Acquisition software. ResultsThe results proved a significant PAM polymer emission in runoff and sediment (P<0.001), a significant AMD monomer emission in output runoff (P<0.02), and no significant AMD residue in the output sediment (P>0.32). The optimal amounts of PAM application that are based on PAM and AMD residues in runoff and sediment and minimum soil loss were at rates of 2 and 0.4, and 2 and 1gm−2, respectively. ConclusionsThe results of this research could be helpful in providing appropriate information to address environmental concerns regarding PAM application for soil erosion control as well as in conservational and engineering planning.

Effects of polyacrylamide on soil erosion and nutrient losses from substrate material in steep rocky slope stabilization projects

Erosion of denuded steep rocky slopes causes increasing losses of nitrogen and phosphorus, which is a severe problem in rocky slope protection. Thus, it is important to determine the appropriate materials that can reduce the erodibility and losses of nitrogen and phosphorus of the soil. In this paper, twenty-seven simulated rainfall events were carried out in a greenhouse, in which the substrate material was artificial soil; nine types of anionic polyacrylamide (PAM) were studied, which consisted of three molecular weight (6, 12, and 18Mgmol−1) and three charge density (10, 20, and 30%) formulations in a 3 by 3 factorial design. The results showed that: (1) Polyacrylamide application reduced total nitrogen losses by 35.3% to 50.0% and total phosphorus losses by 34.9% to 48.0% relative to the control group. (2) The losses of total nitrogen and total phosphorus had significant correlation with the molecular weight. Besides, the losses of total phosphorus, particulate-bound phosphorus and inorganic nitrogen (NH4–N) were significantly correlated with their molecular weight and charge density. However, the losses of dissolved organic nitrogen, inorganic nitrogen (NO3–N), dissolved organic phosphorus, inorganic phosphorus (PO4–P) were non-significantly correlated with molecular weight and charge density. (3) Particulate-bound nitrogen and phosphorus were responsible for the losses of nitrogen and phosphorus during runoff events, where particulate-bound nitrogen made up 71.7% to 73.2% of total nitrogen losses, and particulate-bound phosphorus made up 82.3% to 85.2% of total phosphorus losses. (4) Polyacrylamide treatments increased water-stable aggregates content by 32.3% to 59.1%, total porosity by 11.3% to 49.0%, final infiltrative rate by 41.3% to 72.5%, and reduced soil erosion by 18.9% to 39.8% compared with the control group. Overall, the results of this study indicated that polyacrylamide application in the steep rocky slope stabilization projects could significantly reduce nutrient losses and soil erosion of substrate material.

Efficacy of granular polyacrylamide on runoff, erosion and nitrogen loss at loess slope under rainfall simulation

The chemical control of runoff, sediment and nutrient losses is one of the main measures of soil and water conservation and ecological improvement. A simulation experiment was conducted to investigate the effects of polyacrylamide (PAM) application rates (0, 0.5, 1, 2 and 4 g/m2), rainfall intensities (30, 60 and 90 mm/h) and the applied positions (top, middle and bottom with application rate of 2 g/m2) on runoff, soil and total nitrogen (TN) losses at loess slope. Overall, the results showed that PAM application rate of 1–2 g/m2 reduced runoff compared with no application of PAM on runoff. PAM application rate of 4 g/m2 reduced sediment losses most, but it increased the amount of runoff and TN losses in runoff. The PAM application rate of 2 g/m2 reduced runoff and nitrogen losses significantly. Soil and TN losses in sediment of PAM application position of the middle slope were significantly (p < 0.05) smaller than that of other PAM application positions. Considering the runoff, sediment and TN losses, PAM application rate of 2 g/m2 on the middle slope was the most feasible and beneficial mode for PAM application in the loess region.

Application of Carbon Dioxide and Polyacrylamide in Extracting Magnesium from Brine by Precipitation Method

In this paper, carbon dioxide and polyacrylamide were used to improve the method to abstract magnesium from desalination brine. Experimental results showed that calcium ion in the desali-nation brine can be effectively removed using carbon dioxide, which thereby improves the purity and reaction efficiency of the magnesium hydrate precipitate. 0.1% - 0.2% PAM could help to promote the precipitation of magnesium hydrate colloid. And when hydroxyl anion was between 110% - 130% of theoretical amount, yield of magnesium hydrate exceeds 70% at standing time of 60 hours.

Fuzzy Indicator Approach: Development of Impact Factor of Soil Amendments

Soil amendments have been shown to be useful for improving soil condition, but it is often difficult to make management decisions as to their usefulness. Utilization of Fuzzy Set Theory is a promising method for decision support associated with utilization of soil amendments. In this article a tool based on fuzzy indicator model was developed. The effectiveness of soil amendments in frame of work of this tool can be evaluated by two indicators: Impact Factor Simple (IFS), and Impact Factor Complex (IFC). Using IFS, an estimate of the effectiveness of soil amendments can be determine when only one experimental soil parameter is available. Using IFC, an estimation of soil amendment effectiveness can be calculated based on information about several soil parameters. This methodology was utilized in two case-studies. In the first, evaluation of the effectiveness of using polyacrylamide application as an amendment to reduce subsoil compaction was evaluated. In the second, the evaluation of the organic material “Fluff” as a soil amendment for establishing native prairie grasses was evaluated. In both cases, improved understanding of the effectiveness of the amendments was demonstrated and the decision support associated with utilization of soil amendments was improved.

Effect of residual monomer from polyacrylamide on head lettuce grown in peat substrate

The paper investigates the migration of the acrylamide monomer (AMD) to lettuce chosen as a test plant growing in an organic medium (peat substrate). Polyacrylamide (PAM)-based flocculant added to the growing medium contained no more than 1000 mg kg−1 of AMD. Plants were grown with varied doses of PAM preparation (0.5–3.0 mg dm–3 of peat substrate) to compare the results with the control sample. The determination of AMD content, chlorophyll content, weight of the lettuce head, and also analysis of macro- and micro-elements in lyophilised test material was made under the same analytical conditions. The results showed that lettuce plants absorb AMD to the leaves from the peat substrate. The AMD uptake has a negative impact on the growth of lettuce. It reduces the average fresh weight of heads and destabilises the mineral composition of the plant. Therefore, concern related to the transfer risk of the residual AMD from sludge used for organic fertilisation of edible plants still remains a crucial question from a food and consumer safety point of view. To ensure consumer safety, the fate of the AMD following the application of PAM to cropland should be carefully monitored in the whole food chain.

Interaction effects of polyacrylamide application and slope gradient on potassium and nitrogen losses under simulated rainfall

Soil nutrient loss through erosion depletes farmland productivity and environmental quality. Polyacrylamide (PAM) is often applied to control soil erosion from water but its effectiveness on different nutrients is not clear. This study tested the influence of PAM application rate, PAM molecular weight, and soil slope gradient on K+ and N losses as well as their interactive effects under simulated rainfall in the laboratory. Experimental treatments consisted of four PAM application rates, two PAM molecular weights, and three soil slope gradients. Results indicated that compared with the control treatment, PAM application generally reduced K+ and NH4+ concentrations and mass loss in runoff, except at the application rate of 2.0gm−2, though NO3− concentration and mass loss increased. Polyacrylamide application reduced K+, NH4+, and NO3− concentrations in sediment and generally increased their mass losses with sediment except at a slope gradient of 25°. After PAM application, mass losses of K+, NH4+ and NO3− from soil surface generally increased with increased PAM application rate, and the averaged percentages lost with sediment were 77.7%, 15.7%, and 12.1% of the mass losses from the soil surface, respectively. The concentrations and mass loss of K+, NH4+, and NO3− in runoff increased with the increase of slope gradient. However, concentrations in sediments decreased and mass loss increased with the increase of slope gradient. The effects of PAM molecular weight on K+, NH4+, and NO3− concentrations and their mass losses in both runoff and sediment were not significant. Statistical analysis demonstrated that there existed a significant interaction effect between PAM application rate and soil slope gradient on K+ and NH4+ mass losses from soil surface. Its contribution to the variation of K+ and NH4+ mass losses was 0.86 and 0.50, respectively. The effectiveness of PAM application on constraining nutrient loss is related to nutrient ion type, PAM application rate, and slope gradient. A high PAM application rate is not suitable for the control of soil nutrient loss on a steep slope.

Transport of dissolved polyacrylamide through a clay loam soil

Polyacrylamide (PAM) is becoming a widely used soil conditioning and erosion control agent, and a better understanding of its transport is required to improve its use. In this study vertical PAM transport through a clay loam soil was investigated using thin soil columns (7.62-cm diameter×2-cm thick) under saturated condition. The columns received a water-soluble, anionic PAM solution (16Mgmol−1 with 50mol% charge density) under pulse and step (continuous) inputs using a constant-head method. The pulse input was 500mgL−1 PAM solution applied for 0.6 pore volume (PV), after which the input was switched to deionized (DI) water for 25 PVs. The step input was 25mgL−1 PAM solution applied continuously for 129 PVs. Saturated hydraulic conductivity (Ksat) was measured prior to PAM application and was monitored during PAM and DI water leaching. Leachate samples were collected frequently with time from each column and analyzed for the dissolved PAM concentration. The PAM applications reduced Ksat to 1% of the initial Ksat (4cmh−1) under the pulse input and to 0.3% of the initial Ksat under the step input. Transport of PAM was best-fitted with a two-region (dual-porosity) model. The fitted retardation factor (R) was more than two-fold greater for the step input (R=2695) than for the pulse input (R=1242). The results from transport modeling and pore size distribution analysis suggested that viscous PAM solution contributes to a mechanical entrapment of the PAM molecules, clogging most water-conducting pores smaller than 225–274μm in diameter. Under saturated condition, either the pulse or step input of dissolved PAM could reduce seepage with limited mobility in the soil profile.

Effect of Polyacrylamide Application on Water and Nutrient Movements in Soils

An understanding of nutrient movement in soil is important for developing management strategies to minimize nutrient leaching and surface movement, thus improving nutrient uptake by plants, maintaining a sustainable soil system, and even protecting groundwater quality. Polyacrylamide (PAM) is known as one of soil conditioner that functions to stabilize soil structure, increase infiltration, and reduce surface runoff. This study assesses the effects of PAM on the vertical movement of soil-water and major/minor nutrients (NO3-N, NH3-N, T-N, PO4-P, T-P, K, Ca, Mg, and Fe) in soils. Saturated hydraulic conductivity (Ksat) increases with increasing PAM concen- trations up to 10 mg·L-1 for sand and 20 mg·L-1 for a mixture of sand and clay. Decreases in the loss of soluble nutrients, particularly NH3-N, PO4-P and T-P, are observed as PAM concentrations increase. In contrast, PAM concentration has no effect on nitrate and minor nutrient levels. These results indicate that the application of PAM may be a viable method for protecting water bodies from excessive nutrients and improving nutrient availability for plants.

Enhancement of Waste Activated Sludge Dewaterability by Potassium Ferrate Pretreatment

Potassium ferrate was used to enhance sludge dewatering and the mechanism was studied. Sludge floc structure was effectively destroyed by potassium ferrate, and the soluble COD, proteins and polysaccharides increased with the increase of potassium ferrate. The optimal dose for sludge disintegration was 100 mg/gSS, and the corresponding maximal SCOD, soluble proteins and polysaccharides concentrations were 2455, 800 and 145 mg/L, respectively. Sludge dewaterability was enhanced significantly with cationic polyacrylamide (C-PAM) application, and the SRF decreased to 0.72×1010m/kg from 50.12×1010m/kg. This study indicated that the potassium ferrate pretreatment was helpful for enhancing sludge dewaterability and reducing the coagulant dose.

Synthesis and application of nonionic polyacrylamide with controlled molecular weight for fracturing in low permeability oil reservoirs

ABSTRACTNonionic polyacrylamide (NPAM) with controlled molecular weight was successfully synthesized as a gel fracturing fluid by aqueous solution polymerization. The effects of the monomer concentration, initiator concentration, reaction time, feeding temperature and reaction temperature on the molecular weight were systematically investigated through single‐factor and orthogonal experiments. The NPAM molecular weight can be controlled by adjusting these factors. The decisive factor is the acrylamide concentration, whereas the initiator concentration and feeding temperature are secondary factors. These synthetic NPAMs can be crosslinked with zirconium acetate to produce a gel fracturing fluid for use in low permeability oil reservoirs. Gel fracturing fluids based on synthetic NPAMs have high shear resistance, low filtration performance, easy gel breaking performance, good proppant carrying capability and low core damage capability. By adjusting the NPAM or crosslinker concentrations, the gel fracturing fluid can be adapted for use in low permeability oil reservoirs for a wide temperature range (60–120°C). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41637.

Granular and Dissolved Polyacrylamide Effects on Erosion and Runoff under Simulated Rainfall.

Polyacrylamide (PAM) has been demonstrated to reduce erosion under many conditions, but less is known about the effects of its application method on erosion and concentrations in the runoff water. A rainfall simulation study was conducted to evaluate the performance of an excelsior erosion control blanket (cover) and two PAM application methods. The treatments were (i) no cover + no PAM (control), (ii) cover + no PAM, (iii) cover + granular PAM (GPAM), and (iv) cover + dissolved PAM (DPAM) applied to soil packed in wooden runoff boxes. The GPAM or DPAM (500 mg L) was surface-applied at a rate of 30 kg ha 1 d before rainfall simulation. Rainfall was applied at 83 mm h for 50 min and then repeated for another 20 min after a 30-min rest period. Runoff samples were analyzed for volume, turbidity in nephelometric turbidity units (NTU), total suspended solids (TSS), sediment particle size distribution, and PAM concentration. The cover alone reduced turbidity and TSS in runoff by >60% compared with the control (2315 NTU, 2777 mg TSS L). The PAM further reduced turbidity and TSS by >30% regardless of the application method. The median particle diameter of eroded sediments for PAM treatments was seven to nine times that of the control (12.4 μm). Loss of applied PAM in the runoff water (not sediment) was 19% for the GPAM treatment but only 2% for the DPAM treatment. Both GPAM and DPAM were effective at improving groundcover performance, but DPAM resulted in much less PAM loss.

The effect of conservation practices in sloped croplands on soil hydraulic properties and root‐zone moisture dynamics

AbstractRain‐induced erosion and short‐term drought are the two factors that limit the productivity of croplands in the red soil region of subtropical China. The objective of this study was to estimate the effects of conservation practices on hydraulic properties and root‐zone water dynamics of the soil. A 3‐year experiment was performed on a slope at Xianning. Four treatments were evaluated for their ability to reduce soil erosion and improve soil water conditions. Compared with no practices (CK) and living grass strips (GS), the application of polyacrylamide (PAM) significantly reduced soil crust formation during intense rainfall, whereas rice straw mulching (SM) completely abolished soil crust formation. The SM and PAM treatments improved soil water‐stable aggregates, with a redistribution of micro‐aggregates into macro‐aggregates. PAM and SM significantly increased the soil water‐holding capacity. These practices mitigated the degradation of the soil saturated hydraulic conductivity (Ks) during intense rainfalls. These methods increased soil water storage but with limited effects during heavy rainfalls in the wet period. In contrast, during the dry period, SM had the highest soil water storage, followed by PAM and CK. Grass strips had the lowest soil water storage because of the water uptake during the vigorous grass growth. A slight decline in the soil moisture resulted in a significant decrease in the unsaturated hydraulic conductivity (Ku) of the topsoil. Therefore, the hydraulic conductivity in the field is governed by soil moisture, and the remaining soil moisture is more important than improving soil properties to resist short‐term droughts. As a result, SM is the most effective management practice when compared with PAM and GS, although they all protect the soil hydraulic properties during wet periods. These results suggest that mulching is the best strategy for water management in erosion‐threatened and drought‐threatened red soils. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Interaction Effects of Polyacrylamide Application Rate, Molecular Weight, and Slope Gradient on Runoff and Soil Loss under Sprinkler Irrigation

Runoff and soil loss affect both farmland productivity and environmental quality. This study tested the interaction effects among polyacrylamide (PAM) application rate, PAM molecular weight, and slope gradient on runoff and soil loss under simulated sprinkler irrigation in laboratory. Experimental treatments consisted of four PAM application rates of 0 (control), 0.5, 1.0, and 2.0 g m-2, two PAM molecular weights of 12 and 18 Mg mol-1, and three slope gradients of 5o, 15o, and 25o. Results indicated that compared with the control treatment, PAM application generally decreased total runoff volume but increased soil loss. Total runoff volume and soil loss increased with the increased PAM application rate. Under control treatment, total runoff volume increased with the increased slope gradient. However, total runoff volume was similar for different slope gradients when PAM application rates were 0.5 and 1.0 g m-2, but it decreased with the increased slope gradient when PAM application rate was 2.0 g m-2. Total soil loss increased with the increase of slope gradient under experimental conditions. Polyacrylamide molecular weight did not affect total runoff volume but did soil loss significantly at P &lt; 0.001, and a high PAM molecular weight resulted in less soil loss than a low one did. Statistical analysis demonstrated that there existed a significant interaction effect at P &lt; 0.001 between PAM application rate and soil slope gradient on runoff volume and soil loss. The interaction effects between PAM molecular weight and slope gradient or among PAM application rate, PAM molecular weight, and slope gradient on soil loss were also significant at P &lt; 0.01. A PAM application rate less than 2 g m-2 is suggested to control water and soil loss on sloped lands under sprinkler irrigation.

Application of Polyacrylamide for Methylene Blue Removal from Aqueous Solutions

In this study the removal of methylene blue (MB) dye from aqueous solutions by polyacrylamide (PAA) as a potential adsorbent was reported. PAA was characterized using SEM and FTIR measurements. Batch adsorption experiments were performed as a function of the solution pH, contact time, solute concentration and temperature. Evaluation of the obtained data with isotherm studies indicated that the adsorption process was matched well with the Langmuir model. The maximum capacity of adsorbent for MB was 111.1 mg g−1. Kinetic studies were carried out on various kinetic models and the pseudo-second order kinetic model was fitted very well with experimental data. Moreover, the thermodynamic parameters indicated that the adsorption reaction was endothermic and spontaneous process.