Consider the following statements : Statement I : Activated carbon is a good and an attractive tool to remove pollutants from effluent streams and to remediate contaminants from various industries. Statement II : Activated carbon exhibits a large surface area and a strong potential for adsorbing heavy metals. Statement III : Activated carbon can be easily synthesized from environmental wastes with high carbon content. Which one of the following is correct in respect of the above statements?

Lists adsorption as a recognized control technique for gaseous pollutants (alongside combustion and absorption), which establishes adsorption as a general pollutant-removal mechanism.

A student aware that activated carbon works by adsorption can reasonably infer activated carbon might be applicable for removing adsorbable pollutants from effluents and then check which effluent pollutants are adsorbable.

Describes types of industrial water pollutants, notably organic pollutants such as aromatic compounds, solvents and dyes.

Knowing activated carbon is commonly used to remove organic compounds, a student can connect this list to likely target pollutants for activated carbon in effluent treatment and seek examples or performance data for those organics.

Emphasises heavy loads of untreated industrial effluents entering rivers and the need for action plans to clean rivers, implying the need for effective treatment technologies.

A student can use this to justify investigating which treatment technologies (including activated carbon) are used in municipal/industrial effluent treatment or river-cleaning programs.

Specifically states that 'Treatment of sewage water and the industrial effluents should be done before releasing it into water bodies,' pointing to the policy/operational requirement for effluent treatment methods.

A student could use this as a basis to look up standard unit processes prescribed/used in effluent treatment (e.g., adsorption beds with activated carbon) to evaluate suitability.

Identifies pollutant classes such as biocides, PCBs and heavy metals that have different properties and environmental effects.

A student can combine this with the fact adsorption favors certain chemical classes to reason which of these pollutants are likely or unlikely to be effectively removed by activated carbon and then seek specific performance data.

Lists many industry-generated contaminants (industrial wastes, wastewater, poisonous chemicals, heavy metals) that require remediation.

A student can note that a broad-spectrum remediation agent is useful across such industries and then check whether activated carbon is effective for those contaminant types (e.g., organics, some metals).

Describes ex situ remediation techniques for contaminated soils and oil spills (landfarming, biopiles, bacterial ‘oilzapper’) showing that industries use a range of remediation technologies for different pollutants.

One could infer industries adopt multiple remediation technologies and then investigate whether activated carbon is one commonly applied technology for similar ex situ or treatment applications.

Defines bioremediation—use of microbes to degrade contaminants—demonstrating remediation approaches are tailored to contaminant chemistry and site conditions.

A student can reason that because remediation methods target contaminant chemistry, they should check if activated carbon’s adsorption properties match the chemical classes of the pollutants listed (e.g., organics vs metals).

Mentions remedial action plans for critically polluted industrial clusters, implying regulatory and operational use of remediation technologies across industries.

This suggests looking into common elements of such plans (treatment technologies); a student could investigate whether activated carbon appears in typical remedial action inventories for industrial clusters.

Lists remedial steps to reduce acidic precipitation impacts (emission control, cleaner fuels, technology changes), showing that pollutant mitigation uses both prevention and treatment measures across sectors.

From this, a student might extend to treatment-focused measures and query whether activated carbon is used as a downstream treatment for emissions or effluents in relevant industries.

Mentions an 'absorbent resin' and compares panels to a 'furnace filter' that pulls particles out of air — pointing to materials designed for adsorption/filtration.

A student could note that effective adsorbents/filters are usually highly porous with very large surface area per gram, so they should look up adsorption materials' surface areas (e.g., datasheets, BET measurements) to judge typical values for activated carbon.

Discusses 'carbon capture' and 'carbon sinks' and notes industries have used carbon capture for decades, implying the use of materials/technologies that separate/adsorb CO2.

One could infer that technologies for capture often rely on high-surface-area sorbents; combining this with lookup of capture sorbent properties would help estimate activated carbon's surface area range.

Refers to 'black carbon' produced by burning (soot/particulate matter), implying carbonaceous materials exist as fine particles with high surface-to-mass ratios.

Using the principle that smaller particle size increases surface area, a student could use typical particle size → surface area scaling to see that porous carbon materials can reach very large m^2/g values.

Gives a concrete example linking particle diameter to scale (soil particle diameters 0.02–0.002 mm), illustrating how particle size relates to surface area.

A student could apply geometric surface-area-to-volume reasoning (and realize porous internal structure further raises area) to appreciate why activated carbons have much higher m^2/g than bulk solids.

Discusses that acids and other substances produce ions in aqueous solution — establishes that metals often exist as dissolved ions in water.

A student could combine this with knowledge that adsorption targets dissolved ions to infer that adsorbents (like activated carbon) must interact with ionic species to remove heavy metals.

States that metals occur in nature in the form of their compounds (i.e., salts) and that metals can be present in solution.

One could extend this by noting heavy metals in polluted water are typically present as soluble salts, so testing activated carbon against such salt solutions would be a reasonable way to assess adsorption capacity.

Gives examples of metals in solution (e.g., FeSO4, CuSO4, ZnSO4) and shows chemical interactions (displacement) involving dissolved metal ions.

A student could use these common aqueous metal salts as standard test solutions to experimentally compare how much metal an adsorbent like activated carbon removes.

Explains displacement reactions where a metal displaces another from its salt solution, reinforcing that metals exist as solvated ions accessible to chemical removal processes.

Combining this with adsorption concepts suggests activated carbon would need surface sites or functional groups to capture those solvated metal ions — prompting tests with ionic metal solutions.

Describes precipitation (lime water turning milky when CO2 forms insoluble CaCO3), an example of a method that removes dissolved species from water.

A student could compare precipitation-based removal to adsorption by activated carbon as two different mechanisms for removing dissolved metal species from aqueous solutions.

Defines biomass as 'carbonaceous waste' from agricultural residues, forestry residues and municipal/industrial organic waste — identifies these wastes as carbon-rich feedstocks.

A student could combine this with basic knowledge that activated carbon is made from carbon-rich precursors to hypothesize these wastes are plausible starting materials and then look up pyrolysis/activation methods to test it.

Mentions Waste to Energy and biomass programmes that convert urban, industrial and agricultural wastes into useful products (briquettes, pellets, energy), showing institutional use of such wastes as feedstock for value-added carbon products.

One could infer that similar processing pathways (thermal treatment) might be adapted to produce activated carbon and investigate technical feasibility or existing examples.

Describes sewage as containing food residues and other organic wastes — indicating sewage includes substantial organic (carbon-containing) material.

A student could reason sewage sludge's organic content might serve as a carbon source and check literature/analytical data (volatile solids, fixed carbon) to assess suitability for activated carbon production.

Identifies biomass burning and agricultural fires as sources of particulate 'brown/black carbon', implying agricultural residues are combustible/carbonaceous.

From this pattern, one could infer residues have substantial fixed carbon and could be tested (e.g., proximate analysis) to evaluate conversion to activated carbon.

Gives an example of converting crop residues and cattle dung into vermi-compost — demonstrates that agricultural wastes can be transformed into value-added products by processing.

A student might extend this general pattern of waste-to-product conversion to consider thermal/chemical processing routes for producing activated carbon from similar feedstocks and plan experiments or literature searches.

Describes pyrolysis of carbonaceous wastes (rice husk, sawdust, coconut shell, etc.) yielding charcoal/char — a common precursor to activated carbon.

A student could infer that available chars from pyrolysis could be further activated and then assess ease/cost by comparing activation steps (chemical/thermal) and needed equipment.

Defines biomass as abundant carbonaceous waste feedstock (agricultural residues, timber by-products, municipal organic waste).

Knowing abundant feedstock, a student can judge whether raw-material supply constraints are likely to make production feasible and potentially lower feedstock cost.

Discusses waste-to-energy technologies (pyrolysis, gasification) being used to divert waste and produce useful products/energy, implying technological routes exist to convert wastes into value.

One could infer that integrating activated-carbon production into waste-to-energy plants might improve economics; student could check capital/operational needs versus revenue streams.

Shows large daily volumes of plastic waste and gaps in collection/processing, highlighting logistical/collection challenges for waste-based processes.

A student could extend this to suggest that feedstock collection costs and heterogeneity (especially for plastics) may increase overall production cost and complexity.

Classifies solid wastes (municipal, hospital, hazardous), indicating variability in waste types and the potential need for segregation before processing.

From this, one can reason that contamination/hazardous components would require pre-treatment or raise costs, affecting whether production is easy/cost-effective.