test_that("qe_batch computes correct adsorption capacity", {
  expect_equal(qe_batch(C0 = 50, Ce = 12.5, V = 0.05, m = 0.1), 18.75)
})

test_that("qe_batch errors on non-positive mass", {
  expect_error(qe_batch(C0 = 50, Ce = 10, V = 0.05, m = 0), "must be > 0")
})

test_that("removal_efficiency computes correct percentage", {
  expect_equal(removal_efficiency(C0 = 50, Ce = 12.5), 75)
})

test_that("removal_efficiency warns on zero C0", {
  expect_warning(removal_efficiency(C0 = 0, Ce = 5))
})